From: David Sterba <dsterba@xxxxxxxx> commit 10a3a3edc5b89a8cd095bc63495fb1e0f42047d9 upstream. A remount to a read-write filesystem is not safe when there's tree-log to be replayed. Files that could be opened until now might be affected by the changes in the tree-log. A regular mount is needed to replay the log so the filesystem presents the consistent view with the pending changes included. CC: stable@xxxxxxxxxxxxxxx # 4.4+ Reviewed-by: Anand Jain <anand.jain@xxxxxxxxxx> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx> Signed-off-by: David Sterba <dsterba@xxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/btrfs/super.c | 2 ++ 1 file changed, 2 insertions(+) --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1801,6 +1801,8 @@ static int btrfs_remount(struct super_bl } if (btrfs_super_log_root(fs_info->super_copy) != 0) { + btrfs_warn(fs_info, + "mount required to replay tree-log, cannot remount read-write"); ret = -EINVAL; goto restore; }