Re: [regression, v6.0-rc0, io-uring?] filesystem freeze hangs on sb_wait_write()

[Jens Axboe <axboe@kernel.dk>]

On 10/10/22 8:10 PM, Pavel Begunkov wrote:
> On 10/11/22 03:01, Jens Axboe wrote:
>> On 10/10/22 7:10 PM, Pavel Begunkov wrote:
>>> On 10/11/22 01:40, Dave Chinner wrote:
>>> [...]
>>>> I note that there are changes to the the io_uring IO path and write
>>>> IO end accounting in the io_uring stack that was merged, and there
>>>> was no doubt about the success/failure of the reproducer at each
>>>> step. Hence I think the bisect is good, and the problem is someone
>>>> in the io-uring changes.
>>>>
>>>> Jens, over to you.
>>>>
>>>> The reproducer - generic/068 - is 100% reliable here, io_uring is
>>>> being exercised by fsstress in the background whilst the filesystem
>>>> is being frozen and thawed repeatedly. Some path in the io-uring
>>>> code has an unbalanced sb_start_write()/sb_end_write() pair by the
>>>> look of it....
>>>
>>> A quick guess, it's probably
>>>
>>> b000145e99078 ("io_uring/rw: defer fsnotify calls to task context")
>>>
>>>  From a quick look, it removes  kiocb_end_write() -> sb_end_write()
>>> from kiocb_done(), which is a kind of buffered rw completion path.
>>
>> Yeah, I'll take a look.
>> Didn't get the original email, only Pavel's reply?
> 
> Forwarded.

Looks like the email did get delivered, it just ended up in the
fsdevel inbox.

> Not tested, but should be sth like below. Apart of obvious cases
> like __io_complete_rw_common() we should also keep in mind
> when we don't complete the request but ask for reissue with
> REQ_F_REISSUE, that's for the first hunk

Can we move this into a helper?

-- 
Jens Axboe