From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Shaohua Li <shli@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>,
axboe@kernel.dk, linux-kernel@vger.kernel.org, neilb@suse.de,
martin.petersen@oracle.com
Subject: Re: [patch 1/2]block: handle merged discard request
Date: Wed, 21 Mar 2012 22:32:54 -0400 [thread overview]
Message-ID: <yq18vitwejt.fsf@sermon.lab.mkp.net> (raw)
In-Reply-To: <4F69C62C.7020604@kernel.org> (Shaohua Li's message of "Wed, 21 Mar 2012 20:14:36 +0800")
>>>>> "Shaohua" == Shaohua Li <shli@kernel.org> writes:
Shaohua> The SCSI discard implementation hacks the first bio of request
Shaohua> to add payload, which makes blk_update_request() can't
Shaohua> correctly mark bios finish. The patch solves it. We set
Shaohua> discard bio size to 0 and finish it after the hacked payload
Shaohua> finishes.
Ick!
Also, you can't muck with bi_size because if we get an I/O error and
have to reissue the command we no longer know how much to write.
I have had to deal with the same issue for WRITE SAME. And the only sane
approach is to distinguish between the DMA transfer size and the blocks
"affected" by the command. That's what I'm working on right now for copy
offload...
If this is something you want in 3.4 I guess we could temporarily add a
separate length field to struct request. If you can wait I suggest we
talk at LSF.
--
Martin K. Petersen Oracle Linux Engineering
next prev parent reply other threads:[~2012-03-22 2:33 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-16 7:32 [patch v2 0/6] Add TRIM support for raid linear/0/1/10 Shaohua Li
2012-03-16 7:32 ` [patch v2 1/6] block: makes bio_split support bio without data Shaohua Li
2012-03-16 7:32 ` [patch v2 2/6] blk: dont allow discard request merge temporarily Shaohua Li
2012-03-20 16:21 ` Vivek Goyal
2012-03-21 1:22 ` Shaohua Li
2012-03-21 12:14 ` [patch 1/2]block: handle merged discard request Shaohua Li
2012-03-22 2:32 ` Martin K. Petersen [this message]
2012-03-22 2:39 ` Shaohua Li
2012-03-22 2:53 ` Martin K. Petersen
2012-06-20 8:57 ` Christoph Hellwig
2012-06-22 3:46 ` Martin K. Petersen
2012-08-03 2:10 ` Shaohua Li
2012-08-18 3:06 ` Mike Snitzer
2012-08-18 3:47 ` Martin K. Petersen
2012-08-20 13:57 ` Mike Snitzer
2012-08-20 13:58 ` Christoph Hellwig
2012-08-20 14:12 ` Mike Snitzer
2012-08-20 14:15 ` Christoph Hellwig
2012-03-22 2:18 ` [patch v2 2/6] blk: dont allow discard request merge temporarily Martin K. Petersen
2012-03-22 2:33 ` Shaohua Li
2012-03-22 6:28 ` Christoph Hellwig
2012-03-16 7:32 ` [patch v2 3/6] md: linear supports TRIM Shaohua Li
2012-03-16 7:32 ` [patch v2 4/6] md: raid 0 " Shaohua Li
2012-03-16 7:32 ` [patch v2 5/6] md: raid 1 " Shaohua Li
2012-03-16 7:32 ` [patch v2 6/6] md: raid 10 " Shaohua Li
2012-03-19 19:38 ` [patch v2 0/6] Add TRIM support for raid linear/0/1/10 Holger Kiehl
2012-03-20 1:27 ` Shaohua Li
2012-03-20 9:50 ` Holger Kiehl
2012-03-20 12:09 ` Shaohua Li
2012-03-21 2:08 ` Shaohua Li
2012-03-21 2:24 ` Roberto Spadim
2012-03-21 2:29 ` Mathias Burén
2012-03-21 2:29 ` Mathias Burén
2012-05-08 9:59 ` Patelczyk, Maciej
2012-05-09 2:27 ` Shaohua Li
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