Date: Fri, 22 Mar 2013 17:35:43 -0400
From: Mike Snitzer <snitzer@redhat.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Ben Hutchings <ben@decadent.org.uk>,
        Linus Torvalds <torvalds@linux-foundation.org>, dm-devel@redhat.com,
        linux-kernel@vger.kernel.org, Heinz Mauelshagen <heinzm@redhat.com>,
        Joe Thornber <ejt@redhat.com>, Mikulas Patocka <mpatocka@redhat.com>,
        Paul Taysom <taysom@chromium.org>,
        Randy Dunlap <rdunlap@infradead.org>, stable@vger.kernel.org
Subject: Re: dm: dm-cache fails to write the cache device in writethrough mode
Message-ID: <20130322213543.GA5849@redhat.com>
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 <20130322205005.GD5371@blackbox.djwong.org>
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On Fri, Mar 22 2013 at  4:50pm -0400,
Darrick J. Wong <darrick.wong@oracle.com> wrote:

> On Fri, Mar 22, 2013 at 08:21:56PM +0000, Ben Hutchings wrote:
> > On Fri, 2013-03-22 at 13:11 -0700, Darrick J. Wong wrote:
> > > The new writethrough strategy for dm-cache issues a bio to the origin device,
> > > remaps the bio to the cache device, and issues the bio to the cache device.
> > > However, the block layer modifies bi_sector and bi_size, so we need to preserve
> > > these or else nothing gets written to the cache (bi_size == 0).  This fixes the
> > > problem where someone writes a block through the cache, but a subsequent reread
> > > (from the cache) returns old contents.
> > > 
> > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > > ---
> > [...]
> > 
> > This is not the correct way to submit a change to stable.  See
> > Documentation/stable_kernel_rules.txt
> 
> Frankly, I'm not sure why agk sent the 3.9-fixes pull request to -stable.  7 of
> the 10 commits are for dm-cache, and dm-cache is a new feature for 3.9.  I
> probably could have dropped -stable from the cc: list when I started
> complaining about bugs.  :)

Alasdair's pull mail was sent to stable because commit f046f89a99c ("dm
thin: fix discard corruption") cc'd stable and was included in the pull
request.
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