btrfs: print message when tree-log replay starts

BugLink: https://bugs.launchpad.net/bugs/1868627

[ Upstream commit e8294f2f ]

There's no logged information about tree-log replay although this is
something that points to previous unclean unmount. Other filesystems
report that as well.
Suggested-by: Chris Murphy <lists@colorremedies.com>
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>

fs/btrfs/disk-io.c

@@ -2972,6 +2972,7 @@ int open_ctree(struct super_block *sb,
 
 	/* do not make disk changes in broken FS */
 	if (btrfs_super_log_root(disk_super) != 0) {
+		btrfs_info(fs_info, "start tree-log replay");
 		ret = btrfs_replay_log(fs_info, fs_devices);
 		if (ret) {
 			err = ret;