[users/dwmw2/linux.git] /

// SPDX-License-Identifier: GPL-2.0
#include <linux/ceph/ceph_debug.h>

#include <linux/fs.h>
#include <linux/wait.h>
#include <linux/slab.h>
#include <linux/gfp.h>
#include <linux/sched.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/ratelimit.h>
#include <linux/bits.h>
#include <linux/ktime.h>
#include <linux/bitmap.h>
#include <linux/mnt_idmapping.h>

#include "super.h"
#include "mds_client.h"
#include "crypto.h"

#include <linux/ceph/ceph_features.h>
#include <linux/ceph/messenger.h>
#include <linux/ceph/decode.h>
#include <linux/ceph/pagelist.h>
#include <linux/ceph/auth.h>
#include <linux/ceph/debugfs.h>

#define RECONNECT_MAX_SIZE (INT_MAX - PAGE_SIZE)

/*
 * A cluster of MDS (metadata server) daemons is responsible for
 * managing the file system namespace (the directory hierarchy and
 * inodes) and for coordinating shared access to storage.  Metadata is
 * partitioning hierarchically across a number of servers, and that
 * partition varies over time as the cluster adjusts the distribution
 * in order to balance load.
 *
 * The MDS client is primarily responsible to managing synchronous
 * metadata requests for operations like open, unlink, and so forth.
 * If there is a MDS failure, we find out about it when we (possibly
 * request and) receive a new MDS map, and can resubmit affected
 * requests.
 *
 * For the most part, though, we take advantage of a lossless
 * communications channel to the MDS, and do not need to worry about
 * timing out or resubmitting requests.
 *
 * We maintain a stateful "session" with each MDS we interact with.
 * Within each session, we sent periodic heartbeat messages to ensure
 * any capabilities or leases we have been issues remain valid.  If
 * the session times out and goes stale, our leases and capabilities
 * are no longer valid.
 */

struct ceph_reconnect_state {
        struct ceph_mds_session *session;
        int nr_caps, nr_realms;
        struct ceph_pagelist *pagelist;
        unsigned msg_version;
        bool allow_multi;
};

static void __wake_requests(struct ceph_mds_client *mdsc,
                            struct list_head *head);
static void ceph_cap_release_work(struct work_struct *work);
static void ceph_cap_reclaim_work(struct work_struct *work);

static const struct ceph_connection_operations mds_con_ops;


/*
 * mds reply parsing
 */

static int parse_reply_info_quota(void **p, void *end,
                                  struct ceph_mds_reply_info_in *info)
{
        u8 struct_v, struct_compat;
        u32 struct_len;

        ceph_decode_8_safe(p, end, struct_v, bad);
        ceph_decode_8_safe(p, end, struct_compat, bad);
        /* struct_v is expected to be >= 1. we only
         * understand encoding with struct_compat == 1. */
        if (!struct_v || struct_compat != 1)
                goto bad;
        ceph_decode_32_safe(p, end, struct_len, bad);
        ceph_decode_need(p, end, struct_len, bad);
        end = *p + struct_len;
        ceph_decode_64_safe(p, end, info->max_bytes, bad);
        ceph_decode_64_safe(p, end, info->max_files, bad);
        *p = end;
        return 0;
bad:
        return -EIO;
}

/*
 * parse individual inode info
 */
static int parse_reply_info_in(void **p, void *end,
                               struct ceph_mds_reply_info_in *info,
                               u64 features)
{
        int err = 0;
        u8 struct_v = 0;

        if (features == (u64)-1) {
                u32 struct_len;
                u8 struct_compat;
                ceph_decode_8_safe(p, end, struct_v, bad);
                ceph_decode_8_safe(p, end, struct_compat, bad);
                /* struct_v is expected to be >= 1. we only understand
                 * encoding with struct_compat == 1. */
                if (!struct_v || struct_compat != 1)
                        goto bad;
                ceph_decode_32_safe(p, end, struct_len, bad);
                ceph_decode_need(p, end, struct_len, bad);
                end = *p + struct_len;
        }

        ceph_decode_need(p, end, sizeof(struct ceph_mds_reply_inode), bad);
        info->in = *p;
        *p += sizeof(struct ceph_mds_reply_inode) +
                sizeof(*info->in->fragtree.splits) *
                le32_to_cpu(info->in->fragtree.nsplits);

        ceph_decode_32_safe(p, end, info->symlink_len, bad);
        ceph_decode_need(p, end, info->symlink_len, bad);
        info->symlink = *p;
        *p += info->symlink_len;

        ceph_decode_copy_safe(p, end, &info->dir_layout,
                              sizeof(info->dir_layout), bad);
        ceph_decode_32_safe(p, end, info->xattr_len, bad);
        ceph_decode_need(p, end, info->xattr_len, bad);
        info->xattr_data = *p;
        *p += info->xattr_len;

        if (features == (u64)-1) {
                /* inline data */
                ceph_decode_64_safe(p, end, info->inline_version, bad);
                ceph_decode_32_safe(p, end, info->inline_len, bad);
                ceph_decode_need(p, end, info->inline_len, bad);
                info->inline_data = *p;
                *p += info->inline_len;
                /* quota */
                err = parse_reply_info_quota(p, end, info);
                if (err < 0)
                        goto out_bad;
                /* pool namespace */
                ceph_decode_32_safe(p, end, info->pool_ns_len, bad);
                if (info->pool_ns_len > 0) {
                        ceph_decode_need(p, end, info->pool_ns_len, bad);
                        info->pool_ns_data = *p;
                        *p += info->pool_ns_len;
                }

                /* btime */
                ceph_decode_need(p, end, sizeof(info->btime), bad);
                ceph_decode_copy(p, &info->btime, sizeof(info->btime));

                /* change attribute */
                ceph_decode_64_safe(p, end, info->change_attr, bad);

                /* dir pin */
                if (struct_v >= 2) {
                        ceph_decode_32_safe(p, end, info->dir_pin, bad);
                } else {
                        info->dir_pin = -ENODATA;
                }

                /* snapshot birth time, remains zero for v<=2 */
                if (struct_v >= 3) {
                        ceph_decode_need(p, end, sizeof(info->snap_btime), bad);
                        ceph_decode_copy(p, &info->snap_btime,
                                         sizeof(info->snap_btime));
                } else {
                        memset(&info->snap_btime, 0, sizeof(info->snap_btime));
                }

                /* snapshot count, remains zero for v<=3 */
                if (struct_v >= 4) {
                        ceph_decode_64_safe(p, end, info->rsnaps, bad);
                } else {
                        info->rsnaps = 0;
                }

                if (struct_v >= 5) {
                        u32 alen;

                        ceph_decode_32_safe(p, end, alen, bad);

                        while (alen--) {
                                u32 len;

                                /* key */
                                ceph_decode_32_safe(p, end, len, bad);
                                ceph_decode_skip_n(p, end, len, bad);
                                /* value */
                                ceph_decode_32_safe(p, end, len, bad);
                                ceph_decode_skip_n(p, end, len, bad);
                        }
                }

                /* fscrypt flag -- ignore */
                if (struct_v >= 6)
                        ceph_decode_skip_8(p, end, bad);

                info->fscrypt_auth = NULL;
                info->fscrypt_auth_len = 0;
                info->fscrypt_file = NULL;
                info->fscrypt_file_len = 0;
                if (struct_v >= 7) {
                        ceph_decode_32_safe(p, end, info->fscrypt_auth_len, bad);
                        if (info->fscrypt_auth_len) {
                                info->fscrypt_auth = kmalloc(info->fscrypt_auth_len,
                                                             GFP_KERNEL);
                                if (!info->fscrypt_auth)
                                        return -ENOMEM;
                                ceph_decode_copy_safe(p, end, info->fscrypt_auth,
                                                      info->fscrypt_auth_len, bad);
                        }
                        ceph_decode_32_safe(p, end, info->fscrypt_file_len, bad);
                        if (info->fscrypt_file_len) {
                                info->fscrypt_file = kmalloc(info->fscrypt_file_len,
                                                             GFP_KERNEL);
                                if (!info->fscrypt_file)
                                        return -ENOMEM;
                                ceph_decode_copy_safe(p, end, info->fscrypt_file,
                                                      info->fscrypt_file_len, bad);
                        }
                }
                *p = end;
        } else {
                /* legacy (unversioned) struct */
                if (features & CEPH_FEATURE_MDS_INLINE_DATA) {
                        ceph_decode_64_safe(p, end, info->inline_version, bad);
                        ceph_decode_32_safe(p, end, info->inline_len, bad);
                        ceph_decode_need(p, end, info->inline_len, bad);
                        info->inline_data = *p;
                        *p += info->inline_len;
                } else
                        info->inline_version = CEPH_INLINE_NONE;

                if (features & CEPH_FEATURE_MDS_QUOTA) {
                        err = parse_reply_info_quota(p, end, info);
                        if (err < 0)
                                goto out_bad;
                } else {
                        info->max_bytes = 0;
                        info->max_files = 0;
                }

                info->pool_ns_len = 0;
                info->pool_ns_data = NULL;
                if (features & CEPH_FEATURE_FS_FILE_LAYOUT_V2) {
                        ceph_decode_32_safe(p, end, info->pool_ns_len, bad);
                        if (info->pool_ns_len > 0) {
                                ceph_decode_need(p, end, info->pool_ns_len, bad);
                                info->pool_ns_data = *p;
                                *p += info->pool_ns_len;
                        }
                }

                if (features & CEPH_FEATURE_FS_BTIME) {
                        ceph_decode_need(p, end, sizeof(info->btime), bad);
                        ceph_decode_copy(p, &info->btime, sizeof(info->btime));
                        ceph_decode_64_safe(p, end, info->change_attr, bad);
                }

                info->dir_pin = -ENODATA;
                /* info->snap_btime and info->rsnaps remain zero */
        }
        return 0;
bad:
        err = -EIO;
out_bad:
        return err;
}

static int parse_reply_info_dir(void **p, void *end,
                                struct ceph_mds_reply_dirfrag **dirfrag,
                                u64 features)
{
        if (features == (u64)-1) {
                u8 struct_v, struct_compat;
                u32 struct_len;
                ceph_decode_8_safe(p, end, struct_v, bad);
                ceph_decode_8_safe(p, end, struct_compat, bad);
                /* struct_v is expected to be >= 1. we only understand
                 * encoding whose struct_compat == 1. */
                if (!struct_v || struct_compat != 1)
                        goto bad;
                ceph_decode_32_safe(p, end, struct_len, bad);
                ceph_decode_need(p, end, struct_len, bad);
                end = *p + struct_len;
        }

        ceph_decode_need(p, end, sizeof(**dirfrag), bad);
        *dirfrag = *p;
        *p += sizeof(**dirfrag) + sizeof(u32) * le32_to_cpu((*dirfrag)->ndist);
        if (unlikely(*p > end))
                goto bad;
        if (features == (u64)-1)
                *p = end;
        return 0;
bad:
        return -EIO;
}

static int parse_reply_info_lease(void **p, void *end,
                                  struct ceph_mds_reply_lease **lease,
                                  u64 features, u32 *altname_len, u8 **altname)
{
        u8 struct_v;
        u32 struct_len;
        void *lend;

        if (features == (u64)-1) {
                u8 struct_compat;

                ceph_decode_8_safe(p, end, struct_v, bad);
                ceph_decode_8_safe(p, end, struct_compat, bad);

                /* struct_v is expected to be >= 1. we only understand
                 * encoding whose struct_compat == 1. */
                if (!struct_v || struct_compat != 1)
                        goto bad;

                ceph_decode_32_safe(p, end, struct_len, bad);
        } else {
                struct_len = sizeof(**lease);
                *altname_len = 0;
                *altname = NULL;
        }

        lend = *p + struct_len;
        ceph_decode_need(p, end, struct_len, bad);
        *lease = *p;
        *p += sizeof(**lease);

        if (features == (u64)-1) {
                if (struct_v >= 2) {
                        ceph_decode_32_safe(p, end, *altname_len, bad);
                        ceph_decode_need(p, end, *altname_len, bad);
                        *altname = *p;
                        *p += *altname_len;
                } else {
                        *altname = NULL;
                        *altname_len = 0;
                }
        }
        *p = lend;
        return 0;
bad:
        return -EIO;
}

/*
 * parse a normal reply, which may contain a (dir+)dentry and/or a
 * target inode.
 */
static int parse_reply_info_trace(void **p, void *end,
                                  struct ceph_mds_reply_info_parsed *info,
                                  u64 features)
{
        int err;

        if (info->head->is_dentry) {
                err = parse_reply_info_in(p, end, &info->diri, features);
                if (err < 0)
                        goto out_bad;

                err = parse_reply_info_dir(p, end, &info->dirfrag, features);
                if (err < 0)
                        goto out_bad;

                ceph_decode_32_safe(p, end, info->dname_len, bad);
                ceph_decode_need(p, end, info->dname_len, bad);
                info->dname = *p;
                *p += info->dname_len;

                err = parse_reply_info_lease(p, end, &info->dlease, features,
                                             &info->altname_len, &info->altname);
                if (err < 0)
                        goto out_bad;
        }

        if (info->head->is_target) {
                err = parse_reply_info_in(p, end, &info->targeti, features);
                if (err < 0)
                        goto out_bad;
        }

        if (unlikely(*p != end))
                goto bad;
        return 0;

bad:
        err = -EIO;
out_bad:
        pr_err("problem parsing mds trace %d\n", err);
        return err;
}

/*
 * parse readdir results
 */
static int parse_reply_info_readdir(void **p, void *end,
                                    struct ceph_mds_request *req,
                                    u64 features)
{
        struct ceph_mds_reply_info_parsed *info = &req->r_reply_info;
        struct ceph_client *cl = req->r_mdsc->fsc->client;
        u32 num, i = 0;
        int err;

        err = parse_reply_info_dir(p, end, &info->dir_dir, features);
        if (err < 0)
                goto out_bad;

        ceph_decode_need(p, end, sizeof(num) + 2, bad);
        num = ceph_decode_32(p);
        {
                u16 flags = ceph_decode_16(p);
                info->dir_end = !!(flags & CEPH_READDIR_FRAG_END);
                info->dir_complete = !!(flags & CEPH_READDIR_FRAG_COMPLETE);
                info->hash_order = !!(flags & CEPH_READDIR_HASH_ORDER);
                info->offset_hash = !!(flags & CEPH_READDIR_OFFSET_HASH);
        }
        if (num == 0)
                goto done;

        BUG_ON(!info->dir_entries);
        if ((unsigned long)(info->dir_entries + num) >
            (unsigned long)info->dir_entries + info->dir_buf_size) {
                pr_err_client(cl, "dir contents are larger than expected\n");
                WARN_ON(1);
                goto bad;
        }

        info->dir_nr = num;
        while (num) {
                struct inode *inode = d_inode(req->r_dentry);
                struct ceph_inode_info *ci = ceph_inode(inode);
                struct ceph_mds_reply_dir_entry *rde = info->dir_entries + i;
                struct fscrypt_str tname = FSTR_INIT(NULL, 0);
                struct fscrypt_str oname = FSTR_INIT(NULL, 0);
                struct ceph_fname fname;
                u32 altname_len, _name_len;
                u8 *altname, *_name;

                /* dentry */
                ceph_decode_32_safe(p, end, _name_len, bad);
                ceph_decode_need(p, end, _name_len, bad);
                _name = *p;
                *p += _name_len;
                doutc(cl, "parsed dir dname '%.*s'\n", _name_len, _name);

                if (info->hash_order)
                        rde->raw_hash = ceph_str_hash(ci->i_dir_layout.dl_dir_hash,
                                                      _name, _name_len);

                /* dentry lease */
                err = parse_reply_info_lease(p, end, &rde->lease, features,
                                             &altname_len, &altname);
                if (err)
                        goto out_bad;

                /*
                 * Try to dencrypt the dentry names and update them
                 * in the ceph_mds_reply_dir_entry struct.
                 */
                fname.dir = inode;
                fname.name = _name;
                fname.name_len = _name_len;
                fname.ctext = altname;
                fname.ctext_len = altname_len;
                /*
                 * The _name_len maybe larger than altname_len, such as
                 * when the human readable name length is in range of
                 * (CEPH_NOHASH_NAME_MAX, CEPH_NOHASH_NAME_MAX + SHA256_DIGEST_SIZE),
                 * then the copy in ceph_fname_to_usr will corrupt the
                 * data if there has no encryption key.
                 *
                 * Just set the no_copy flag and then if there has no
                 * encryption key the oname.name will be assigned to
                 * _name always.
                 */
                fname.no_copy = true;
                if (altname_len == 0) {
                        /*
                         * Set tname to _name, and this will be used
                         * to do the base64_decode in-place. It's
                         * safe because the decoded string should
                         * always be shorter, which is 3/4 of origin
                         * string.
                         */
                        tname.name = _name;

                        /*
                         * Set oname to _name too, and this will be
                         * used to do the dencryption in-place.
                         */
                        oname.name = _name;
                        oname.len = _name_len;
                } else {
                        /*
                         * This will do the decryption only in-place
                         * from altname cryptext directly.
                         */
                        oname.name = altname;
                        oname.len = altname_len;
                }
                rde->is_nokey = false;
                err = ceph_fname_to_usr(&fname, &tname, &oname, &rde->is_nokey);
                if (err) {
                        pr_err_client(cl, "unable to decode %.*s, got %d\n",
                                      _name_len, _name, err);
                        goto out_bad;
                }
                rde->name = oname.name;
                rde->name_len = oname.len;

                /* inode */
                err = parse_reply_info_in(p, end, &rde->inode, features);
                if (err < 0)
                        goto out_bad;
                /* ceph_readdir_prepopulate() will update it */
                rde->offset = 0;
                i++;
                num--;
        }

done:
        /* Skip over any unrecognized fields */
        *p = end;
        return 0;

bad:
        err = -EIO;
out_bad:
        pr_err_client(cl, "problem parsing dir contents %d\n", err);
        return err;
}

/*
 * parse fcntl F_GETLK results
 */
static int parse_reply_info_filelock(void **p, void *end,
                                     struct ceph_mds_reply_info_parsed *info,
                                     u64 features)
{
        if (*p + sizeof(*info->filelock_reply) > end)
                goto bad;

        info->filelock_reply = *p;

        /* Skip over any unrecognized fields */
        *p = end;
        return 0;
bad:
        return -EIO;
}


#if BITS_PER_LONG == 64

#define DELEGATED_INO_AVAILABLE         xa_mk_value(1)

static int ceph_parse_deleg_inos(void **p, void *end,
                                 struct ceph_mds_session *s)
{
        struct ceph_client *cl = s->s_mdsc->fsc->client;
        u32 sets;

        ceph_decode_32_safe(p, end, sets, bad);
        doutc(cl, "got %u sets of delegated inodes\n", sets);
        while (sets--) {
                u64 start, len;

                ceph_decode_64_safe(p, end, start, bad);
                ceph_decode_64_safe(p, end, len, bad);

                /* Don't accept a delegation of system inodes */
                if (start < CEPH_INO_SYSTEM_BASE) {
                        pr_warn_ratelimited_client(cl,
                                "ignoring reserved inode range delegation (start=0x%llx len=0x%llx)\n",
                                start, len);
                        continue;
                }
                while (len--) {
                        int err = xa_insert(&s->s_delegated_inos, start++,
                                            DELEGATED_INO_AVAILABLE,
                                            GFP_KERNEL);
                        if (!err) {
                                doutc(cl, "added delegated inode 0x%llx\n", start - 1);
                        } else if (err == -EBUSY) {
                                pr_warn_client(cl,
                                        "MDS delegated inode 0x%llx more than once.\n",
                                        start - 1);
                        } else {
                                return err;
                        }
                }
        }
        return 0;
bad:
        return -EIO;
}

u64 ceph_get_deleg_ino(struct ceph_mds_session *s)
{
        unsigned long ino;
        void *val;

        xa_for_each(&s->s_delegated_inos, ino, val) {
                val = xa_erase(&s->s_delegated_inos, ino);
                if (val == DELEGATED_INO_AVAILABLE)
                        return ino;
        }
        return 0;
}

int ceph_restore_deleg_ino(struct ceph_mds_session *s, u64 ino)
{
        return xa_insert(&s->s_delegated_inos, ino, DELEGATED_INO_AVAILABLE,
                         GFP_KERNEL);
}
#else /* BITS_PER_LONG == 64 */
/*
 * FIXME: xarrays can't handle 64-bit indexes on a 32-bit arch. For now, just
 * ignore delegated_inos on 32 bit arch. Maybe eventually add xarrays for top
 * and bottom words?
 */
static int ceph_parse_deleg_inos(void **p, void *end,
                                 struct ceph_mds_session *s)
{
        u32 sets;

        ceph_decode_32_safe(p, end, sets, bad);
        if (sets)
                ceph_decode_skip_n(p, end, sets * 2 * sizeof(__le64), bad);
        return 0;
bad:
        return -EIO;
}

u64 ceph_get_deleg_ino(struct ceph_mds_session *s)
{
        return 0;
}

int ceph_restore_deleg_ino(struct ceph_mds_session *s, u64 ino)
{
        return 0;
}
#endif /* BITS_PER_LONG == 64 */

/*
 * parse create results
 */
static int parse_reply_info_create(void **p, void *end,
                                  struct ceph_mds_reply_info_parsed *info,
                                  u64 features, struct ceph_mds_session *s)
{
        int ret;

        if (features == (u64)-1 ||
            (features & CEPH_FEATURE_REPLY_CREATE_INODE)) {
                if (*p == end) {
                        /* Malformed reply? */
                        info->has_create_ino = false;
                } else if (test_bit(CEPHFS_FEATURE_DELEG_INO, &s->s_features)) {
                        info->has_create_ino = true;
                        /* struct_v, struct_compat, and len */
                        ceph_decode_skip_n(p, end, 2 + sizeof(u32), bad);
                        ceph_decode_64_safe(p, end, info->ino, bad);
                        ret = ceph_parse_deleg_inos(p, end, s);
                        if (ret)
                                return ret;
                } else {
                        /* legacy */
                        ceph_decode_64_safe(p, end, info->ino, bad);
                        info->has_create_ino = true;
                }
        } else {
                if (*p != end)
                        goto bad;
        }

        /* Skip over any unrecognized fields */
        *p = end;
        return 0;
bad:
        return -EIO;
}

static int parse_reply_info_getvxattr(void **p, void *end,
                                      struct ceph_mds_reply_info_parsed *info,
                                      u64 features)
{
        u32 value_len;

        ceph_decode_skip_8(p, end, bad); /* skip current version: 1 */
        ceph_decode_skip_8(p, end, bad); /* skip first version: 1 */
        ceph_decode_skip_32(p, end, bad); /* skip payload length */

        ceph_decode_32_safe(p, end, value_len, bad);

        if (value_len == end - *p) {
          info->xattr_info.xattr_value = *p;
          info->xattr_info.xattr_value_len = value_len;
          *p = end;
          return value_len;
        }
bad:
        return -EIO;
}

/*
 * parse extra results
 */
static int parse_reply_info_extra(void **p, void *end,
                                  struct ceph_mds_request *req,
                                  u64 features, struct ceph_mds_session *s)
{
        struct ceph_mds_reply_info_parsed *info = &req->r_reply_info;
        u32 op = le32_to_cpu(info->head->op);

        if (op == CEPH_MDS_OP_GETFILELOCK)
                return parse_reply_info_filelock(p, end, info, features);
        else if (op == CEPH_MDS_OP_READDIR || op == CEPH_MDS_OP_LSSNAP)
                return parse_reply_info_readdir(p, end, req, features);
        else if (op == CEPH_MDS_OP_CREATE)
                return parse_reply_info_create(p, end, info, features, s);
        else if (op == CEPH_MDS_OP_GETVXATTR)
                return parse_reply_info_getvxattr(p, end, info, features);
        else
                return -EIO;
}

/*
 * parse entire mds reply
 */
static int parse_reply_info(struct ceph_mds_session *s, struct ceph_msg *msg,
                            struct ceph_mds_request *req, u64 features)
{
        struct ceph_mds_reply_info_parsed *info = &req->r_reply_info;
        struct ceph_client *cl = s->s_mdsc->fsc->client;
        void *p, *end;
        u32 len;
        int err;

        info->head = msg->front.iov_base;
        p = msg->front.iov_base + sizeof(struct ceph_mds_reply_head);
        end = p + msg->front.iov_len - sizeof(struct ceph_mds_reply_head);

        /* trace */
        ceph_decode_32_safe(&p, end, len, bad);
        if (len > 0) {
                ceph_decode_need(&p, end, len, bad);
                err = parse_reply_info_trace(&p, p+len, info, features);
                if (err < 0)
                        goto out_bad;
        }

        /* extra */
        ceph_decode_32_safe(&p, end, len, bad);
        if (len > 0) {
                ceph_decode_need(&p, end, len, bad);
                err = parse_reply_info_extra(&p, p+len, req, features, s);
                if (err < 0)
                        goto out_bad;
        }

        /* snap blob */
        ceph_decode_32_safe(&p, end, len, bad);
        info->snapblob_len = len;
        info->snapblob = p;
        p += len;

        if (p != end)
                goto bad;
        return 0;

bad:
        err = -EIO;
out_bad:
        pr_err_client(cl, "mds parse_reply err %d\n", err);
        ceph_msg_dump(msg);
        return err;
}

static void destroy_reply_info(struct ceph_mds_reply_info_parsed *info)
{
        int i;

        kfree(info->diri.fscrypt_auth);
        kfree(info->diri.fscrypt_file);
        kfree(info->targeti.fscrypt_auth);
        kfree(info->targeti.fscrypt_file);
        if (!info->dir_entries)
                return;

        for (i = 0; i < info->dir_nr; i++) {
                struct ceph_mds_reply_dir_entry *rde = info->dir_entries + i;

                kfree(rde->inode.fscrypt_auth);
                kfree(rde->inode.fscrypt_file);
        }
        free_pages((unsigned long)info->dir_entries, get_order(info->dir_buf_size));
}

/*
 * In async unlink case the kclient won't wait for the first reply
 * from MDS and just drop all the links and unhash the dentry and then
 * succeeds immediately.
 *
 * For any new create/link/rename,etc requests followed by using the
 * same file names we must wait for the first reply of the inflight
 * unlink request, or the MDS possibly will fail these following
 * requests with -EEXIST if the inflight async unlink request was
 * delayed for some reasons.
 *
 * And the worst case is that for the none async openc request it will
 * successfully open the file if the CDentry hasn't been unlinked yet,
 * but later the previous delayed async unlink request will remove the
 * CDentry. That means the just created file is possibly deleted later
 * by accident.
 *
 * We need to wait for the inflight async unlink requests to finish
 * when creating new files/directories by using the same file names.
 */
int ceph_wait_on_conflict_unlink(struct dentry *dentry)
{
        struct ceph_fs_client *fsc = ceph_sb_to_fs_client(dentry->d_sb);
        struct ceph_client *cl = fsc->client;
        struct dentry *pdentry = dentry->d_parent;
        struct dentry *udentry, *found = NULL;
        struct ceph_dentry_info *di;
        struct qstr dname;
        u32 hash = dentry->d_name.hash;
        int err;

        dname.name = dentry->d_name.name;
        dname.len = dentry->d_name.len;

        rcu_read_lock();
        hash_for_each_possible_rcu(fsc->async_unlink_conflict, di,
                                   hnode, hash) {
                udentry = di->dentry;

                spin_lock(&udentry->d_lock);
                if (udentry->d_name.hash != hash)
                        goto next;
                if (unlikely(udentry->d_parent != pdentry))
                        goto next;
                if (!hash_hashed(&di->hnode))
                        goto next;

                if (!test_bit(CEPH_DENTRY_ASYNC_UNLINK_BIT, &di->flags))
                        pr_warn_client(cl, "dentry %p:%pd async unlink bit is not set\n",
                                       dentry, dentry);

                if (!d_same_name(udentry, pdentry, &dname))
                        goto next;

                found = dget_dlock(udentry);
                spin_unlock(&udentry->d_lock);
                break;
next:
                spin_unlock(&udentry->d_lock);
        }
        rcu_read_unlock();

        if (likely(!found))
                return 0;

        doutc(cl, "dentry %p:%pd conflict with old %p:%pd\n", dentry, dentry,
              found, found);

        err = wait_on_bit(&di->flags, CEPH_DENTRY_ASYNC_UNLINK_BIT,
                          TASK_KILLABLE);
        dput(found);
        return err;
}


