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From: Josef Bacik <josef@toxicpanda.com>
To: Mike Christie <mchristi@redhat.com>
Cc: Josef Bacik <josef@toxicpanda.com>, linux-block@vger.kernel.org
Subject: Re: [PATCH 4/4] nbd: fix zero cmd timeout handling
Date: Tue, 13 Aug 2019 12:15:02 -0400	[thread overview]
Message-ID: <20190813161501.lkly7iqzvzzro3i3@MacBook-Pro-91.local> (raw)
In-Reply-To: <5D52DB33.8070307@redhat.com>

On Tue, Aug 13, 2019 at 10:45:55AM -0500, Mike Christie wrote:
> On 08/13/2019 08:13 AM, Josef Bacik wrote:
> > On Fri, Aug 09, 2019 at 04:26:10PM -0500, Mike Christie wrote:
> >> This fixes a regression added in 4.9 with commit:
> >>
> >> commit 0eadf37afc2500e1162c9040ec26a705b9af8d47
> >> Author: Josef Bacik <jbacik@fb.com>
> >> Date:   Thu Sep 8 12:33:40 2016 -0700
> >>
> >>     nbd: allow block mq to deal with timeouts
> >>
> >> where before the patch userspace would set the timeout to 0 to disable
> >> it. With the above patch, a zero timeout tells the block layer to use
> >> the default value of 30 seconds. For setups where commands can take a
> >> long time or experience transient issues like network disruptions this
> >> then results in IO errors being sent to the application.
> >>
> >> To fix this, the patch still uses the common block layer timeout
> >> framework, but if zero is set, nbd just logs a message and then resets
> >> the timer when it expires.
> >>
> >> Josef,
> >>
> >> I did not cc stable, but I think we want to port the patches to some
> >> releases. We originally hit this with users using the longterm kernels
> >> with ceph. The patch does not apply anywhere cleanly with older ones
> >> like 4.9, so I was not sure how we wanted to handle it.
> >>
> > 
> > I assume you tested this?  IIRC there was a problem where 0 really meant 0 and
> 
> Yes.
> 
> > commands would insta-timeout.  But my memory is foggy here, so I'm not sure if
> > it was setting the tag_set timeout to 0 that made things go wrong, or what.  Or
> > I could be making it all up, who knows.
> 
> Yes, if you call blk_queue_rq_timeout with 0, then the command will
> timeout almost immediately. I added a check for this in the first patch.
> 

Ahhh that's what it was, thank you.  I'm cool then, you can add

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Thanks,

Josef

      parent reply	other threads:[~2019-08-13 16:15 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-09 21:26 [PATCH 0/4] nbd: cmd timeout fixes Mike Christie
2019-08-09 21:26 ` [PATCH 1/4] nbd: add set cmd timeout helper Mike Christie
2019-08-09 21:32   ` Mike Christie
2019-08-13 13:11   ` Josef Bacik
2019-08-09 21:26 ` [PATCH 2/4] nbd: add function to convert blk req op to nbd cmd Mike Christie
2019-08-13 13:11   ` Josef Bacik
2019-08-09 21:26 ` [PATCH 3/4] nbd: add missing config put Mike Christie
2019-08-13 13:11   ` Josef Bacik
2019-08-09 21:26 ` [PATCH 4/4] nbd: fix zero cmd timeout handling Mike Christie
2019-08-13 13:13   ` Josef Bacik
2019-08-13 15:45     ` Mike Christie
2019-08-13 15:54       ` Mike Christie
2019-08-13 15:59         ` Mike Christie
2019-08-13 16:15       ` Josef Bacik [this message]

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