attr.o bad_inode.o file.o filesystems.o namespace.o \
seq_file.o xattr.o libfs.o fs-writeback.o \
pnode.o splice.o sync.o utimes.o d_path.o \
- stack.o fs_struct.o statfs.o fs_pin.o nsfs.o
+ stack.o fs_struct.o statfs.o fs_pin.o nsfs.o \
+ fs_context.o
ifeq ($(CONFIG_BLOCK),y)
obj-y += buffer.o block_dev.o direct-io.o mpage.o
--- /dev/null
+/* Provide a way to create a superblock configuration context within the kernel
+ * that allows a superblock to be set up prior to mounting.
+ *
+ * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/fs_context.h>
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/nsproxy.h>
+#include <linux/slab.h>
+#include <linux/magic.h>
+#include <linux/security.h>
+#include <linux/mnt_namespace.h>
+#include <linux/pid_namespace.h>
+#include <linux/user_namespace.h>
+#include <net/net_namespace.h>
+#include "mount.h"
+#include "internal.h"
+
+struct legacy_fs_context {
+ char *legacy_data; /* Data page for legacy filesystems */
+ size_t data_size;
+};
+
+static int legacy_init_fs_context(struct fs_context *fc);
+
+/**
+ * alloc_fs_context - Create a filesystem context.
+ * @fs_type: The filesystem type.
+ * @reference: The dentry from which this one derives (or NULL)
+ * @sb_flags: Filesystem/superblock flags (SB_*)
+ * @sb_flags_mask: Applicable members of @sb_flags
+ * @purpose: The purpose that this configuration shall be used for.
+ *
+ * Open a filesystem and create a mount context. The mount context is
+ * initialised with the supplied flags and, if a submount/automount from
+ * another superblock (referred to by @reference) is supplied, may have
+ * parameters such as namespaces copied across from that superblock.
+ */
+static struct fs_context *alloc_fs_context(struct file_system_type *fs_type,
+ struct dentry *reference,
+ unsigned int sb_flags,
+ unsigned int sb_flags_mask,
+ enum fs_context_purpose purpose)
+{
+ struct fs_context *fc;
+ int ret = -ENOMEM;
+
+ fc = kzalloc(sizeof(struct fs_context), GFP_KERNEL);
+ if (!fc)
+ return ERR_PTR(-ENOMEM);
+
+ fc->purpose = purpose;
+ fc->sb_flags = sb_flags;
+ fc->sb_flags_mask = sb_flags_mask;
+ fc->fs_type = get_filesystem(fs_type);
+ fc->cred = get_current_cred();
+ fc->net_ns = get_net(current->nsproxy->net_ns);
+
+ switch (purpose) {
+ case FS_CONTEXT_FOR_MOUNT:
+ fc->user_ns = get_user_ns(fc->cred->user_ns);
+ break;
+ }
+
+ ret = legacy_init_fs_context(fc);
+ if (ret < 0)
+ goto err_fc;
+ fc->need_free = true;
+ return fc;
+
+err_fc:
+ put_fs_context(fc);
+ return ERR_PTR(ret);
+}
+
+struct fs_context *fs_context_for_mount(struct file_system_type *fs_type,
+ unsigned int sb_flags)
+{
+ return alloc_fs_context(fs_type, NULL, sb_flags, 0,
+ FS_CONTEXT_FOR_MOUNT);
+}
+EXPORT_SYMBOL(fs_context_for_mount);
+
+static void legacy_fs_context_free(struct fs_context *fc);
+/**
+ * put_fs_context - Dispose of a superblock configuration context.
+ * @fc: The context to dispose of.
+ */
+void put_fs_context(struct fs_context *fc)
+{
+ struct super_block *sb;
+
+ if (fc->root) {
+ sb = fc->root->d_sb;
+ dput(fc->root);
+ fc->root = NULL;
+ deactivate_super(sb);
+ }
+
+ if (fc->need_free)
+ legacy_fs_context_free(fc);
+
+ security_free_mnt_opts(&fc->security);
+ if (fc->net_ns)
+ put_net(fc->net_ns);
+ put_user_ns(fc->user_ns);
+ put_cred(fc->cred);
+ kfree(fc->subtype);
+ put_filesystem(fc->fs_type);
+ kfree(fc->source);
+ kfree(fc);
+}
+EXPORT_SYMBOL(put_fs_context);
+
+/*
+ * Free the config for a filesystem that doesn't support fs_context.
+ */
+static void legacy_fs_context_free(struct fs_context *fc)
+{
+ kfree(fc->fs_private);
+}
+
+/*
+ * Add monolithic mount data.
