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authorMike Snitzer <snitzer@redhat.com>2014-10-08 18:26:13 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-11-14 08:47:55 -0800
commita63bea06c1617175c68677da4810dfd120da2bd5 (patch)
tree32a3f11f23ffe8bc9a22f4bbe6650d131f972fce /include/linux
parent29772e3e199f2c13cd5f00694e633fb80bbb0415 (diff)
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 <snitzer@redhat.com> Acked-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/blkdev.h5
1 files changed, 2 insertions, 3 deletions
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 2fdb4a451b49..494d228a91dd 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1187,10 +1187,9 @@ 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)