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authorMike Snitzer <snitzer@redhat.com>2014-10-08 18:26:13 -0400
committerJens Axboe <axboe@fb.com>2014-10-09 09:41:40 -0600
commitb8839b8c55f3fdd60dc36abcda7e0266aff7985c (patch)
tree27372945d214df68a1f5e750399084642dbc04f9 /block/blk-settings.c
parent9d8f0bcca6ffa024a822ce4ab1008ab663f06672 (diff)
downloadlinux-linaro-stable-b8839b8c55f3fdd60dc36abcda7e0266aff7985c.tar.gz
block: fix alignment_offset math that assumes io_min is a power-of-2
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 <snitzer@redhat.com> Cc: stable@vger.kernel.org Acked-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block/blk-settings.c')
-rw-r--r--block/blk-settings.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c
index f1a1795a5683..aa02247d227e 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -574,7 +574,7 @@ 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;
}
@@ -619,7 +619,7 @@ 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)) {