From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vivek Goyal Subject: Re: [patch 7/7] blk: use correct sectors limitation for discard request Date: Tue, 13 Mar 2012 12:00:24 -0400 Message-ID: <20120313160024.GH29169@redhat.com> References: <20120312030412.375458948@fusionio.com> <20120312031306.030156009@fusionio.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20120312031306.030156009@fusionio.com> Sender: linux-kernel-owner@vger.kernel.org Cc: linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, neilb@suse.de, axboe@kernel.dk, Shaohua Li List-Id: linux-raid.ids On Mon, Mar 12, 2012 at 11:04:19AM +0800, Shaohua Li wrote: > max_discard_sectors doesn't equal to max_sectors/max_hw_sectors. Without this, > discard request merge might be ignored. > > Signed-off-by: Shaohua Li > --- > block/blk-merge.c | 9 +++++++-- > include/linux/blkdev.h | 5 +++++ > 2 files changed, 12 insertions(+), 2 deletions(-) > > Index: linux/block/blk-merge.c > =================================================================== > --- linux.orig/block/blk-merge.c 2012-03-09 14:05:35.562062857 +0800 > +++ linux/block/blk-merge.c 2012-03-09 14:07:55.432062246 +0800 > @@ -228,13 +228,16 @@ no_merge: > int ll_back_merge_fn(struct request_queue *q, struct request *req, > struct bio *bio) > { > - unsigned short max_sectors; > + unsigned int max_sectors; > > if (unlikely(req->cmd_type == REQ_TYPE_BLOCK_PC)) > max_sectors = queue_max_hw_sectors(q); > else > max_sectors = queue_max_sectors(q); > > + if (unlikely(req->cmd_flags & REQ_DISCARD)) > + max_sectors = queue_max_discard_sectors(q); > + May be make above check an "else if" condition above instead of starting another "if" block. Thanks Vivek