From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 4/5] blk-lib.c: generic_make_request() handles large bios now Date: Wed, 27 Nov 2013 04:54:05 -0800 Message-ID: <20131127125405.GA21086@infradead.org> References: <1385418633-9753-1-git-send-email-kmo@daterainc.com> <1385418633-9753-5-git-send-email-kmo@daterainc.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, axboe@kernel.dk To: Kent Overstreet Return-path: Content-Disposition: inline In-Reply-To: <1385418633-9753-5-git-send-email-kmo@daterainc.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org > int blkdev_issue_discard(struct block_device *bdev, sector_t sector, > sector_t nr_sects, gfp_t gfp_mask, unsigned long flags) > { > - DECLARE_COMPLETION_ONSTACK(wait); > struct request_queue *q = bdev_get_queue(bdev); > int type = REQ_WRITE | REQ_DISCARD; > - unsigned int max_discard_sectors, granularity; > - int alignment; > - struct bio_batch bb; > struct bio *bio; > int ret = 0; > - struct blk_plug plug; > > if (!q) > return -ENXIO; > @@ -56,78 +34,28 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, > if (!blk_queue_discard(q)) > return -EOPNOTSUPP; > > - /* Zero-sector (unknown) and one-sector granularities are the same. */ > - granularity = max(q->limits.discard_granularity >> 9, 1U); > - alignment = (bdev_discard_alignment(bdev) >> 9) % granularity; > - > - /* > - * Ensure that max_discard_sectors is of the proper > - * granularity, so that requests stay aligned after a split. > - */ > - max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9); > - max_discard_sectors -= max_discard_sectors % granularity; Seems like this is also missing the code to trim down the request to be properly aligned to the device limit. I don't think our low-level drivers are ready to handle this, and even if they were it should be a separate change.