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>
diff --git a/fs/xfs/libxfs/xfs_bmap_btree.c b/fs/xfs/libxfs/xfs_bmap_btree.c
index 2c44c8e..6b0cf65 100644
--- a/fs/xfs/libxfs/xfs_bmap_btree.c
+++ b/fs/xfs/libxfs/xfs_bmap_btree.c
@@ -349,7 +349,8 @@
if (xfs_sb_version_hascrc(&mp->m_sb)) {
ASSERT(rblock->bb_magic == cpu_to_be32(XFS_BMAP_CRC_MAGIC));
- ASSERT(uuid_equal(&rblock->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid));
+ ASSERT(uuid_equal(&rblock->bb_u.l.bb_uuid,
+ &mp->m_sb.sb_meta_uuid));
ASSERT(rblock->bb_u.l.bb_blkno ==
cpu_to_be64(XFS_BUF_DADDR_NULL));
} else
@@ -647,7 +648,7 @@
case cpu_to_be32(XFS_BMAP_CRC_MAGIC):
if (!xfs_sb_version_hascrc(&mp->m_sb))
return false;
- if (!uuid_equal(&block->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid))
+ if (!uuid_equal(&block->bb_u.l.bb_uuid, &mp->m_sb.sb_meta_uuid))
return false;
if (be64_to_cpu(block->bb_u.l.bb_blkno) != bp->b_bn)
return false;
