[06/30] block: Fix incorrect reporting of partition alignment

[Greg KH]

2.6.32-stable review patch.  If anyone has any objections, please let us know.

------------------

From: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx>

commit 81744ee44ab2845c16ffd7d6f762f7b4a49a4750 upstream

queue_sector_alignment_offset returned the wrong value which caused
partitions to report an incorrect alignment_offset. Since offset
calculation is needed several places it has been split into a separate
helper function.

Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Tested-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Cc: Jens Axboe <jens.axboe@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 include/linux/blkdev.h |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1114,11 +1114,18 @@ static inline int queue_alignment_offset
 	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)


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