/*
 * sessions
 */
const char *ceph_session_state_name(int s)
{
        switch (s) {
        case CEPH_MDS_SESSION_NEW: return "new";
        case CEPH_MDS_SESSION_OPENING: return "opening";
        case CEPH_MDS_SESSION_OPEN: return "open";
        case CEPH_MDS_SESSION_HUNG: return "hung";
        case CEPH_MDS_SESSION_CLOSING: return "closing";
        case CEPH_MDS_SESSION_CLOSED: return "closed";
        case CEPH_MDS_SESSION_RESTARTING: return "restarting";
        case CEPH_MDS_SESSION_RECONNECTING: return "reconnecting";
        case CEPH_MDS_SESSION_REJECTED: return "rejected";
        default: return "???";
        }
}

struct ceph_mds_session *ceph_get_mds_session(struct ceph_mds_session *s)
{
        if (refcount_inc_not_zero(&s->s_ref))
                return s;
        return NULL;
}

void ceph_put_mds_session(struct ceph_mds_session *s)
{
        if (IS_ERR_OR_NULL(s))
                return;

        if (refcount_dec_and_test(&s->s_ref)) {
                if (s->s_auth.authorizer)
                        ceph_auth_destroy_authorizer(s->s_auth.authorizer);
                WARN_ON(mutex_is_locked(&s->s_mutex));
                xa_destroy(&s->s_delegated_inos);
                kfree(s);
        }
}

/*
 * called under mdsc->mutex
 */
struct ceph_mds_session *__ceph_lookup_mds_session(struct ceph_mds_client *mdsc,
                                                   int mds)
{
        if (mds >= mdsc->max_sessions || !mdsc->sessions[mds])
                return NULL;
        return ceph_get_mds_session(mdsc->sessions[mds]);
}

static bool __have_session(struct ceph_mds_client *mdsc, int mds)
{
        if (mds >= mdsc->max_sessions || !mdsc->sessions[mds])
                return false;
        else
                return true;
}

static int __verify_registered_session(struct ceph_mds_client *mdsc,
                                       struct ceph_mds_session *s)
{
        if (s->s_mds >= mdsc->max_sessions ||
            mdsc->sessions[s->s_mds] != s)
                return -ENOENT;
        return 0;
}

/*
 * create+register a new session for given mds.
 * called under mdsc->mutex.
 */
static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc,
                                                 int mds)
{
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_mds_session *s;

        if (READ_ONCE(mdsc->fsc->mount_state) == CEPH_MOUNT_FENCE_IO)
                return ERR_PTR(-EIO);

        if (mds >= mdsc->mdsmap->possible_max_rank)
                return ERR_PTR(-EINVAL);

        s = kzalloc(sizeof(*s), GFP_NOFS);
        if (!s)
                return ERR_PTR(-ENOMEM);

        if (mds >= mdsc->max_sessions) {
                int newmax = 1 << get_count_order(mds + 1);
                struct ceph_mds_session **sa;
                size_t ptr_size = sizeof(struct ceph_mds_session *);

                doutc(cl, "realloc to %d\n", newmax);
                sa = kcalloc(newmax, ptr_size, GFP_NOFS);
                if (!sa)
                        goto fail_realloc;
                if (mdsc->sessions) {
                        memcpy(sa, mdsc->sessions,
                               mdsc->max_sessions * ptr_size);
                        kfree(mdsc->sessions);
                }
                mdsc->sessions = sa;
                mdsc->max_sessions = newmax;
        }

        doutc(cl, "mds%d\n", mds);
        s->s_mdsc = mdsc;
        s->s_mds = mds;
        s->s_state = CEPH_MDS_SESSION_NEW;
        mutex_init(&s->s_mutex);

        ceph_con_init(&s->s_con, s, &mds_con_ops, &mdsc->fsc->client->msgr);

        atomic_set(&s->s_cap_gen, 1);
        s->s_cap_ttl = jiffies - 1;

        spin_lock_init(&s->s_cap_lock);
        INIT_LIST_HEAD(&s->s_caps);
        refcount_set(&s->s_ref, 1);
        INIT_LIST_HEAD(&s->s_waiting);
        INIT_LIST_HEAD(&s->s_unsafe);
        xa_init(&s->s_delegated_inos);
        INIT_LIST_HEAD(&s->s_cap_releases);
        INIT_WORK(&s->s_cap_release_work, ceph_cap_release_work);

        INIT_LIST_HEAD(&s->s_cap_dirty);
        INIT_LIST_HEAD(&s->s_cap_flushing);

        mdsc->sessions[mds] = s;
        atomic_inc(&mdsc->num_sessions);
        refcount_inc(&s->s_ref);  /* one ref to sessions[], one to caller */

        ceph_con_open(&s->s_con, CEPH_ENTITY_TYPE_MDS, mds,
                      ceph_mdsmap_get_addr(mdsc->mdsmap, mds));

        return s;

fail_realloc:
        kfree(s);
        return ERR_PTR(-ENOMEM);
}

/*
 * called under mdsc->mutex
 */
static void __unregister_session(struct ceph_mds_client *mdsc,
                               struct ceph_mds_session *s)
{
        doutc(mdsc->fsc->client, "mds%d %p\n", s->s_mds, s);
        BUG_ON(mdsc->sessions[s->s_mds] != s);
        mdsc->sessions[s->s_mds] = NULL;
        ceph_con_close(&s->s_con);
        ceph_put_mds_session(s);
        atomic_dec(&mdsc->num_sessions);
}

/*
 * drop session refs in request.
 *
 * should be last request ref, or hold mdsc->mutex
 */
static void put_request_session(struct ceph_mds_request *req)
{
        if (req->r_session) {
                ceph_put_mds_session(req->r_session);
                req->r_session = NULL;
        }
}

void ceph_mdsc_iterate_sessions(struct ceph_mds_client *mdsc,
                                void (*cb)(struct ceph_mds_session *),
                                bool check_state)
{
        int mds;

        mutex_lock(&mdsc->mutex);
        for (mds = 0; mds < mdsc->max_sessions; ++mds) {
                struct ceph_mds_session *s;

                s = __ceph_lookup_mds_session(mdsc, mds);
                if (!s)
                        continue;

                if (check_state && !check_session_state(s)) {
                        ceph_put_mds_session(s);
                        continue;
                }

                mutex_unlock(&mdsc->mutex);
                cb(s);
                ceph_put_mds_session(s);
                mutex_lock(&mdsc->mutex);
        }
        mutex_unlock(&mdsc->mutex);
}

void ceph_mdsc_release_request(struct kref *kref)
{
        struct ceph_mds_request *req = container_of(kref,
                                                    struct ceph_mds_request,
                                                    r_kref);
        ceph_mdsc_release_dir_caps_async(req);
        destroy_reply_info(&req->r_reply_info);
        if (req->r_request)
                ceph_msg_put(req->r_request);
        if (req->r_reply)
                ceph_msg_put(req->r_reply);
        if (req->r_inode) {
                ceph_put_cap_refs(ceph_inode(req->r_inode), CEPH_CAP_PIN);
                iput(req->r_inode);
        }
        if (req->r_parent) {
                ceph_put_cap_refs(ceph_inode(req->r_parent), CEPH_CAP_PIN);
                iput(req->r_parent);
        }
        iput(req->r_target_inode);
        iput(req->r_new_inode);
        if (req->r_dentry)
                dput(req->r_dentry);
        if (req->r_old_dentry)
                dput(req->r_old_dentry);
        if (req->r_old_dentry_dir) {
                /*
                 * track (and drop pins for) r_old_dentry_dir
                 * separately, since r_old_dentry's d_parent may have
                 * changed between the dir mutex being dropped and
                 * this request being freed.
                 */
                ceph_put_cap_refs(ceph_inode(req->r_old_dentry_dir),
                                  CEPH_CAP_PIN);
                iput(req->r_old_dentry_dir);
        }
        kfree(req->r_path1);
        kfree(req->r_path2);
        put_cred(req->r_cred);
        if (req->r_mnt_idmap)
                mnt_idmap_put(req->r_mnt_idmap);
        if (req->r_pagelist)
                ceph_pagelist_release(req->r_pagelist);
        kfree(req->r_fscrypt_auth);
        kfree(req->r_altname);
        put_request_session(req);
        ceph_unreserve_caps(req->r_mdsc, &req->r_caps_reservation);
        WARN_ON_ONCE(!list_empty(&req->r_wait));
        kmem_cache_free(ceph_mds_request_cachep, req);
}

DEFINE_RB_FUNCS(request, struct ceph_mds_request, r_tid, r_node)

/*
 * lookup session, bump ref if found.
 *
 * called under mdsc->mutex.
 */
static struct ceph_mds_request *
lookup_get_request(struct ceph_mds_client *mdsc, u64 tid)
{
        struct ceph_mds_request *req;

        req = lookup_request(&mdsc->request_tree, tid);
        if (req)
                ceph_mdsc_get_request(req);

        return req;
}

/*
 * Register an in-flight request, and assign a tid.  Link to directory
 * are modifying (if any).
 *
 * Called under mdsc->mutex.
 */
static void __register_request(struct ceph_mds_client *mdsc,
                               struct ceph_mds_request *req,
                               struct inode *dir)
{
        struct ceph_client *cl = mdsc->fsc->client;
        int ret = 0;

        req->r_tid = ++mdsc->last_tid;
        if (req->r_num_caps) {
                ret = ceph_reserve_caps(mdsc, &req->r_caps_reservation,
                                        req->r_num_caps);
                if (ret < 0) {
                        pr_err_client(cl, "%p failed to reserve caps: %d\n",
                                      req, ret);
                        /* set req->r_err to fail early from __do_request */
                        req->r_err = ret;
                        return;
                }
        }
        doutc(cl, "%p tid %lld\n", req, req->r_tid);
        ceph_mdsc_get_request(req);
        insert_request(&mdsc->request_tree, req);

        req->r_cred = get_current_cred();
        if (!req->r_mnt_idmap)
                req->r_mnt_idmap = &nop_mnt_idmap;

        if (mdsc->oldest_tid == 0 && req->r_op != CEPH_MDS_OP_SETFILELOCK)
                mdsc->oldest_tid = req->r_tid;

        if (dir) {
                struct ceph_inode_info *ci = ceph_inode(dir);

                ihold(dir);
                req->r_unsafe_dir = dir;
                spin_lock(&ci->i_unsafe_lock);
                list_add_tail(&req->r_unsafe_dir_item, &ci->i_unsafe_dirops);
                spin_unlock(&ci->i_unsafe_lock);
        }
}

static void __unregister_request(struct ceph_mds_client *mdsc,
                                 struct ceph_mds_request *req)
{
        doutc(mdsc->fsc->client, "%p tid %lld\n", req, req->r_tid);

        /* Never leave an unregistered request on an unsafe list! */
        list_del_init(&req->r_unsafe_item);

        if (req->r_tid == mdsc->oldest_tid) {
                struct rb_node *p = rb_next(&req->r_node);
                mdsc->oldest_tid = 0;
                while (p) {
                        struct ceph_mds_request *next_req =
                                rb_entry(p, struct ceph_mds_request, r_node);
                        if (next_req->r_op != CEPH_MDS_OP_SETFILELOCK) {
                                mdsc->oldest_tid = next_req->r_tid;
                                break;
                        }
                        p = rb_next(p);
                }
        }

        erase_request(&mdsc->request_tree, req);

        if (req->r_unsafe_dir) {
                struct ceph_inode_info *ci = ceph_inode(req->r_unsafe_dir);
                spin_lock(&ci->i_unsafe_lock);
                list_del_init(&req->r_unsafe_dir_item);
                spin_unlock(&ci->i_unsafe_lock);
        }
        if (req->r_target_inode &&
            test_bit(CEPH_MDS_R_GOT_UNSAFE, &req->r_req_flags)) {
                struct ceph_inode_info *ci = ceph_inode(req->r_target_inode);
                spin_lock(&ci->i_unsafe_lock);
                list_del_init(&req->r_unsafe_target_item);
                spin_unlock(&ci->i_unsafe_lock);
        }

        if (req->r_unsafe_dir) {
                iput(req->r_unsafe_dir);
                req->r_unsafe_dir = NULL;
        }

        complete_all(&req->r_safe_completion);

        ceph_mdsc_put_request(req);
}

/*
 * Walk back up the dentry tree until we hit a dentry representing a
 * non-snapshot inode. We do this using the rcu_read_lock (which must be held
 * when calling this) to ensure that the objects won't disappear while we're
 * working with them. Once we hit a candidate dentry, we attempt to take a
 * reference to it, and return that as the result.
 */
static struct inode *get_nonsnap_parent(struct dentry *dentry)
{
        struct inode *inode = NULL;

        while (dentry && !IS_ROOT(dentry)) {
                inode = d_inode_rcu(dentry);
                if (!inode || ceph_snap(inode) == CEPH_NOSNAP)
                        break;
                dentry = dentry->d_parent;
        }
        if (inode)
                inode = igrab(inode);
        return inode;
}

/*
 * Choose mds to send request to next.  If there is a hint set in the
 * request (e.g., due to a prior forward hint from the mds), use that.
 * Otherwise, consult frag tree and/or caps to identify the
 * appropriate mds.  If all else fails, choose randomly.
 *
 * Called under mdsc->mutex.
 */
static int __choose_mds(struct ceph_mds_client *mdsc,
                        struct ceph_mds_request *req,
                        bool *random)
{
        struct inode *inode;
        struct ceph_inode_info *ci;
        struct ceph_cap *cap;
        int mode = req->r_direct_mode;
        int mds = -1;
        u32 hash = req->r_direct_hash;
        bool is_hash = test_bit(CEPH_MDS_R_DIRECT_IS_HASH, &req->r_req_flags);
        struct ceph_client *cl = mdsc->fsc->client;

        if (random)
                *random = false;

        /*
         * is there a specific mds we should try?  ignore hint if we have
         * no session and the mds is not up (active or recovering).
         */
        if (req->r_resend_mds >= 0 &&
            (__have_session(mdsc, req->r_resend_mds) ||
             ceph_mdsmap_get_state(mdsc->mdsmap, req->r_resend_mds) > 0)) {
                doutc(cl, "using resend_mds mds%d\n", req->r_resend_mds);
                return req->r_resend_mds;
        }

        if (mode == USE_RANDOM_MDS)
                goto random;

        inode = NULL;
        if (req->r_inode) {
                if (ceph_snap(req->r_inode) != CEPH_SNAPDIR) {
                        inode = req->r_inode;
                        ihold(inode);
                } else {
                        /* req->r_dentry is non-null for LSSNAP request */
                        rcu_read_lock();
                        inode = get_nonsnap_parent(req->r_dentry);
                        rcu_read_unlock();
                        doutc(cl, "using snapdir's parent %p %llx.%llx\n",
                              inode, ceph_vinop(inode));
                }
        } else if (req->r_dentry) {
                /* ignore race with rename; old or new d_parent is okay */
                struct dentry *parent;
                struct inode *dir;

                rcu_read_lock();
                parent = READ_ONCE(req->r_dentry->d_parent);
                dir = req->r_parent ? : d_inode_rcu(parent);

                if (!dir || dir->i_sb != mdsc->fsc->sb) {
                        /*  not this fs or parent went negative */
                        inode = d_inode(req->r_dentry);
                        if (inode)
                                ihold(inode);
                } else if (ceph_snap(dir) != CEPH_NOSNAP) {
                        /* direct snapped/virtual snapdir requests
                         * based on parent dir inode */
                        inode = get_nonsnap_parent(parent);
                        doutc(cl, "using nonsnap parent %p %llx.%llx\n",
                              inode, ceph_vinop(inode));
                } else {
                        /* dentry target */
                        inode = d_inode(req->r_dentry);
                        if (!inode || mode == USE_AUTH_MDS) {
                                /* dir + name */
                                inode = igrab(dir);
                                hash = ceph_dentry_hash(dir, req->r_dentry);
                                is_hash = true;
                        } else {
                                ihold(inode);
                        }
                }
                rcu_read_unlock();
        }

        if (!inode)
                goto random;

        doutc(cl, "%p %llx.%llx is_hash=%d (0x%x) mode %d\n", inode,
              ceph_vinop(inode), (int)is_hash, hash, mode);
        ci = ceph_inode(inode);

        if (is_hash && S_ISDIR(inode->i_mode)) {
                struct ceph_inode_frag frag;
                int found;

                ceph_choose_frag(ci, hash, &frag, &found);
                if (found) {
                        if (mode == USE_ANY_MDS && frag.ndist > 0) {
                                u8 r;

                                /* choose a random replica */
                                get_random_bytes(&r, 1);
                                r %= frag.ndist;
                                mds = frag.dist[r];
                                doutc(cl, "%p %llx.%llx frag %u mds%d (%d/%d)\n",
                                      inode, ceph_vinop(inode), frag.frag,
                                      mds, (int)r, frag.ndist);
                                if (ceph_mdsmap_get_state(mdsc->mdsmap, mds) >=
                                    CEPH_MDS_STATE_ACTIVE &&
                                    !ceph_mdsmap_is_laggy(mdsc->mdsmap, mds))
                                        goto out;
                        }

                        /* since this file/dir wasn't known to be
                         * replicated, then we want to look for the
                         * authoritative mds. */
                        if (frag.mds >= 0) {
                                /* choose auth mds */
                                mds = frag.mds;
                                doutc(cl, "%p %llx.%llx frag %u mds%d (auth)\n",
                                      inode, ceph_vinop(inode), frag.frag, mds);
                                if (ceph_mdsmap_get_state(mdsc->mdsmap, mds) >=
                                    CEPH_MDS_STATE_ACTIVE) {
                                        if (!ceph_mdsmap_is_laggy(mdsc->mdsmap,
                                                                  mds))
                                                goto out;
                                }
                        }
                        mode = USE_AUTH_MDS;
                }
        }

        spin_lock(&ci->i_ceph_lock);
        cap = NULL;
        if (mode == USE_AUTH_MDS)
                cap = ci->i_auth_cap;
        if (!cap && !RB_EMPTY_ROOT(&ci->i_caps))
                cap = rb_entry(rb_first(&ci->i_caps), struct ceph_cap, ci_node);
        if (!cap) {
                spin_unlock(&ci->i_ceph_lock);
                iput(inode);
                goto random;
        }
        mds = cap->session->s_mds;
        doutc(cl, "%p %llx.%llx mds%d (%scap %p)\n", inode,
              ceph_vinop(inode), mds,
              cap == ci->i_auth_cap ? "auth " : "", cap);
        spin_unlock(&ci->i_ceph_lock);
out:
        iput(inode);
        return mds;

random:
        if (random)
                *random = true;

        mds = ceph_mdsmap_get_random_mds(mdsc->mdsmap);
        doutc(cl, "chose random mds%d\n", mds);
        return mds;
}


/*
 * session messages
 */
struct ceph_msg *ceph_create_session_msg(u32 op, u64 seq)
{
        struct ceph_msg *msg;
        struct ceph_mds_session_head *h;

        msg = ceph_msg_new(CEPH_MSG_CLIENT_SESSION, sizeof(*h), GFP_NOFS,
                           false);
        if (!msg) {
                pr_err("ENOMEM creating session %s msg\n",
                       ceph_session_op_name(op));
                return NULL;
        }
        h = msg->front.iov_base;
        h->op = cpu_to_le32(op);
        h->seq = cpu_to_le64(seq);

        return msg;
}

static const unsigned char feature_bits[] = CEPHFS_FEATURES_CLIENT_SUPPORTED;
#define FEATURE_BYTES(c) (DIV_ROUND_UP((size_t)feature_bits[c - 1] + 1, 64) * 8)
static int encode_supported_features(void **p, void *end)
{
        static const size_t count = ARRAY_SIZE(feature_bits);

        if (count > 0) {
                size_t i;
                size_t size = FEATURE_BYTES(count);
                unsigned long bit;

                if (WARN_ON_ONCE(*p + 4 + size > end))
                        return -ERANGE;

                ceph_encode_32(p, size);
                memset(*p, 0, size);
                for (i = 0; i < count; i++) {
                        bit = feature_bits[i];
                        ((unsigned char *)(*p))[bit / 8] |= BIT(bit % 8);
                }
                *p += size;
        } else {
                if (WARN_ON_ONCE(*p + 4 > end))
                        return -ERANGE;

                ceph_encode_32(p, 0);
        }

        return 0;
}

static const unsigned char metric_bits[] = CEPHFS_METRIC_SPEC_CLIENT_SUPPORTED;
#define METRIC_BYTES(cnt) (DIV_ROUND_UP((size_t)metric_bits[cnt - 1] + 1, 64) * 8)
static int encode_metric_spec(void **p, void *end)
{
        static const size_t count = ARRAY_SIZE(metric_bits);

        /* header */
        if (WARN_ON_ONCE(*p + 2 > end))
                return -ERANGE;

        ceph_encode_8(p, 1); /* version */
        ceph_encode_8(p, 1); /* compat */

        if (count > 0) {
                size_t i;
                size_t size = METRIC_BYTES(count);

                if (WARN_ON_ONCE(*p + 4 + 4 + size > end))
                        return -ERANGE;

                /* metric spec info length */
                ceph_encode_32(p, 4 + size);

                /* metric spec */
                ceph_encode_32(p, size);
                memset(*p, 0, size);
                for (i = 0; i < count; i++)
                        ((unsigned char *)(*p))[i / 8] |= BIT(metric_bits[i] % 8);
                *p += size;
        } else {
                if (WARN_ON_ONCE(*p + 4 + 4 > end))
                        return -ERANGE;

                /* metric spec info length */
                ceph_encode_32(p, 4);
                /* metric spec */
                ceph_encode_32(p, 0);
        }

        return 0;
}

/*
 * session message, specialization for CEPH_SESSION_REQUEST_OPEN
 * to include additional client metadata fields.
 */
static struct ceph_msg *
create_session_full_msg(struct ceph_mds_client *mdsc, int op, u64 seq)
{
        struct ceph_msg *msg;
        struct ceph_mds_session_head *h;
        int i;
        int extra_bytes = 0;
        int metadata_key_count = 0;
        struct ceph_options *opt = mdsc->fsc->client->options;
        struct ceph_mount_options *fsopt = mdsc->fsc->mount_options;
        struct ceph_client *cl = mdsc->fsc->client;
        size_t size, count;
        void *p, *end;
        int ret;

        const char* metadata[][2] = {
                {"hostname", mdsc->nodename},
                {"kernel_version", init_utsname()->release},
                {"entity_id", opt->name ? : ""},
                {"root", fsopt->server_path ? : "/"},
                {NULL, NULL}
        };

        /* Calculate serialized length of metadata */
        extra_bytes = 4;  /* map length */
        for (i = 0; metadata[i][0]; ++i) {
                extra_bytes += 8 + strlen(metadata[i][0]) +
                        strlen(metadata[i][1]);
                metadata_key_count++;
        }

        /* supported feature */
        size = 0;
        count = ARRAY_SIZE(feature_bits);
        if (count > 0)
                size = FEATURE_BYTES(count);
        extra_bytes += 4 + size;

        /* metric spec */
        size = 0;
        count = ARRAY_SIZE(metric_bits);
        if (count > 0)
                size = METRIC_BYTES(count);
        extra_bytes += 2 + 4 + 4 + size;

        /* flags, mds auth caps and oldest_client_tid */
        extra_bytes += 4 + 4 + 8;

        /* Allocate the message */
        msg = ceph_msg_new(CEPH_MSG_CLIENT_SESSION, sizeof(*h) + extra_bytes,
                           GFP_NOFS, false);
        if (!msg) {
                pr_err_client(cl, "ENOMEM creating session open msg\n");
                return ERR_PTR(-ENOMEM);
        }
        p = msg->front.iov_base;
        end = p + msg->front.iov_len;

        h = p;
        h->op = cpu_to_le32(op);
        h->seq = cpu_to_le64(seq);

        /*
         * Serialize client metadata into waiting buffer space, using
         * the format that userspace expects for map<string, string>
         *
         * ClientSession messages with metadata are v7
         */
        msg->hdr.version = cpu_to_le16(7);
        msg->hdr.compat_version = cpu_to_le16(1);

        /* The write pointer, following the session_head structure */
        p += sizeof(*h);

        /* Number of entries in the map */
        ceph_encode_32(&p, metadata_key_count);

        /* Two length-prefixed strings for each entry in the map */
        for (i = 0; metadata[i][0]; ++i) {
                size_t const key_len = strlen(metadata[i][0]);
                size_t const val_len = strlen(metadata[i][1]);

                ceph_encode_32(&p, key_len);
                memcpy(p, metadata[i][0], key_len);
                p += key_len;
                ceph_encode_32(&p, val_len);
                memcpy(p, metadata[i][1], val_len);
                p += val_len;
        }

        ret = encode_supported_features(&p, end);
        if (ret) {
                pr_err_client(cl, "encode_supported_features failed!\n");
                ceph_msg_put(msg);
                return ERR_PTR(ret);
        }

        ret = encode_metric_spec(&p, end);
        if (ret) {
                pr_err_client(cl, "encode_metric_spec failed!\n");
                ceph_msg_put(msg);
                return ERR_PTR(ret);
        }

        /* version == 5, flags */
        ceph_encode_32(&p, 0);

        /* version == 6, mds auth caps */
        ceph_encode_32(&p, 0);

        /* version == 7, oldest_client_tid */
        ceph_encode_64(&p, mdsc->oldest_tid);

        msg->front.iov_len = p - msg->front.iov_base;
        msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);

        return msg;
}

/*
 * send session open request.
 *
 * called under mdsc->mutex
 */
static int __open_session(struct ceph_mds_client *mdsc,
                          struct ceph_mds_session *session)
{
        struct ceph_msg *msg;
        int mstate;
        int mds = session->s_mds;

        if (READ_ONCE(mdsc->fsc->mount_state) == CEPH_MOUNT_FENCE_IO)
                return -EIO;

        /* wait for mds to go active? */
        mstate = ceph_mdsmap_get_state(mdsc->mdsmap, mds);
        doutc(mdsc->fsc->client, "open_session to mds%d (%s)\n", mds,
              ceph_mds_state_name(mstate));
        session->s_state = CEPH_MDS_SESSION_OPENING;
        session->s_renew_requested = jiffies;

        /* send connect message */
        msg = create_session_full_msg(mdsc, CEPH_SESSION_REQUEST_OPEN,
                                      session->s_seq);
        if (IS_ERR(msg))
                return PTR_ERR(msg);
        ceph_con_send(&session->s_con, msg);
        return 0;
}

