btrfs: use btrfs_record_snapshot_destroy() during rmdir

We are setting the parent directory's last_unlink_trans directly which
may result in a concurrent task starting to log the directory not see the
update and therefore can log the directory after we removed a child
directory which had a snapshot within instead of falling back to a
transaction commit. Replaying such a log tree would result in a mount
failure since we can't currently delete snapshots (and subvolumes) during
log replay. This is the type of failure described in commit 1ec9a1ae1e30
("Btrfs: fix unreplayable log after snapshot delete + parent dir fsync").

Fix this by using btrfs_record_snapshot_destroy() which updates the
last_unlink_trans field while holding the inode's log_mutex lock.

Fixes: 44f714dae50a ("Btrfs: improve performance on fsync against new inode after rename/unlink")
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 5a5c43586adfcbc00e1c6402b7d9df112ce9c186..fc66872b4c747f1814fe787f394e15be2831db88 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4750,7 +4750,7 @@ static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
         * deletes for directory foo.
         */
        if (BTRFS_I(inode)->last_unlink_trans >= trans->transid)
-               BTRFS_I(dir)->last_unlink_trans = BTRFS_I(inode)->last_unlink_trans;
+               btrfs_record_snapshot_destroy(trans, BTRFS_I(dir));
 
        if (unlikely(btrfs_ino(BTRFS_I(inode)) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)) {
                ret = btrfs_unlink_subvol(trans, BTRFS_I(dir), dentry);