Re: [PATCH v3 0/3] io_uring getdents

[Hao Xu <hao.xu@linux.dev>]

On 7/12/23 08:53, Dominique Martinet wrote:
> Jens Axboe wrote on Tue, Jul 11, 2023 at 05:51:46PM -0600:
>>> So what filesystem actually uses this new NOWAIT functionality?
>>> Unless I'm blind (quite possibly) I don't see any filesystem
>>> implementation of this functionality in the patch series.
> 
> I had implemented this for kernfs and libfs (so sysfs, debugfs, possibly
> tmpfs/proc?) in v2
> 
> The patch as of v2's mail has a bug, but my branch has it fixed as of
> https://github.com/martinetd/linux/commits/io_uring_getdents

I see, I'll try this, those in v2 causes issues when I boot my VM with them.

> 
> (I guess these aren't "real" enough though)
> 
>>> I know I posted a prototype for XFS to use it, and I expected that
>>> it would become part of this patch series to avoid the "we don't add
>>> unused code to the kernel" problem. i.e. the authors would take the
>>> XFS prototype, make it work, add support into for the new io_uring
>>> operation to fsstress in fstests and then use that to stress test
>>> the new infrastructure before it gets merged....
>>>
>>> But I don't see any of this?
>>
>> That would indeed be great if we could get NOWAIT, that might finally
>> convince me that it's worth plumbing up! Do you have a link to that
>> prototype? That seems like what should be the base for this, and be an
>> inspiration for other file systems to get efficient getdents via this
>> (rather than io-wq punt, which I'm not a huge fan of...).
> 
> the xfs poc was in this mail:
> https://lore.kernel.org/all/20230501071603.GE2155823@dread.disaster.area/
> 
> I never spent time debugging it, but it should definitely be workable
>