/*
 * open sessions for any export targets for the given mds
 *
 * called under mdsc->mutex
 */
static struct ceph_mds_session *
__open_export_target_session(struct ceph_mds_client *mdsc, int target)
{
        struct ceph_mds_session *session;
        int ret;

        session = __ceph_lookup_mds_session(mdsc, target);
        if (!session) {
                session = register_session(mdsc, target);
                if (IS_ERR(session))
                        return session;
        }
        if (session->s_state == CEPH_MDS_SESSION_NEW ||
            session->s_state == CEPH_MDS_SESSION_CLOSING) {
                ret = __open_session(mdsc, session);
                if (ret)
                        return ERR_PTR(ret);
        }

        return session;
}

struct ceph_mds_session *
ceph_mdsc_open_export_target_session(struct ceph_mds_client *mdsc, int target)
{
        struct ceph_mds_session *session;
        struct ceph_client *cl = mdsc->fsc->client;

        doutc(cl, "to mds%d\n", target);

        mutex_lock(&mdsc->mutex);
        session = __open_export_target_session(mdsc, target);
        mutex_unlock(&mdsc->mutex);

        return session;
}

static void __open_export_target_sessions(struct ceph_mds_client *mdsc,
                                          struct ceph_mds_session *session)
{
        struct ceph_mds_info *mi;
        struct ceph_mds_session *ts;
        int i, mds = session->s_mds;
        struct ceph_client *cl = mdsc->fsc->client;

        if (mds >= mdsc->mdsmap->possible_max_rank)
                return;

        mi = &mdsc->mdsmap->m_info[mds];
        doutc(cl, "for mds%d (%d targets)\n", session->s_mds,
              mi->num_export_targets);

        for (i = 0; i < mi->num_export_targets; i++) {
                ts = __open_export_target_session(mdsc, mi->export_targets[i]);
                ceph_put_mds_session(ts);
        }
}

/*
 * session caps
 */

static void detach_cap_releases(struct ceph_mds_session *session,
                                struct list_head *target)
{
        struct ceph_client *cl = session->s_mdsc->fsc->client;

        lockdep_assert_held(&session->s_cap_lock);

        list_splice_init(&session->s_cap_releases, target);
        session->s_num_cap_releases = 0;
        doutc(cl, "mds%d\n", session->s_mds);
}

static void dispose_cap_releases(struct ceph_mds_client *mdsc,
                                 struct list_head *dispose)
{
        while (!list_empty(dispose)) {
                struct ceph_cap *cap;
                /* zero out the in-progress message */
                cap = list_first_entry(dispose, struct ceph_cap, session_caps);
                list_del(&cap->session_caps);
                ceph_put_cap(mdsc, cap);
        }
}

static void cleanup_session_requests(struct ceph_mds_client *mdsc,
                                     struct ceph_mds_session *session)
{
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_mds_request *req;
        struct rb_node *p;

        doutc(cl, "mds%d\n", session->s_mds);
        mutex_lock(&mdsc->mutex);
        while (!list_empty(&session->s_unsafe)) {
                req = list_first_entry(&session->s_unsafe,
                                       struct ceph_mds_request, r_unsafe_item);
                pr_warn_ratelimited_client(cl, " dropping unsafe request %llu\n",
                                           req->r_tid);
                if (req->r_target_inode)
                        mapping_set_error(req->r_target_inode->i_mapping, -EIO);
                if (req->r_unsafe_dir)
                        mapping_set_error(req->r_unsafe_dir->i_mapping, -EIO);
                __unregister_request(mdsc, req);
        }
        /* zero r_attempts, so kick_requests() will re-send requests */
        p = rb_first(&mdsc->request_tree);
        while (p) {
                req = rb_entry(p, struct ceph_mds_request, r_node);
                p = rb_next(p);
                if (req->r_session &&
                    req->r_session->s_mds == session->s_mds)
                        req->r_attempts = 0;
        }
        mutex_unlock(&mdsc->mutex);
}

/*
 * Helper to safely iterate over all caps associated with a session, with
 * special care taken to handle a racing __ceph_remove_cap().
 *
 * Caller must hold session s_mutex.
 */
int ceph_iterate_session_caps(struct ceph_mds_session *session,
                              int (*cb)(struct inode *, int mds, void *),
                              void *arg)
{
        struct ceph_client *cl = session->s_mdsc->fsc->client;
        struct list_head *p;
        struct ceph_cap *cap;
        struct inode *inode, *last_inode = NULL;
        struct ceph_cap *old_cap = NULL;
        int ret;

        doutc(cl, "%p mds%d\n", session, session->s_mds);
        spin_lock(&session->s_cap_lock);
        p = session->s_caps.next;
        while (p != &session->s_caps) {
                int mds;

                cap = list_entry(p, struct ceph_cap, session_caps);
                inode = igrab(&cap->ci->netfs.inode);
                if (!inode) {
                        p = p->next;
                        continue;
                }
                session->s_cap_iterator = cap;
                mds = cap->mds;
                spin_unlock(&session->s_cap_lock);

                if (last_inode) {
                        iput(last_inode);
                        last_inode = NULL;
                }
                if (old_cap) {
                        ceph_put_cap(session->s_mdsc, old_cap);
                        old_cap = NULL;
                }

                ret = cb(inode, mds, arg);
                last_inode = inode;

                spin_lock(&session->s_cap_lock);
                p = p->next;
                if (!cap->ci) {
                        doutc(cl, "finishing cap %p removal\n", cap);
                        BUG_ON(cap->session != session);
                        cap->session = NULL;
                        list_del_init(&cap->session_caps);
                        session->s_nr_caps--;
                        atomic64_dec(&session->s_mdsc->metric.total_caps);
                        if (cap->queue_release)
                                __ceph_queue_cap_release(session, cap);
                        else
                                old_cap = cap;  /* put_cap it w/o locks held */
                }
                if (ret < 0)
                        goto out;
        }
        ret = 0;
out:
        session->s_cap_iterator = NULL;
        spin_unlock(&session->s_cap_lock);

        iput(last_inode);
        if (old_cap)
                ceph_put_cap(session->s_mdsc, old_cap);

        return ret;
}

static int remove_session_caps_cb(struct inode *inode, int mds, void *arg)
{
        struct ceph_inode_info *ci = ceph_inode(inode);
        struct ceph_client *cl = ceph_inode_to_client(inode);
        bool invalidate = false;
        struct ceph_cap *cap;
        int iputs = 0;

        spin_lock(&ci->i_ceph_lock);
        cap = __get_cap_for_mds(ci, mds);
        if (cap) {
                doutc(cl, " removing cap %p, ci is %p, inode is %p\n",
                      cap, ci, &ci->netfs.inode);

                iputs = ceph_purge_inode_cap(inode, cap, &invalidate);
        }
        spin_unlock(&ci->i_ceph_lock);

        if (cap)
                wake_up_all(&ci->i_cap_wq);
        if (invalidate)
                ceph_queue_invalidate(inode);
        while (iputs--)
                iput(inode);
        return 0;
}

/*
 * caller must hold session s_mutex
 */
static void remove_session_caps(struct ceph_mds_session *session)
{
        struct ceph_fs_client *fsc = session->s_mdsc->fsc;
        struct super_block *sb = fsc->sb;
        LIST_HEAD(dispose);

        doutc(fsc->client, "on %p\n", session);
        ceph_iterate_session_caps(session, remove_session_caps_cb, fsc);

        wake_up_all(&fsc->mdsc->cap_flushing_wq);

        spin_lock(&session->s_cap_lock);
        if (session->s_nr_caps > 0) {
                struct inode *inode;
                struct ceph_cap *cap, *prev = NULL;
                struct ceph_vino vino;
                /*
                 * iterate_session_caps() skips inodes that are being
                 * deleted, we need to wait until deletions are complete.
                 * __wait_on_freeing_inode() is designed for the job,
                 * but it is not exported, so use lookup inode function
                 * to access it.
                 */
                while (!list_empty(&session->s_caps)) {
                        cap = list_entry(session->s_caps.next,
                                         struct ceph_cap, session_caps);
                        if (cap == prev)
                                break;
                        prev = cap;
                        vino = cap->ci->i_vino;
                        spin_unlock(&session->s_cap_lock);

                        inode = ceph_find_inode(sb, vino);
                        iput(inode);

                        spin_lock(&session->s_cap_lock);
                }
        }

        // drop cap expires and unlock s_cap_lock
        detach_cap_releases(session, &dispose);

        BUG_ON(session->s_nr_caps > 0);
        BUG_ON(!list_empty(&session->s_cap_flushing));
        spin_unlock(&session->s_cap_lock);
        dispose_cap_releases(session->s_mdsc, &dispose);
}

enum {
        RECONNECT,
        RENEWCAPS,
        FORCE_RO,
};

/*
 * wake up any threads waiting on this session's caps.  if the cap is
 * old (didn't get renewed on the client reconnect), remove it now.
 *
 * caller must hold s_mutex.
 */
static int wake_up_session_cb(struct inode *inode, int mds, void *arg)
{
        struct ceph_inode_info *ci = ceph_inode(inode);
        unsigned long ev = (unsigned long)arg;

        if (ev == RECONNECT) {
                spin_lock(&ci->i_ceph_lock);
                ci->i_wanted_max_size = 0;
                ci->i_requested_max_size = 0;
                spin_unlock(&ci->i_ceph_lock);
        } else if (ev == RENEWCAPS) {
                struct ceph_cap *cap;

                spin_lock(&ci->i_ceph_lock);
                cap = __get_cap_for_mds(ci, mds);
                /* mds did not re-issue stale cap */
                if (cap && cap->cap_gen < atomic_read(&cap->session->s_cap_gen))
                        cap->issued = cap->implemented = CEPH_CAP_PIN;
                spin_unlock(&ci->i_ceph_lock);
        } else if (ev == FORCE_RO) {
        }
        wake_up_all(&ci->i_cap_wq);
        return 0;
}

static void wake_up_session_caps(struct ceph_mds_session *session, int ev)
{
        struct ceph_client *cl = session->s_mdsc->fsc->client;

        doutc(cl, "session %p mds%d\n", session, session->s_mds);
        ceph_iterate_session_caps(session, wake_up_session_cb,
                                  (void *)(unsigned long)ev);
}

/*
 * Send periodic message to MDS renewing all currently held caps.  The
 * ack will reset the expiration for all caps from this session.
 *
 * caller holds s_mutex
 */
static int send_renew_caps(struct ceph_mds_client *mdsc,
                           struct ceph_mds_session *session)
{
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_msg *msg;
        int state;

        if (time_after_eq(jiffies, session->s_cap_ttl) &&
            time_after_eq(session->s_cap_ttl, session->s_renew_requested))
                pr_info_client(cl, "mds%d caps stale\n", session->s_mds);
        session->s_renew_requested = jiffies;

        /* do not try to renew caps until a recovering mds has reconnected
         * with its clients. */
        state = ceph_mdsmap_get_state(mdsc->mdsmap, session->s_mds);
        if (state < CEPH_MDS_STATE_RECONNECT) {
                doutc(cl, "ignoring mds%d (%s)\n", session->s_mds,
                      ceph_mds_state_name(state));
                return 0;
        }

        doutc(cl, "to mds%d (%s)\n", session->s_mds,
              ceph_mds_state_name(state));
        msg = create_session_full_msg(mdsc, CEPH_SESSION_REQUEST_RENEWCAPS,
                                      ++session->s_renew_seq);
        if (IS_ERR(msg))
                return PTR_ERR(msg);
        ceph_con_send(&session->s_con, msg);
        return 0;
}

static int send_flushmsg_ack(struct ceph_mds_client *mdsc,
                             struct ceph_mds_session *session, u64 seq)
{
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_msg *msg;

        doutc(cl, "to mds%d (%s)s seq %lld\n", session->s_mds,
              ceph_session_state_name(session->s_state), seq);
        msg = ceph_create_session_msg(CEPH_SESSION_FLUSHMSG_ACK, seq);
        if (!msg)
                return -ENOMEM;
        ceph_con_send(&session->s_con, msg);
        return 0;
}


/*
 * Note new cap ttl, and any transition from stale -> not stale (fresh?).
 *
 * Called under session->s_mutex
 */
static void renewed_caps(struct ceph_mds_client *mdsc,
                         struct ceph_mds_session *session, int is_renew)
{
        struct ceph_client *cl = mdsc->fsc->client;
        int was_stale;
        int wake = 0;

        spin_lock(&session->s_cap_lock);
        was_stale = is_renew && time_after_eq(jiffies, session->s_cap_ttl);

        session->s_cap_ttl = session->s_renew_requested +
                mdsc->mdsmap->m_session_timeout*HZ;

        if (was_stale) {
                if (time_before(jiffies, session->s_cap_ttl)) {
                        pr_info_client(cl, "mds%d caps renewed\n",
                                       session->s_mds);
                        wake = 1;
                } else {
                        pr_info_client(cl, "mds%d caps still stale\n",
                                       session->s_mds);
                }
        }
        doutc(cl, "mds%d ttl now %lu, was %s, now %s\n", session->s_mds,
              session->s_cap_ttl, was_stale ? "stale" : "fresh",
              time_before(jiffies, session->s_cap_ttl) ? "stale" : "fresh");
        spin_unlock(&session->s_cap_lock);

        if (wake)
                wake_up_session_caps(session, RENEWCAPS);
}

/*
 * send a session close request
 */
static int request_close_session(struct ceph_mds_session *session)
{
        struct ceph_client *cl = session->s_mdsc->fsc->client;
        struct ceph_msg *msg;

        doutc(cl, "mds%d state %s seq %lld\n", session->s_mds,
              ceph_session_state_name(session->s_state), session->s_seq);
        msg = ceph_create_session_msg(CEPH_SESSION_REQUEST_CLOSE,
                                      session->s_seq);
        if (!msg)
                return -ENOMEM;
        ceph_con_send(&session->s_con, msg);
        return 1;
}

/*
 * Called with s_mutex held.
 */
static int __close_session(struct ceph_mds_client *mdsc,
                         struct ceph_mds_session *session)
{
        if (session->s_state >= CEPH_MDS_SESSION_CLOSING)
                return 0;
        session->s_state = CEPH_MDS_SESSION_CLOSING;
        return request_close_session(session);
}

static bool drop_negative_children(struct dentry *dentry)
{
        struct dentry *child;
        bool all_negative = true;

        if (!d_is_dir(dentry))
                goto out;

        spin_lock(&dentry->d_lock);
        hlist_for_each_entry(child, &dentry->d_children, d_sib) {
                if (d_really_is_positive(child)) {
                        all_negative = false;
                        break;
                }
        }
        spin_unlock(&dentry->d_lock);

        if (all_negative)
                shrink_dcache_parent(dentry);
out:
        return all_negative;
}

/*
 * Trim old(er) caps.
 *
 * Because we can't cache an inode without one or more caps, we do
 * this indirectly: if a cap is unused, we prune its aliases, at which
 * point the inode will hopefully get dropped to.
 *
 * Yes, this is a bit sloppy.  Our only real goal here is to respond to
 * memory pressure from the MDS, though, so it needn't be perfect.
 */
static int trim_caps_cb(struct inode *inode, int mds, void *arg)
{
        struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb);
        struct ceph_client *cl = mdsc->fsc->client;
        int *remaining = arg;
        struct ceph_inode_info *ci = ceph_inode(inode);
        int used, wanted, oissued, mine;
        struct ceph_cap *cap;

        if (*remaining <= 0)
                return -1;

        spin_lock(&ci->i_ceph_lock);
        cap = __get_cap_for_mds(ci, mds);
        if (!cap) {
                spin_unlock(&ci->i_ceph_lock);
                return 0;
        }
        mine = cap->issued | cap->implemented;
        used = __ceph_caps_used(ci);
        wanted = __ceph_caps_file_wanted(ci);
        oissued = __ceph_caps_issued_other(ci, cap);

        doutc(cl, "%p %llx.%llx cap %p mine %s oissued %s used %s wanted %s\n",
              inode, ceph_vinop(inode), cap, ceph_cap_string(mine),
              ceph_cap_string(oissued), ceph_cap_string(used),
              ceph_cap_string(wanted));
        if (cap == ci->i_auth_cap) {
                if (ci->i_dirty_caps || ci->i_flushing_caps ||
                    !list_empty(&ci->i_cap_snaps))
                        goto out;
                if ((used | wanted) & CEPH_CAP_ANY_WR)
                        goto out;
                /* Note: it's possible that i_filelock_ref becomes non-zero
                 * after dropping auth caps. It doesn't hurt because reply
                 * of lock mds request will re-add auth caps. */
                if (atomic_read(&ci->i_filelock_ref) > 0)
                        goto out;
        }
        /* The inode has cached pages, but it's no longer used.
         * we can safely drop it */
        if (S_ISREG(inode->i_mode) &&
            wanted == 0 && used == CEPH_CAP_FILE_CACHE &&
            !(oissued & CEPH_CAP_FILE_CACHE)) {
          used = 0;
          oissued = 0;
        }
        if ((used | wanted) & ~oissued & mine)
                goto out;   /* we need these caps */

        if (oissued) {
                /* we aren't the only cap.. just remove us */
                ceph_remove_cap(mdsc, cap, true);
                (*remaining)--;
        } else {
                struct dentry *dentry;
                /* try dropping referring dentries */
                spin_unlock(&ci->i_ceph_lock);
                dentry = d_find_any_alias(inode);
                if (dentry && drop_negative_children(dentry)) {
                        int count;
                        dput(dentry);
                        d_prune_aliases(inode);
                        count = icount_read(inode);
                        if (count == 1)
                                (*remaining)--;
                        doutc(cl, "%p %llx.%llx cap %p pruned, count now %d\n",
                              inode, ceph_vinop(inode), cap, count);
                } else {
                        dput(dentry);
                }
                return 0;
        }

out:
        spin_unlock(&ci->i_ceph_lock);
        return 0;
}

/*
 * Trim session cap count down to some max number.
 */
int ceph_trim_caps(struct ceph_mds_client *mdsc,
                   struct ceph_mds_session *session,
                   int max_caps)
{
        struct ceph_client *cl = mdsc->fsc->client;
        int trim_caps = session->s_nr_caps - max_caps;

        doutc(cl, "mds%d start: %d / %d, trim %d\n", session->s_mds,
              session->s_nr_caps, max_caps, trim_caps);
        if (trim_caps > 0) {
                int remaining = trim_caps;

                ceph_iterate_session_caps(session, trim_caps_cb, &remaining);
                doutc(cl, "mds%d done: %d / %d, trimmed %d\n",
                      session->s_mds, session->s_nr_caps, max_caps,
                      trim_caps - remaining);
        }

        ceph_flush_session_cap_releases(mdsc, session);
        return 0;
}

static int check_caps_flush(struct ceph_mds_client *mdsc,
                            u64 want_flush_tid)
{
        struct ceph_client *cl = mdsc->fsc->client;
        int ret = 1;

        spin_lock(&mdsc->cap_dirty_lock);
        if (!list_empty(&mdsc->cap_flush_list)) {
                struct ceph_cap_flush *cf =
                        list_first_entry(&mdsc->cap_flush_list,
                                         struct ceph_cap_flush, g_list);
                if (cf->tid <= want_flush_tid) {
                        doutc(cl, "still flushing tid %llu <= %llu\n",
                              cf->tid, want_flush_tid);
                        ret = 0;
                }
        }
        spin_unlock(&mdsc->cap_dirty_lock);
        return ret;
}

/*
 * flush all dirty inode data to disk.
 *
 * returns true if we've flushed through want_flush_tid
 */
static void wait_caps_flush(struct ceph_mds_client *mdsc,
                            u64 want_flush_tid)
{
        struct ceph_client *cl = mdsc->fsc->client;

        doutc(cl, "want %llu\n", want_flush_tid);

        wait_event(mdsc->cap_flushing_wq,
                   check_caps_flush(mdsc, want_flush_tid));

        doutc(cl, "ok, flushed thru %llu\n", want_flush_tid);
}

/*
 * called under s_mutex
 */
static void ceph_send_cap_releases(struct ceph_mds_client *mdsc,
                                   struct ceph_mds_session *session)
{
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_msg *msg = NULL;
        struct ceph_mds_cap_release *head;
        struct ceph_mds_cap_item *item;
        struct ceph_osd_client *osdc = &mdsc->fsc->client->osdc;
        struct ceph_cap *cap;
        LIST_HEAD(tmp_list);
        int num_cap_releases;
        __le32  barrier, *cap_barrier;

        down_read(&osdc->lock);
        barrier = cpu_to_le32(osdc->epoch_barrier);
        up_read(&osdc->lock);

        spin_lock(&session->s_cap_lock);
again:
        list_splice_init(&session->s_cap_releases, &tmp_list);
        num_cap_releases = session->s_num_cap_releases;
        session->s_num_cap_releases = 0;
        spin_unlock(&session->s_cap_lock);

        while (!list_empty(&tmp_list)) {
                if (!msg) {
                        msg = ceph_msg_new(CEPH_MSG_CLIENT_CAPRELEASE,
                                        PAGE_SIZE, GFP_NOFS, false);
                        if (!msg)
                                goto out_err;
                        head = msg->front.iov_base;
                        head->num = cpu_to_le32(0);
                        msg->front.iov_len = sizeof(*head);

                        msg->hdr.version = cpu_to_le16(2);
                        msg->hdr.compat_version = cpu_to_le16(1);
                }

                cap = list_first_entry(&tmp_list, struct ceph_cap,
                                        session_caps);
                list_del(&cap->session_caps);
                num_cap_releases--;

                head = msg->front.iov_base;
                put_unaligned_le32(get_unaligned_le32(&head->num) + 1,
                                   &head->num);
                item = msg->front.iov_base + msg->front.iov_len;
                item->ino = cpu_to_le64(cap->cap_ino);
                item->cap_id = cpu_to_le64(cap->cap_id);
                item->migrate_seq = cpu_to_le32(cap->mseq);
                item->issue_seq = cpu_to_le32(cap->issue_seq);
                msg->front.iov_len += sizeof(*item);

                ceph_put_cap(mdsc, cap);

                if (le32_to_cpu(head->num) == CEPH_CAPS_PER_RELEASE) {
                        // Append cap_barrier field
                        cap_barrier = msg->front.iov_base + msg->front.iov_len;
                        *cap_barrier = barrier;
                        msg->front.iov_len += sizeof(*cap_barrier);

                        msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);
                        doutc(cl, "mds%d %p\n", session->s_mds, msg);
                        ceph_con_send(&session->s_con, msg);
                        msg = NULL;
                }
        }

        BUG_ON(num_cap_releases != 0);

        spin_lock(&session->s_cap_lock);
        if (!list_empty(&session->s_cap_releases))
                goto again;
        spin_unlock(&session->s_cap_lock);

        if (msg) {
                // Append cap_barrier field
                cap_barrier = msg->front.iov_base + msg->front.iov_len;
                *cap_barrier = barrier;
                msg->front.iov_len += sizeof(*cap_barrier);

                msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);
                doutc(cl, "mds%d %p\n", session->s_mds, msg);
                ceph_con_send(&session->s_con, msg);
        }
        return;
out_err:
        pr_err_client(cl, "mds%d, failed to allocate message\n",
                      session->s_mds);
        spin_lock(&session->s_cap_lock);
        list_splice(&tmp_list, &session->s_cap_releases);
        session->s_num_cap_releases += num_cap_releases;
        spin_unlock(&session->s_cap_lock);
}

static void ceph_cap_release_work(struct work_struct *work)
{
        struct ceph_mds_session *session =
                container_of(work, struct ceph_mds_session, s_cap_release_work);

        mutex_lock(&session->s_mutex);
        if (session->s_state == CEPH_MDS_SESSION_OPEN ||
            session->s_state == CEPH_MDS_SESSION_HUNG)
                ceph_send_cap_releases(session->s_mdsc, session);
        mutex_unlock(&session->s_mutex);
        ceph_put_mds_session(session);
}

void ceph_flush_session_cap_releases(struct ceph_mds_client *mdsc,
                             struct ceph_mds_session *session)
{
        struct ceph_client *cl = mdsc->fsc->client;
        if (mdsc->stopping)
                return;

        ceph_get_mds_session(session);
        if (queue_work(mdsc->fsc->cap_wq,
                       &session->s_cap_release_work)) {
                doutc(cl, "cap release work queued\n");
        } else {
                ceph_put_mds_session(session);
                doutc(cl, "failed to queue cap release work\n");
        }
}

/*
 * caller holds session->s_cap_lock
 */
void __ceph_queue_cap_release(struct ceph_mds_session *session,
                              struct ceph_cap *cap)
{
        list_add_tail(&cap->session_caps, &session->s_cap_releases);
        session->s_num_cap_releases++;

        if (!(session->s_num_cap_releases % CEPH_CAPS_PER_RELEASE))
                ceph_flush_session_cap_releases(session->s_mdsc, session);
}

static void ceph_cap_reclaim_work(struct work_struct *work)
{
        struct ceph_mds_client *mdsc =
                container_of(work, struct ceph_mds_client, cap_reclaim_work);
        int ret = ceph_trim_dentries(mdsc);
        if (ret == -EAGAIN)
                ceph_queue_cap_reclaim_work(mdsc);
}

void ceph_queue_cap_reclaim_work(struct ceph_mds_client *mdsc)
{
        struct ceph_client *cl = mdsc->fsc->client;
        if (mdsc->stopping)
                return;

        if (queue_work(mdsc->fsc->cap_wq, &mdsc->cap_reclaim_work)) {
                doutc(cl, "caps reclaim work queued\n");
        } else {
                doutc(cl, "failed to queue caps release work\n");
        }
}

void ceph_reclaim_caps_nr(struct ceph_mds_client *mdsc, int nr)
{
        int val;
        if (!nr)
                return;
        val = atomic_add_return(nr, &mdsc->cap_reclaim_pending);
        if ((val % CEPH_CAPS_PER_RELEASE) < nr) {
                atomic_set(&mdsc->cap_reclaim_pending, 0);
                ceph_queue_cap_reclaim_work(mdsc);
        }
}

void ceph_queue_cap_unlink_work(struct ceph_mds_client *mdsc)
{
        struct ceph_client *cl = mdsc->fsc->client;
        if (mdsc->stopping)
                return;

        if (queue_work(mdsc->fsc->cap_wq, &mdsc->cap_unlink_work)) {
                doutc(cl, "caps unlink work queued\n");
        } else {
                doutc(cl, "failed to queue caps unlink work\n");
        }
}

static void ceph_cap_unlink_work(struct work_struct *work)
{
        struct ceph_mds_client *mdsc =
                container_of(work, struct ceph_mds_client, cap_unlink_work);
        struct ceph_client *cl = mdsc->fsc->client;

        doutc(cl, "begin\n");
        spin_lock(&mdsc->cap_delay_lock);
        while (!list_empty(&mdsc->cap_unlink_delay_list)) {
                struct ceph_inode_info *ci;
                struct inode *inode;

                ci = list_first_entry(&mdsc->cap_unlink_delay_list,
                                      struct ceph_inode_info,
                                      i_cap_delay_list);
                list_del_init(&ci->i_cap_delay_list);

                inode = igrab(&ci->netfs.inode);
                if (inode) {
                        spin_unlock(&mdsc->cap_delay_lock);
                        doutc(cl, "on %p %llx.%llx\n", inode,
                              ceph_vinop(inode));
                        ceph_check_caps(ci, CHECK_CAPS_FLUSH);
                        iput(inode);
                        spin_lock(&mdsc->cap_delay_lock);
                }
        }
        spin_unlock(&mdsc->cap_delay_lock);
        doutc(cl, "done\n");
}

/*
 * requests
 */

int ceph_alloc_readdir_reply_buffer(struct ceph_mds_request *req,
                                    struct inode *dir)
{
        struct ceph_inode_info *ci = ceph_inode(dir);
        struct ceph_mds_reply_info_parsed *rinfo = &req->r_reply_info;
        struct ceph_mount_options *opt = req->r_mdsc->fsc->mount_options;
        size_t size = sizeof(struct ceph_mds_reply_dir_entry);
        unsigned int num_entries;
        u64 bytes_count;
        int order;

        spin_lock(&ci->i_ceph_lock);
        num_entries = ci->i_files + ci->i_subdirs;
        spin_unlock(&ci->i_ceph_lock);
        num_entries = max(num_entries, 1U);
        num_entries = min(num_entries, opt->max_readdir);

        bytes_count = (u64)size * num_entries;
        if (unlikely(bytes_count > ULONG_MAX))
                bytes_count = ULONG_MAX;

        order = get_order((unsigned long)bytes_count);
        while (order >= 0) {
                rinfo->dir_entries = (void*)__get_free_pages(GFP_KERNEL |
                                                             __GFP_NOWARN |
                                                             __GFP_ZERO,
                                                             order);
                if (rinfo->dir_entries)
                        break;
                order--;
        }
        if (!rinfo->dir_entries || unlikely(order < 0))
                return -ENOMEM;

        num_entries = (PAGE_SIZE << order) / size;
        num_entries = min(num_entries, opt->max_readdir);

        rinfo->dir_buf_size = PAGE_SIZE << order;
        req->r_num_caps = num_entries + 1;
        req->r_args.readdir.max_entries = cpu_to_le32(num_entries);
        req->r_args.readdir.max_bytes = cpu_to_le32(opt->max_readdir_bytes);
        return 0;
}

