Re: [PATCH] btrfs-progs: mkfs: add uuid and otime to ROOT_ITEM of FS_TREE

[Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>]

On 2018/03/22 2:48, David Sterba wrote:
> On Mon, Mar 19, 2018 at 05:16:42PM +0900, Misono, Tomohiro wrote:
>> Currently, the top-level subvolume lacks the UUID. As a result, both
>> non-snapshot subvolume and snapshot of top-level subvolume do not have
>> Parent UUID and cannot be distinguisued. Therefore "fi show" of
>> top-level lists all the subvolumes which lacks the UUID in
>> "Snapshot(s)" filed.  Also, it lacks the otime information.
>>
>> Fix this by adding the UUID and otime at the mkfs time.  As a
>> consequence, snapshots of top-level subvolume now have a Parent UUID and
>> UUID tree will create an entry for top-level subvolume at mount time.
>> This should not cause the problem for current kernel, but user program
>> which relies on the empty Parent UUID may be affected by this change.
>>
>> Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
> 
> So this adds uuid, ctime and otime to FS_TEEE but also to UUID_TREE and
> DATA_RELOC_TREE. This is harmelss, but would be nice to mention in the
> changelog, I'll apply the patch add that. Thanks.

UUID is cleared at create_tree(), so I think you mean otime and ctime.
However, other tree's ROOT_ITEM does not hold o/ctime and I'd like to
clear o/ctime for UUID/DATA_RELOC_TREE too.

So, I will send v2 patch and could you please use that instead of this?

Regards,
Tomohiro Misono