From: Christoph Hellwig <hch@infradead.org>
To: Jens Axboe <axboe@kernel.dk>
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 04:29:16 -0400 [thread overview]
Message-ID: <20101022082916.GA14070@infradead.org> (raw)
In-Reply-To: <4CC148E5.2030605@kernel.dk>
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).
next prev parent reply other threads:[~2010-10-22 8:29 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 [this message]
2010-10-22 8:54 ` Jens Axboe
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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