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| author | Mike Snitzer <snitzer@redhat.com> | 2014-10-08 18:26:13 -0400 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2014-10-09 09:41:40 -0600 |
| commit | b8839b8c55f3fdd60dc36abcda7e0266aff7985c (patch) | |
| tree | 27372945d214df68a1f5e750399084642dbc04f9 | |
| parent | 9d8f0bcca6ffa024a822ce4ab1008ab663f06672 (diff) | |
| download | lwn-b8839b8c55f3fdd60dc36abcda7e0266aff7985c.tar.gz lwn-b8839b8c55f3fdd60dc36abcda7e0266aff7985c.zip | |
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>
| -rw-r--r-- | block/blk-settings.c | 4 | ||||
| -rw-r--r-- | include/linux/blkdev.h | 5 |
2 files changed, 4 insertions, 5 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)) { diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 038b40f84c7a..554639249fd6 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1279,10 +1279,9 @@ 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) |