From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756006Ab2LNDPp (ORCPT ); Thu, 13 Dec 2012 22:15:45 -0500 Received: from mail-pb0-f46.google.com ([209.85.160.46]:51167 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755621Ab2LNDPo (ORCPT ); Thu, 13 Dec 2012 22:15:44 -0500 Date: Fri, 14 Dec 2012 11:15:36 +0800 From: Shaohua Li To: axboe@kernel.dk Cc: neilb@suse.de, linux-kernel@vger.kernel.org Subject: [patch 1/2]block: discard granularity might not be power of 2 Message-ID: <20121214031536.GA30345@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In MD raid case, discard granularity might not be power of 2, for example, a 4-disk raid5 has 3*chunk_size discard granularity. Correct the calculation for such cases. Reported-by: Neil Brown Signed-off-by: Shaohua Li --- block/blk-lib.c | 23 +++++++++++++---------- block/blk-settings.c | 6 +++--- include/linux/blkdev.h | 7 ++++--- 3 files changed, 20 insertions(+), 16 deletions(-) Index: linux/block/blk-lib.c =================================================================== --- linux.orig/block/blk-lib.c 2012-10-15 10:01:52.763544641 +0800 +++ linux/block/blk-lib.c 2012-12-14 08:56:24.539932760 +0800 @@ -43,8 +43,8 @@ int blkdev_issue_discard(struct block_de DECLARE_COMPLETION_ONSTACK(wait); struct request_queue *q = bdev_get_queue(bdev); int type = REQ_WRITE | REQ_DISCARD; - unsigned int max_discard_sectors; - unsigned int granularity, alignment, mask; + sector_t max_discard_sectors; + sector_t granularity, alignment; struct bio_batch bb; struct bio *bio; int ret = 0; @@ -57,15 +57,16 @@ int blkdev_issue_discard(struct block_de /* Zero-sector (unknown) and one-sector granularities are the same. */ granularity = max(q->limits.discard_granularity >> 9, 1U); - mask = granularity - 1; - alignment = (bdev_discard_alignment(bdev) >> 9) & mask; + alignment = bdev_discard_alignment(bdev) >> 9; + alignment = sector_div(alignment, 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 = round_down(max_discard_sectors, granularity); + sector_div(max_discard_sectors, granularity); + max_discard_sectors *= granularity; if (unlikely(!max_discard_sectors)) { /* Avoid infinite loop below. Being cautious never hurts. */ return -EOPNOTSUPP; @@ -83,7 +84,7 @@ int blkdev_issue_discard(struct block_de while (nr_sects) { unsigned int req_sects; - sector_t end_sect; + sector_t end_sect, tmp; bio = bio_alloc(gfp_mask, 1); if (!bio) { @@ -98,10 +99,12 @@ int blkdev_issue_discard(struct block_de * misaligned, stop the discard at the previous aligned sector. */ end_sect = sector + req_sects; - if (req_sects < nr_sects && (end_sect & mask) != alignment) { - end_sect = - round_down(end_sect - alignment, granularity) - + alignment; + 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; } Index: linux/block/blk-settings.c =================================================================== --- linux.orig/block/blk-settings.c 2012-10-15 10:01:52.763544641 +0800 +++ linux/block/blk-settings.c 2012-12-14 09:53:18.493013557 +0800 @@ -611,7 +611,7 @@ int blk_stack_limits(struct queue_limits bottom = b->discard_granularity + alignment; /* Verify that top and bottom intervals line up */ - if (max(top, bottom) & (min(top, bottom) - 1)) + if ((max(top, bottom) % min(top, bottom)) != 0) t->discard_misaligned = 1; } @@ -619,8 +619,8 @@ int blk_stack_limits(struct queue_limits b->max_discard_sectors); t->discard_granularity = max(t->discard_granularity, b->discard_granularity); - t->discard_alignment = lcm(t->discard_alignment, alignment) & - (t->discard_granularity - 1); + t->discard_alignment = lcm(t->discard_alignment, alignment) % + t->discard_granularity; } return ret; Index: linux/include/linux/blkdev.h =================================================================== --- linux.orig/include/linux/blkdev.h 2012-10-15 10:01:52.999541673 +0800 +++ linux/include/linux/blkdev.h 2012-12-13 14:26:25.469877308 +0800 @@ -1180,13 +1180,14 @@ static inline int queue_discard_alignmen static inline int queue_limit_discard_alignment(struct queue_limits *lim, sector_t sector) { - unsigned int alignment = (sector << 9) & (lim->discard_granularity - 1); + sector_t alignment = sector << 9; + alignment = sector_div(alignment, lim->discard_granularity); if (!lim->max_discard_sectors) return 0; - return (lim->discard_granularity + lim->discard_alignment - alignment) - & (lim->discard_granularity - 1); + alignment = lim->discard_granularity + lim->discard_alignment - alignment; + return sector_div(alignment, lim->discard_granularity); } static inline int bdev_discard_alignment(struct block_device *bdev)