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: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1283162296-13650-1-git-send-email-tj@kernel.org>
2010-08-30 9:58 ` [PATCH 1/5] block: make __blk_rq_prep_clone() copy most command flags Tejun Heo
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
2010-08-30 9:58 ` [PATCH 4/5] dm: implement REQ_FLUSH/FUA support for request-based dm Tejun Heo
2010-08-30 9:58 ` [PATCH 5/5] block: remove the WRITE_BARRIER flag Tejun Heo
[not found] ` <1283162296-13650-5-git-send-email-tj@kernel.org>
2010-08-30 13:28 ` [PATCH 4/5] dm: implement REQ_FLUSH/FUA support for request-based dm Mike Snitzer
[not found] ` <20100830132836.GB5283@redhat.com>
2010-08-30 13:59 ` Tejun Heo
[not found] ` <4C7BB932.1070405@kernel.org>
2010-08-30 15:07 ` 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
[not found] ` <4C7BC942.7070703@kernel.org>
2010-08-30 19:08 ` [PATCH " Mike Snitzer
[not found] ` <20100830190835.GA8458@redhat.com>
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
[not found] ` <4C7BD202.4040700@kernel.org>
2010-08-30 19:18 ` [PATCH UPDATED " Mike Snitzer
[not found] ` <20100830194731.GA10702@redhat.com>
2010-09-01 10:31 ` Mikulas Patocka
2010-09-01 11:20 ` Tejun Heo
2010-09-01 12:12 ` Mikulas Patocka
2010-09-01 12:42 ` Tejun Heo
2010-09-01 12:54 ` Mike Snitzer
2010-09-01 15:20 ` Mike Snitzer
2010-09-01 15:35 ` Mikulas Patocka
2010-09-01 17:07 ` Mike Snitzer
2010-09-01 18:59 ` Mike Snitzer
2010-09-02 3:22 ` Mike Snitzer
2010-09-02 10:24 ` Tejun Heo
2010-09-02 15:11 ` Mike Snitzer
2010-09-09 15:26 ` [REGRESSION][BISECTED] virtio-blk serial attribute causes guest to hang [Was: Re: [PATCH UPDATED 4/5] dm: implement REQ_FLUSH/FUA support for request-based dm] Mike Snitzer
2010-09-09 15:44 ` Ryan Harper
2010-09-09 15:57 ` Mike Snitzer
2010-09-09 16:03 ` Ryan Harper
2010-09-09 17:55 ` Mike Snitzer
2010-09-09 18:35 ` Ryan Harper
2010-09-09 19:15 ` Mike Snitzer
2010-09-09 19:43 ` Mike Snitzer
2010-09-09 20:14 ` Mike Snitzer
2010-09-09 20:30 ` Ryan Harper
2010-09-09 21:00 ` [PATCH] virtio-blk: put request that was created to retrieve the device id Mike Snitzer
2010-09-09 21:15 ` Christoph Hellwig
2010-09-17 14:58 ` Ryan Harper
2010-09-21 21:00 ` Christoph Hellwig
2010-10-08 16:06 ` [2.6.36 REGRESSION] " Mike Snitzer
2010-10-09 1:41 ` [PATCH] " Rusty Russell
[not found] ` <1283162296-13650-4-git-send-email-tj@kernel.org>
2010-09-01 13:51 ` [PATCH 3/5] dm: relax ordering of bio-based flush implementation Mike Snitzer
2010-09-01 13:56 ` Tejun Heo
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