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authorMartin K. Petersen <martin.petersen@oracle.com>2009-12-29 08:35:35 +0100
committerJens Axboe <jens.axboe@oracle.com>2009-12-29 08:35:35 +0100
commit81744ee44ab2845c16ffd7d6f762f7b4a49a4750 (patch)
treec3d0cca0e71080ecd8423cef8af1c632fc444764 /include
parent2f7a2d89a8b5915d89ad9ebeb0065db7d5831cea (diff)
block: Fix incorrect alignment offset reporting and update documentation
queue_sector_alignment_offset returned the wrong value which caused partitions to report an incorrect alignment_offset. Since offset alignment calculation is needed several places it has been split into a separate helper function. The topology stacking function has been updated accordingly. Furthermore, comments have been added to clarify how the stacking function works. Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Tested-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'include')
-rw-r--r--include/linux/blkdev.h11
1 files changed, 9 insertions, 2 deletions
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 784a919aa0d0..59b832be3044 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1116,11 +1116,18 @@ static inline int queue_alignment_offset(struct request_queue *q)
return q->limits.alignment_offset;
}
+static inline int queue_limit_alignment_offset(struct queue_limits *lim, sector_t offset)
+{
+ unsigned int granularity = max(lim->physical_block_size, lim->io_min);
+
+ offset &= granularity - 1;
+ return (granularity + lim->alignment_offset - offset) & (granularity - 1);
+}
+
static inline int queue_sector_alignment_offset(struct request_queue *q,
sector_t sector)
{
- return ((sector << 9) - q->limits.alignment_offset)
- & (q->limits.io_min - 1);
+ return queue_limit_alignment_offset(&q->limits, sector << 9);
}
static inline int bdev_alignment_offset(struct block_device *bdev)