/*
 * Create an mds request.
 */
struct ceph_mds_request *
ceph_mdsc_create_request(struct ceph_mds_client *mdsc, int op, int mode)
{
        struct ceph_mds_request *req;

        req = kmem_cache_zalloc(ceph_mds_request_cachep, GFP_NOFS);
        if (!req)
                return ERR_PTR(-ENOMEM);

        mutex_init(&req->r_fill_mutex);
        req->r_mdsc = mdsc;
        req->r_started = jiffies;
        req->r_start_latency = ktime_get();
        req->r_resend_mds = -1;
        INIT_LIST_HEAD(&req->r_unsafe_dir_item);
        INIT_LIST_HEAD(&req->r_unsafe_target_item);
        req->r_fmode = -1;
        req->r_feature_needed = -1;
        kref_init(&req->r_kref);
        RB_CLEAR_NODE(&req->r_node);
        INIT_LIST_HEAD(&req->r_wait);
        init_completion(&req->r_completion);
        init_completion(&req->r_safe_completion);
        INIT_LIST_HEAD(&req->r_unsafe_item);

        ktime_get_coarse_real_ts64(&req->r_stamp);

        req->r_op = op;
        req->r_direct_mode = mode;
        return req;
}

/*
 * return oldest (lowest) request, tid in request tree, 0 if none.
 *
 * called under mdsc->mutex.
 */
static struct ceph_mds_request *__get_oldest_req(struct ceph_mds_client *mdsc)
{
        if (RB_EMPTY_ROOT(&mdsc->request_tree))
                return NULL;
        return rb_entry(rb_first(&mdsc->request_tree),
                        struct ceph_mds_request, r_node);
}

static inline  u64 __get_oldest_tid(struct ceph_mds_client *mdsc)
{
        return mdsc->oldest_tid;
}

#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
static u8 *get_fscrypt_altname(const struct ceph_mds_request *req, u32 *plen)
{
        struct inode *dir = req->r_parent;
        struct dentry *dentry = req->r_dentry;
        const struct qstr *name = req->r_dname;
        u8 *cryptbuf = NULL;
        u32 len = 0;
        int ret = 0;

        /* only encode if we have parent and dentry */
        if (!dir || !dentry)
                goto success;

        /* No-op unless this is encrypted */
        if (!IS_ENCRYPTED(dir))
                goto success;

        ret = ceph_fscrypt_prepare_readdir(dir);
        if (ret < 0)
                return ERR_PTR(ret);

        /* No key? Just ignore it. */
        if (!fscrypt_has_encryption_key(dir))
                goto success;

        if (!name)
                name = &dentry->d_name;

        if (!fscrypt_fname_encrypted_size(dir, name->len, NAME_MAX, &len)) {
                WARN_ON_ONCE(1);
                return ERR_PTR(-ENAMETOOLONG);
        }

        /* No need to append altname if name is short enough */
        if (len <= CEPH_NOHASH_NAME_MAX) {
                len = 0;
                goto success;
        }

        cryptbuf = kmalloc(len, GFP_KERNEL);
        if (!cryptbuf)
                return ERR_PTR(-ENOMEM);

        ret = fscrypt_fname_encrypt(dir, name, cryptbuf, len);
        if (ret) {
                kfree(cryptbuf);
                return ERR_PTR(ret);
        }
success:
        *plen = len;
        return cryptbuf;
}
#else
static u8 *get_fscrypt_altname(const struct ceph_mds_request *req, u32 *plen)
{
        *plen = 0;
        return NULL;
}
#endif

/**
 * ceph_mdsc_build_path - build a path string to a given dentry
 * @mdsc: mds client
 * @dentry: dentry to which path should be built
 * @path_info: output path, length, base ino+snap, and freepath ownership flag
 * @for_wire: is this path going to be sent to the MDS?
 *
 * Build a string that represents the path to the dentry. This is mostly called
 * for two different purposes:
 *
 * 1) we need to build a path string to send to the MDS (for_wire == true)
 * 2) we need a path string for local presentation (e.g. debugfs)
 *    (for_wire == false)
 *
 * The path is built in reverse, starting with the dentry. Walk back up toward
 * the root, building the path until the first non-snapped inode is reached
 * (for_wire) or the root inode is reached (!for_wire).
 *
 * Encode hidden .snap dirs as a double /, i.e.
 *   foo/.snap/bar -> foo//bar
 */
char *ceph_mdsc_build_path(struct ceph_mds_client *mdsc, struct dentry *dentry,
                           struct ceph_path_info *path_info, int for_wire)
{
        struct ceph_client *cl = mdsc->fsc->client;
        struct dentry *cur;
        struct inode *inode;
        char *path;
        int pos;
        unsigned seq;
        u64 base;

        if (!dentry)
                return ERR_PTR(-EINVAL);

        path = __getname();
        if (!path)
                return ERR_PTR(-ENOMEM);
retry:
        pos = PATH_MAX - 1;
        path[pos] = '\0';

        seq = read_seqbegin(&rename_lock);
        cur = dget(dentry);
        for (;;) {
                struct dentry *parent;

                spin_lock(&cur->d_lock);
                inode = d_inode(cur);
                if (inode && ceph_snap(inode) == CEPH_SNAPDIR) {
                        doutc(cl, "path+%d: %p SNAPDIR\n", pos, cur);
                        spin_unlock(&cur->d_lock);
                        parent = dget_parent(cur);
                } else if (for_wire && inode && dentry != cur &&
                           ceph_snap(inode) == CEPH_NOSNAP) {
                        spin_unlock(&cur->d_lock);
                        pos++; /* get rid of any prepended '/' */
                        break;
                } else if (!for_wire || !IS_ENCRYPTED(d_inode(cur->d_parent))) {
                        pos -= cur->d_name.len;
                        if (pos < 0) {
                                spin_unlock(&cur->d_lock);
                                break;
                        }
                        memcpy(path + pos, cur->d_name.name, cur->d_name.len);
                        spin_unlock(&cur->d_lock);
                        parent = dget_parent(cur);
                } else {
                        int len, ret;
                        char buf[NAME_MAX];

                        /*
                         * Proactively copy name into buf, in case we need to
                         * present it as-is.
                         */
                        memcpy(buf, cur->d_name.name, cur->d_name.len);
                        len = cur->d_name.len;
                        spin_unlock(&cur->d_lock);
                        parent = dget_parent(cur);

                        ret = ceph_fscrypt_prepare_readdir(d_inode(parent));
                        if (ret < 0) {
                                dput(parent);
                                dput(cur);
                                return ERR_PTR(ret);
                        }

                        if (fscrypt_has_encryption_key(d_inode(parent))) {
                                len = ceph_encode_encrypted_dname(d_inode(parent),
                                                                  buf, len);
                                if (len < 0) {
                                        dput(parent);
                                        dput(cur);
                                        return ERR_PTR(len);
                                }
                        }
                        pos -= len;
                        if (pos < 0) {
                                dput(parent);
                                break;
                        }
                        memcpy(path + pos, buf, len);
                }
                dput(cur);
                cur = parent;

                /* Are we at the root? */
                if (IS_ROOT(cur))
                        break;

                /* Are we out of buffer? */
                if (--pos < 0)
                        break;

                path[pos] = '/';
        }
        inode = d_inode(cur);
        base = inode ? ceph_ino(inode) : 0;
        dput(cur);

        if (read_seqretry(&rename_lock, seq))
                goto retry;

        if (pos < 0) {
                /*
                 * The path is longer than PATH_MAX and this function
                 * cannot ever succeed.  Creating paths that long is
                 * possible with Ceph, but Linux cannot use them.
                 */
                return ERR_PTR(-ENAMETOOLONG);
        }

        /* Initialize the output structure */
        memset(path_info, 0, sizeof(*path_info));

        path_info->vino.ino = base;
        path_info->pathlen = PATH_MAX - 1 - pos;
        path_info->path = path + pos;
        path_info->freepath = true;

        /* Set snap from dentry if available */
        if (d_inode(dentry))
                path_info->vino.snap = ceph_snap(d_inode(dentry));
        else
                path_info->vino.snap = CEPH_NOSNAP;

        doutc(cl, "on %p %d built %llx '%.*s'\n", dentry, d_count(dentry),
              base, PATH_MAX - 1 - pos, path + pos);
        return path + pos;
}

static int build_dentry_path(struct ceph_mds_client *mdsc, struct dentry *dentry,
                             struct inode *dir, struct ceph_path_info *path_info,
                             bool parent_locked)
{
        char *path;

        rcu_read_lock();
        if (!dir)
                dir = d_inode_rcu(dentry->d_parent);
        if (dir && parent_locked && ceph_snap(dir) == CEPH_NOSNAP &&
            !IS_ENCRYPTED(dir)) {
                path_info->vino.ino = ceph_ino(dir);
                path_info->vino.snap = ceph_snap(dir);
                rcu_read_unlock();
                path_info->path = dentry->d_name.name;
                path_info->pathlen = dentry->d_name.len;
                path_info->freepath = false;
                return 0;
        }
        rcu_read_unlock();
        path = ceph_mdsc_build_path(mdsc, dentry, path_info, 1);
        if (IS_ERR(path))
                return PTR_ERR(path);
        /*
         * ceph_mdsc_build_path already fills path_info, including snap handling.
         */
        return 0;
}

static int build_inode_path(struct inode *inode, struct ceph_path_info *path_info)
{
        struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb);
        struct dentry *dentry;
        char *path;

        if (ceph_snap(inode) == CEPH_NOSNAP) {
                path_info->vino.ino = ceph_ino(inode);
                path_info->vino.snap = ceph_snap(inode);
                path_info->pathlen = 0;
                path_info->freepath = false;
                return 0;
        }
        dentry = d_find_alias(inode);
        path = ceph_mdsc_build_path(mdsc, dentry, path_info, 1);
        dput(dentry);
        if (IS_ERR(path))
                return PTR_ERR(path);
        /*
         * ceph_mdsc_build_path already fills path_info, including snap from dentry.
         * Override with inode's snap since that's what this function is for.
         */
        path_info->vino.snap = ceph_snap(inode);
        return 0;
}

/*
 * request arguments may be specified via an inode *, a dentry *, or
 * an explicit ino+path.
 */
static int set_request_path_attr(struct ceph_mds_client *mdsc, struct inode *rinode,
                                 struct dentry *rdentry, struct inode *rdiri,
                                 const char *rpath, u64 rino,
                                 struct ceph_path_info *path_info,
                                 bool parent_locked)
{
        struct ceph_client *cl = mdsc->fsc->client;
        int r = 0;

        /* Initialize the output structure */
        memset(path_info, 0, sizeof(*path_info));

        if (rinode) {
                r = build_inode_path(rinode, path_info);
                doutc(cl, " inode %p %llx.%llx\n", rinode, ceph_ino(rinode),
                      ceph_snap(rinode));
        } else if (rdentry) {
                r = build_dentry_path(mdsc, rdentry, rdiri, path_info, parent_locked);
                doutc(cl, " dentry %p %llx/%.*s\n", rdentry, path_info->vino.ino,
                      path_info->pathlen, path_info->path);
        } else if (rpath || rino) {
                path_info->vino.ino = rino;
                path_info->vino.snap = CEPH_NOSNAP;
                path_info->path = rpath;
                path_info->pathlen = rpath ? strlen(rpath) : 0;
                path_info->freepath = false;

                doutc(cl, " path %.*s\n", path_info->pathlen, rpath);
        }

        return r;
}

static void encode_mclientrequest_tail(void **p,
                                       const struct ceph_mds_request *req)
{
        struct ceph_timespec ts;
        int i;

        ceph_encode_timespec64(&ts, &req->r_stamp);
        ceph_encode_copy(p, &ts, sizeof(ts));

        /* v4: gid_list */
        ceph_encode_32(p, req->r_cred->group_info->ngroups);
        for (i = 0; i < req->r_cred->group_info->ngroups; i++)
                ceph_encode_64(p, from_kgid(&init_user_ns,
                                            req->r_cred->group_info->gid[i]));

        /* v5: altname */
        ceph_encode_32(p, req->r_altname_len);
        ceph_encode_copy(p, req->r_altname, req->r_altname_len);

        /* v6: fscrypt_auth and fscrypt_file */
        if (req->r_fscrypt_auth) {
                u32 authlen = ceph_fscrypt_auth_len(req->r_fscrypt_auth);

                ceph_encode_32(p, authlen);
                ceph_encode_copy(p, req->r_fscrypt_auth, authlen);
        } else {
                ceph_encode_32(p, 0);
        }
        if (test_bit(CEPH_MDS_R_FSCRYPT_FILE, &req->r_req_flags)) {
                ceph_encode_32(p, sizeof(__le64));
                ceph_encode_64(p, req->r_fscrypt_file);
        } else {
                ceph_encode_32(p, 0);
        }
}

static inline u16 mds_supported_head_version(struct ceph_mds_session *session)
{
        if (!test_bit(CEPHFS_FEATURE_32BITS_RETRY_FWD, &session->s_features))
                return 1;

        if (!test_bit(CEPHFS_FEATURE_HAS_OWNER_UIDGID, &session->s_features))
                return 2;

        return CEPH_MDS_REQUEST_HEAD_VERSION;
}

static struct ceph_mds_request_head_legacy *
find_legacy_request_head(void *p, u64 features)
{
        bool legacy = !(features & CEPH_FEATURE_FS_BTIME);
        struct ceph_mds_request_head *head;

        if (legacy)
                return (struct ceph_mds_request_head_legacy *)p;
        head = (struct ceph_mds_request_head *)p;
        return (struct ceph_mds_request_head_legacy *)&head->oldest_client_tid;
}

/*
 * called under mdsc->mutex
 */
static struct ceph_msg *create_request_message(struct ceph_mds_session *session,
                                               struct ceph_mds_request *req,
                                               bool drop_cap_releases)
{
        int mds = session->s_mds;
        struct ceph_mds_client *mdsc = session->s_mdsc;
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_msg *msg;
        struct ceph_mds_request_head_legacy *lhead;
        struct ceph_path_info path_info1 = {0};
        struct ceph_path_info path_info2 = {0};
        struct dentry *old_dentry = NULL;
        int len;
        u16 releases;
        void *p, *end;
        int ret;
        bool legacy = !(session->s_con.peer_features & CEPH_FEATURE_FS_BTIME);
        u16 request_head_version = mds_supported_head_version(session);
        kuid_t caller_fsuid = req->r_cred->fsuid;
        kgid_t caller_fsgid = req->r_cred->fsgid;
        bool parent_locked = test_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);

        ret = set_request_path_attr(mdsc, req->r_inode, req->r_dentry,
                                    req->r_parent, req->r_path1, req->r_ino1.ino,
                                    &path_info1, parent_locked);
        if (ret < 0) {
                msg = ERR_PTR(ret);
                goto out;
        }

        /*
         * When the parent directory's i_rwsem is *not* locked, req->r_parent may
         * have become stale (e.g. after a concurrent rename) between the time the
         * dentry was looked up and now.  If we detect that the stored r_parent
         * does not match the inode number we just encoded for the request, switch
         * to the correct inode so that the MDS receives a valid parent reference.
         */
        if (!parent_locked && req->r_parent && path_info1.vino.ino &&
            ceph_ino(req->r_parent) != path_info1.vino.ino) {
                struct inode *old_parent = req->r_parent;
                struct inode *correct_dir = ceph_get_inode(mdsc->fsc->sb, path_info1.vino, NULL);
                if (!IS_ERR(correct_dir)) {
                        WARN_ONCE(1, "ceph: r_parent mismatch (had %llx wanted %llx) - updating\n",
                                  ceph_ino(old_parent), path_info1.vino.ino);
                        /*
                         * Transfer CEPH_CAP_PIN from the old parent to the new one.
                         * The pin was taken earlier in ceph_mdsc_submit_request().
                         */
                        ceph_put_cap_refs(ceph_inode(old_parent), CEPH_CAP_PIN);
                        iput(old_parent);
                        req->r_parent = correct_dir;
                        ceph_get_cap_refs(ceph_inode(req->r_parent), CEPH_CAP_PIN);
                }
        }

        /* If r_old_dentry is set, then assume that its parent is locked */
        if (req->r_old_dentry &&
            !(req->r_old_dentry->d_flags & DCACHE_DISCONNECTED))
                old_dentry = req->r_old_dentry;
        ret = set_request_path_attr(mdsc, NULL, old_dentry,
                                    req->r_old_dentry_dir,
                                    req->r_path2, req->r_ino2.ino,
                                    &path_info2, true);
        if (ret < 0) {
                msg = ERR_PTR(ret);
                goto out_free1;
        }

        req->r_altname = get_fscrypt_altname(req, &req->r_altname_len);
        if (IS_ERR(req->r_altname)) {
                msg = ERR_CAST(req->r_altname);
                req->r_altname = NULL;
                goto out_free2;
        }

        /*
         * For old cephs without supporting the 32bit retry/fwd feature
         * it will copy the raw memories directly when decoding the
         * requests. While new cephs will decode the head depending the
         * version member, so we need to make sure it will be compatible
         * with them both.
         */
        if (legacy)
                len = sizeof(struct ceph_mds_request_head_legacy);
        else if (request_head_version == 1)
                len = offsetofend(struct ceph_mds_request_head, args);
        else if (request_head_version == 2)
                len = offsetofend(struct ceph_mds_request_head, ext_num_fwd);
        else
                len = sizeof(struct ceph_mds_request_head);

        /* filepaths */
        len += 2 * (1 + sizeof(u32) + sizeof(u64));
        len += path_info1.pathlen + path_info2.pathlen;

        /* cap releases */
        len += sizeof(struct ceph_mds_request_release) *
                (!!req->r_inode_drop + !!req->r_dentry_drop +
                 !!req->r_old_inode_drop + !!req->r_old_dentry_drop);

        if (req->r_dentry_drop)
                len += path_info1.pathlen;
        if (req->r_old_dentry_drop)
                len += path_info2.pathlen;

        /* MClientRequest tail */

        /* req->r_stamp */
        len += sizeof(struct ceph_timespec);

        /* gid list */
        len += sizeof(u32) + (sizeof(u64) * req->r_cred->group_info->ngroups);

        /* alternate name */
        len += sizeof(u32) + req->r_altname_len;

        /* fscrypt_auth */
        len += sizeof(u32); // fscrypt_auth
        if (req->r_fscrypt_auth)
                len += ceph_fscrypt_auth_len(req->r_fscrypt_auth);

        /* fscrypt_file */
        len += sizeof(u32);
        if (test_bit(CEPH_MDS_R_FSCRYPT_FILE, &req->r_req_flags))
                len += sizeof(__le64);

        msg = ceph_msg_new2(CEPH_MSG_CLIENT_REQUEST, len, 1, GFP_NOFS, false);
        if (!msg) {
                msg = ERR_PTR(-ENOMEM);
                goto out_free2;
        }

        msg->hdr.tid = cpu_to_le64(req->r_tid);

        lhead = find_legacy_request_head(msg->front.iov_base,
                                         session->s_con.peer_features);

        if ((req->r_mnt_idmap != &nop_mnt_idmap) &&
            !test_bit(CEPHFS_FEATURE_HAS_OWNER_UIDGID, &session->s_features)) {
                WARN_ON_ONCE(!IS_CEPH_MDS_OP_NEWINODE(req->r_op));

                if (enable_unsafe_idmap) {
                        pr_warn_once_client(cl,
                                "idmapped mount is used and CEPHFS_FEATURE_HAS_OWNER_UIDGID"
                                " is not supported by MDS. UID/GID-based restrictions may"
                                " not work properly.\n");

                        caller_fsuid = from_vfsuid(req->r_mnt_idmap, &init_user_ns,
                                                   VFSUIDT_INIT(req->r_cred->fsuid));
                        caller_fsgid = from_vfsgid(req->r_mnt_idmap, &init_user_ns,
                                                   VFSGIDT_INIT(req->r_cred->fsgid));
                } else {
                        pr_err_ratelimited_client(cl,
                                "idmapped mount is used and CEPHFS_FEATURE_HAS_OWNER_UIDGID"
                                " is not supported by MDS. Fail request with -EIO.\n");

                        ret = -EIO;
                        goto out_err;
                }
        }

        /*
         * The ceph_mds_request_head_legacy didn't contain a version field, and
         * one was added when we moved the message version from 3->4.
         */
        if (legacy) {
                msg->hdr.version = cpu_to_le16(3);
                p = msg->front.iov_base + sizeof(*lhead);
        } else if (request_head_version == 1) {
                struct ceph_mds_request_head *nhead = msg->front.iov_base;

                msg->hdr.version = cpu_to_le16(4);
                nhead->version = cpu_to_le16(1);
                p = msg->front.iov_base + offsetofend(struct ceph_mds_request_head, args);
        } else if (request_head_version == 2) {
                struct ceph_mds_request_head *nhead = msg->front.iov_base;

                msg->hdr.version = cpu_to_le16(6);
                nhead->version = cpu_to_le16(2);

                p = msg->front.iov_base + offsetofend(struct ceph_mds_request_head, ext_num_fwd);
        } else {
                struct ceph_mds_request_head *nhead = msg->front.iov_base;
                kuid_t owner_fsuid;
                kgid_t owner_fsgid;

                msg->hdr.version = cpu_to_le16(6);
                nhead->version = cpu_to_le16(CEPH_MDS_REQUEST_HEAD_VERSION);
                nhead->struct_len = cpu_to_le32(sizeof(struct ceph_mds_request_head));

                if (IS_CEPH_MDS_OP_NEWINODE(req->r_op)) {
                        owner_fsuid = from_vfsuid(req->r_mnt_idmap, &init_user_ns,
                                                VFSUIDT_INIT(req->r_cred->fsuid));
                        owner_fsgid = from_vfsgid(req->r_mnt_idmap, &init_user_ns,
                                                VFSGIDT_INIT(req->r_cred->fsgid));
                        nhead->owner_uid = cpu_to_le32(from_kuid(&init_user_ns, owner_fsuid));
                        nhead->owner_gid = cpu_to_le32(from_kgid(&init_user_ns, owner_fsgid));
                } else {
                        nhead->owner_uid = cpu_to_le32(-1);
                        nhead->owner_gid = cpu_to_le32(-1);
                }

                p = msg->front.iov_base + sizeof(*nhead);
        }

        end = msg->front.iov_base + msg->front.iov_len;

        lhead->mdsmap_epoch = cpu_to_le32(mdsc->mdsmap->m_epoch);
        lhead->op = cpu_to_le32(req->r_op);
        lhead->caller_uid = cpu_to_le32(from_kuid(&init_user_ns,
                                                  caller_fsuid));
        lhead->caller_gid = cpu_to_le32(from_kgid(&init_user_ns,
                                                  caller_fsgid));
        lhead->ino = cpu_to_le64(req->r_deleg_ino);
        lhead->args = req->r_args;

        ceph_encode_filepath(&p, end, path_info1.vino.ino, path_info1.path);
        ceph_encode_filepath(&p, end, path_info2.vino.ino, path_info2.path);

        /* make note of release offset, in case we need to replay */
        req->r_request_release_offset = p - msg->front.iov_base;

        /* cap releases */
        releases = 0;
        if (req->r_inode_drop)
                releases += ceph_encode_inode_release(&p,
                      req->r_inode ? req->r_inode : d_inode(req->r_dentry),
                      mds, req->r_inode_drop, req->r_inode_unless,
                      req->r_op == CEPH_MDS_OP_READDIR);
        if (req->r_dentry_drop) {
                ret = ceph_encode_dentry_release(&p, req->r_dentry,
                                req->r_parent, mds, req->r_dentry_drop,
                                req->r_dentry_unless);
                if (ret < 0)
                        goto out_err;
                releases += ret;
        }
        if (req->r_old_dentry_drop) {
                ret = ceph_encode_dentry_release(&p, req->r_old_dentry,
                                req->r_old_dentry_dir, mds,
                                req->r_old_dentry_drop,
                                req->r_old_dentry_unless);
                if (ret < 0)
                        goto out_err;
                releases += ret;
        }
        if (req->r_old_inode_drop)
                releases += ceph_encode_inode_release(&p,
                      d_inode(req->r_old_dentry),
                      mds, req->r_old_inode_drop, req->r_old_inode_unless, 0);

        if (drop_cap_releases) {
                releases = 0;
                p = msg->front.iov_base + req->r_request_release_offset;
        }

        lhead->num_releases = cpu_to_le16(releases);

        encode_mclientrequest_tail(&p, req);

        if (WARN_ON_ONCE(p > end)) {
                ceph_msg_put(msg);
                msg = ERR_PTR(-ERANGE);
                goto out_free2;
        }

        msg->front.iov_len = p - msg->front.iov_base;
        msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);

        if (req->r_pagelist) {
                struct ceph_pagelist *pagelist = req->r_pagelist;
                ceph_msg_data_add_pagelist(msg, pagelist);
                msg->hdr.data_len = cpu_to_le32(pagelist->length);
        } else {
                msg->hdr.data_len = 0;
        }

        msg->hdr.data_off = cpu_to_le16(0);

out_free2:
        ceph_mdsc_free_path_info(&path_info2);
out_free1:
        ceph_mdsc_free_path_info(&path_info1);
out:
        return msg;
out_err:
        ceph_msg_put(msg);
        msg = ERR_PTR(ret);
        goto out_free2;
}

/*
 * called under mdsc->mutex if error, under no mutex if
 * success.
 */
static void complete_request(struct ceph_mds_client *mdsc,
                             struct ceph_mds_request *req)
{
        req->r_end_latency = ktime_get();

        if (req->r_callback)
                req->r_callback(mdsc, req);
        complete_all(&req->r_completion);
}

/*
 * called under mdsc->mutex
 */
static int __prepare_send_request(struct ceph_mds_session *session,
                                  struct ceph_mds_request *req,
                                  bool drop_cap_releases)
{
        int mds = session->s_mds;
        struct ceph_mds_client *mdsc = session->s_mdsc;
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_mds_request_head_legacy *lhead;
        struct ceph_mds_request_head *nhead;
        struct ceph_msg *msg;
        int flags = 0, old_max_retry;
        bool old_version = !test_bit(CEPHFS_FEATURE_32BITS_RETRY_FWD,
                                     &session->s_features);

        /*
         * Avoid infinite retrying after overflow. The client will
         * increase the retry count and if the MDS is old version,
         * so we limit to retry at most 256 times.
         */
        if (req->r_attempts) {
               old_max_retry = sizeof_field(struct ceph_mds_request_head,
                                            num_retry);
               old_max_retry = 1 << (old_max_retry * BITS_PER_BYTE);
               if ((old_version && req->r_attempts >= old_max_retry) ||
                   ((uint32_t)req->r_attempts >= U32_MAX)) {
                        pr_warn_ratelimited_client(cl, "request tid %llu seq overflow\n",
                                                   req->r_tid);
                        return -EMULTIHOP;
               }
        }

        req->r_attempts++;
        if (req->r_inode) {
                struct ceph_cap *cap =
                        ceph_get_cap_for_mds(ceph_inode(req->r_inode), mds);

                if (cap)
                        req->r_sent_on_mseq = cap->mseq;
                else
                        req->r_sent_on_mseq = -1;
        }
        doutc(cl, "%p tid %lld %s (attempt %d)\n", req, req->r_tid,
              ceph_mds_op_name(req->r_op), req->r_attempts);

        if (test_bit(CEPH_MDS_R_GOT_UNSAFE, &req->r_req_flags)) {
                void *p;

