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

Amir Goldstein
2017-06-23T13:56:15Z

On Wed, Jun 21, 2017 at 12:48 PM, 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.

Wait a minute, if we want to keep the handling for merge dir separate,
then this patch is perfectly valid for handling merge dir (and impure
dir if we know about it at open time).

Yes, it does not cover the two corner cases that you mentioned, but it
covers the likely real world cases, as proven by xfstest overlay/017.

Given that solving the corner cases requires completely new code that
is mostly independent of this patch, why not merge this patch for v4.13?

Amir.