Re: [PATCH v3 5/5] ovl: consistent st_ino/d_ino

Amir Goldstein
2017-07-28T09:25:57Z

On Thu, Jul 27, 2017 at 11:00 PM, Miklos Szeredi <miklos@szeredi.hu> wrote:
> On Wed, Jun 21, 2017 at 11:48 AM, Miklos Szeredi <miklos@szeredi.hu> wrote:
>> On Wed, Jun 21, 2017 at 11:36 AM, Amir Goldstein <amir73il@gmail.com> wrote:
>>> On Wed, Jun 21, 2017 at 12:20 PM, Miklos Szeredi <miklos@szeredi.hu> wrote:
>>>> On Wed, Jun 21, 2017 at 11:05 AM, Amir Goldstein <amir73il@gmail.com> wrote:
>>>
>>>>>
>>>>> Following up on your idea:
>>>>> - check in ovl_iterate() if version has changed and if dir became impure
>>>>> - if it did, populate od->cache, but keep the dir od->is_real
>>>>> - iterate upper cache entries and call ovl_cache_update_ino()
>>>>> - Then actor of real dir iterator can use the cache to ommit entries or use
>>>>> p->ino from cache if p->real_ino match real d_ino, but differs from p->ino.
>>>>
>>>> For non-merge dirs we can have a simplified cache just containing the
>>>> entries with origin, recreated when the version changes or updated in
>>>> rename, whichever is simpler. A non-merge dir will never become a
>>>> merge one, so we can keep the handling separate.
>>>>
>>>
>>> And use this cache to ommit/fix entries with actor?
>>
>> Right. I think fixing up is better, because to correctly omit entries
>> we'd need separate lists for each open directory. For fixing up we
>> can use a common one, just like for the merged dir.
>
> And back to this, I pushed a branch named "ovl-d_ino" to my vfs tree.
>
> Please test.
>

I can confirm that xfstest overlay/017, the only test I have for
constant d_ino,
passes. Although it does not cover all cases handled by the patch set
(e.g. d_ino of merge parent).

Chandan,

Can you take on the task of improving test coverage for constant d_ino?
You should create a new xfstest and cover more cases of constant d_ino
and possibly also a test for clearing of impure xattr.

When the basic test is in place, I will be able to point at more corner cases
to cover.

Also need to prepare a test to verify constant d_ino for non samefs
for after this patch is integrated with your work.
overlay/017 is a good starting point, but can't use the standard _scratch_mount
helpers that mount samefs overlay.

Thanks,
Amir.