                /*
                 * Replay.  Do not regenerate message (and rebuild
                 * paths, etc.); just use the original message.
                 * Rebuilding paths will break for renames because
                 * d_move mangles the src name.
                 */
                msg = req->r_request;
                lhead = find_legacy_request_head(msg->front.iov_base,
                                                 session->s_con.peer_features);

                flags = le32_to_cpu(lhead->flags);
                flags |= CEPH_MDS_FLAG_REPLAY;
                lhead->flags = cpu_to_le32(flags);

                if (req->r_target_inode)
                        lhead->ino = cpu_to_le64(ceph_ino(req->r_target_inode));

                lhead->num_retry = req->r_attempts - 1;
                if (!old_version) {
                        nhead = (struct ceph_mds_request_head*)msg->front.iov_base;
                        nhead->ext_num_retry = cpu_to_le32(req->r_attempts - 1);
                }

                /* remove cap/dentry releases from message */
                lhead->num_releases = 0;

                p = msg->front.iov_base + req->r_request_release_offset;
                encode_mclientrequest_tail(&p, req);

                msg->front.iov_len = p - msg->front.iov_base;
                msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);
                return 0;
        }

        if (req->r_request) {
                ceph_msg_put(req->r_request);
                req->r_request = NULL;
        }
        msg = create_request_message(session, req, drop_cap_releases);
        if (IS_ERR(msg)) {
                req->r_err = PTR_ERR(msg);
                return PTR_ERR(msg);
        }
        req->r_request = msg;

        lhead = find_legacy_request_head(msg->front.iov_base,
                                         session->s_con.peer_features);
        lhead->oldest_client_tid = cpu_to_le64(__get_oldest_tid(mdsc));
        if (test_bit(CEPH_MDS_R_GOT_UNSAFE, &req->r_req_flags))
                flags |= CEPH_MDS_FLAG_REPLAY;
        if (test_bit(CEPH_MDS_R_ASYNC, &req->r_req_flags))
                flags |= CEPH_MDS_FLAG_ASYNC;
        if (req->r_parent)
                flags |= CEPH_MDS_FLAG_WANT_DENTRY;
        lhead->flags = cpu_to_le32(flags);
        lhead->num_fwd = req->r_num_fwd;
        lhead->num_retry = req->r_attempts - 1;
        if (!old_version) {
                nhead = (struct ceph_mds_request_head*)msg->front.iov_base;
                nhead->ext_num_fwd = cpu_to_le32(req->r_num_fwd);
                nhead->ext_num_retry = cpu_to_le32(req->r_attempts - 1);
        }

        doutc(cl, " r_parent = %p\n", req->r_parent);
        return 0;
}

/*
 * called under mdsc->mutex
 */
static int __send_request(struct ceph_mds_session *session,
                          struct ceph_mds_request *req,
                          bool drop_cap_releases)
{
        int err;

        err = __prepare_send_request(session, req, drop_cap_releases);
        if (!err) {
                ceph_msg_get(req->r_request);
                ceph_con_send(&session->s_con, req->r_request);
        }

        return err;
}

/*
 * send request, or put it on the appropriate wait list.
 */
static void __do_request(struct ceph_mds_client *mdsc,
                        struct ceph_mds_request *req)
{
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_mds_session *session = NULL;
        int mds = -1;
        int err = 0;
        bool random;

        if (req->r_err || test_bit(CEPH_MDS_R_GOT_RESULT, &req->r_req_flags)) {
                if (test_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags))
                        __unregister_request(mdsc, req);
                return;
        }

        if (READ_ONCE(mdsc->fsc->mount_state) == CEPH_MOUNT_FENCE_IO) {
                doutc(cl, "metadata corrupted\n");
                err = -EIO;
                goto finish;
        }
        if (req->r_timeout &&
            time_after_eq(jiffies, req->r_started + req->r_timeout)) {
                doutc(cl, "timed out\n");
                err = -ETIMEDOUT;
                goto finish;
        }
        if (READ_ONCE(mdsc->fsc->mount_state) == CEPH_MOUNT_SHUTDOWN) {
                doutc(cl, "forced umount\n");
                err = -EIO;
                goto finish;
        }
        if (READ_ONCE(mdsc->fsc->mount_state) == CEPH_MOUNT_MOUNTING) {
                if (mdsc->mdsmap_err) {
                        err = mdsc->mdsmap_err;
                        doutc(cl, "mdsmap err %d\n", err);
                        goto finish;
                }
                if (mdsc->mdsmap->m_epoch == 0) {
                        doutc(cl, "no mdsmap, waiting for map\n");
                        list_add(&req->r_wait, &mdsc->waiting_for_map);
                        return;
                }
                if (!(mdsc->fsc->mount_options->flags &
                      CEPH_MOUNT_OPT_MOUNTWAIT) &&
                    !ceph_mdsmap_is_cluster_available(mdsc->mdsmap)) {
                        err = -EHOSTUNREACH;
                        goto finish;
                }
        }

        put_request_session(req);

        mds = __choose_mds(mdsc, req, &random);
        if (mds < 0 ||
            ceph_mdsmap_get_state(mdsc->mdsmap, mds) < CEPH_MDS_STATE_ACTIVE) {
                if (test_bit(CEPH_MDS_R_ASYNC, &req->r_req_flags)) {
                        err = -EJUKEBOX;
                        goto finish;
                }
                doutc(cl, "no mds or not active, waiting for map\n");
                list_add(&req->r_wait, &mdsc->waiting_for_map);
                return;
        }

        /* get, open session */
        session = __ceph_lookup_mds_session(mdsc, mds);
        if (!session) {
                session = register_session(mdsc, mds);
                if (IS_ERR(session)) {
                        err = PTR_ERR(session);
                        goto finish;
                }
        }
        req->r_session = ceph_get_mds_session(session);

        doutc(cl, "mds%d session %p state %s\n", mds, session,
              ceph_session_state_name(session->s_state));

        /*
         * The old ceph will crash the MDSs when see unknown OPs
         */
        if (req->r_feature_needed > 0 &&
            !test_bit(req->r_feature_needed, &session->s_features)) {
                err = -EOPNOTSUPP;
                goto out_session;
        }

        if (session->s_state != CEPH_MDS_SESSION_OPEN &&
            session->s_state != CEPH_MDS_SESSION_HUNG) {
                /*
                 * We cannot queue async requests since the caps and delegated
                 * inodes are bound to the session. Just return -EJUKEBOX and
                 * let the caller retry a sync request in that case.
                 */
                if (test_bit(CEPH_MDS_R_ASYNC, &req->r_req_flags)) {
                        err = -EJUKEBOX;
                        goto out_session;
                }

                /*
                 * If the session has been REJECTED, then return a hard error,
                 * unless it's a CLEANRECOVER mount, in which case we'll queue
                 * it to the mdsc queue.
                 */
                if (session->s_state == CEPH_MDS_SESSION_REJECTED) {
                        if (ceph_test_mount_opt(mdsc->fsc, CLEANRECOVER))
                                list_add(&req->r_wait, &mdsc->waiting_for_map);
                        else
                                err = -EACCES;
                        goto out_session;
                }

                if (session->s_state == CEPH_MDS_SESSION_NEW ||
                    session->s_state == CEPH_MDS_SESSION_CLOSING) {
                        err = __open_session(mdsc, session);
                        if (err)
                                goto out_session;
                        /* retry the same mds later */
                        if (random)
                                req->r_resend_mds = mds;
                }
                list_add(&req->r_wait, &session->s_waiting);
                goto out_session;
        }

        /* send request */
        req->r_resend_mds = -1;   /* forget any previous mds hint */

        if (req->r_request_started == 0)   /* note request start time */
                req->r_request_started = jiffies;

        /*
         * For async create we will choose the auth MDS of frag in parent
         * directory to send the request and usually this works fine, but
         * if the migrated the dirtory to another MDS before it could handle
         * it the request will be forwarded.
         *
         * And then the auth cap will be changed.
         */
        if (test_bit(CEPH_MDS_R_ASYNC, &req->r_req_flags) && req->r_num_fwd) {
                struct ceph_dentry_info *di = ceph_dentry(req->r_dentry);
                struct ceph_inode_info *ci;
                struct ceph_cap *cap;

                /*
                 * The request maybe handled very fast and the new inode
                 * hasn't been linked to the dentry yet. We need to wait
                 * for the ceph_finish_async_create(), which shouldn't be
                 * stuck too long or fail in thoery, to finish when forwarding
                 * the request.
                 */
                if (!d_inode(req->r_dentry)) {
                        err = wait_on_bit(&di->flags, CEPH_DENTRY_ASYNC_CREATE_BIT,
                                          TASK_KILLABLE);
                        if (err) {
                                mutex_lock(&req->r_fill_mutex);
                                set_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags);
                                mutex_unlock(&req->r_fill_mutex);
                                goto out_session;
                        }
                }

                ci = ceph_inode(d_inode(req->r_dentry));

                spin_lock(&ci->i_ceph_lock);
                cap = ci->i_auth_cap;
                if (ci->i_ceph_flags & CEPH_I_ASYNC_CREATE && mds != cap->mds) {
                        doutc(cl, "session changed for auth cap %d -> %d\n",
                              cap->session->s_mds, session->s_mds);

                        /* Remove the auth cap from old session */
                        spin_lock(&cap->session->s_cap_lock);
                        cap->session->s_nr_caps--;
                        list_del_init(&cap->session_caps);
                        spin_unlock(&cap->session->s_cap_lock);

                        /* Add the auth cap to the new session */
                        cap->mds = mds;
                        cap->session = session;
                        spin_lock(&session->s_cap_lock);
                        session->s_nr_caps++;
                        list_add_tail(&cap->session_caps, &session->s_caps);
                        spin_unlock(&session->s_cap_lock);

                        change_auth_cap_ses(ci, session);
                }
                spin_unlock(&ci->i_ceph_lock);
        }

        err = __send_request(session, req, false);

out_session:
        ceph_put_mds_session(session);
finish:
        if (err) {
                doutc(cl, "early error %d\n", err);
                req->r_err = err;
                complete_request(mdsc, req);
                __unregister_request(mdsc, req);
        }
        return;
}

/*
 * called under mdsc->mutex
 */
static void __wake_requests(struct ceph_mds_client *mdsc,
                            struct list_head *head)
{
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_mds_request *req;
        LIST_HEAD(tmp_list);

        list_splice_init(head, &tmp_list);

        while (!list_empty(&tmp_list)) {
                req = list_entry(tmp_list.next,
                                 struct ceph_mds_request, r_wait);
                list_del_init(&req->r_wait);
                doutc(cl, " wake request %p tid %llu\n", req,
                      req->r_tid);
                __do_request(mdsc, req);
        }
}

/*
 * Wake up threads with requests pending for @mds, so that they can
 * resubmit their requests to a possibly different mds.
 */
static void kick_requests(struct ceph_mds_client *mdsc, int mds)
{
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_mds_request *req;
        struct rb_node *p = rb_first(&mdsc->request_tree);

        doutc(cl, "kick_requests mds%d\n", mds);
        while (p) {
                req = rb_entry(p, struct ceph_mds_request, r_node);
                p = rb_next(p);
                if (test_bit(CEPH_MDS_R_GOT_UNSAFE, &req->r_req_flags))
                        continue;
                if (req->r_attempts > 0)
                        continue; /* only new requests */
                if (req->r_session &&
                    req->r_session->s_mds == mds) {
                        doutc(cl, " kicking tid %llu\n", req->r_tid);
                        list_del_init(&req->r_wait);
                        __do_request(mdsc, req);
                }
        }
}

int ceph_mdsc_submit_request(struct ceph_mds_client *mdsc, struct inode *dir,
                              struct ceph_mds_request *req)
{
        struct ceph_client *cl = mdsc->fsc->client;
        int err = 0;

        /* take CAP_PIN refs for r_inode, r_parent, r_old_dentry */
        if (req->r_inode)
                ceph_get_cap_refs(ceph_inode(req->r_inode), CEPH_CAP_PIN);
        if (req->r_parent) {
                struct ceph_inode_info *ci = ceph_inode(req->r_parent);
                int fmode = (req->r_op & CEPH_MDS_OP_WRITE) ?
                            CEPH_FILE_MODE_WR : CEPH_FILE_MODE_RD;
                spin_lock(&ci->i_ceph_lock);
                ceph_take_cap_refs(ci, CEPH_CAP_PIN, false);
                __ceph_touch_fmode(ci, mdsc, fmode);
                spin_unlock(&ci->i_ceph_lock);
        }
        if (req->r_old_dentry_dir)
                ceph_get_cap_refs(ceph_inode(req->r_old_dentry_dir),
                                  CEPH_CAP_PIN);

        if (req->r_inode) {
                err = ceph_wait_on_async_create(req->r_inode);
                if (err) {
                        doutc(cl, "wait for async create returned: %d\n", err);
                        return err;
                }
        }

        if (!err && req->r_old_inode) {
                err = ceph_wait_on_async_create(req->r_old_inode);
                if (err) {
                        doutc(cl, "wait for async create returned: %d\n", err);
                        return err;
                }
        }

        doutc(cl, "submit_request on %p for inode %p\n", req, dir);
        mutex_lock(&mdsc->mutex);
        __register_request(mdsc, req, dir);
        __do_request(mdsc, req);
        err = req->r_err;
        mutex_unlock(&mdsc->mutex);
        return err;
}

int ceph_mdsc_wait_request(struct ceph_mds_client *mdsc,
                           struct ceph_mds_request *req,
                           ceph_mds_request_wait_callback_t wait_func)
{
        struct ceph_client *cl = mdsc->fsc->client;
        int err;

        /* wait */
        doutc(cl, "do_request waiting\n");
        if (wait_func) {
                err = wait_func(mdsc, req);
        } else {
                long timeleft = wait_for_completion_killable_timeout(
                                        &req->r_completion,
                                        ceph_timeout_jiffies(req->r_timeout));
                if (timeleft > 0)
                        err = 0;
                else if (!timeleft)
                        err = -ETIMEDOUT;  /* timed out */
                else
                        err = timeleft;  /* killed */
        }
        doutc(cl, "do_request waited, got %d\n", err);
        mutex_lock(&mdsc->mutex);

        /* only abort if we didn't race with a real reply */
        if (test_bit(CEPH_MDS_R_GOT_RESULT, &req->r_req_flags)) {
                err = le32_to_cpu(req->r_reply_info.head->result);
        } else if (err < 0) {
                doutc(cl, "aborted request %lld with %d\n", req->r_tid, err);

                /*
                 * ensure we aren't running concurrently with
                 * ceph_fill_trace or ceph_readdir_prepopulate, which
                 * rely on locks (dir mutex) held by our caller.
                 */
                mutex_lock(&req->r_fill_mutex);
                req->r_err = err;
                set_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags);
                mutex_unlock(&req->r_fill_mutex);

                if (req->r_parent &&
                    (req->r_op & CEPH_MDS_OP_WRITE))
                        ceph_invalidate_dir_request(req);
        } else {
                err = req->r_err;
        }

        mutex_unlock(&mdsc->mutex);
        return err;
}

/*
 * Synchrously perform an mds request.  Take care of all of the
 * session setup, forwarding, retry details.
 */
int ceph_mdsc_do_request(struct ceph_mds_client *mdsc,
                         struct inode *dir,
                         struct ceph_mds_request *req)
{
        struct ceph_client *cl = mdsc->fsc->client;
        int err;

        doutc(cl, "do_request on %p\n", req);

        /* issue */
        err = ceph_mdsc_submit_request(mdsc, dir, req);
        if (!err)
                err = ceph_mdsc_wait_request(mdsc, req, NULL);
        doutc(cl, "do_request %p done, result %d\n", req, err);
        return err;
}

/*
 * Invalidate dir's completeness, dentry lease state on an aborted MDS
 * namespace request.
 */
void ceph_invalidate_dir_request(struct ceph_mds_request *req)
{
        struct inode *dir = req->r_parent;
        struct inode *old_dir = req->r_old_dentry_dir;
        struct ceph_client *cl = req->r_mdsc->fsc->client;

        doutc(cl, "invalidate_dir_request %p %p (complete, lease(s))\n",
              dir, old_dir);

        ceph_dir_clear_complete(dir);
        if (old_dir)
                ceph_dir_clear_complete(old_dir);
        if (req->r_dentry)
                ceph_invalidate_dentry_lease(req->r_dentry);
        if (req->r_old_dentry)
                ceph_invalidate_dentry_lease(req->r_old_dentry);
}

/*
 * Handle mds reply.
 *
 * We take the session mutex and parse and process the reply immediately.
 * This preserves the logical ordering of replies, capabilities, etc., sent
 * by the MDS as they are applied to our local cache.
 */
static void handle_reply(struct ceph_mds_session *session, struct ceph_msg *msg)
{
        struct ceph_mds_client *mdsc = session->s_mdsc;
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_mds_request *req;
        struct ceph_mds_reply_head *head = msg->front.iov_base;
        struct ceph_mds_reply_info_parsed *rinfo;  /* parsed reply info */
        struct ceph_snap_realm *realm;
        u64 tid;
        int err, result;
        int mds = session->s_mds;
        bool close_sessions = false;

        if (msg->front.iov_len < sizeof(*head)) {
                pr_err_client(cl, "got corrupt (short) reply\n");
                ceph_msg_dump(msg);
                return;
        }

        /* get request, session */
        tid = le64_to_cpu(msg->hdr.tid);
        mutex_lock(&mdsc->mutex);
        req = lookup_get_request(mdsc, tid);
        if (!req) {
                doutc(cl, "on unknown tid %llu\n", tid);
                mutex_unlock(&mdsc->mutex);
                return;
        }
        doutc(cl, "handle_reply %p\n", req);

        /* correct session? */
        if (req->r_session != session) {
                pr_err_client(cl, "got %llu on session mds%d not mds%d\n",
                              tid, session->s_mds,
                              req->r_session ? req->r_session->s_mds : -1);
                mutex_unlock(&mdsc->mutex);
                goto out;
        }

        /* dup? */
        if ((test_bit(CEPH_MDS_R_GOT_UNSAFE, &req->r_req_flags) && !head->safe) ||
            (test_bit(CEPH_MDS_R_GOT_SAFE, &req->r_req_flags) && head->safe)) {
                pr_warn_client(cl, "got a dup %s reply on %llu from mds%d\n",
                               head->safe ? "safe" : "unsafe", tid, mds);
                mutex_unlock(&mdsc->mutex);
                goto out;
        }
        if (test_bit(CEPH_MDS_R_GOT_SAFE, &req->r_req_flags)) {
                pr_warn_client(cl, "got unsafe after safe on %llu from mds%d\n",
                               tid, mds);
                mutex_unlock(&mdsc->mutex);
                goto out;
        }

        result = le32_to_cpu(head->result);

        if (head->safe) {
                set_bit(CEPH_MDS_R_GOT_SAFE, &req->r_req_flags);
                __unregister_request(mdsc, req);

                /* last request during umount? */
                if (mdsc->stopping && !__get_oldest_req(mdsc))
                        complete_all(&mdsc->safe_umount_waiters);

                if (test_bit(CEPH_MDS_R_GOT_UNSAFE, &req->r_req_flags)) {
                        /*
                         * We already handled the unsafe response, now do the
                         * cleanup.  No need to examine the response; the MDS
                         * doesn't include any result info in the safe
                         * response.  And even if it did, there is nothing
                         * useful we could do with a revised return value.
                         */
                        doutc(cl, "got safe reply %llu, mds%d\n", tid, mds);

                        mutex_unlock(&mdsc->mutex);
                        goto out;
                }
        } else {
                set_bit(CEPH_MDS_R_GOT_UNSAFE, &req->r_req_flags);
                list_add_tail(&req->r_unsafe_item, &req->r_session->s_unsafe);
        }

        doutc(cl, "tid %lld result %d\n", tid, result);
        if (test_bit(CEPHFS_FEATURE_REPLY_ENCODING, &session->s_features))
                err = parse_reply_info(session, msg, req, (u64)-1);
        else
                err = parse_reply_info(session, msg, req,
                                       session->s_con.peer_features);
        mutex_unlock(&mdsc->mutex);

        /* Must find target inode outside of mutexes to avoid deadlocks */
        rinfo = &req->r_reply_info;
        if ((err >= 0) && rinfo->head->is_target) {
                struct inode *in = xchg(&req->r_new_inode, NULL);
                struct ceph_vino tvino = {
                        .ino  = le64_to_cpu(rinfo->targeti.in->ino),
                        .snap = le64_to_cpu(rinfo->targeti.in->snapid)
                };

                /*
                 * If we ended up opening an existing inode, discard
                 * r_new_inode
                 */
                if (req->r_op == CEPH_MDS_OP_CREATE &&
                    !req->r_reply_info.has_create_ino) {
                        /* This should never happen on an async create */
                        WARN_ON_ONCE(req->r_deleg_ino);
                        iput(in);
                        in = NULL;
                }

                in = ceph_get_inode(mdsc->fsc->sb, tvino, in);
                if (IS_ERR(in)) {
                        err = PTR_ERR(in);
                        mutex_lock(&session->s_mutex);
                        goto out_err;
                }
                req->r_target_inode = in;
        }

        mutex_lock(&session->s_mutex);
        if (err < 0) {
                pr_err_client(cl, "got corrupt reply mds%d(tid:%lld)\n",
                              mds, tid);
                ceph_msg_dump(msg);
                goto out_err;
        }

        /* snap trace */
        realm = NULL;
        if (rinfo->snapblob_len) {
                down_write(&mdsc->snap_rwsem);
                err = ceph_update_snap_trace(mdsc, rinfo->snapblob,
                                rinfo->snapblob + rinfo->snapblob_len,
                                le32_to_cpu(head->op) == CEPH_MDS_OP_RMSNAP,
                                &realm);
                if (err) {
                        up_write(&mdsc->snap_rwsem);
                        close_sessions = true;
                        if (err == -EIO)
                                ceph_msg_dump(msg);
                        goto out_err;
                }
                downgrade_write(&mdsc->snap_rwsem);
        } else {
                down_read(&mdsc->snap_rwsem);
        }

        /* insert trace into our cache */
        mutex_lock(&req->r_fill_mutex);
        current->journal_info = req;
        err = ceph_fill_trace(mdsc->fsc->sb, req);
        if (err == 0) {
                if (result == 0 && (req->r_op == CEPH_MDS_OP_READDIR ||
                                    req->r_op == CEPH_MDS_OP_LSSNAP))
                        err = ceph_readdir_prepopulate(req, req->r_session);
        }
        current->journal_info = NULL;
        mutex_unlock(&req->r_fill_mutex);

        up_read(&mdsc->snap_rwsem);
        if (realm)
                ceph_put_snap_realm(mdsc, realm);

        if (err == 0) {
                if (req->r_target_inode &&
                    test_bit(CEPH_MDS_R_GOT_UNSAFE, &req->r_req_flags)) {
                        struct ceph_inode_info *ci =
                                ceph_inode(req->r_target_inode);
                        spin_lock(&ci->i_unsafe_lock);
                        list_add_tail(&req->r_unsafe_target_item,
                                      &ci->i_unsafe_iops);
                        spin_unlock(&ci->i_unsafe_lock);
                }

                ceph_unreserve_caps(mdsc, &req->r_caps_reservation);
        }
out_err:
        mutex_lock(&mdsc->mutex);
        if (!test_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags)) {
                if (err) {
                        req->r_err = err;
                } else {
                        req->r_reply =  ceph_msg_get(msg);
                        set_bit(CEPH_MDS_R_GOT_RESULT, &req->r_req_flags);
                }
        } else {
                doutc(cl, "reply arrived after request %lld was aborted\n", tid);
        }
        mutex_unlock(&mdsc->mutex);

        mutex_unlock(&session->s_mutex);

        /* kick calling process */
        complete_request(mdsc, req);

        ceph_update_metadata_metrics(&mdsc->metric, req->r_start_latency,
                                     req->r_end_latency, err);
out:
        ceph_mdsc_put_request(req);

        /* Defer closing the sessions after s_mutex lock being released */
        if (close_sessions)
                ceph_mdsc_close_sessions(mdsc);
        return;
}



/*
 * handle mds notification that our request has been forwarded.
 */
static void handle_forward(struct ceph_mds_client *mdsc,
                           struct ceph_mds_session *session,
                           struct ceph_msg *msg)
{
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_mds_request *req;
        u64 tid = le64_to_cpu(msg->hdr.tid);
        u32 next_mds;
        u32 fwd_seq;
        int err = -EINVAL;
        void *p = msg->front.iov_base;
        void *end = p + msg->front.iov_len;
        bool aborted = false;

        ceph_decode_need(&p, end, 2*sizeof(u32), bad);
        next_mds = ceph_decode_32(&p);
        fwd_seq = ceph_decode_32(&p);

        mutex_lock(&mdsc->mutex);
        req = lookup_get_request(mdsc, tid);
        if (!req) {
                mutex_unlock(&mdsc->mutex);
                doutc(cl, "forward tid %llu to mds%d - req dne\n", tid, next_mds);
                return;  /* dup reply? */
        }

        if (test_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags)) {
                doutc(cl, "forward tid %llu aborted, unregistering\n", tid);
                __unregister_request(mdsc, req);
        } else if (fwd_seq <= req->r_num_fwd || (uint32_t)fwd_seq >= U32_MAX) {
                /*
                 * Avoid infinite retrying after overflow.
                 *
                 * The MDS will increase the fwd count and in client side
                 * if the num_fwd is less than the one saved in request
                 * that means the MDS is an old version and overflowed of
                 * 8 bits.
                 */
                mutex_lock(&req->r_fill_mutex);
                req->r_err = -EMULTIHOP;
                set_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags);
                mutex_unlock(&req->r_fill_mutex);
                aborted = true;
                pr_warn_ratelimited_client(cl, "forward tid %llu seq overflow\n",
                                           tid);
        } else {
                /* resend. forward race not possible; mds would drop */
                doutc(cl, "forward tid %llu to mds%d (we resend)\n", tid, next_mds);
                BUG_ON(req->r_err);
                BUG_ON(test_bit(CEPH_MDS_R_GOT_RESULT, &req->r_req_flags));
                req->r_attempts = 0;
                req->r_num_fwd = fwd_seq;
                req->r_resend_mds = next_mds;
                put_request_session(req);
                __do_request(mdsc, req);
        }
        mutex_unlock(&mdsc->mutex);

        /* kick calling process */
        if (aborted)
                complete_request(mdsc, req);
        ceph_mdsc_put_request(req);
        return;

bad:
        pr_err_client(cl, "decode error err=%d\n", err);
        ceph_msg_dump(msg);
}

static int __decode_session_metadata(void **p, void *end,
                                     bool *blocklisted)
{
        /* map<string,string> */
        u32 n;
        bool err_str;
        ceph_decode_32_safe(p, end, n, bad);
        while (n-- > 0) {
                u32 len;
                ceph_decode_32_safe(p, end, len, bad);
                ceph_decode_need(p, end, len, bad);
                err_str = !strncmp(*p, "error_string", len);
                *p += len;
                ceph_decode_32_safe(p, end, len, bad);
                ceph_decode_need(p, end, len, bad);
                /*
                 * Match "blocklisted (blacklisted)" from newer MDSes,
                 * or "blacklisted" from older MDSes.
                 */
                if (err_str && strnstr(*p, "blacklisted", len))
                        *blocklisted = true;
                *p += len;
        }
        return 0;
bad:
        return -1;
}

/*
 * handle a mds session control message
 */
static void handle_session(struct ceph_mds_session *session,
                           struct ceph_msg *msg)
{
        struct ceph_mds_client *mdsc = session->s_mdsc;
        struct ceph_client *cl = mdsc->fsc->client;
        int mds = session->s_mds;
        int msg_version = le16_to_cpu(msg->hdr.version);
        void *p = msg->front.iov_base;
        void *end = p + msg->front.iov_len;
        struct ceph_mds_session_head *h;
        struct ceph_mds_cap_auth *cap_auths = NULL;
        u32 op, cap_auths_num = 0;
        u64 seq, features = 0;
        int wake = 0;
        bool blocklisted = false;
        u32 i;


