From: Christoph Hellwig <hch@infradead.org>
To: Mike Snitzer <snitzer@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Eric Sandeen <sandeen@sandeen.net>,
linux-xfs <linux-xfs@vger.kernel.org>,
dm-devel@redhat.com
Subject: Re: error propagation problem on xfs over dm stripe
Date: Wed, 1 Feb 2017 06:49:35 -0800 [thread overview]
Message-ID: <20170201144935.GB27071@infradead.org> (raw)
In-Reply-To: <20170201143351.GA18848@redhat.com>
On Wed, Feb 01, 2017 at 09:33:51AM -0500, Mike Snitzer wrote:
> > FYI, what we do both in the XFS buffer cache and the new direct I/O
> > code is to use a
> >
> > cmpxchg(&dio->error, 0, ret);
> >
> > in a similar situation, which should work here, too.
>
> What is the benefit? Faster than the conditional?
In the cases where I added the code the concern is that multiple
bio completions could race updating the flag, cmpxchg is a good
protection against that. I'll need to take a look at the dm
case Eric reported in more detail to comment on it, though.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@infradead.org>
To: Mike Snitzer <snitzer@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>,
linux-xfs <linux-xfs@vger.kernel.org>,
dm-devel@redhat.com, Eric Sandeen <sandeen@sandeen.net>
Subject: Re: error propagation problem on xfs over dm stripe
Date: Wed, 1 Feb 2017 06:49:35 -0800 [thread overview]
Message-ID: <20170201144935.GB27071@infradead.org> (raw)
In-Reply-To: <20170201143351.GA18848@redhat.com>
On Wed, Feb 01, 2017 at 09:33:51AM -0500, Mike Snitzer wrote:
> > FYI, what we do both in the XFS buffer cache and the new direct I/O
> > code is to use a
> >
> > cmpxchg(&dio->error, 0, ret);
> >
> > in a similar situation, which should work here, too.
>
> What is the benefit? Faster than the conditional?
In the cases where I added the code the concern is that multiple
bio completions could race updating the flag, cmpxchg is a good
protection against that. I'll need to take a look at the dm
case Eric reported in more detail to comment on it, though.
next prev parent reply other threads:[~2017-02-01 14:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-01 3:12 error propagation problem on xfs over dm stripe Eric Sandeen
2017-02-01 7:42 ` [dm-devel] " Christoph Hellwig
2017-02-01 7:42 ` Christoph Hellwig
2017-02-01 14:33 ` Mike Snitzer
2017-02-01 14:33 ` Mike Snitzer
2017-02-01 14:49 ` Christoph Hellwig [this message]
2017-02-01 14:49 ` Christoph Hellwig
2017-02-01 10:28 ` [dm-devel] " Junichi Nomura
2017-02-01 10:28 ` Junichi Nomura
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