From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755575AbcAWAFo (ORCPT ); Fri, 22 Jan 2016 19:05:44 -0500 Received: from mail-pf0-f194.google.com ([209.85.192.194]:33133 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753876AbcAWAFm (ORCPT ); Fri, 22 Jan 2016 19:05:42 -0500 From: Ming Lei To: Jens Axboe , linux-kernel@vger.kernel.org Cc: linux-block@vger.kernel.org, Linus Torvalds , Stefan Haberland , Keith Busch , Ming Lei Subject: [PATCH v1] block: fix bio splitting on max sectors Date: Sat, 23 Jan 2016 08:05:33 +0800 Message-Id: <1453507533-25593-1-git-send-email-tom.leiming@gmail.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org After commit e36f62042880(block: split bios to maxpossible length), bio can be splitted in the middle of a vector entry, then it is easy to split out one bio which size isn't aligned with block size, especially when the block size is bigger than 512. This patch fixes the issue by making the max io size aligned to logical block size. Fixes: e36f62042880(block: split bios to maxpossible length) Reported-by: Stefan Haberland Cc: Keith Busch Suggested-by: Linus Torvalds Signed-off-by: Ming Lei --- V1: - avoid double shift as suggested by Linus - compute 'max_sectors' once as suggested by Keith block/blk-merge.c | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index 1699df5..888a7fe 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -70,6 +70,18 @@ static struct bio *blk_bio_write_same_split(struct request_queue *q, return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs); } +static inline unsigned get_max_io_size(struct request_queue *q, + struct bio *bio) +{ + unsigned sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector); + unsigned mask = queue_logical_block_size(q) - 1; + + /* aligned to logical block size */ + sectors &= ~(mask >> 9); + + return sectors; +} + static struct bio *blk_bio_segment_split(struct request_queue *q, struct bio *bio, struct bio_set *bs, @@ -81,6 +93,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, unsigned front_seg_size = bio->bi_seg_front_size; bool do_split = true; struct bio *new = NULL; + const unsigned max_sectors = get_max_io_size(q, bio); bio_for_each_segment(bv, bio, iter) { /* @@ -90,20 +103,19 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset)) goto split; - if (sectors + (bv.bv_len >> 9) > - blk_max_size_offset(q, bio->bi_iter.bi_sector)) { + if (sectors + (bv.bv_len >> 9) > max_sectors) { /* * Consider this a new segment if we're splitting in * the middle of this vector. */ if (nsegs < queue_max_segments(q) && - sectors < blk_max_size_offset(q, - bio->bi_iter.bi_sector)) { + sectors < max_sectors) { nsegs++; - sectors = blk_max_size_offset(q, - bio->bi_iter.bi_sector); + sectors = max_sectors; } - goto split; + if (sectors) + goto split; + /* Make this single bvec as the 1st segment */ } if (bvprvp && blk_queue_cluster(q)) { -- 1.9.1