        /* decode */
        ceph_decode_need(&p, end, sizeof(*h), bad);
        h = p;
        p += sizeof(*h);

        op = le32_to_cpu(h->op);
        seq = le64_to_cpu(h->seq);

        if (msg_version >= 3) {
                u32 len;
                /* version >= 2 and < 5, decode metadata, skip otherwise
                 * as it's handled via flags.
                 */
                if (msg_version >= 5)
                        ceph_decode_skip_map(&p, end, string, string, bad);
                else if (__decode_session_metadata(&p, end, &blocklisted) < 0)
                        goto bad;

                /* version >= 3, feature bits */
                ceph_decode_32_safe(&p, end, len, bad);
                if (len) {
                        ceph_decode_64_safe(&p, end, features, bad);
                        p += len - sizeof(features);
                }
        }

        if (msg_version >= 5) {
                u32 flags, len;

                /* version >= 4 */
                ceph_decode_skip_16(&p, end, bad); /* struct_v, struct_cv */
                ceph_decode_32_safe(&p, end, len, bad); /* len */
                ceph_decode_skip_n(&p, end, len, bad); /* metric_spec */

                /* version >= 5, flags   */
                ceph_decode_32_safe(&p, end, flags, bad);
                if (flags & CEPH_SESSION_BLOCKLISTED) {
                        pr_warn_client(cl, "mds%d session blocklisted\n",
                                       session->s_mds);
                        blocklisted = true;
                }
        }

        if (msg_version >= 6) {
                ceph_decode_32_safe(&p, end, cap_auths_num, bad);
                doutc(cl, "cap_auths_num %d\n", cap_auths_num);

                if (cap_auths_num && op != CEPH_SESSION_OPEN) {
                        WARN_ON_ONCE(op != CEPH_SESSION_OPEN);
                        goto skip_cap_auths;
                }

                cap_auths = kcalloc(cap_auths_num,
                                    sizeof(struct ceph_mds_cap_auth),
                                    GFP_KERNEL);
                if (!cap_auths) {
                        pr_err_client(cl, "No memory for cap_auths\n");
                        return;
                }

                for (i = 0; i < cap_auths_num; i++) {
                        u32 _len, j;

                        /* struct_v, struct_compat, and struct_len in MDSCapAuth */
                        ceph_decode_skip_n(&p, end, 2 + sizeof(u32), bad);

                        /* struct_v, struct_compat, and struct_len in MDSCapMatch */
                        ceph_decode_skip_n(&p, end, 2 + sizeof(u32), bad);
                        ceph_decode_64_safe(&p, end, cap_auths[i].match.uid, bad);
                        ceph_decode_32_safe(&p, end, _len, bad);
                        if (_len) {
                                cap_auths[i].match.gids = kcalloc(_len, sizeof(u32),
                                                                  GFP_KERNEL);
                                if (!cap_auths[i].match.gids) {
                                        pr_err_client(cl, "No memory for gids\n");
                                        goto fail;
                                }

                                cap_auths[i].match.num_gids = _len;
                                for (j = 0; j < _len; j++)
                                        ceph_decode_32_safe(&p, end,
                                                            cap_auths[i].match.gids[j],
                                                            bad);
                        }

                        ceph_decode_32_safe(&p, end, _len, bad);
                        if (_len) {
                                cap_auths[i].match.path = kcalloc(_len + 1, sizeof(char),
                                                                  GFP_KERNEL);
                                if (!cap_auths[i].match.path) {
                                        pr_err_client(cl, "No memory for path\n");
                                        goto fail;
                                }
                                ceph_decode_copy(&p, cap_auths[i].match.path, _len);

                                /* Remove the tailing '/' */
                                while (_len && cap_auths[i].match.path[_len - 1] == '/') {
                                        cap_auths[i].match.path[_len - 1] = '\0';
                                        _len -= 1;
                                }
                        }

                        ceph_decode_32_safe(&p, end, _len, bad);
                        if (_len) {
                                cap_auths[i].match.fs_name = kcalloc(_len + 1, sizeof(char),
                                                                     GFP_KERNEL);
                                if (!cap_auths[i].match.fs_name) {
                                        pr_err_client(cl, "No memory for fs_name\n");
                                        goto fail;
                                }
                                ceph_decode_copy(&p, cap_auths[i].match.fs_name, _len);
                        }

                        ceph_decode_8_safe(&p, end, cap_auths[i].match.root_squash, bad);
                        ceph_decode_8_safe(&p, end, cap_auths[i].readable, bad);
                        ceph_decode_8_safe(&p, end, cap_auths[i].writeable, bad);
                        doutc(cl, "uid %lld, num_gids %u, path %s, fs_name %s, root_squash %d, readable %d, writeable %d\n",
                              cap_auths[i].match.uid, cap_auths[i].match.num_gids,
                              cap_auths[i].match.path, cap_auths[i].match.fs_name,
                              cap_auths[i].match.root_squash,
                              cap_auths[i].readable, cap_auths[i].writeable);
                }
        }

skip_cap_auths:
        mutex_lock(&mdsc->mutex);
        if (op == CEPH_SESSION_OPEN) {
                if (mdsc->s_cap_auths) {
                        for (i = 0; i < mdsc->s_cap_auths_num; i++) {
                                kfree(mdsc->s_cap_auths[i].match.gids);
                                kfree(mdsc->s_cap_auths[i].match.path);
                                kfree(mdsc->s_cap_auths[i].match.fs_name);
                        }
                        kfree(mdsc->s_cap_auths);
                }
                mdsc->s_cap_auths_num = cap_auths_num;
                mdsc->s_cap_auths = cap_auths;
        }
        if (op == CEPH_SESSION_CLOSE) {
                ceph_get_mds_session(session);
                __unregister_session(mdsc, session);
        }
        /* FIXME: this ttl calculation is generous */
        session->s_ttl = jiffies + HZ*mdsc->mdsmap->m_session_autoclose;
        mutex_unlock(&mdsc->mutex);

        mutex_lock(&session->s_mutex);

        doutc(cl, "mds%d %s %p state %s seq %llu\n", mds,
              ceph_session_op_name(op), session,
              ceph_session_state_name(session->s_state), seq);

        if (session->s_state == CEPH_MDS_SESSION_HUNG) {
                session->s_state = CEPH_MDS_SESSION_OPEN;
                pr_info_client(cl, "mds%d came back\n", session->s_mds);
        }

        switch (op) {
        case CEPH_SESSION_OPEN:
                if (session->s_state == CEPH_MDS_SESSION_RECONNECTING)
                        pr_info_client(cl, "mds%d reconnect success\n",
                                       session->s_mds);

                session->s_features = features;
                if (session->s_state == CEPH_MDS_SESSION_OPEN) {
                        pr_notice_client(cl, "mds%d is already opened\n",
                                         session->s_mds);
                } else {
                        session->s_state = CEPH_MDS_SESSION_OPEN;
                        renewed_caps(mdsc, session, 0);
                        if (test_bit(CEPHFS_FEATURE_METRIC_COLLECT,
                                     &session->s_features))
                                metric_schedule_delayed(&mdsc->metric);
                }

                /*
                 * The connection maybe broken and the session in client
                 * side has been reinitialized, need to update the seq
                 * anyway.
                 */
                if (!session->s_seq && seq)
                        session->s_seq = seq;

                wake = 1;
                if (mdsc->stopping)
                        __close_session(mdsc, session);
                break;

        case CEPH_SESSION_RENEWCAPS:
                if (session->s_renew_seq == seq)
                        renewed_caps(mdsc, session, 1);
                break;

        case CEPH_SESSION_CLOSE:
                if (session->s_state == CEPH_MDS_SESSION_RECONNECTING)
                        pr_info_client(cl, "mds%d reconnect denied\n",
                                       session->s_mds);
                session->s_state = CEPH_MDS_SESSION_CLOSED;
                cleanup_session_requests(mdsc, session);
                remove_session_caps(session);
                wake = 2; /* for good measure */
                wake_up_all(&mdsc->session_close_wq);
                break;

        case CEPH_SESSION_STALE:
                pr_info_client(cl, "mds%d caps went stale, renewing\n",
                               session->s_mds);
                atomic_inc(&session->s_cap_gen);
                session->s_cap_ttl = jiffies - 1;
                send_renew_caps(mdsc, session);
                break;

        case CEPH_SESSION_RECALL_STATE:
                ceph_trim_caps(mdsc, session, le32_to_cpu(h->max_caps));
                break;

        case CEPH_SESSION_FLUSHMSG:
                /* flush cap releases */
                spin_lock(&session->s_cap_lock);
                if (session->s_num_cap_releases)
                        ceph_flush_session_cap_releases(mdsc, session);
                spin_unlock(&session->s_cap_lock);

                send_flushmsg_ack(mdsc, session, seq);
                break;

        case CEPH_SESSION_FORCE_RO:
                doutc(cl, "force_session_readonly %p\n", session);
                spin_lock(&session->s_cap_lock);
                session->s_readonly = true;
                spin_unlock(&session->s_cap_lock);
                wake_up_session_caps(session, FORCE_RO);
                break;

        case CEPH_SESSION_REJECT:
                WARN_ON(session->s_state != CEPH_MDS_SESSION_OPENING);
                pr_info_client(cl, "mds%d rejected session\n",
                               session->s_mds);
                session->s_state = CEPH_MDS_SESSION_REJECTED;
                cleanup_session_requests(mdsc, session);
                remove_session_caps(session);
                if (blocklisted)
                        mdsc->fsc->blocklisted = true;
                wake = 2; /* for good measure */
                break;

        default:
                pr_err_client(cl, "bad op %d mds%d\n", op, mds);
                WARN_ON(1);
        }

        mutex_unlock(&session->s_mutex);
        if (wake) {
                mutex_lock(&mdsc->mutex);
                __wake_requests(mdsc, &session->s_waiting);
                if (wake == 2)
                        kick_requests(mdsc, mds);
                mutex_unlock(&mdsc->mutex);
        }
        if (op == CEPH_SESSION_CLOSE)
                ceph_put_mds_session(session);
        return;

bad:
        pr_err_client(cl, "corrupt message mds%d len %d\n", mds,
                      (int)msg->front.iov_len);
        ceph_msg_dump(msg);
fail:
        for (i = 0; i < cap_auths_num; i++) {
                kfree(cap_auths[i].match.gids);
                kfree(cap_auths[i].match.path);
                kfree(cap_auths[i].match.fs_name);
        }
        kfree(cap_auths);
        return;
}

void ceph_mdsc_release_dir_caps(struct ceph_mds_request *req)
{
        struct ceph_client *cl = req->r_mdsc->fsc->client;
        int dcaps;

        dcaps = xchg(&req->r_dir_caps, 0);
        if (dcaps) {
                doutc(cl, "releasing r_dir_caps=%s\n", ceph_cap_string(dcaps));
                ceph_put_cap_refs(ceph_inode(req->r_parent), dcaps);
        }
}

void ceph_mdsc_release_dir_caps_async(struct ceph_mds_request *req)
{
        struct ceph_client *cl = req->r_mdsc->fsc->client;
        int dcaps;

        dcaps = xchg(&req->r_dir_caps, 0);
        if (dcaps) {
                doutc(cl, "releasing r_dir_caps=%s\n", ceph_cap_string(dcaps));
                ceph_put_cap_refs_async(ceph_inode(req->r_parent), dcaps);
        }
}

/*
 * called under session->mutex.
 */
static void replay_unsafe_requests(struct ceph_mds_client *mdsc,
                                   struct ceph_mds_session *session)
{
        struct ceph_mds_request *req, *nreq;
        struct rb_node *p;

        doutc(mdsc->fsc->client, "mds%d\n", session->s_mds);

        mutex_lock(&mdsc->mutex);
        list_for_each_entry_safe(req, nreq, &session->s_unsafe, r_unsafe_item)
                __send_request(session, req, true);

        /*
         * also re-send old requests when MDS enters reconnect stage. So that MDS
         * can process completed request in clientreplay stage.
         */
        p = rb_first(&mdsc->request_tree);
        while (p) {
                req = rb_entry(p, struct ceph_mds_request, r_node);
                p = rb_next(p);
                if (test_bit(CEPH_MDS_R_GOT_UNSAFE, &req->r_req_flags))
                        continue;
                if (req->r_attempts == 0)
                        continue; /* only old requests */
                if (!req->r_session)
                        continue;
                if (req->r_session->s_mds != session->s_mds)
                        continue;

                ceph_mdsc_release_dir_caps_async(req);

                __send_request(session, req, true);
        }
        mutex_unlock(&mdsc->mutex);
}

static int send_reconnect_partial(struct ceph_reconnect_state *recon_state)
{
        struct ceph_msg *reply;
        struct ceph_pagelist *_pagelist;
        struct page *page;
        __le32 *addr;
        int err = -ENOMEM;

        if (!recon_state->allow_multi)
                return -ENOSPC;

        /* can't handle message that contains both caps and realm */
        BUG_ON(!recon_state->nr_caps == !recon_state->nr_realms);

        /* pre-allocate new pagelist */
        _pagelist = ceph_pagelist_alloc(GFP_NOFS);
        if (!_pagelist)
                return -ENOMEM;

        reply = ceph_msg_new2(CEPH_MSG_CLIENT_RECONNECT, 0, 1, GFP_NOFS, false);
        if (!reply)
                goto fail_msg;

        /* placeholder for nr_caps */
        err = ceph_pagelist_encode_32(_pagelist, 0);
        if (err < 0)
                goto fail;

        if (recon_state->nr_caps) {
                /* currently encoding caps */
                err = ceph_pagelist_encode_32(recon_state->pagelist, 0);
                if (err)
                        goto fail;
        } else {
                /* placeholder for nr_realms (currently encoding relams) */
                err = ceph_pagelist_encode_32(_pagelist, 0);
                if (err < 0)
                        goto fail;
        }

        err = ceph_pagelist_encode_8(recon_state->pagelist, 1);
        if (err)
                goto fail;

        page = list_first_entry(&recon_state->pagelist->head, struct page, lru);
        addr = kmap_atomic(page);
        if (recon_state->nr_caps) {
                /* currently encoding caps */
                *addr = cpu_to_le32(recon_state->nr_caps);
        } else {
                /* currently encoding relams */
                *(addr + 1) = cpu_to_le32(recon_state->nr_realms);
        }
        kunmap_atomic(addr);

        reply->hdr.version = cpu_to_le16(5);
        reply->hdr.compat_version = cpu_to_le16(4);

        reply->hdr.data_len = cpu_to_le32(recon_state->pagelist->length);
        ceph_msg_data_add_pagelist(reply, recon_state->pagelist);

        ceph_con_send(&recon_state->session->s_con, reply);
        ceph_pagelist_release(recon_state->pagelist);

        recon_state->pagelist = _pagelist;
        recon_state->nr_caps = 0;
        recon_state->nr_realms = 0;
        recon_state->msg_version = 5;
        return 0;
fail:
        ceph_msg_put(reply);
fail_msg:
        ceph_pagelist_release(_pagelist);
        return err;
}

static struct dentry* d_find_primary(struct inode *inode)
{
        struct dentry *alias, *dn = NULL;

        if (hlist_empty(&inode->i_dentry))
                return NULL;

        spin_lock(&inode->i_lock);
        if (hlist_empty(&inode->i_dentry))
                goto out_unlock;

        if (S_ISDIR(inode->i_mode)) {
                alias = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias);
                if (!IS_ROOT(alias))
                        dn = dget(alias);
                goto out_unlock;
        }

        hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
                spin_lock(&alias->d_lock);
                if (!d_unhashed(alias) &&
                    (ceph_dentry(alias)->flags & CEPH_DENTRY_PRIMARY_LINK)) {
                        dn = dget_dlock(alias);
                }
                spin_unlock(&alias->d_lock);
                if (dn)
                        break;
        }
out_unlock:
        spin_unlock(&inode->i_lock);
        return dn;
}

/*
 * Encode information about a cap for a reconnect with the MDS.
 */
static int reconnect_caps_cb(struct inode *inode, int mds, void *arg)
{
        struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb);
        struct ceph_client *cl = ceph_inode_to_client(inode);
        union {
                struct ceph_mds_cap_reconnect v2;
                struct ceph_mds_cap_reconnect_v1 v1;
        } rec;
        struct ceph_inode_info *ci = ceph_inode(inode);
        struct ceph_reconnect_state *recon_state = arg;
        struct ceph_pagelist *pagelist = recon_state->pagelist;
        struct dentry *dentry;
        struct ceph_cap *cap;
        struct ceph_path_info path_info = {0};
        int err;
        u64 snap_follows;

        dentry = d_find_primary(inode);
        if (dentry) {
                /* set pathbase to parent dir when msg_version >= 2 */
                char *path = ceph_mdsc_build_path(mdsc, dentry, &path_info,
                                            recon_state->msg_version >= 2);
                dput(dentry);
                if (IS_ERR(path)) {
                        err = PTR_ERR(path);
                        goto out_err;
                }
        }

        spin_lock(&ci->i_ceph_lock);
        cap = __get_cap_for_mds(ci, mds);
        if (!cap) {
                spin_unlock(&ci->i_ceph_lock);
                err = 0;
                goto out_err;
        }
        doutc(cl, " adding %p ino %llx.%llx cap %p %lld %s\n", inode,
              ceph_vinop(inode), cap, cap->cap_id,
              ceph_cap_string(cap->issued));

        cap->seq = 0;        /* reset cap seq */
        cap->issue_seq = 0;  /* and issue_seq */
        cap->mseq = 0;       /* and migrate_seq */
        cap->cap_gen = atomic_read(&cap->session->s_cap_gen);

        /* These are lost when the session goes away */
        if (S_ISDIR(inode->i_mode)) {
                if (cap->issued & CEPH_CAP_DIR_CREATE) {
                        ceph_put_string(rcu_dereference_raw(ci->i_cached_layout.pool_ns));
                        memset(&ci->i_cached_layout, 0, sizeof(ci->i_cached_layout));
                }
                cap->issued &= ~CEPH_CAP_ANY_DIR_OPS;
        }

        if (recon_state->msg_version >= 2) {
                rec.v2.cap_id = cpu_to_le64(cap->cap_id);
                rec.v2.wanted = cpu_to_le32(__ceph_caps_wanted(ci));
                rec.v2.issued = cpu_to_le32(cap->issued);
                rec.v2.snaprealm = cpu_to_le64(ci->i_snap_realm->ino);
                rec.v2.pathbase = cpu_to_le64(path_info.vino.ino);
                rec.v2.flock_len = (__force __le32)
                        ((ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) ? 0 : 1);
        } else {
                struct timespec64 ts;

                rec.v1.cap_id = cpu_to_le64(cap->cap_id);
                rec.v1.wanted = cpu_to_le32(__ceph_caps_wanted(ci));
                rec.v1.issued = cpu_to_le32(cap->issued);
                rec.v1.size = cpu_to_le64(i_size_read(inode));
                ts = inode_get_mtime(inode);
                ceph_encode_timespec64(&rec.v1.mtime, &ts);
                ts = inode_get_atime(inode);
                ceph_encode_timespec64(&rec.v1.atime, &ts);
                rec.v1.snaprealm = cpu_to_le64(ci->i_snap_realm->ino);
                rec.v1.pathbase = cpu_to_le64(path_info.vino.ino);
        }

        if (list_empty(&ci->i_cap_snaps)) {
                snap_follows = ci->i_head_snapc ? ci->i_head_snapc->seq : 0;
        } else {
                struct ceph_cap_snap *capsnap =
                        list_first_entry(&ci->i_cap_snaps,
                                         struct ceph_cap_snap, ci_item);
                snap_follows = capsnap->follows;
        }
        spin_unlock(&ci->i_ceph_lock);

        if (recon_state->msg_version >= 2) {
                int num_fcntl_locks, num_flock_locks;
                struct ceph_filelock *flocks = NULL;
                size_t struct_len, total_len = sizeof(u64);
                u8 struct_v = 0;

encode_again:
                if (rec.v2.flock_len) {
                        ceph_count_locks(inode, &num_fcntl_locks, &num_flock_locks);
                } else {
                        num_fcntl_locks = 0;
                        num_flock_locks = 0;
                }
                if (num_fcntl_locks + num_flock_locks > 0) {
                        flocks = kmalloc_array(num_fcntl_locks + num_flock_locks,
                                               sizeof(struct ceph_filelock),
                                               GFP_NOFS);
                        if (!flocks) {
                                err = -ENOMEM;
                                goto out_err;
                        }
                        err = ceph_encode_locks_to_buffer(inode, flocks,
                                                          num_fcntl_locks,
                                                          num_flock_locks);
                        if (err) {
                                kfree(flocks);
                                flocks = NULL;
                                if (err == -ENOSPC)
                                        goto encode_again;
                                goto out_err;
                        }
                } else {
                        kfree(flocks);
                        flocks = NULL;
                }

                if (recon_state->msg_version >= 3) {
                        /* version, compat_version and struct_len */
                        total_len += 2 * sizeof(u8) + sizeof(u32);
                        struct_v = 2;
                }
                /*
                 * number of encoded locks is stable, so copy to pagelist
                 */
                struct_len = 2 * sizeof(u32) +
                            (num_fcntl_locks + num_flock_locks) *
                            sizeof(struct ceph_filelock);
                rec.v2.flock_len = cpu_to_le32(struct_len);

                struct_len += sizeof(u32) + path_info.pathlen + sizeof(rec.v2);

                if (struct_v >= 2)
                        struct_len += sizeof(u64); /* snap_follows */

                total_len += struct_len;

                if (pagelist->length + total_len > RECONNECT_MAX_SIZE) {
                        err = send_reconnect_partial(recon_state);
                        if (err)
                                goto out_freeflocks;
                        pagelist = recon_state->pagelist;
                }

                err = ceph_pagelist_reserve(pagelist, total_len);
                if (err)
                        goto out_freeflocks;

                ceph_pagelist_encode_64(pagelist, ceph_ino(inode));
                if (recon_state->msg_version >= 3) {
                        ceph_pagelist_encode_8(pagelist, struct_v);
                        ceph_pagelist_encode_8(pagelist, 1);
                        ceph_pagelist_encode_32(pagelist, struct_len);
                }
                ceph_pagelist_encode_string(pagelist, (char *)path_info.path, path_info.pathlen);
                ceph_pagelist_append(pagelist, &rec, sizeof(rec.v2));
                ceph_locks_to_pagelist(flocks, pagelist,
                                       num_fcntl_locks, num_flock_locks);
                if (struct_v >= 2)
                        ceph_pagelist_encode_64(pagelist, snap_follows);
out_freeflocks:
                kfree(flocks);
        } else {
                err = ceph_pagelist_reserve(pagelist,
                                            sizeof(u64) + sizeof(u32) +
                                            path_info.pathlen + sizeof(rec.v1));
                if (err)
                        goto out_err;

                ceph_pagelist_encode_64(pagelist, ceph_ino(inode));
                ceph_pagelist_encode_string(pagelist, (char *)path_info.path, path_info.pathlen);
                ceph_pagelist_append(pagelist, &rec, sizeof(rec.v1));
        }

out_err:
        ceph_mdsc_free_path_info(&path_info);
        if (!err)
                recon_state->nr_caps++;
        return err;
}

static int encode_snap_realms(struct ceph_mds_client *mdsc,
                              struct ceph_reconnect_state *recon_state)
{
        struct rb_node *p;
        struct ceph_pagelist *pagelist = recon_state->pagelist;
        struct ceph_client *cl = mdsc->fsc->client;
        int err = 0;

        if (recon_state->msg_version >= 4) {
                err = ceph_pagelist_encode_32(pagelist, mdsc->num_snap_realms);
                if (err < 0)
                        goto fail;
        }

        /*
         * snaprealms.  we provide mds with the ino, seq (version), and
         * parent for all of our realms.  If the mds has any newer info,
         * it will tell us.
         */
        for (p = rb_first(&mdsc->snap_realms); p; p = rb_next(p)) {
                struct ceph_snap_realm *realm =
                       rb_entry(p, struct ceph_snap_realm, node);
                struct ceph_mds_snaprealm_reconnect sr_rec;

                if (recon_state->msg_version >= 4) {
                        size_t need = sizeof(u8) * 2 + sizeof(u32) +
                                      sizeof(sr_rec);

                        if (pagelist->length + need > RECONNECT_MAX_SIZE) {
                                err = send_reconnect_partial(recon_state);
                                if (err)
                                        goto fail;
                                pagelist = recon_state->pagelist;
                        }

                        err = ceph_pagelist_reserve(pagelist, need);
                        if (err)
                                goto fail;

                        ceph_pagelist_encode_8(pagelist, 1);
                        ceph_pagelist_encode_8(pagelist, 1);
                        ceph_pagelist_encode_32(pagelist, sizeof(sr_rec));
                }

                doutc(cl, " adding snap realm %llx seq %lld parent %llx\n",
                      realm->ino, realm->seq, realm->parent_ino);
                sr_rec.ino = cpu_to_le64(realm->ino);
                sr_rec.seq = cpu_to_le64(realm->seq);
                sr_rec.parent = cpu_to_le64(realm->parent_ino);

                err = ceph_pagelist_append(pagelist, &sr_rec, sizeof(sr_rec));
                if (err)
                        goto fail;

                recon_state->nr_realms++;
        }
fail:
        return err;
}


/*
 * If an MDS fails and recovers, clients need to reconnect in order to
 * reestablish shared state.  This includes all caps issued through
 * this session _and_ the snap_realm hierarchy.  Because it's not
 * clear which snap realms the mds cares about, we send everything we
 * know about.. that ensures we'll then get any new info the
 * recovering MDS might have.
 *
 * This is a relatively heavyweight operation, but it's rare.
 */
static void send_mds_reconnect(struct ceph_mds_client *mdsc,
                               struct ceph_mds_session *session)
{
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_msg *reply;
        int mds = session->s_mds;
        int err = -ENOMEM;
        struct ceph_reconnect_state recon_state = {
                .session = session,
        };
        LIST_HEAD(dispose);

        pr_info_client(cl, "mds%d reconnect start\n", mds);

        recon_state.pagelist = ceph_pagelist_alloc(GFP_NOFS);
        if (!recon_state.pagelist)
                goto fail_nopagelist;

        reply = ceph_msg_new2(CEPH_MSG_CLIENT_RECONNECT, 0, 1, GFP_NOFS, false);
        if (!reply)
                goto fail_nomsg;

        xa_destroy(&session->s_delegated_inos);

        mutex_lock(&session->s_mutex);
        session->s_state = CEPH_MDS_SESSION_RECONNECTING;
        session->s_seq = 0;

        doutc(cl, "session %p state %s\n", session,
              ceph_session_state_name(session->s_state));

        atomic_inc(&session->s_cap_gen);

        spin_lock(&session->s_cap_lock);
        /* don't know if session is readonly */
        session->s_readonly = 0;
        /*
         * notify __ceph_remove_cap() that we are composing cap reconnect.
         * If a cap get released before being added to the cap reconnect,
         * __ceph_remove_cap() should skip queuing cap release.
         */
        session->s_cap_reconnect = 1;
        /* drop old cap expires; we're about to reestablish that state */
        detach_cap_releases(session, &dispose);
        spin_unlock(&session->s_cap_lock);
        dispose_cap_releases(mdsc, &dispose);

        /* trim unused caps to reduce MDS's cache rejoin time */
        if (mdsc->fsc->sb->s_root)
                shrink_dcache_parent(mdsc->fsc->sb->s_root);

        ceph_con_close(&session->s_con);
        ceph_con_open(&session->s_con,
                      CEPH_ENTITY_TYPE_MDS, mds,
                      ceph_mdsmap_get_addr(mdsc->mdsmap, mds));

