From: Jens Axboe <axboe@kernel.dk>
To: Christoph Hellwig <hch@infradead.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
Andreas Dilger <adilger.kernel@dilger.ca>,
"Theodore Ts'o" <tytso@mit.edu>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"Xen-devel@lists.xensource.com" <Xen-devel@lists.xensource.com>
Subject: Re: linux-next regression: IO errors in with ext4 and xen-blkfront
Date: Fri, 22 Oct 2010 10:54:54 +0200 [thread overview]
Message-ID: <4CC1515E.6080006@kernel.dk> (raw)
In-Reply-To: <20101022082916.GA14070@infradead.org>
On 2010-10-22 10:29, Christoph Hellwig wrote:
> In the barriers tree Xen claims to support flushes, but I doesn't.
> It never handles REQ_FLUSH requests. Try commenting out the
>
> blk_queue_flush(info->rq, info->feature_flush);
>
> call and things should improve. I still need to hear back from Xen
> folks how to actually implement a cache flush - they only implement
> a barrier write privilegue which could never implement an empty
> cache flush. Up to current kernels that meant it would implement
> barrier writes with content correctly and silently ignore empty barriers
> leading to very interesting data integrity bugs. From 2.6.37 onwards
> it simply won't work anymore at all, which is at least consistent
> (modulo the bug of actually claiming to support flushes).
So how about we just disable barriers for Xen atm? I would really really
like to push that branch out as well now, since I'll be travelling for
most of the merge window this time.
--
Jens Axboe
next prev parent reply other threads:[~2010-10-22 8:54 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-21 0:04 linux-next regression: IO errors in with ext4 and xen-blkfront Jeremy Fitzhardinge
2010-10-21 0:09 ` Jeremy Fitzhardinge
2010-10-22 8:18 ` Jens Axboe
2010-10-22 8:29 ` Christoph Hellwig
2010-10-22 8:54 ` Jens Axboe [this message]
2010-10-22 8:56 ` Christoph Hellwig
2010-10-22 8:57 ` Jens Axboe
2010-10-22 9:20 ` Christoph Hellwig
2010-10-25 18:26 ` [Xen-devel] " Konrad Rzeszutek Wilk
2010-10-25 18:47 ` Christoph Hellwig
2010-10-25 19:05 ` Konrad Rzeszutek Wilk
2010-10-26 12:49 ` Daniel Stodden
2010-10-27 10:23 ` Christoph Hellwig
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