From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Snitzer Subject: Re: [PATCH 2/2] block: defer the use of inline biovecs for discard requests Date: Mon, 28 Jun 2010 08:37:42 -0400 Message-ID: <20100628123742.GB19497@redhat.com> References: <20100622180029.GA15950@redhat.com> <1277582211-10725-2-git-send-email-snitzer@redhat.com> <4C2896C6.9030607@kernel.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <4C2896C6.9030607@kernel.dk> Sender: linux-kernel-owner@vger.kernel.org To: Jens Axboe 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 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". > What is the point of this?! Enables discard requests with _not_ return true for bio_has_data(). > > bio_{enable,disable}_inline_vecs are not expected to be widely used so > > they were exported using EXPORT_SYMBOL_GPL. > > Never export anything that doesn't have an in-kernel modular user. Yeap, v2 removed the exports. > > This patch avoids the need for the following VM accounting fix for > > discards: http://lkml.org/lkml/2010/6/23/361 > > NOTE: Jens, you said you applied Tao Ma's fix but I cannot see it in > > your linux-2.6-block's for-next or for-2.6.36... as such I didn't revert > > it in this patch. > > It's in the for-linus branch, that is stuff headed for the current > kernel. OK. Mike