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

[Pavel Begunkov <asml.silence@gmail.com>]

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.

-- 
Pavel Begunkov