From: Tejun Heo <tj@kernel.org>
To: Mike Snitzer <snitzer@redhat.com>
Cc: jaxboe@fusionio.com, k-ueda@ct.jp.nec.com,
j-nomura@ce.jp.nec.com, jamie@shareable.org,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-raid@vger.kernel.org, hch@lst.de, dm-devel@redhat.com
Subject: Re: [PATCH 2/5] dm: implement REQ_FLUSH/FUA support for bio-based dm
Date: Wed, 01 Sep 2010 15:56:09 +0200 [thread overview]
Message-ID: <4C7E5B79.3080709@kernel.org> (raw)
In-Reply-To: <20100901135433.GB25251@redhat.com>
On 09/01/2010 03:54 PM, Mike Snitzer wrote:
>> It just doesn't happen anymore. If the underlying device doesn't
>> support FLUSH/FUA, the block layer simply make those parts noop. IOW,
>> it no longer distinguishes between writeback cache which doesn't
>> support cache flush at all and writethrough cache. Devices which have
>> WB cache w/o flush very difficult to come by these days and there's
>> nothing much we can do anyway, so it doesn't make sense to require
>> everyone to implement -EOPNOTSUPP.
>>
>> One scheduled feature is to implement falling back to REQ_FLUSH when
>> the device advertises REQ_FUA but fails to process it, but one way or
>> the other, the goal is encapsulating REQ_FLUSH/FUA support in block
>> layer proper. If FLUSH/FUA can be retried using a different strategy,
>> it should be done inside request_queue proper instead of pushing retry
>> logic to all its users.
>
> OK, so maybe add this info to the patch header one of the primary
> FLUSH+FUA conversion patches?
Sure.
Thanks.
--
tejun
next prev parent reply other threads:[~2010-09-01 13:56 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-30 9:58 [PATCHSET 2.6.36-rc2] block, dm: finish REQ_FLUSH/FUA conversion, take#2 Tejun Heo
2010-08-30 9:58 ` [PATCH 1/5] block: make __blk_rq_prep_clone() copy most command flags Tejun Heo
2010-09-01 15:30 ` Christoph Hellwig
2010-08-30 9:58 ` [PATCH 2/5] dm: implement REQ_FLUSH/FUA support for bio-based dm Tejun Heo
2010-09-01 13:43 ` Mike Snitzer
2010-09-01 13:50 ` Tejun Heo
2010-09-01 13:54 ` Mike Snitzer
2010-09-01 13:56 ` Tejun Heo [this message]
2010-08-30 9:58 ` [PATCH 3/5] dm: relax ordering of bio-based flush implementation Tejun Heo
2010-09-01 13:51 ` Mike Snitzer
2010-09-01 13:56 ` Tejun Heo
2010-09-03 6:04 ` Kiyoshi Ueda
2010-09-03 9:42 ` Tejun Heo
2010-08-30 9:58 ` [PATCH 4/5] dm: implement REQ_FLUSH/FUA support for request-based dm Tejun Heo
2010-08-30 13:28 ` Mike Snitzer
2010-08-30 13:59 ` Tejun Heo
2010-08-30 15:07 ` Tejun Heo
2010-08-30 19:08 ` Mike Snitzer
2010-08-30 21:28 ` Mike Snitzer
2010-08-31 10:29 ` Tejun Heo
2010-08-31 13:02 ` Mike Snitzer
2010-08-31 13:14 ` Tejun Heo
2010-08-30 15:42 ` [PATCH] block: initialize flush request with WRITE_FLUSH instead of REQ_FLUSH Tejun Heo
2010-08-30 15:45 ` [PATCH UPDATED 4/5] dm: implement REQ_FLUSH/FUA support for request-based dm Tejun Heo
2010-08-30 19:18 ` Mike Snitzer
2010-09-01 7:15 ` Kiyoshi Ueda
2010-09-01 12:25 ` Mike Snitzer
2010-09-02 13:22 ` Tejun Heo
2010-09-02 13:32 ` Tejun Heo
2010-09-03 5:46 ` Kiyoshi Ueda
2010-09-02 17:43 ` [PATCH] block: make sure FSEQ_DATA request has the same rq_disk as the original Tejun Heo
2010-09-03 5:47 ` Kiyoshi Ueda
2010-09-03 9:33 ` Tejun Heo
2010-09-03 10:28 ` Kiyoshi Ueda
2010-09-03 11:42 ` Tejun Heo
2010-09-03 11:51 ` Kiyoshi Ueda
2010-08-30 9:58 ` [PATCH 5/5] block: remove the WRITE_BARRIER flag Tejun Heo
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