[RFC PATCH] xfs: show uuid when mount fails due to duplicate uuid

[Mitsuo Hayasaka <mitsuo.hayasaka.hu@xxxxxxxxxxx>]

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: Mitsuo Hayasaka <mitsuo.hayasaka.hu@xxxxxxxxxxx>
Cc: Ben Myers <bpm@xxxxxxx>
Cc: Alex Elder <elder@xxxxxxxxxx>
---

 fs/xfs/xfs_mount.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index d06afbc..6b96d6e 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -158,7 +158,10 @@ 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 - can't mount: uuid = %pU",
+               uuid);
+
        return XFS_ERROR(EINVAL);
 }