btrfs: send: prepare for v2 protocol

This is preparatory work for send protocol update to version 2 and
higher.

We have many pending protocol update requests but still don't have the
basic protocol rev in place, the first thing that must happen is to do
the actual versioning support.

The protocol version is u32 and is a new member in the send ioctl
struct. Validity of the version field is backed by a new flag bit. Old
kernels would fail when a higher version is requested. Version protocol
0 will pick the highest supported version, BTRFS_SEND_STREAM_VERSION,
  that's also exported in sysfs.

The version is still unchanged and will be increased once we have new
incompatible commands or stream updates.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index c474f7e2416328eecb5fda0db1b00f973b2a4885..92424a22d8d68f183abf792c9e4cddd63bbe1ae6 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -82,7 +82,8 @@ struct btrfs_ioctl_send_args_32 {
        compat_uptr_t clone_sources;    /* in */
        __u64 parent_root;              /* in */
        __u64 flags;                    /* in */
-       __u64 reserved[4];              /* in */
+       __u32 version;                  /* in */
+       __u8  reserved[28];             /* in */
 } __attribute__ ((__packed__));
 
 #define BTRFS_IOC_SEND_32 _IOW(BTRFS_IOCTL_MAGIC, 38, \

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index afdcbe7844e0e3d7a984ef5f57c9ecf5cc13be27..040324d71118893420674d78818d98bdf889fa65 100644 (file)
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -84,6 +84,8 @@ struct send_ctx {
        u64 total_send_size;
        u64 cmd_send_size[BTRFS_SEND_C_MAX + 1];
        u64 flags;      /* 'flags' member of btrfs_ioctl_send_args is u64 */
+       /* Protocol version compatibility requested */
+       u32 proto;
 
        struct btrfs_root *send_root;
        struct btrfs_root *parent_root;
@@ -312,6 +314,16 @@ static void inconsistent_snapshot_error(struct send_ctx *sctx,
                   sctx->parent_root->root_key.objectid : 0));
 }
 
+__maybe_unused
+static bool proto_cmd_ok(const struct send_ctx *sctx, int cmd)
+{
+       switch (sctx->proto) {
+       case 1:  return cmd < __BTRFS_SEND_C_MAX_V1;
+       case 2:  return cmd < __BTRFS_SEND_C_MAX_V2;
+       default: return false;
+       }
+}
+
 static int is_waiting_for_move(struct send_ctx *sctx, u64 ino);
 
 static struct waiting_dir_move *
@@ -7269,6 +7281,17 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg)
 
        sctx->flags = arg->flags;
 
+       if (arg->flags & BTRFS_SEND_FLAG_VERSION) {
+               if (arg->version > BTRFS_SEND_STREAM_VERSION) {
+                       ret = -EPROTO;
+                       goto out;
+               }
+               /* Zero means "use the highest version" */
+               sctx->proto = arg->version ?: BTRFS_SEND_STREAM_VERSION;
+       } else {
+               sctx->proto = 1;
+       }
+
        sctx->send_filp = fget(arg->send_fd);
        if (!sctx->send_filp) {
                ret = -EBADF;

diff --git a/fs/btrfs/send.h b/fs/btrfs/send.h
index de91488b7cd003de0d7822b2fc2a521062bcb052..23bcefc84e49abc89aaf8dc8a6f09441144890d9 100644 (file)
--- a/fs/btrfs/send.h
+++ b/fs/btrfs/send.h
@@ -48,6 +48,7 @@ struct btrfs_tlv_header {
 enum btrfs_send_cmd {
        BTRFS_SEND_C_UNSPEC,
 
+       /* Version 1 */
        BTRFS_SEND_C_SUBVOL,
        BTRFS_SEND_C_SNAPSHOT,
 
@@ -76,6 +77,12 @@ enum btrfs_send_cmd {
 
        BTRFS_SEND_C_END,
        BTRFS_SEND_C_UPDATE_EXTENT,
+       __BTRFS_SEND_C_MAX_V1,
+
+       /* Version 2 */
+       __BTRFS_SEND_C_MAX_V2,
+
+       /* End */
        __BTRFS_SEND_C_MAX,
 };
 #define BTRFS_SEND_C_MAX (__BTRFS_SEND_C_MAX - 1)

diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index d7d3cfead056354ab28db9699fb4ab87b1d3afef..738619994e26114c4705a7e307f710a419684964 100644 (file)
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -771,10 +771,16 @@ struct btrfs_ioctl_received_subvol_args {
  */
 #define BTRFS_SEND_FLAG_OMIT_END_CMD           0x4
 
+/*
+ * Read the protocol version in the structure
+ */
+#define BTRFS_SEND_FLAG_VERSION                        0x8
+
 #define BTRFS_SEND_FLAG_MASK \
        (BTRFS_SEND_FLAG_NO_FILE_DATA | \
         BTRFS_SEND_FLAG_OMIT_STREAM_HEADER | \
-        BTRFS_SEND_FLAG_OMIT_END_CMD)
+        BTRFS_SEND_FLAG_OMIT_END_CMD | \
+        BTRFS_SEND_FLAG_VERSION)
 
 struct btrfs_ioctl_send_args {
        __s64 send_fd;                  /* in */
@@ -782,7 +788,8 @@ struct btrfs_ioctl_send_args {
        __u64 __user *clone_sources;    /* in */
        __u64 parent_root;              /* in */
        __u64 flags;                    /* in */
-       __u64 reserved[4];              /* in */
+       __u32 version;                  /* in */
+       __u8  reserved[28];             /* in */
 };
 
 /*