[PATCH 1/3] xfs: create new metadata UUID field and incompat flag

[Eric Sandeen]

On 7/16/15 10:57 AM, Eric Sandeen wrote:
> 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 at redhat.com>

This one was also

Reviewed-by: Brian Foster <bfoster at redhat.com>

but again has small changes to address Dave's points, and rebase
changes.

THanks,
-Eric