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: Zefan Li <lizefan@huawei.com>
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 6502841..0373334 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1078,10 +1078,9 @@
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)