block: remove the alignment_offset field from struct hd_struct

The alignment offset is only used in slow path callers, so just calculate
it on the fly.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/partitions/core.c

@@ -199,7 +199,10 @@ static ssize_t part_alignment_offset_show(struct device *dev,
 					  struct device_attribute *attr, char *buf)
 {
 	struct hd_struct *p = dev_to_part(dev);
-	return sprintf(buf, "%llu\n", (unsigned long long)p->alignment_offset);
+
+	return sprintf(buf, "%u\n",
+		queue_limit_alignment_offset(&part_to_disk(p)->queue->limits,
+				p->start_sect));
 }
 
 static ssize_t part_discard_alignment_show(struct device *dev,
@@ -405,8 +408,6 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno,
 	pdev = part_to_dev(p);
 
 	p->start_sect = start;
-	p->alignment_offset =
-		queue_limit_alignment_offset(&disk->queue->limits, start);
 	p->discard_alignment =
 		queue_limit_discard_alignment(&disk->queue->limits, start);
 	p->nr_sects = len;

include/linux/blkdev.h

@@ -1456,10 +1456,9 @@ static inline int bdev_alignment_offset(struct block_device *bdev)
 
 	if (q->limits.misaligned)
 		return -1;
-
 	if (bdev != bdev->bd_contains)
-		return bdev->bd_part->alignment_offset;
-
+		return queue_limit_alignment_offset(&q->limits,
+				bdev->bd_part->start_sect);
 	return q->limits.alignment_offset;
 }
 

include/linux/genhd.h

@@ -65,7 +65,6 @@ struct hd_struct {
 	struct disk_stats __percpu *dkstats;
 	struct percpu_ref ref;
 
-	sector_t alignment_offset;
 	unsigned int discard_alignment;
 	struct device __dev;
 	struct kobject *holder_dir;