xfs: show uuid when mount fails due to duplicate uuid

When a system tries to mount a filesystem (FS) using UUID, the xfs
returns -EINVAL and shows a message if a FS with the same UUID has
been already mounted. It is useful to output the duplicate UUID
with it.
Signed-off-by: NMitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Cc: Ben Myers <bpm@sgi.com>
Cc: Alex Elder <elder@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NBen Myers <bpm@sgi.com>

fs/xfs/xfs_mount.c

@@ -158,7 +158,7 @@ xfs_uuid_mount(
 
  out_duplicate:
 	mutex_unlock(&xfs_uuid_table_mutex);
-	xfs_warn(mp, "Filesystem has duplicate UUID - can't mount");
+	xfs_warn(mp, "Filesystem has duplicate UUID %pU - can't mount", uuid);
 	return XFS_ERROR(EINVAL);
 }