Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933881AbaKLCTx (ORCPT ); Tue, 11 Nov 2014 21:19:53 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:32799 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966003AbaKLBvH (ORCPT ); Tue, 11 Nov 2014 20:51:07 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mike Snitzer , "Martin K. Petersen" , Jens Axboe Subject: [PATCH 3.10 038/123] block: fix alignment_offset math that assumes io_min is a power-of-2 Date: Wed, 12 Nov 2014 10:16:44 +0900 Message-Id: <20141112011720.747397646@linuxfoundation.org> X-Mailer: git-send-email 2.1.3 In-Reply-To: <20141112011718.985171261@linuxfoundation.org> References: <20141112011718.985171261@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mike Snitzer 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: Greg Kroah-Hartman --- block/blk-settings.c | 4 ++-- include/linux/blkdev.h | 5 ++--- 2 files changed, 4 insertions(+), 5 deletions(-) --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -553,7 +553,7 @@ int blk_stack_limits(struct queue_limits 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; } @@ -594,7 +594,7 @@ int blk_stack_limits(struct queue_limits /* 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)) { --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1187,10 +1187,9 @@ static inline int queue_alignment_offset 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) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/