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_dquot_buf.c b/fs/xfs/libxfs/xfs_dquot_buf.c
index 6fbf2d8..5331b7f 100644
--- a/fs/xfs/libxfs/xfs_dquot_buf.c
+++ b/fs/xfs/libxfs/xfs_dquot_buf.c
@@ -163,7 +163,7 @@
d->dd_diskdq.d_id = cpu_to_be32(id);
if (xfs_sb_version_hascrc(&mp->m_sb)) {
- uuid_copy(&d->dd_uuid, &mp->m_sb.sb_uuid);
+ uuid_copy(&d->dd_uuid, &mp->m_sb.sb_meta_uuid);
xfs_update_cksum((char *)d, sizeof(struct xfs_dqblk),
XFS_DQUOT_CRC_OFF);
}
@@ -198,7 +198,7 @@
if (!xfs_verify_cksum((char *)d, sizeof(struct xfs_dqblk),
XFS_DQUOT_CRC_OFF))
return false;
- if (!uuid_equal(&d->dd_uuid, &mp->m_sb.sb_uuid))
+ if (!uuid_equal(&d->dd_uuid, &mp->m_sb.sb_meta_uuid))
return false;
}
return true;