From 5c250851e1f7850dfe765ff8f6d04ef4ce6e19a7 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Wed, 8 Oct 2014 18:26:13 -0400 Subject: block: fix alignment_offset math that assumes io_min is a power-of-2 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: Ben Hutchings --- block/blk-settings.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'block') diff --git a/block/blk-settings.c b/block/blk-settings.c index fa1eb04..d55a3e4 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -521,7 +521,7 @@ 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; } @@ -562,7 +562,7 @@ 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)) { -- cgit v1.1