+ */
+static int legacy_parse_monolithic(struct fs_context *fc, void *data)
+{
+ struct legacy_fs_context *ctx = fc->fs_private;
+ ctx->legacy_data = data;
+ if (!ctx->legacy_data)
+ return 0;
+ if (fc->fs_type->fs_flags & FS_BINARY_MOUNTDATA)
+ return 0;
+ return security_sb_eat_lsm_opts(ctx->legacy_data, &fc->security);
+}
+
+/*
+ * Get a mountable root with the legacy mount command.
+ */
+int legacy_get_tree(struct fs_context *fc)
+{
+ struct legacy_fs_context *ctx = fc->fs_private;
+ struct super_block *sb;
+ struct dentry *root;
+
+ root = fc->fs_type->mount(fc->fs_type, fc->sb_flags,
+ fc->source, ctx->legacy_data);
+ if (IS_ERR(root))
+ return PTR_ERR(root);
+
+ sb = root->d_sb;
+ BUG_ON(!sb);
+
+ fc->root = root;
+ return 0;
+}
+
+/*
+ * Initialise a legacy context for a filesystem that doesn't support
+ * fs_context.
+ */
+static int legacy_init_fs_context(struct fs_context *fc)
+{
+ fc->fs_private = kzalloc(sizeof(struct legacy_fs_context), GFP_KERNEL);
+ if (!fc->fs_private)
+ return -ENOMEM;
+ return 0;
+}
+
+int parse_monolithic_mount_data(struct fs_context *fc, void *data)
+{
+ return legacy_parse_monolithic(fc, data);
+}
struct path;
struct mount;
struct shrink_control;
+struct fs_context;
/*
* block_dev.c
*/
extern void __init chrdev_init(void);
+/*
+ * fs_context.c
+ */
+extern int legacy_get_tree(struct fs_context *fc);
+extern int parse_monolithic_mount_data(struct fs_context *, void *);
+
/*
* namei.c
*/
*/
extern int do_remount_sb(struct super_block *, int, void *, int);
extern bool trylock_super(struct super_block *sb);
-extern struct dentry *mount_fs(struct file_system_type *,
- int, const char *, void *);
extern struct super_block *user_get_super(dev_t);
/*
#include <linux/task_work.h>
#include <linux/sched/task.h>
#include <uapi/linux/mount.h>
+#include <linux/fs_context.h>
#include "pnode.h"
#include "internal.h"
return p;
}
-struct vfsmount *
-vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
+struct vfsmount *vfs_kern_mount(struct file_system_type *type,
+ int flags, const char *name,
+ void *data)
{
+ struct fs_context *fc;
struct mount *mnt;
- struct dentry *root;
+ int ret = 0;
if (!type)
return ERR_PTR(-ENODEV);
+ fc = fs_context_for_mount(type, flags);
+ if (IS_ERR(fc))
+ return ERR_CAST(fc);
+
+ if (name) {
+ fc->source = kstrdup(name, GFP_KERNEL);
+ if (!fc->source)
+ ret = -ENOMEM;
+ }
+ if (!ret)
+ ret = parse_monolithic_mount_data(fc, data);
+ if (!ret)
+ ret = vfs_get_tree(fc);
+ if (ret) {
+ put_fs_context(fc);
+ return ERR_PTR(ret);
+ }
+ up_write(&fc->root->d_sb->s_umount);
mnt = alloc_vfsmnt(name);
- if (!mnt)
+ if (!mnt) {
+ put_fs_context(fc);
return ERR_PTR(-ENOMEM);
+ }
if (flags & SB_KERNMOUNT)
mnt->mnt.mnt_flags = MNT_INTERNAL;
- root = mount_fs(type, flags, name, data);
- if (IS_ERR(root)) {
- mnt_free_id(mnt);
- free_vfsmnt(mnt);
- return ERR_CAST(root);
- }
-
- mnt->mnt.mnt_root = root;
- mnt->mnt.mnt_sb = root->d_sb;
+ atomic_inc(&fc->root->d_sb->s_active);
+ mnt->mnt.mnt_root = dget(fc->root);
+ mnt->mnt.mnt_sb = fc->root->d_sb;
mnt->mnt_mountpoint = mnt->mnt.mnt_root;
mnt->mnt_parent = mnt;
lock_mount_hash();
- list_add_tail(&mnt->mnt_instance, &root->d_sb->s_mounts);
+ list_add_tail(&mnt->mnt_instance, &fc->root->d_sb->s_mounts);
unlock_mount_hash();
+ put_fs_context(fc);
return &mnt->mnt;
}
EXPORT_SYMBOL_GPL(vfs_kern_mount);
#include <linux/fsnotify.h>
#include <linux/lockdep.h>
#include <linux/user_namespace.h>
+#include <linux/fs_context.h>
#include <uapi/linux/mount.h>
#include "internal.h"
}
EXPORT_SYMBOL(mount_single);
-struct dentry *
-mount_fs(struct file_system_type *type, int flags, const char *name, void *data)
+/**
+ * vfs_get_tree - Get the mountable root
+ * @fc: The superblock configuration context.
