Re: [PATCH] block: virtio-blk: Fix handling of zone append command completion

Re: [PATCH] block: virtio-blk: Fix handling of zone append command completion

[Michael S. Tsirkin]

On Fri, Jun 23, 2023 at 06:55:24AM +0900, Damien Le Moal wrote:
> On 6/22/23 23:32, Suwan Kim wrote:
> > On Tue, Jun 20, 2023 at 5:39 PM Damien Le Moal <dlemoal@kernel.org> wrote:
> >>
> >> The introduction of completion batching with commit 07b679f70d73
> >> ("virtio-blk: support completion batching for the IRQ path") overlloked
> >> handling correctly the completion of zone append operations, which
> >> require an update of the request __sector field, as is done in
> >> virtblk_request_done(): the function virtblk_complete_batch() only
> >> executes virtblk_unmap_data() and virtblk_cleanup_cmd() without doing
> >> this update. This causes problems with zone append operations, e.g.
> >> zonefs complains about invalid zone append locations.
> >>
> > 
> > Hi Damien Le Moal,
> > 
> > Unfortunately, this commit was reverted due to io hang.
> > (afd384f0dbea2229fd11159efb86a5b41051c4a9)
> > You can see the mail thread at the block layer mailing list.
> 
> There is no commit afd384f0dbea2229fd11159efb86a5b41051c4a9 in Linus tree. What
> patch are you talking about ? Where is it ?

Either you didn't check recently enough, or  there's some
breakage and your CDN's not updating. If the later try
poking kernel.org admins.

This is the commit:

commit afd384f0dbea2229fd11159efb86a5b41051c4a9
Author: Michael S. Tsirkin <mst@redhat.com>
Date:   Thu Jun 8 17:42:53 2023 -0400

    Revert "virtio-blk: support completion batching for the IRQ path"

you can get the patch from lore too:
    Message-Id: <336455b4f630f329380a8f53ee8cad3868764d5c.1686295549.git.mst@redhat.com>


> 
> > We don't have a solution about io hang yet..
> > So I have one question.
> > Is there any possibility of virtblk-driver io hang on zoned devices
> > without this patch?
> 
> If you are talking about the batch completion support being reverted, then my
> fix patch is not necessary. The issue I fixed is not about IO hang but the fact
> that completion processing was not identical for batch case vs non batch. That
> led to breakage of the zone append command completion. The original support for
> zone append without batch completion is fine.

Yes that's great! I expect we'll reapply the batch completion
down the road and then your patch would help!

> > 
> > Regards,
> > Suwan Kim
> 
> -- 
> Damien Le Moal
> Western Digital Research

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