block: Fix incorrect alignment offset reporting and update documentation
[linux-2.6.git] / include / linux / blkdev.h
index 784a919..59b832b 100644 (file)
@@ -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)