From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761294AbbA1ESA (ORCPT ); Tue, 27 Jan 2015 23:18:00 -0500 Received: from mail.kernel.org ([198.145.29.136]:38308 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756158AbbA1ER5 (ORCPT ); Tue, 27 Jan 2015 23:17:57 -0500 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Mike Snitzer , Jens Axboe , Zefan Li Subject: [PATCH 3.4 048/177] block: fix alignment_offset math that assumes io_min is a power-of-2 Date: Wed, 28 Jan 2015 12:07:42 +0800 Message-Id: <1422418236-12852-95-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1422418050-12581-1-git-send-email-lizf@kernel.org> References: <1422418050-12581-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mike Snitzer 3.4.106-rc1 review patch. If anyone has any objections, please let me know. ------------------ commit b8839b8c55f3fdd60dc36abcda7e0266aff7985c upstream. The math in both blk_stack_limits() and queue_limit_alignment_offset() assume that a block device's io_min (aka minimum_io_size) is always a power-of-2. Fix the math such that it works for non-power-of-2 io_min. This issue (of alignment_offset != 0) became apparent when testing dm-thinp with a thinp blocksize that matches a RAID6 stripesize of 1280K. Commit fdfb4c8c1 ("dm thin: set minimum_io_size to pool's data block size") unlocked the potential for alignment_offset != 0 due to the dm-thin-pool's io_min possibly being a non-power-of-2. Signed-off-by: Mike Snitzer Acked-by: Martin K. Petersen Signed-off-by: Jens Axboe Signed-off-by: Zefan Li --- block/blk-settings.c | 4 ++-- include/linux/blkdev.h | 5 ++--- 2 files changed, 4 insertions(+), 5 deletions(-) diff --git a/block/blk-settings.c b/block/blk-settings.c index b74cc58..14f1d30 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -538,7 +538,7 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, bottom = max(b->physical_block_size, b->io_min) + alignment; /* Verify that top and bottom intervals line up */ - if (max(top, bottom) & (min(top, bottom) - 1)) { + if (max(top, bottom) % min(top, bottom)) { t->misaligned = 1; ret = -1; } @@ -579,7 +579,7 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, /* Find lowest common alignment_offset */ t->alignment_offset = lcm(t->alignment_offset, alignment) - & (max(t->physical_block_size, t->io_min) - 1); + % max(t->physical_block_size, t->io_min); /* Verify that new alignment_offset is on a logical block boundary */ if (t->alignment_offset & (t->logical_block_size - 1)) { diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 4d4ac24..01b7047 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1069,10 +1069,9 @@ static inline int queue_alignment_offset(struct request_queue *q) static inline int queue_limit_alignment_offset(struct queue_limits *lim, sector_t sector) { unsigned int granularity = max(lim->physical_block_size, lim->io_min); - unsigned int alignment = (sector << 9) & (granularity - 1); + unsigned int alignment = sector_div(sector, granularity >> 9) << 9; - return (granularity + lim->alignment_offset - alignment) - & (granularity - 1); + return (granularity + lim->alignment_offset - alignment) % granularity; } static inline int bdev_alignment_offset(struct block_device *bdev) -- 1.9.1