max_discard_sectors doesn't equal to max_sectors/max_hw_sectors. Without this,
discard request merge might be ignored.
Signed-off-by: Shaohua Li <shli@xxxxxxxxxxxx>
---
block/blk-merge.c | 9 +++++++--
include/linux/blkdev.h | 5 +++++
2 files changed, 12 insertions(+), 2 deletions(-)
Index: linux/block/blk-merge.c
===================================================================
--- linux.orig/block/blk-merge.c 2012-03-09 14:05:35.562062857 +0800
+++ linux/block/blk-merge.c 2012-03-09 14:07:55.432062246 +0800
@@ -228,13 +228,16 @@ no_merge:
int ll_back_merge_fn(struct request_queue *q, struct request *req,
struct bio *bio)
{
- unsigned short max_sectors;
+ unsigned int max_sectors;
if (unlikely(req->cmd_type == REQ_TYPE_BLOCK_PC))
max_sectors = queue_max_hw_sectors(q);
else
max_sectors = queue_max_sectors(q);
+ if (unlikely(req->cmd_flags & REQ_DISCARD))
+ max_sectors = queue_max_discard_sectors(q);
+
if (blk_rq_sectors(req) + bio_sectors(bio) > max_sectors) {
req->cmd_flags |= REQ_NOMERGE;
if (req == q->last_merge)
@@ -252,13 +255,15 @@ int ll_back_merge_fn(struct request_queu
int ll_front_merge_fn(struct request_queue *q, struct request *req,
struct bio *bio)
{
- unsigned short max_sectors;
+ unsigned int max_sectors;
if (unlikely(req->cmd_type == REQ_TYPE_BLOCK_PC))
max_sectors = queue_max_hw_sectors(q);
else
max_sectors = queue_max_sectors(q);
+ if (unlikely(req->cmd_flags & REQ_DISCARD))
+ max_sectors = queue_max_discard_sectors(q);
if (blk_rq_sectors(req) + bio_sectors(bio) > max_sectors) {
req->cmd_flags |= REQ_NOMERGE;
Index: linux/include/linux/blkdev.h
===================================================================
--- linux.orig/include/linux/blkdev.h 2012-03-09 14:05:35.562062857 +0800
+++ linux/include/linux/blkdev.h 2012-03-09 14:07:55.432062246 +0800
@@ -1006,6 +1006,11 @@ static inline unsigned int queue_max_hw_
return q->limits.max_hw_sectors;
}
+static inline unsigned int queue_max_discard_sectors(struct request_queue *q)
+{
+ return q->limits.max_discard_sectors;
+}
+
static inline unsigned short queue_max_segments(struct request_queue *q)
{
return q->limits.max_segments;
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