        /* replay unsafe requests */
        replay_unsafe_requests(mdsc, session);

        ceph_early_kick_flushing_caps(mdsc, session);

        down_read(&mdsc->snap_rwsem);

        /* placeholder for nr_caps */
        err = ceph_pagelist_encode_32(recon_state.pagelist, 0);
        if (err)
                goto fail;

        if (test_bit(CEPHFS_FEATURE_MULTI_RECONNECT, &session->s_features)) {
                recon_state.msg_version = 3;
                recon_state.allow_multi = true;
        } else if (session->s_con.peer_features & CEPH_FEATURE_MDSENC) {
                recon_state.msg_version = 3;
        } else {
                recon_state.msg_version = 2;
        }
        /* traverse this session's caps */
        err = ceph_iterate_session_caps(session, reconnect_caps_cb, &recon_state);

        spin_lock(&session->s_cap_lock);
        session->s_cap_reconnect = 0;
        spin_unlock(&session->s_cap_lock);

        if (err < 0)
                goto fail;

        /* check if all realms can be encoded into current message */
        if (mdsc->num_snap_realms) {
                size_t total_len =
                        recon_state.pagelist->length +
                        mdsc->num_snap_realms *
                        sizeof(struct ceph_mds_snaprealm_reconnect);
                if (recon_state.msg_version >= 4) {
                        /* number of realms */
                        total_len += sizeof(u32);
                        /* version, compat_version and struct_len */
                        total_len += mdsc->num_snap_realms *
                                     (2 * sizeof(u8) + sizeof(u32));
                }
                if (total_len > RECONNECT_MAX_SIZE) {
                        if (!recon_state.allow_multi) {
                                err = -ENOSPC;
                                goto fail;
                        }
                        if (recon_state.nr_caps) {
                                err = send_reconnect_partial(&recon_state);
                                if (err)
                                        goto fail;
                        }
                        recon_state.msg_version = 5;
                }
        }

        err = encode_snap_realms(mdsc, &recon_state);
        if (err < 0)
                goto fail;

        if (recon_state.msg_version >= 5) {
                err = ceph_pagelist_encode_8(recon_state.pagelist, 0);
                if (err < 0)
                        goto fail;
        }

        if (recon_state.nr_caps || recon_state.nr_realms) {
                struct page *page =
                        list_first_entry(&recon_state.pagelist->head,
                                        struct page, lru);
                __le32 *addr = kmap_atomic(page);
                if (recon_state.nr_caps) {
                        WARN_ON(recon_state.nr_realms != mdsc->num_snap_realms);
                        *addr = cpu_to_le32(recon_state.nr_caps);
                } else if (recon_state.msg_version >= 4) {
                        *(addr + 1) = cpu_to_le32(recon_state.nr_realms);
                }
                kunmap_atomic(addr);
        }

        reply->hdr.version = cpu_to_le16(recon_state.msg_version);
        if (recon_state.msg_version >= 4)
                reply->hdr.compat_version = cpu_to_le16(4);

        reply->hdr.data_len = cpu_to_le32(recon_state.pagelist->length);
        ceph_msg_data_add_pagelist(reply, recon_state.pagelist);

        ceph_con_send(&session->s_con, reply);

        mutex_unlock(&session->s_mutex);

        mutex_lock(&mdsc->mutex);
        __wake_requests(mdsc, &session->s_waiting);
        mutex_unlock(&mdsc->mutex);

        up_read(&mdsc->snap_rwsem);
        ceph_pagelist_release(recon_state.pagelist);
        return;

fail:
        ceph_msg_put(reply);
        up_read(&mdsc->snap_rwsem);
        mutex_unlock(&session->s_mutex);
fail_nomsg:
        ceph_pagelist_release(recon_state.pagelist);
fail_nopagelist:
        pr_err_client(cl, "error %d preparing reconnect for mds%d\n",
                      err, mds);
        return;
}


/*
 * compare old and new mdsmaps, kicking requests
 * and closing out old connections as necessary
 *
 * called under mdsc->mutex.
 */
static void check_new_map(struct ceph_mds_client *mdsc,
                          struct ceph_mdsmap *newmap,
                          struct ceph_mdsmap *oldmap)
{
        int i, j, err;
        int oldstate, newstate;
        struct ceph_mds_session *s;
        unsigned long targets[DIV_ROUND_UP(CEPH_MAX_MDS, sizeof(unsigned long))] = {0};
        struct ceph_client *cl = mdsc->fsc->client;

        doutc(cl, "new %u old %u\n", newmap->m_epoch, oldmap->m_epoch);

        if (newmap->m_info) {
                for (i = 0; i < newmap->possible_max_rank; i++) {
                        for (j = 0; j < newmap->m_info[i].num_export_targets; j++)
                                set_bit(newmap->m_info[i].export_targets[j], targets);
                }
        }

        for (i = 0; i < oldmap->possible_max_rank && i < mdsc->max_sessions; i++) {
                if (!mdsc->sessions[i])
                        continue;
                s = mdsc->sessions[i];
                oldstate = ceph_mdsmap_get_state(oldmap, i);
                newstate = ceph_mdsmap_get_state(newmap, i);

                doutc(cl, "mds%d state %s%s -> %s%s (session %s)\n",
                      i, ceph_mds_state_name(oldstate),
                      ceph_mdsmap_is_laggy(oldmap, i) ? " (laggy)" : "",
                      ceph_mds_state_name(newstate),
                      ceph_mdsmap_is_laggy(newmap, i) ? " (laggy)" : "",
                      ceph_session_state_name(s->s_state));

                if (i >= newmap->possible_max_rank) {
                        /* force close session for stopped mds */
                        ceph_get_mds_session(s);
                        __unregister_session(mdsc, s);
                        __wake_requests(mdsc, &s->s_waiting);
                        mutex_unlock(&mdsc->mutex);

                        mutex_lock(&s->s_mutex);
                        cleanup_session_requests(mdsc, s);
                        remove_session_caps(s);
                        mutex_unlock(&s->s_mutex);

                        ceph_put_mds_session(s);

                        mutex_lock(&mdsc->mutex);
                        kick_requests(mdsc, i);
                        continue;
                }

                if (memcmp(ceph_mdsmap_get_addr(oldmap, i),
                           ceph_mdsmap_get_addr(newmap, i),
                           sizeof(struct ceph_entity_addr))) {
                        /* just close it */
                        mutex_unlock(&mdsc->mutex);
                        mutex_lock(&s->s_mutex);
                        mutex_lock(&mdsc->mutex);
                        ceph_con_close(&s->s_con);
                        mutex_unlock(&s->s_mutex);
                        s->s_state = CEPH_MDS_SESSION_RESTARTING;
                } else if (oldstate == newstate) {
                        continue;  /* nothing new with this mds */
                }

                /*
                 * send reconnect?
                 */
                if (s->s_state == CEPH_MDS_SESSION_RESTARTING &&
                    newstate >= CEPH_MDS_STATE_RECONNECT) {
                        mutex_unlock(&mdsc->mutex);
                        clear_bit(i, targets);
                        send_mds_reconnect(mdsc, s);
                        mutex_lock(&mdsc->mutex);
                }

                /*
                 * kick request on any mds that has gone active.
                 */
                if (oldstate < CEPH_MDS_STATE_ACTIVE &&
                    newstate >= CEPH_MDS_STATE_ACTIVE) {
                        if (oldstate != CEPH_MDS_STATE_CREATING &&
                            oldstate != CEPH_MDS_STATE_STARTING)
                                pr_info_client(cl, "mds%d recovery completed\n",
                                               s->s_mds);
                        kick_requests(mdsc, i);
                        mutex_unlock(&mdsc->mutex);
                        mutex_lock(&s->s_mutex);
                        mutex_lock(&mdsc->mutex);
                        ceph_kick_flushing_caps(mdsc, s);
                        mutex_unlock(&s->s_mutex);
                        wake_up_session_caps(s, RECONNECT);
                }
        }

        /*
         * Only open and reconnect sessions that don't exist yet.
         */
        for (i = 0; i < newmap->possible_max_rank; i++) {
                /*
                 * In case the import MDS is crashed just after
                 * the EImportStart journal is flushed, so when
                 * a standby MDS takes over it and is replaying
                 * the EImportStart journal the new MDS daemon
                 * will wait the client to reconnect it, but the
                 * client may never register/open the session yet.
                 *
                 * Will try to reconnect that MDS daemon if the
                 * rank number is in the export targets array and
                 * is the up:reconnect state.
                 */
                newstate = ceph_mdsmap_get_state(newmap, i);
                if (!test_bit(i, targets) || newstate != CEPH_MDS_STATE_RECONNECT)
                        continue;

                /*
                 * The session maybe registered and opened by some
                 * requests which were choosing random MDSes during
                 * the mdsc->mutex's unlock/lock gap below in rare
                 * case. But the related MDS daemon will just queue
                 * that requests and be still waiting for the client's
                 * reconnection request in up:reconnect state.
                 */
                s = __ceph_lookup_mds_session(mdsc, i);
                if (likely(!s)) {
                        s = __open_export_target_session(mdsc, i);
                        if (IS_ERR(s)) {
                                err = PTR_ERR(s);
                                pr_err_client(cl,
                                              "failed to open export target session, err %d\n",
                                              err);
                                continue;
                        }
                }
                doutc(cl, "send reconnect to export target mds.%d\n", i);
                mutex_unlock(&mdsc->mutex);
                send_mds_reconnect(mdsc, s);
                ceph_put_mds_session(s);
                mutex_lock(&mdsc->mutex);
        }

        for (i = 0; i < newmap->possible_max_rank && i < mdsc->max_sessions; i++) {
                s = mdsc->sessions[i];
                if (!s)
                        continue;
                if (!ceph_mdsmap_is_laggy(newmap, i))
                        continue;
                if (s->s_state == CEPH_MDS_SESSION_OPEN ||
                    s->s_state == CEPH_MDS_SESSION_HUNG ||
                    s->s_state == CEPH_MDS_SESSION_CLOSING) {
                        doutc(cl, " connecting to export targets of laggy mds%d\n", i);
                        __open_export_target_sessions(mdsc, s);
                }
        }
}



/*
 * leases
 */

/*
 * caller must hold session s_mutex, dentry->d_lock
 */
void __ceph_mdsc_drop_dentry_lease(struct dentry *dentry)
{
        struct ceph_dentry_info *di = ceph_dentry(dentry);

        ceph_put_mds_session(di->lease_session);
        di->lease_session = NULL;
}

static void handle_lease(struct ceph_mds_client *mdsc,
                         struct ceph_mds_session *session,
                         struct ceph_msg *msg)
{
        struct ceph_client *cl = mdsc->fsc->client;
        struct super_block *sb = mdsc->fsc->sb;
        struct inode *inode;
        struct dentry *parent, *dentry;
        struct ceph_dentry_info *di;
        int mds = session->s_mds;
        struct ceph_mds_lease *h = msg->front.iov_base;
        u32 seq;
        struct ceph_vino vino;
        struct qstr dname;
        int release = 0;

        doutc(cl, "from mds%d\n", mds);

        if (!ceph_inc_mds_stopping_blocker(mdsc, session))
                return;

        /* decode */
        if (msg->front.iov_len < sizeof(*h) + sizeof(u32))
                goto bad;
        vino.ino = le64_to_cpu(h->ino);
        vino.snap = CEPH_NOSNAP;
        seq = le32_to_cpu(h->seq);
        dname.len = get_unaligned_le32(h + 1);
        if (msg->front.iov_len < sizeof(*h) + sizeof(u32) + dname.len)
                goto bad;
        dname.name = (void *)(h + 1) + sizeof(u32);

        /* lookup inode */
        inode = ceph_find_inode(sb, vino);
        doutc(cl, "%s, ino %llx %p %.*s\n", ceph_lease_op_name(h->action),
              vino.ino, inode, dname.len, dname.name);

        mutex_lock(&session->s_mutex);
        if (!inode) {
                doutc(cl, "no inode %llx\n", vino.ino);
                goto release;
        }

        /* dentry */
        parent = d_find_alias(inode);
        if (!parent) {
                doutc(cl, "no parent dentry on inode %p\n", inode);
                WARN_ON(1);
                goto release;  /* hrm... */
        }
        dname.hash = full_name_hash(parent, dname.name, dname.len);
        dentry = d_lookup(parent, &dname);
        dput(parent);
        if (!dentry)
                goto release;

        spin_lock(&dentry->d_lock);
        di = ceph_dentry(dentry);
        switch (h->action) {
        case CEPH_MDS_LEASE_REVOKE:
                if (di->lease_session == session) {
                        if (ceph_seq_cmp(di->lease_seq, seq) > 0)
                                h->seq = cpu_to_le32(di->lease_seq);
                        __ceph_mdsc_drop_dentry_lease(dentry);
                }
                release = 1;
                break;

        case CEPH_MDS_LEASE_RENEW:
                if (di->lease_session == session &&
                    di->lease_gen == atomic_read(&session->s_cap_gen) &&
                    di->lease_renew_from &&
                    di->lease_renew_after == 0) {
                        unsigned long duration =
                                msecs_to_jiffies(le32_to_cpu(h->duration_ms));

                        di->lease_seq = seq;
                        di->time = di->lease_renew_from + duration;
                        di->lease_renew_after = di->lease_renew_from +
                                (duration >> 1);
                        di->lease_renew_from = 0;
                }
                break;
        }
        spin_unlock(&dentry->d_lock);
        dput(dentry);

        if (!release)
                goto out;

release:
        /* let's just reuse the same message */
        h->action = CEPH_MDS_LEASE_REVOKE_ACK;
        ceph_msg_get(msg);
        ceph_con_send(&session->s_con, msg);

out:
        mutex_unlock(&session->s_mutex);
        iput(inode);

        ceph_dec_mds_stopping_blocker(mdsc);
        return;

bad:
        ceph_dec_mds_stopping_blocker(mdsc);

        pr_err_client(cl, "corrupt lease message\n");
        ceph_msg_dump(msg);
}

void ceph_mdsc_lease_send_msg(struct ceph_mds_session *session,
                              struct dentry *dentry, char action,
                              u32 seq)
{
        struct ceph_client *cl = session->s_mdsc->fsc->client;
        struct ceph_msg *msg;
        struct ceph_mds_lease *lease;
        struct inode *dir;
        int len = sizeof(*lease) + sizeof(u32) + NAME_MAX;

        doutc(cl, "identry %p %s to mds%d\n", dentry, ceph_lease_op_name(action),
              session->s_mds);

        msg = ceph_msg_new(CEPH_MSG_CLIENT_LEASE, len, GFP_NOFS, false);
        if (!msg)
                return;
        lease = msg->front.iov_base;
        lease->action = action;
        lease->seq = cpu_to_le32(seq);

        spin_lock(&dentry->d_lock);
        dir = d_inode(dentry->d_parent);
        lease->ino = cpu_to_le64(ceph_ino(dir));
        lease->first = lease->last = cpu_to_le64(ceph_snap(dir));

        put_unaligned_le32(dentry->d_name.len, lease + 1);
        memcpy((void *)(lease + 1) + 4,
               dentry->d_name.name, dentry->d_name.len);
        spin_unlock(&dentry->d_lock);

        ceph_con_send(&session->s_con, msg);
}

/*
 * lock unlock the session, to wait ongoing session activities
 */
static void lock_unlock_session(struct ceph_mds_session *s)
{
        mutex_lock(&s->s_mutex);
        mutex_unlock(&s->s_mutex);
}

static void maybe_recover_session(struct ceph_mds_client *mdsc)
{
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_fs_client *fsc = mdsc->fsc;

        if (!ceph_test_mount_opt(fsc, CLEANRECOVER))
                return;

        if (READ_ONCE(fsc->mount_state) != CEPH_MOUNT_MOUNTED)
                return;

        if (!READ_ONCE(fsc->blocklisted))
                return;

        pr_info_client(cl, "auto reconnect after blocklisted\n");
        ceph_force_reconnect(fsc->sb);
}

bool check_session_state(struct ceph_mds_session *s)
{
        struct ceph_client *cl = s->s_mdsc->fsc->client;

        switch (s->s_state) {
        case CEPH_MDS_SESSION_OPEN:
                if (s->s_ttl && time_after(jiffies, s->s_ttl)) {
                        s->s_state = CEPH_MDS_SESSION_HUNG;
                        pr_info_client(cl, "mds%d hung\n", s->s_mds);
                }
                break;
        case CEPH_MDS_SESSION_CLOSING:
        case CEPH_MDS_SESSION_NEW:
        case CEPH_MDS_SESSION_RESTARTING:
        case CEPH_MDS_SESSION_CLOSED:
        case CEPH_MDS_SESSION_REJECTED:
                return false;
        }

        return true;
}

/*
 * If the sequence is incremented while we're waiting on a REQUEST_CLOSE reply,
 * then we need to retransmit that request.
 */
void inc_session_sequence(struct ceph_mds_session *s)
{
        struct ceph_client *cl = s->s_mdsc->fsc->client;

        lockdep_assert_held(&s->s_mutex);

        s->s_seq++;

        if (s->s_state == CEPH_MDS_SESSION_CLOSING) {
                int ret;

                doutc(cl, "resending session close request for mds%d\n", s->s_mds);
                ret = request_close_session(s);
                if (ret < 0)
                        pr_err_client(cl, "unable to close session to mds%d: %d\n",
                                      s->s_mds, ret);
        }
}

/*
 * delayed work -- periodically trim expired leases, renew caps with mds.  If
 * the @delay parameter is set to 0 or if it's more than 5 secs, the default
 * workqueue delay value of 5 secs will be used.
 */
static void schedule_delayed(struct ceph_mds_client *mdsc, unsigned long delay)
{
        unsigned long max_delay = HZ * 5;

        /* 5 secs default delay */
        if (!delay || (delay > max_delay))
                delay = max_delay;
        schedule_delayed_work(&mdsc->delayed_work,
                              round_jiffies_relative(delay));
}

static void delayed_work(struct work_struct *work)
{
        struct ceph_mds_client *mdsc =
                container_of(work, struct ceph_mds_client, delayed_work.work);
        unsigned long delay;
        int renew_interval;
        int renew_caps;
        int i;

        doutc(mdsc->fsc->client, "mdsc delayed_work\n");

        if (mdsc->stopping >= CEPH_MDSC_STOPPING_FLUSHED)
                return;

        mutex_lock(&mdsc->mutex);
        renew_interval = mdsc->mdsmap->m_session_timeout >> 2;
        renew_caps = time_after_eq(jiffies, HZ*renew_interval +
                                   mdsc->last_renew_caps);
        if (renew_caps)
                mdsc->last_renew_caps = jiffies;

        for (i = 0; i < mdsc->max_sessions; i++) {
                struct ceph_mds_session *s = __ceph_lookup_mds_session(mdsc, i);
                if (!s)
                        continue;

                if (!check_session_state(s)) {
                        ceph_put_mds_session(s);
                        continue;
                }
                mutex_unlock(&mdsc->mutex);

                ceph_flush_session_cap_releases(mdsc, s);

                mutex_lock(&s->s_mutex);
                if (renew_caps)
                        send_renew_caps(mdsc, s);
                else
                        ceph_con_keepalive(&s->s_con);
                if (s->s_state == CEPH_MDS_SESSION_OPEN ||
                    s->s_state == CEPH_MDS_SESSION_HUNG)
                        ceph_send_cap_releases(mdsc, s);
                mutex_unlock(&s->s_mutex);
                ceph_put_mds_session(s);

                mutex_lock(&mdsc->mutex);
        }
        mutex_unlock(&mdsc->mutex);

        delay = ceph_check_delayed_caps(mdsc);

        ceph_queue_cap_reclaim_work(mdsc);

        ceph_trim_snapid_map(mdsc);

        maybe_recover_session(mdsc);

        schedule_delayed(mdsc, delay);
}

int ceph_mdsc_init(struct ceph_fs_client *fsc)

{
        struct ceph_mds_client *mdsc;
        int err;

        mdsc = kzalloc(sizeof(struct ceph_mds_client), GFP_NOFS);
        if (!mdsc)
                return -ENOMEM;
        mdsc->fsc = fsc;
        mutex_init(&mdsc->mutex);
        mdsc->mdsmap = kzalloc(sizeof(*mdsc->mdsmap), GFP_NOFS);
        if (!mdsc->mdsmap) {
                err = -ENOMEM;
                goto err_mdsc;
        }

        init_completion(&mdsc->safe_umount_waiters);
        spin_lock_init(&mdsc->stopping_lock);
        atomic_set(&mdsc->stopping_blockers, 0);
        init_completion(&mdsc->stopping_waiter);
        atomic64_set(&mdsc->dirty_folios, 0);
        init_waitqueue_head(&mdsc->flush_end_wq);
        init_waitqueue_head(&mdsc->session_close_wq);
        INIT_LIST_HEAD(&mdsc->waiting_for_map);
        mdsc->quotarealms_inodes = RB_ROOT;
        mutex_init(&mdsc->quotarealms_inodes_mutex);
        init_rwsem(&mdsc->snap_rwsem);
        mdsc->snap_realms = RB_ROOT;
        INIT_LIST_HEAD(&mdsc->snap_empty);
        spin_lock_init(&mdsc->snap_empty_lock);
        mdsc->request_tree = RB_ROOT;
        INIT_DELAYED_WORK(&mdsc->delayed_work, delayed_work);
        mdsc->last_renew_caps = jiffies;
        INIT_LIST_HEAD(&mdsc->cap_delay_list);
#ifdef CONFIG_DEBUG_FS
        INIT_LIST_HEAD(&mdsc->cap_wait_list);
#endif
        spin_lock_init(&mdsc->cap_delay_lock);
        INIT_LIST_HEAD(&mdsc->cap_unlink_delay_list);
        INIT_LIST_HEAD(&mdsc->snap_flush_list);
        spin_lock_init(&mdsc->snap_flush_lock);
        mdsc->last_cap_flush_tid = 1;
        INIT_LIST_HEAD(&mdsc->cap_flush_list);
        INIT_LIST_HEAD(&mdsc->cap_dirty_migrating);
        spin_lock_init(&mdsc->cap_dirty_lock);
        init_waitqueue_head(&mdsc->cap_flushing_wq);
        INIT_WORK(&mdsc->cap_reclaim_work, ceph_cap_reclaim_work);
        INIT_WORK(&mdsc->cap_unlink_work, ceph_cap_unlink_work);
        err = ceph_metric_init(&mdsc->metric);
        if (err)
                goto err_mdsmap;

        spin_lock_init(&mdsc->dentry_list_lock);
        INIT_LIST_HEAD(&mdsc->dentry_leases);
        INIT_LIST_HEAD(&mdsc->dentry_dir_leases);

        ceph_caps_init(mdsc);
        ceph_adjust_caps_max_min(mdsc, fsc->mount_options);

        spin_lock_init(&mdsc->snapid_map_lock);
        mdsc->snapid_map_tree = RB_ROOT;
        INIT_LIST_HEAD(&mdsc->snapid_map_lru);

        init_rwsem(&mdsc->pool_perm_rwsem);
        mdsc->pool_perm_tree = RB_ROOT;

        strscpy(mdsc->nodename, utsname()->nodename,
                sizeof(mdsc->nodename));

        fsc->mdsc = mdsc;
        return 0;

err_mdsmap:
        kfree(mdsc->mdsmap);
err_mdsc:
        kfree(mdsc);
        return err;
}

/*
 * Wait for safe replies on open mds requests.  If we time out, drop
 * all requests from the tree to avoid dangling dentry refs.
 */
static void wait_requests(struct ceph_mds_client *mdsc)
{
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_options *opts = mdsc->fsc->client->options;
        struct ceph_mds_request *req;

        mutex_lock(&mdsc->mutex);
        if (__get_oldest_req(mdsc)) {
                mutex_unlock(&mdsc->mutex);

                doutc(cl, "waiting for requests\n");
                wait_for_completion_timeout(&mdsc->safe_umount_waiters,
                                    ceph_timeout_jiffies(opts->mount_timeout));

                /* tear down remaining requests */
                mutex_lock(&mdsc->mutex);
                while ((req = __get_oldest_req(mdsc))) {
                        doutc(cl, "timed out on tid %llu\n", req->r_tid);
                        list_del_init(&req->r_wait);
                        __unregister_request(mdsc, req);
                }
        }
        mutex_unlock(&mdsc->mutex);
        doutc(cl, "done\n");
}

void send_flush_mdlog(struct ceph_mds_session *s)
{
        struct ceph_client *cl = s->s_mdsc->fsc->client;
        struct ceph_msg *msg;

        /*
         * Pre-luminous MDS crashes when it sees an unknown session request
         */
        if (!CEPH_HAVE_FEATURE(s->s_con.peer_features, SERVER_LUMINOUS))
                return;

        mutex_lock(&s->s_mutex);
        doutc(cl, "request mdlog flush to mds%d (%s)s seq %lld\n",
              s->s_mds, ceph_session_state_name(s->s_state), s->s_seq);
        msg = ceph_create_session_msg(CEPH_SESSION_REQUEST_FLUSH_MDLOG,
                                      s->s_seq);
        if (!msg) {
                pr_err_client(cl, "failed to request mdlog flush to mds%d (%s) seq %lld\n",
                              s->s_mds, ceph_session_state_name(s->s_state), s->s_seq);
        } else {
                ceph_con_send(&s->s_con, msg);
        }
        mutex_unlock(&s->s_mutex);
}

static int ceph_mds_auth_match(struct ceph_mds_client *mdsc,
                               struct ceph_mds_cap_auth *auth,
                               const struct cred *cred,
                               char *tpath)
{
        u32 caller_uid = from_kuid(&init_user_ns, cred->fsuid);
        u32 caller_gid = from_kgid(&init_user_ns, cred->fsgid);
        struct ceph_client *cl = mdsc->fsc->client;
        const char *fs_name = mdsc->fsc->mount_options->mds_namespace;
        const char *spath = mdsc->fsc->mount_options->server_path;
        bool gid_matched = false;
        u32 gid, tlen, len;
        int i, j;

        doutc(cl, "fsname check fs_name=%s  match.fs_name=%s\n",
              fs_name, auth->match.fs_name ? auth->match.fs_name : "");
        if (auth->match.fs_name && strcmp(auth->match.fs_name, fs_name)) {
                /* fsname mismatch, try next one */
                return 0;
        }

        doutc(cl, "match.uid %lld\n", auth->match.uid);
        if (auth->match.uid != MDS_AUTH_UID_ANY) {
                if (auth->match.uid != caller_uid)
                        return 0;
                if (auth->match.num_gids) {
                        for (i = 0; i < auth->match.num_gids; i++) {
                                if (caller_gid == auth->match.gids[i])
                                        gid_matched = true;
                        }
                        if (!gid_matched && cred->group_info->ngroups) {
                                for (i = 0; i < cred->group_info->ngroups; i++) {
                                        gid = from_kgid(&init_user_ns,
                                                        cred->group_info->gid[i]);
                                        for (j = 0; j < auth->match.num_gids; j++) {
                                                if (gid == auth->match.gids[j]) {
                                                        gid_matched = true;
                                                        break;
                                                }
                                        }
                                        if (gid_matched)
                                                break;
                                }
                        }
                        if (!gid_matched)
                                return 0;
                }
        }

        /* path match */
        if (auth->match.path) {
                if (!tpath)
                        return 0;

                tlen = strlen(tpath);
                len = strlen(auth->match.path);
                if (len) {
                        char *_tpath = tpath;
                        bool free_tpath = false;
                        int m, n;

                        doutc(cl, "server path %s, tpath %s, match.path %s\n",
                              spath, tpath, auth->match.path);
                        if (spath && (m = strlen(spath)) != 1) {
                                /* mount path + '/' + tpath + an extra space */
                                n = m + 1 + tlen + 1;
                                _tpath = kmalloc(n, GFP_NOFS);
                                if (!_tpath)
                                        return -ENOMEM;
                                /* remove the leading '/' */
                                snprintf(_tpath, n, "%s/%s", spath + 1, tpath);
                                free_tpath = true;
                                tlen = strlen(_tpath);
                        }

