xfs: create new metadata UUID field and incompat flag

This adds a new superblock field, sb_meta_uuid.  If set, along with
a new incompat flag, the code will use that field on a V5 filesystem
to compare to metadata UUIDs, which allows us to change the user-
visible UUID at will.  Userspace handles the setting and clearing
of the incompat flag as appropriate, as the UUID gets changed; i.e.
setting the user-visible UUID back to the original UUID (as stored in
the new field) will remove the incompatible feature flag.

If the incompat flag is not set, this copies the user-visible UUID into
into the meta_uuid slot in memory when the superblock is read from disk;
the meta_uuid field is not written back to disk in this case.

The remainder of this patch simply switches verifiers, initializers,
etc to use the new sb_meta_uuid field.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/xfs/libxfs/xfs_ialloc_btree.c b/fs/xfs/libxfs/xfs_ialloc_btree.c
index 674ad8f760be..f39b285beb19 100644
--- a/fs/xfs/libxfs/xfs_ialloc_btree.c
+++ b/fs/xfs/libxfs/xfs_ialloc_btree.c
@@ -239,7 +239,7 @@ xfs_inobt_verify(
         case cpu_to_be32(XFS_FIBT_CRC_MAGIC):
                 if (!xfs_sb_version_hascrc(&mp->m_sb))
                         return false;
-                if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_uuid))
+                if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_meta_uuid))
                         return false;
                 if (block->bb_u.s.bb_blkno != cpu_to_be64(bp->b_bn))
                         return false;