Btrfs: do not backup tree roots when fsync

It doesn't make sense to backup tree roots when doing fsync, since
during fsync those tree roots have not been consistent on disk.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Qu Wenruo <quwenruo.btrfs@gmx.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 27d4586..0f22718 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3641,7 +3641,14 @@ int write_all_supers(struct btrfs_fs_info *fs_info, int max_mirrors)
        u64 flags;
 
        do_barriers = !btrfs_test_opt(fs_info, NOBARRIER);
-       backup_super_roots(fs_info);
+
+       /*
+        * max_mirrors == 0 indicates we're from commit_transaction,
+        * not from fsync where the tree roots in fs_info have not
+        * been consistent on disk.
+        */
+       if (max_mirrors == 0)
+               backup_super_roots(fs_info);
 
        sb = fs_info->super_for_commit;
        dev_item = &sb->dev_item;