                        /*
                         * Please note the tailing '/' for match.path has already
                         * been removed when parsing.
                         *
                         * Remove the tailing '/' for the target path.
                         */
                        while (tlen && _tpath[tlen - 1] == '/') {
                                _tpath[tlen - 1] = '\0';
                                tlen -= 1;
                        }
                        doutc(cl, "_tpath %s\n", _tpath);

                        /*
                         * In case first == _tpath && tlen == len:
                         *  match.path=/foo  --> /foo _path=/foo     --> match
                         *  match.path=/foo/ --> /foo _path=/foo     --> match
                         *
                         * In case first == _tmatch.path && tlen > len:
                         *  match.path=/foo/ --> /foo _path=/foo/    --> match
                         *  match.path=/foo  --> /foo _path=/foo/    --> match
                         *  match.path=/foo/ --> /foo _path=/foo/d   --> match
                         *  match.path=/foo  --> /foo _path=/food    --> mismatch
                         *
                         * All the other cases                       --> mismatch
                         */
                        bool path_matched = true;
                        char *first = strstr(_tpath, auth->match.path);
                        if (first != _tpath ||
                            (tlen > len && _tpath[len] != '/')) {
                                path_matched = false;
                        }

                        if (free_tpath)
                                kfree(_tpath);

                        if (!path_matched)
                                return 0;
                }
        }

        doutc(cl, "matched\n");
        return 1;
}

int ceph_mds_check_access(struct ceph_mds_client *mdsc, char *tpath, int mask)
{
        const struct cred *cred = get_current_cred();
        u32 caller_uid = from_kuid(&init_user_ns, cred->fsuid);
        u32 caller_gid = from_kgid(&init_user_ns, cred->fsgid);
        struct ceph_mds_cap_auth *rw_perms_s = NULL;
        struct ceph_client *cl = mdsc->fsc->client;
        bool root_squash_perms = true;
        int i, err;

        doutc(cl, "tpath '%s', mask %d, caller_uid %d, caller_gid %d\n",
              tpath, mask, caller_uid, caller_gid);

        for (i = 0; i < mdsc->s_cap_auths_num; i++) {
                struct ceph_mds_cap_auth *s = &mdsc->s_cap_auths[i];

                err = ceph_mds_auth_match(mdsc, s, cred, tpath);
                if (err < 0) {
                        put_cred(cred);
                        return err;
                } else if (err > 0) {
                        /* always follow the last auth caps' permission */
                        root_squash_perms = true;
                        rw_perms_s = NULL;
                        if ((mask & MAY_WRITE) && s->writeable &&
                            s->match.root_squash && (!caller_uid || !caller_gid))
                                root_squash_perms = false;

                        if (((mask & MAY_WRITE) && !s->writeable) ||
                            ((mask & MAY_READ) && !s->readable))
                                rw_perms_s = s;
                }
        }

        put_cred(cred);

        doutc(cl, "root_squash_perms %d, rw_perms_s %p\n", root_squash_perms,
              rw_perms_s);
        if (root_squash_perms && rw_perms_s == NULL) {
                doutc(cl, "access allowed\n");
                return 0;
        }

        if (!root_squash_perms) {
                doutc(cl, "root_squash is enabled and user(%d %d) isn't allowed to write",
                      caller_uid, caller_gid);
        }
        if (rw_perms_s) {
                doutc(cl, "mds auth caps readable/writeable %d/%d while request r/w %d/%d",
                      rw_perms_s->readable, rw_perms_s->writeable,
                      !!(mask & MAY_READ), !!(mask & MAY_WRITE));
        }
        doutc(cl, "access denied\n");
        return -EACCES;
}

/*
 * called before mount is ro, and before dentries are torn down.
 * (hmm, does this still race with new lookups?)
 */
void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc)
{
        doutc(mdsc->fsc->client, "begin\n");
        mdsc->stopping = CEPH_MDSC_STOPPING_BEGIN;

        ceph_mdsc_iterate_sessions(mdsc, send_flush_mdlog, true);
        ceph_mdsc_iterate_sessions(mdsc, lock_unlock_session, false);
        ceph_flush_dirty_caps(mdsc);
        wait_requests(mdsc);

        /*
         * wait for reply handlers to drop their request refs and
         * their inode/dcache refs
         */
        ceph_msgr_flush();

        ceph_cleanup_quotarealms_inodes(mdsc);
        doutc(mdsc->fsc->client, "done\n");
}

/*
 * flush the mdlog and wait for all write mds requests to flush.
 */
static void flush_mdlog_and_wait_mdsc_unsafe_requests(struct ceph_mds_client *mdsc,
                                                 u64 want_tid)
{
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_mds_request *req = NULL, *nextreq;
        struct ceph_mds_session *last_session = NULL;
        struct rb_node *n;

        mutex_lock(&mdsc->mutex);
        doutc(cl, "want %lld\n", want_tid);
restart:
        req = __get_oldest_req(mdsc);
        while (req && req->r_tid <= want_tid) {
                /* find next request */
                n = rb_next(&req->r_node);
                if (n)
                        nextreq = rb_entry(n, struct ceph_mds_request, r_node);
                else
                        nextreq = NULL;
                if (req->r_op != CEPH_MDS_OP_SETFILELOCK &&
                    (req->r_op & CEPH_MDS_OP_WRITE)) {
                        struct ceph_mds_session *s = req->r_session;

                        if (!s) {
                                req = nextreq;
                                continue;
                        }

                        /* write op */
                        ceph_mdsc_get_request(req);
                        if (nextreq)
                                ceph_mdsc_get_request(nextreq);
                        s = ceph_get_mds_session(s);
                        mutex_unlock(&mdsc->mutex);

                        /* send flush mdlog request to MDS */
                        if (last_session != s) {
                                send_flush_mdlog(s);
                                ceph_put_mds_session(last_session);
                                last_session = s;
                        } else {
                                ceph_put_mds_session(s);
                        }
                        doutc(cl, "wait on %llu (want %llu)\n",
                              req->r_tid, want_tid);
                        wait_for_completion(&req->r_safe_completion);

                        mutex_lock(&mdsc->mutex);
                        ceph_mdsc_put_request(req);
                        if (!nextreq)
                                break;  /* next dne before, so we're done! */
                        if (RB_EMPTY_NODE(&nextreq->r_node)) {
                                /* next request was removed from tree */
                                ceph_mdsc_put_request(nextreq);
                                goto restart;
                        }
                        ceph_mdsc_put_request(nextreq);  /* won't go away */
                }
                req = nextreq;
        }
        mutex_unlock(&mdsc->mutex);
        ceph_put_mds_session(last_session);
        doutc(cl, "done\n");
}

void ceph_mdsc_sync(struct ceph_mds_client *mdsc)
{
        struct ceph_client *cl = mdsc->fsc->client;
        u64 want_tid, want_flush;

        if (READ_ONCE(mdsc->fsc->mount_state) >= CEPH_MOUNT_SHUTDOWN)
                return;

        doutc(cl, "sync\n");
        mutex_lock(&mdsc->mutex);
        want_tid = mdsc->last_tid;
        mutex_unlock(&mdsc->mutex);

        ceph_flush_dirty_caps(mdsc);
        ceph_flush_cap_releases(mdsc);
        spin_lock(&mdsc->cap_dirty_lock);
        want_flush = mdsc->last_cap_flush_tid;
        if (!list_empty(&mdsc->cap_flush_list)) {
                struct ceph_cap_flush *cf =
                        list_last_entry(&mdsc->cap_flush_list,
                                        struct ceph_cap_flush, g_list);
                cf->wake = true;
        }
        spin_unlock(&mdsc->cap_dirty_lock);

        doutc(cl, "sync want tid %lld flush_seq %lld\n", want_tid, want_flush);

        flush_mdlog_and_wait_mdsc_unsafe_requests(mdsc, want_tid);
        wait_caps_flush(mdsc, want_flush);
}

/*
 * true if all sessions are closed, or we force unmount
 */
static bool done_closing_sessions(struct ceph_mds_client *mdsc, int skipped)
{
        if (READ_ONCE(mdsc->fsc->mount_state) == CEPH_MOUNT_SHUTDOWN)
                return true;
        return atomic_read(&mdsc->num_sessions) <= skipped;
}

/*
 * called after sb is ro or when metadata corrupted.
 */
void ceph_mdsc_close_sessions(struct ceph_mds_client *mdsc)
{
        struct ceph_options *opts = mdsc->fsc->client->options;
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_mds_session *session;
        int i;
        int skipped = 0;

        doutc(cl, "begin\n");

        /* close sessions */
        mutex_lock(&mdsc->mutex);
        for (i = 0; i < mdsc->max_sessions; i++) {
                session = __ceph_lookup_mds_session(mdsc, i);
                if (!session)
                        continue;
                mutex_unlock(&mdsc->mutex);
                mutex_lock(&session->s_mutex);
                if (__close_session(mdsc, session) <= 0)
                        skipped++;
                mutex_unlock(&session->s_mutex);
                ceph_put_mds_session(session);
                mutex_lock(&mdsc->mutex);
        }
        mutex_unlock(&mdsc->mutex);

        doutc(cl, "waiting for sessions to close\n");
        wait_event_timeout(mdsc->session_close_wq,
                           done_closing_sessions(mdsc, skipped),
                           ceph_timeout_jiffies(opts->mount_timeout));

        /* tear down remaining sessions */
        mutex_lock(&mdsc->mutex);
        for (i = 0; i < mdsc->max_sessions; i++) {
                if (mdsc->sessions[i]) {
                        session = ceph_get_mds_session(mdsc->sessions[i]);
                        __unregister_session(mdsc, session);
                        mutex_unlock(&mdsc->mutex);
                        mutex_lock(&session->s_mutex);
                        remove_session_caps(session);
                        mutex_unlock(&session->s_mutex);
                        ceph_put_mds_session(session);
                        mutex_lock(&mdsc->mutex);
                }
        }
        WARN_ON(!list_empty(&mdsc->cap_delay_list));
        mutex_unlock(&mdsc->mutex);

        ceph_cleanup_snapid_map(mdsc);
        ceph_cleanup_global_and_empty_realms(mdsc);

        cancel_work_sync(&mdsc->cap_reclaim_work);
        cancel_work_sync(&mdsc->cap_unlink_work);
        cancel_delayed_work_sync(&mdsc->delayed_work); /* cancel timer */

        doutc(cl, "done\n");
}

void ceph_mdsc_force_umount(struct ceph_mds_client *mdsc)
{
        struct ceph_mds_session *session;
        int mds;

        doutc(mdsc->fsc->client, "force umount\n");

        mutex_lock(&mdsc->mutex);
        for (mds = 0; mds < mdsc->max_sessions; mds++) {
                session = __ceph_lookup_mds_session(mdsc, mds);
                if (!session)
                        continue;

                if (session->s_state == CEPH_MDS_SESSION_REJECTED)
                        __unregister_session(mdsc, session);
                __wake_requests(mdsc, &session->s_waiting);
                mutex_unlock(&mdsc->mutex);

                mutex_lock(&session->s_mutex);
                __close_session(mdsc, session);
                if (session->s_state == CEPH_MDS_SESSION_CLOSING) {
                        cleanup_session_requests(mdsc, session);
                        remove_session_caps(session);
                }
                mutex_unlock(&session->s_mutex);
                ceph_put_mds_session(session);

                mutex_lock(&mdsc->mutex);
                kick_requests(mdsc, mds);
        }
        __wake_requests(mdsc, &mdsc->waiting_for_map);
        mutex_unlock(&mdsc->mutex);
}

static void ceph_mdsc_stop(struct ceph_mds_client *mdsc)
{
        doutc(mdsc->fsc->client, "stop\n");
        /*
         * Make sure the delayed work stopped before releasing
         * the resources.
         *
         * Because the cancel_delayed_work_sync() will only
         * guarantee that the work finishes executing. But the
         * delayed work will re-arm itself again after that.
         */
        flush_delayed_work(&mdsc->delayed_work);

        if (mdsc->mdsmap)
                ceph_mdsmap_destroy(mdsc->mdsmap);
        kfree(mdsc->sessions);
        ceph_caps_finalize(mdsc);

        if (mdsc->s_cap_auths) {
                int i;

                for (i = 0; i < mdsc->s_cap_auths_num; i++) {
                        kfree(mdsc->s_cap_auths[i].match.gids);
                        kfree(mdsc->s_cap_auths[i].match.path);
                        kfree(mdsc->s_cap_auths[i].match.fs_name);
                }
                kfree(mdsc->s_cap_auths);
        }

        ceph_pool_perm_destroy(mdsc);
}

void ceph_mdsc_destroy(struct ceph_fs_client *fsc)
{
        struct ceph_mds_client *mdsc = fsc->mdsc;
        doutc(fsc->client, "%p\n", mdsc);

        if (!mdsc)
                return;

        /* flush out any connection work with references to us */
        ceph_msgr_flush();

        ceph_mdsc_stop(mdsc);

        ceph_metric_destroy(&mdsc->metric);

        fsc->mdsc = NULL;
        kfree(mdsc);
        doutc(fsc->client, "%p done\n", mdsc);
}

void ceph_mdsc_handle_fsmap(struct ceph_mds_client *mdsc, struct ceph_msg *msg)
{
        struct ceph_fs_client *fsc = mdsc->fsc;
        struct ceph_client *cl = fsc->client;
        const char *mds_namespace = fsc->mount_options->mds_namespace;
        void *p = msg->front.iov_base;
        void *end = p + msg->front.iov_len;
        u32 epoch;
        u32 num_fs;
        u32 mount_fscid = (u32)-1;
        int err = -EINVAL;

        ceph_decode_need(&p, end, sizeof(u32), bad);
        epoch = ceph_decode_32(&p);

        doutc(cl, "epoch %u\n", epoch);

        /* struct_v, struct_cv, map_len, epoch, legacy_client_fscid */
        ceph_decode_skip_n(&p, end, 2 + sizeof(u32) * 3, bad);

        ceph_decode_32_safe(&p, end, num_fs, bad);
        while (num_fs-- > 0) {
                void *info_p, *info_end;
                u32 info_len;
                u32 fscid, namelen;

                ceph_decode_need(&p, end, 2 + sizeof(u32), bad);
                p += 2;         // info_v, info_cv
                info_len = ceph_decode_32(&p);
                ceph_decode_need(&p, end, info_len, bad);
                info_p = p;
                info_end = p + info_len;
                p = info_end;

                ceph_decode_need(&info_p, info_end, sizeof(u32) * 2, bad);
                fscid = ceph_decode_32(&info_p);
                namelen = ceph_decode_32(&info_p);
                ceph_decode_need(&info_p, info_end, namelen, bad);

                if (mds_namespace &&
                    strlen(mds_namespace) == namelen &&
                    !strncmp(mds_namespace, (char *)info_p, namelen)) {
                        mount_fscid = fscid;
                        break;
                }
        }

        ceph_monc_got_map(&fsc->client->monc, CEPH_SUB_FSMAP, epoch);
        if (mount_fscid != (u32)-1) {
                fsc->client->monc.fs_cluster_id = mount_fscid;
                ceph_monc_want_map(&fsc->client->monc, CEPH_SUB_MDSMAP,
                                   0, true);
                ceph_monc_renew_subs(&fsc->client->monc);
        } else {
                err = -ENOENT;
                goto err_out;
        }
        return;

bad:
        pr_err_client(cl, "error decoding fsmap %d. Shutting down mount.\n",
                      err);
        ceph_umount_begin(mdsc->fsc->sb);
        ceph_msg_dump(msg);
err_out:
        mutex_lock(&mdsc->mutex);
        mdsc->mdsmap_err = err;
        __wake_requests(mdsc, &mdsc->waiting_for_map);
        mutex_unlock(&mdsc->mutex);
}

/*
 * handle mds map update.
 */
void ceph_mdsc_handle_mdsmap(struct ceph_mds_client *mdsc, struct ceph_msg *msg)
{
        struct ceph_client *cl = mdsc->fsc->client;
        u32 epoch;
        u32 maplen;
        void *p = msg->front.iov_base;
        void *end = p + msg->front.iov_len;
        struct ceph_mdsmap *newmap, *oldmap;
        struct ceph_fsid fsid;
        int err = -EINVAL;

        ceph_decode_need(&p, end, sizeof(fsid)+2*sizeof(u32), bad);
        ceph_decode_copy(&p, &fsid, sizeof(fsid));
        if (ceph_check_fsid(mdsc->fsc->client, &fsid) < 0)
                return;
        epoch = ceph_decode_32(&p);
        maplen = ceph_decode_32(&p);
        doutc(cl, "epoch %u len %d\n", epoch, (int)maplen);

        /* do we need it? */
        mutex_lock(&mdsc->mutex);
        if (mdsc->mdsmap && epoch <= mdsc->mdsmap->m_epoch) {
                doutc(cl, "epoch %u <= our %u\n", epoch, mdsc->mdsmap->m_epoch);
                mutex_unlock(&mdsc->mutex);
                return;
        }

        newmap = ceph_mdsmap_decode(mdsc, &p, end, ceph_msgr2(mdsc->fsc->client));
        if (IS_ERR(newmap)) {
                err = PTR_ERR(newmap);
                goto bad_unlock;
        }

        /* swap into place */
        if (mdsc->mdsmap) {
                oldmap = mdsc->mdsmap;
                mdsc->mdsmap = newmap;
                check_new_map(mdsc, newmap, oldmap);
                ceph_mdsmap_destroy(oldmap);
        } else {
                mdsc->mdsmap = newmap;  /* first mds map */
        }
        mdsc->fsc->max_file_size = min((loff_t)mdsc->mdsmap->m_max_file_size,
                                        MAX_LFS_FILESIZE);

        __wake_requests(mdsc, &mdsc->waiting_for_map);
        ceph_monc_got_map(&mdsc->fsc->client->monc, CEPH_SUB_MDSMAP,
                          mdsc->mdsmap->m_epoch);

        mutex_unlock(&mdsc->mutex);
        schedule_delayed(mdsc, 0);
        return;

bad_unlock:
        mutex_unlock(&mdsc->mutex);
bad:
        pr_err_client(cl, "error decoding mdsmap %d. Shutting down mount.\n",
                      err);
        ceph_umount_begin(mdsc->fsc->sb);
        ceph_msg_dump(msg);
        return;
}

static struct ceph_connection *mds_get_con(struct ceph_connection *con)
{
        struct ceph_mds_session *s = con->private;

        if (ceph_get_mds_session(s))
                return con;
        return NULL;
}

static void mds_put_con(struct ceph_connection *con)
{
        struct ceph_mds_session *s = con->private;

        ceph_put_mds_session(s);
}

/*
 * if the client is unresponsive for long enough, the mds will kill
 * the session entirely.
 */
static void mds_peer_reset(struct ceph_connection *con)
{
        struct ceph_mds_session *s = con->private;
        struct ceph_mds_client *mdsc = s->s_mdsc;

        pr_warn_client(mdsc->fsc->client, "mds%d closed our session\n",
                       s->s_mds);
        if (READ_ONCE(mdsc->fsc->mount_state) != CEPH_MOUNT_FENCE_IO &&
            ceph_mdsmap_get_state(mdsc->mdsmap, s->s_mds) >= CEPH_MDS_STATE_RECONNECT)
                send_mds_reconnect(mdsc, s);
}

static void mds_dispatch(struct ceph_connection *con, struct ceph_msg *msg)
{
        struct ceph_mds_session *s = con->private;
        struct ceph_mds_client *mdsc = s->s_mdsc;
        struct ceph_client *cl = mdsc->fsc->client;
        int type = le16_to_cpu(msg->hdr.type);

        mutex_lock(&mdsc->mutex);
        if (__verify_registered_session(mdsc, s) < 0) {
                mutex_unlock(&mdsc->mutex);
                goto out;
        }
        mutex_unlock(&mdsc->mutex);

        switch (type) {
        case CEPH_MSG_MDS_MAP:
                ceph_mdsc_handle_mdsmap(mdsc, msg);
                break;
        case CEPH_MSG_FS_MAP_USER:
                ceph_mdsc_handle_fsmap(mdsc, msg);
                break;
        case CEPH_MSG_CLIENT_SESSION:
                handle_session(s, msg);
                break;
        case CEPH_MSG_CLIENT_REPLY:
                handle_reply(s, msg);
                break;
        case CEPH_MSG_CLIENT_REQUEST_FORWARD:
                handle_forward(mdsc, s, msg);
                break;
        case CEPH_MSG_CLIENT_CAPS:
                ceph_handle_caps(s, msg);
                break;
        case CEPH_MSG_CLIENT_SNAP:
                ceph_handle_snap(mdsc, s, msg);
                break;
        case CEPH_MSG_CLIENT_LEASE:
                handle_lease(mdsc, s, msg);
                break;
        case CEPH_MSG_CLIENT_QUOTA:
                ceph_handle_quota(mdsc, s, msg);
                break;

        default:
                pr_err_client(cl, "received unknown message type %d %s\n",
                              type, ceph_msg_type_name(type));
        }
out:
        ceph_msg_put(msg);
}

/*
 * authentication
 */

/*
 * Note: returned pointer is the address of a structure that's
 * managed separately.  Caller must *not* attempt to free it.
 */
static struct ceph_auth_handshake *
mds_get_authorizer(struct ceph_connection *con, int *proto, int force_new)
{
        struct ceph_mds_session *s = con->private;
        struct ceph_mds_client *mdsc = s->s_mdsc;
        struct ceph_auth_client *ac = mdsc->fsc->client->monc.auth;
        struct ceph_auth_handshake *auth = &s->s_auth;
        int ret;

        ret = __ceph_auth_get_authorizer(ac, auth, CEPH_ENTITY_TYPE_MDS,
                                         force_new, proto, NULL, NULL);
        if (ret)
                return ERR_PTR(ret);

        return auth;
}

static int mds_add_authorizer_challenge(struct ceph_connection *con,
                                    void *challenge_buf, int challenge_buf_len)
{
        struct ceph_mds_session *s = con->private;
        struct ceph_mds_client *mdsc = s->s_mdsc;
        struct ceph_auth_client *ac = mdsc->fsc->client->monc.auth;

        return ceph_auth_add_authorizer_challenge(ac, s->s_auth.authorizer,
                                            challenge_buf, challenge_buf_len);
}

static int mds_verify_authorizer_reply(struct ceph_connection *con)
{
        struct ceph_mds_session *s = con->private;
        struct ceph_mds_client *mdsc = s->s_mdsc;
        struct ceph_auth_client *ac = mdsc->fsc->client->monc.auth;
        struct ceph_auth_handshake *auth = &s->s_auth;

        return ceph_auth_verify_authorizer_reply(ac, auth->authorizer,
                auth->authorizer_reply_buf, auth->authorizer_reply_buf_len,
                NULL, NULL, NULL, NULL);
}

static int mds_invalidate_authorizer(struct ceph_connection *con)
{
        struct ceph_mds_session *s = con->private;
        struct ceph_mds_client *mdsc = s->s_mdsc;
        struct ceph_auth_client *ac = mdsc->fsc->client->monc.auth;

        ceph_auth_invalidate_authorizer(ac, CEPH_ENTITY_TYPE_MDS);

        return ceph_monc_validate_auth(&mdsc->fsc->client->monc);
}

static int mds_get_auth_request(struct ceph_connection *con,
                                void *buf, int *buf_len,
                                void **authorizer, int *authorizer_len)
{
        struct ceph_mds_session *s = con->private;
        struct ceph_auth_client *ac = s->s_mdsc->fsc->client->monc.auth;
        struct ceph_auth_handshake *auth = &s->s_auth;
        int ret;

        ret = ceph_auth_get_authorizer(ac, auth, CEPH_ENTITY_TYPE_MDS,
                                       buf, buf_len);
        if (ret)
                return ret;

        *authorizer = auth->authorizer_buf;
        *authorizer_len = auth->authorizer_buf_len;
        return 0;
}

static int mds_handle_auth_reply_more(struct ceph_connection *con,
                                      void *reply, int reply_len,
                                      void *buf, int *buf_len,
                                      void **authorizer, int *authorizer_len)
{
        struct ceph_mds_session *s = con->private;
        struct ceph_auth_client *ac = s->s_mdsc->fsc->client->monc.auth;
        struct ceph_auth_handshake *auth = &s->s_auth;
        int ret;

        ret = ceph_auth_handle_svc_reply_more(ac, auth, reply, reply_len,
                                              buf, buf_len);
        if (ret)
                return ret;

        *authorizer = auth->authorizer_buf;
        *authorizer_len = auth->authorizer_buf_len;
        return 0;
}

static int mds_handle_auth_done(struct ceph_connection *con,
                                u64 global_id, void *reply, int reply_len,
                                u8 *session_key, int *session_key_len,
                                u8 *con_secret, int *con_secret_len)
{
        struct ceph_mds_session *s = con->private;
        struct ceph_auth_client *ac = s->s_mdsc->fsc->client->monc.auth;
        struct ceph_auth_handshake *auth = &s->s_auth;

        return ceph_auth_handle_svc_reply_done(ac, auth, reply, reply_len,
                                               session_key, session_key_len,
                                               con_secret, con_secret_len);
}

static int mds_handle_auth_bad_method(struct ceph_connection *con,
                                      int used_proto, int result,
                                      const int *allowed_protos, int proto_cnt,
                                      const int *allowed_modes, int mode_cnt)
{
        struct ceph_mds_session *s = con->private;
        struct ceph_mon_client *monc = &s->s_mdsc->fsc->client->monc;
        int ret;

        if (ceph_auth_handle_bad_authorizer(monc->auth, CEPH_ENTITY_TYPE_MDS,
                                            used_proto, result,
                                            allowed_protos, proto_cnt,
                                            allowed_modes, mode_cnt)) {
                ret = ceph_monc_validate_auth(monc);
                if (ret)
                        return ret;
        }

        return -EACCES;
}

static struct ceph_msg *mds_alloc_msg(struct ceph_connection *con,
                                struct ceph_msg_header *hdr, int *skip)
{
        struct ceph_msg *msg;
        int type = (int) le16_to_cpu(hdr->type);
        int front_len = (int) le32_to_cpu(hdr->front_len);

        if (con->in_msg)
                return con->in_msg;

        *skip = 0;
        msg = ceph_msg_new(type, front_len, GFP_NOFS, false);
        if (!msg) {
                pr_err("unable to allocate msg type %d len %d\n",
                       type, front_len);
                return NULL;
        }

        return msg;
}

static int mds_sign_message(struct ceph_msg *msg)
{
       struct ceph_mds_session *s = msg->con->private;
       struct ceph_auth_handshake *auth = &s->s_auth;

       return ceph_auth_sign_message(auth, msg);
}

static int mds_check_message_signature(struct ceph_msg *msg)
{
       struct ceph_mds_session *s = msg->con->private;
       struct ceph_auth_handshake *auth = &s->s_auth;

       return ceph_auth_check_message_signature(auth, msg);
}

static const struct ceph_connection_operations mds_con_ops = {
        .get = mds_get_con,
        .put = mds_put_con,
        .alloc_msg = mds_alloc_msg,
        .dispatch = mds_dispatch,
        .peer_reset = mds_peer_reset,
        .get_authorizer = mds_get_authorizer,
        .add_authorizer_challenge = mds_add_authorizer_challenge,
        .verify_authorizer_reply = mds_verify_authorizer_reply,
        .invalidate_authorizer = mds_invalidate_authorizer,
        .sign_message = mds_sign_message,
        .check_message_signature = mds_check_message_signature,
        .get_auth_request = mds_get_auth_request,
        .handle_auth_reply_more = mds_handle_auth_reply_more,
        .handle_auth_done = mds_handle_auth_done,
        .handle_auth_bad_method = mds_handle_auth_bad_method,
};

/* eof */