[PATCH] block: Remove extra discard_alignment from hd_struct.

[Tao Ma <tm@tao.ma>]

From: Tao Ma <boyu.mt@taobao.com>

Currently, hd_struct.discard_alignment is only used when we
show /sys/block/sdx/sdx/discard_alignment. So remove it and
calculate when it is asked to show.

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
---
 fs/partitions/check.c |    9 ++++++---
 include/linux/genhd.h |    1 -
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index ac54697..ec4f4ae 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -255,7 +255,12 @@ ssize_t part_discard_alignment_show(struct device *dev,
 				   struct device_attribute *attr, char *buf)
 {
 	struct hd_struct *p = dev_to_part(dev);
-	return sprintf(buf, "%u\n", p->discard_alignment);
+	struct gendisk *disk = dev_to_disk(dev);
+
+	return sprintf(buf, "%u\n",
+		       (unsigned long long)queue_limit_discard_alignment(
+							&disk->queue->limits,
+							p->start_sect));
 }
 
 ssize_t part_stat_show(struct device *dev,
@@ -449,8 +454,6 @@ struct hd_struct *add_partition(struct gendisk *disk, int partno,
 	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;
 	p->partno = partno;
 	p->policy = get_disk_ro(disk);
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index d764a42..b4c233f 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -100,7 +100,6 @@ struct hd_struct {
 	sector_t start_sect;
 	sector_t nr_sects;
 	sector_t alignment_offset;
-	unsigned int discard_alignment;
 	struct device __dev;
 	struct kobject *holder_dir;
 	int policy, partno;
-- 
1.7.4