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_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
index 6526e76..268c00f 100644
--- a/fs/xfs/libxfs/xfs_inode_buf.c
+++ b/fs/xfs/libxfs/xfs_inode_buf.c
@@ -304,7 +304,7 @@
return false;
if (be64_to_cpu(dip->di_ino) != ip->i_ino)
return false;
- if (!uuid_equal(&dip->di_uuid, &mp->m_sb.sb_uuid))
+ if (!uuid_equal(&dip->di_uuid, &mp->m_sb.sb_meta_uuid))
return false;
return true;
}
@@ -366,7 +366,7 @@
if (xfs_sb_version_hascrc(&mp->m_sb)) {
ip->i_d.di_version = 3;
ip->i_d.di_ino = ip->i_ino;
- uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_uuid);
+ uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_meta_uuid);
} else
ip->i_d.di_version = 2;
return 0;