Btrfs: make sure we wait on logged extents when fsycning two subvols

If we have two fsync()'s race on different subvols one will do all of its work
to get into the log_tree, wait on it's outstanding IO, and then allow the
log_tree to finish it's commit.  The problem is we were just free'ing that
subvols logged extents instead of waiting on them, so whoever lost the race
wouldn't really have their data on disk.  Fix this by waiting properly instead
of freeing the logged extents.  Thanks,

cc: stable@vger.kernel.org
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 286213cec86132188a9db6e687769902f06613a9..fc715ff31d260bf4fe29374d9ac5d2d9ba55cfe9 100644 (file)
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2600,9 +2600,9 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
        if (atomic_read(&log_root_tree->log_commit[index2])) {
                blk_finish_plug(&plug);
                btrfs_wait_marked_extents(log, &log->dirty_log_pages, mark);
+               btrfs_wait_logged_extents(log, log_transid);
                wait_log_commit(trans, log_root_tree,
                                root_log_ctx.log_transid);
-               btrfs_free_logged_extents(log, log_transid);
                mutex_unlock(&log_root_tree->log_mutex);
                ret = root_log_ctx.log_ret;
                goto out;