From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH 2/2] block: defer the use of inline biovecs for discard requests Date: Mon, 28 Jun 2010 14:41:30 +0200 Message-ID: <4C28987A.7000701@kernel.dk> References: <20100622180029.GA15950@redhat.com> <1277582211-10725-2-git-send-email-snitzer@redhat.com> <4C2896C6.9030607@kernel.dk> <20100628123742.GB19497@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20100628123742.GB19497@redhat.com> Sender: linux-kernel-owner@vger.kernel.org To: Mike Snitzer Cc: Christoph Hellwig , dm-devel@redhat.com, James.Bottomley@suse.de, linux-kernel@vger.kernel.org, martin.petersen@oracle.com, akpm@linux-foundation.org List-Id: dm-devel.ids On 2010-06-28 14:37, Mike Snitzer wrote: > On Mon, Jun 28 2010 at 8:34am -0400, > Jens Axboe wrote: > >> On 2010-06-26 21:56, Mike Snitzer wrote: >>> Don't alloc discard bio with a biovec in blkdev_issue_discard. Doing so >>> means bio_has_data() will not be true until the SCSI layer adds the >>> payload to the discard request via blk_add_request_payload. >> >> Sorry, this looks horrible. > > Your judgment isn't giving me much to work with... not sure where I go > with "horrible". The horrible part is working around that issue by fiddling with the assignment of the internal vec. THAT looks like a horrible solution to that problem. How about just adding a check to bio_has_data() for non-zero bio->bi_vcnt? -- Jens Axboe