+ *
+ * The filesystem is invoked to get or create a superblock which can then later
+ * be used for mounting. The filesystem places a pointer to the root to be
+ * used for mounting in @fc->root.
+ */
+int vfs_get_tree(struct fs_context *fc)
{
- struct dentry *root;
struct super_block *sb;
- int error = -ENOMEM;
- void *sec_opts = NULL;
+ int error;
- if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
- error = security_sb_eat_lsm_opts(data, &sec_opts);
- if (error)
- return ERR_PTR(error);
- }
+ error = legacy_get_tree(fc);
+ if (error < 0)
+ return error;
- root = type->mount(type, flags, name, data);
- if (IS_ERR(root)) {
- error = PTR_ERR(root);
- goto out_free_secdata;
- }
- sb = root->d_sb;
- BUG_ON(!sb);
+ sb = fc->root->d_sb;
WARN_ON(!sb->s_bdi);
/*
smp_wmb();
sb->s_flags |= SB_BORN;
- error = security_sb_set_mnt_opts(sb, sec_opts, 0, NULL);
+ error = security_sb_set_mnt_opts(sb, fc->security, 0, NULL);
if (error)
goto out_sb;
- if (!(flags & (MS_KERNMOUNT|MS_SUBMOUNT))) {
+ if (!(fc->sb_flags & (MS_KERNMOUNT|MS_SUBMOUNT))) {
error = security_sb_kern_mount(sb);
if (error)
goto out_sb;
* violate this rule.
*/
WARN((sb->s_maxbytes < 0), "%s set sb->s_maxbytes to "
- "negative value (%lld)\n", type->name, sb->s_maxbytes);
+ "negative value (%lld)\n", fc->fs_type->name, sb->s_maxbytes);
- up_write(&sb->s_umount);
- security_free_mnt_opts(&sec_opts);
- return root;
+ return 0;
out_sb:
- dput(root);
+ dput(fc->root);
+ fc->root = NULL;
deactivate_locked_super(sb);
-out_free_secdata:
- security_free_mnt_opts(&sec_opts);
- return ERR_PTR(error);
+ return error;
}
+EXPORT_SYMBOL(vfs_get_tree);
/*
* Setup private BDI for given superblock. It gets automatically cleaned up
--- /dev/null
+/* Filesystem superblock creation and reconfiguration context.
+ *
+ * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#ifndef _LINUX_FS_CONTEXT_H
+#define _LINUX_FS_CONTEXT_H
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/security.h>
+
+struct cred;
+struct dentry;
+struct file_operations;
+struct file_system_type;
+struct net;
+struct user_namespace;
+
+enum fs_context_purpose {
+ FS_CONTEXT_FOR_MOUNT, /* New superblock for explicit mount */
+};
+
+/*
+ * Filesystem context for holding the parameters used in the creation or
+ * reconfiguration of a superblock.
+ *
+ * Superblock creation fills in ->root whereas reconfiguration begins with this
+ * already set.
+ *
+ * See Documentation/filesystems/mounting.txt
+ */
+struct fs_context {
+ struct file_system_type *fs_type;
+ void *fs_private; /* The filesystem's context */
+ struct dentry *root; /* The root and superblock */
+ struct user_namespace *user_ns; /* The user namespace for this mount */
+ struct net *net_ns; /* The network namespace for this mount */
+ const struct cred *cred; /* The mounter's credentials */
+ const char *source; /* The source name (eg. dev path) */
+ const char *subtype; /* The subtype to set on the superblock */
+ void *security; /* Linux S&M options */
+ unsigned int sb_flags; /* Proposed superblock flags (SB_*) */
+ unsigned int sb_flags_mask; /* Superblock flags that were changed */
+ enum fs_context_purpose purpose:8;
+ bool need_free:1; /* Need to call ops->free() */
+};
+
+/*
+ * fs_context manipulation functions.
+ */
+extern struct fs_context *fs_context_for_mount(struct file_system_type *fs_type,
+ unsigned int sb_flags);
+
+extern int vfs_get_tree(struct fs_context *fc);
+extern void put_fs_context(struct fs_context *fc);
+
+#endif /* _LINUX_FS_CONTEXT_H */
projects / users / hch / xfs.git / commitdiff