btrfs: create sprout should rename fsid on the sysfs as well

Creating sprout will change the fsid of the mounted root.
do the same on the sysfs as well.

reproducer:
 mount /dev/sdb /btrfs (seed disk)
 btrfs dev add /dev/sdc /btrfs
 mount -o rw,remount /btrfs
 btrfs dev del /dev/sdb /btrfs
 mount /dev/sdb /btrfs

Error:
kobject_add_internal failed for fe350492-dc28-4051-a601-e017b17e6145 with -EEXIST, don't try to register things with the same name in the same directory.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 19b67e9..6ca0d9c 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2154,6 +2154,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
        mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
 
        if (seeding_dev) {
+               char fsid_buf[BTRFS_UUID_UNPARSED_SIZE];
                ret = init_first_rw_device(trans, root, device);
                if (ret) {
                        btrfs_abort_transaction(trans, root, ret);
@@ -2164,6 +2165,14 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
                        btrfs_abort_transaction(trans, root, ret);
                        goto error_trans;
                }
+
+               /* Sprouting would change fsid of the mounted root,
+                * so rename the fsid on the sysfs
+                */
+               snprintf(fsid_buf, BTRFS_UUID_UNPARSED_SIZE, "%pU",
+                                               root->fs_info->fsid);
+               if (kobject_rename(&root->fs_info->super_kobj, fsid_buf))
+                       goto error_trans;
        } else {
                ret = btrfs_add_device(trans, root, device);
                if (ret) {

diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 6f9c38c..2f47824 100644 (file)
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -38,6 +38,7 @@ struct btrfs_ioctl_vol_args {
 #define BTRFS_SUBVOL_QGROUP_INHERIT    (1ULL << 2)
 #define BTRFS_FSID_SIZE 16
 #define BTRFS_UUID_SIZE 16
+#define BTRFS_UUID_UNPARSED_SIZE       37
 
 #define BTRFS_QGROUP_INHERIT_SET_LIMITS        (1ULL << 0)