[PATCH v1 4/4] xfs: export meta uuid via xfs_fsop_geom

[Catherine Hoang <catherine.hoang@oracle.com>]

Export the meta uuid to userspace so that we can restore the original uuid after
it has been changed.

Signed-off-by: Catherine Hoang <catherine.hoang@oracle.com>
---
 fs/xfs/libxfs/xfs_fs.h | 3 ++-
 fs/xfs/libxfs/xfs_sb.c | 5 +++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index a350966cce99..d88adaf9369f 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -186,7 +186,8 @@ struct xfs_fsop_geom {
 	__u32		logsunit;	/* log stripe unit, bytes	*/
 	uint32_t	sick;		/* o: unhealthy fs & rt metadata */
 	uint32_t	checked;	/* o: checked fs & rt metadata	*/
-	__u64		reserved[17];	/* reserved space		*/
+	unsigned char	metauuid[16];	/* metadata id of the filesystem*/
+	__u64		reserved[15];	/* reserved space		*/
 };
 
 #define XFS_FSOP_GEOM_SICK_COUNTERS	(1 << 0)  /* summary counters */
diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
index 99cc03a298e2..4c24f3314122 100644
--- a/fs/xfs/libxfs/xfs_sb.c
+++ b/fs/xfs/libxfs/xfs_sb.c
@@ -1213,6 +1213,11 @@ xfs_fs_geometry(
 		return;
 
 	geo->version = XFS_FSOP_GEOM_VERSION_V5;
+
+	if (xfs_has_metauuid(mp)) {
+		BUILD_BUG_ON(sizeof(geo->metauuid) != sizeof(sbp->sb_meta_uuid));
+		memcpy(geo->metauuid, &sbp->sb_meta_uuid, sizeof(sbp->sb_meta_uuid));
+	}
 }
 
 /* Read a secondary superblock. */
-- 
2.34.1