Re: [PATCH 0/3] io_uring: consistent behaviour with linked read/write

[Dylan Yudaken <dylany@fb.com>]

On Thu, 2022-02-17 at 12:45 -0700, Jens Axboe wrote:
> On 2/17/22 8:58 AM, Dylan Yudaken wrote:
> > Currently submitting multiple read/write for one file with
> > IOSQE_IO_LINK
> > and offset = -1 will not behave as if calling read(2)/write(2)
> > multiple
> > times. The offset may be pinned to the same value for each
> > submission (for
> > example if they are punted to the async worker) and so each
> > read/write will
> > have the same offset.
> > 
> > This patchset fixes this by grabbing the file position at execution
> > time,
> > rather than when the job is queued to be run.
> > 
> > A test for this will be submitted to liburing separately.
> > 
> > Worth noting that this does not purposefully change the result of
> > submitting multiple read/write without IOSQE_IO_LINK (for example
> > as in
> > [1]). But then I do not know what the correct approach should be
> > when
> > submitting multiple r/w without any explicit ordering.
> > 
> > [1]:
> > https://lore.kernel.org/io-uring/8a9e55bf-3195-5282-2907-41b2f2b23cc8@kernel.dk/
> 
> I think this series looks great, clean and to the point. My only real
> question is one you reference here already, which is the fpos locking
> that we really should get done. Care to respin the referenced patch
> on
> top of this series? Would hate to make that part harder...
> 

Sure, I will try and figure that out and add it to the series.