From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:59260 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727048AbeJRIK4 (ORCPT ); Thu, 18 Oct 2018 04:10:56 -0400 Date: Thu, 18 Oct 2018 08:12:31 +0800 From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, stable@vger.kernel.org, Mariusz Dabrowski , Ming Lin , Mike Snitzer , Christoph Hellwig , Xiao Ni Subject: Re: [PATCH] block: don't deal with discard limit in blkdev_issue_discard() Message-ID: <20181018001230.GA9379@ming.t460p> References: <20181012075310.4587-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181012075310.4587-1-ming.lei@redhat.com> Sender: stable-owner@vger.kernel.org List-ID: On Fri, Oct 12, 2018 at 03:53:10PM +0800, Ming Lei wrote: > blk_queue_split() does respect this limit via bio splitting, so no > need to do that in blkdev_issue_discard(), then we can align to > normal bio submit(bio_add_page() & submit_bio()). > > More importantly, this patch fixes one issue introduced in a22c4d7e34402cc > ("block: re-add discard_granularity and alignment checks"), in which > zero discard bio may be generated in case of zero alignment. > > Fixes: a22c4d7e34402ccdf3 ("block: re-add discard_granularity and alignment checks") > Cc: stable@vger.kernel.org > Cc: Mariusz Dabrowski > Cc: Ming Lin > Cc: Mike Snitzer > Cc: Christoph Hellwig > Cc: Xiao Ni > Signed-off-by: Ming Lei > --- > block/blk-lib.c | 28 ++-------------------------- > 1 file changed, 2 insertions(+), 26 deletions(-) > > diff --git a/block/blk-lib.c b/block/blk-lib.c > index d1b9dd03da25..bbd44666f2b5 100644 > --- a/block/blk-lib.c > +++ b/block/blk-lib.c > @@ -29,9 +29,7 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, > { > struct request_queue *q = bdev_get_queue(bdev); > struct bio *bio = *biop; > - unsigned int granularity; > unsigned int op; > - int alignment; > sector_t bs_mask; > > if (!q) > @@ -54,38 +52,16 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, > if ((sector | nr_sects) & bs_mask) > return -EINVAL; > > - /* 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; > - > while (nr_sects) { > - unsigned int req_sects; > - sector_t end_sect, tmp; > + unsigned int req_sects = nr_sects; > + sector_t end_sect; > > - /* > - * Issue in chunks of the user defined max discard setting, > - * ensuring that bi_size doesn't overflow > - */ > - req_sects = min_t(sector_t, nr_sects, > - q->limits.max_discard_sectors); > if (!req_sects) > goto fail; > if (req_sects > UINT_MAX >> 9) > req_sects = UINT_MAX >> 9; > > - /* > - * If splitting a request, and the next starting sector would be > - * misaligned, stop the discard at the previous aligned sector. > - */ > end_sect = sector + req_sects; > - tmp = end_sect; > - if (req_sects < nr_sects && > - sector_div(tmp, granularity) != alignment) { > - end_sect = end_sect - alignment; > - sector_div(end_sect, granularity); > - end_sect = end_sect * granularity + alignment; > - req_sects = end_sect - sector; > - } > > bio = next_bio(bio, 0, gfp_mask); > bio->bi_iter.bi_sector = sector; > -- > 2.9.5 > Ping... This patch fixes BUG() in blk_mq_end_request() when zero-length discard bio is generated from __blkdev_issue_discard(). Thanks, Ming