[PATCH 7/7] [BLOCK] Allow elevators to sort/merge discard requests

[David Woodhouse <dwmw2@infradead.org>]

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
---
 block/blk-core.c       |    2 +-
 block/blk-merge.c      |   12 +++++++-----
 block/elevator.c       |    4 +++-
 include/linux/blkdev.h |    5 +++--
 4 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 2442fb7..0c8ed97 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1078,7 +1078,7 @@ void init_request_from_bio(struct request *req, struct bio *bio)
 	if (unlikely(bio_barrier(bio)))
 		req->cmd_flags |= (REQ_HARDBARRIER | REQ_NOMERGE);
 	if (unlikely(bio_discard(bio))) {
-		req->cmd_flags |= (REQ_SOFTBARRIER | REQ_DISCARD);
+		req->cmd_flags |= REQ_DISCARD;
 		req->q->prepare_discard_fn(req->q, req);
 	}
 
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 5efc9e7..58a0ea3 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -11,7 +11,7 @@
 
 void blk_recalc_rq_sectors(struct request *rq, int nsect)
 {
-	if (blk_fs_request(rq)) {
+	if (blk_fs_request(rq) || blk_discard_rq(rq)) {
 		rq->hard_sector += nsect;
 		rq->hard_nr_sectors -= nsect;
 
@@ -317,8 +317,9 @@ int ll_back_merge_fn(struct request_queue *q, struct request *req,
 	if (!bio_flagged(bio, BIO_SEG_VALID))
 		blk_recount_segments(q, bio);
 	len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size;
-	if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio))
-	    && !BIOVEC_VIRT_OVERSIZE(len)) {
+	if (!bio_has_data(bio) || 
+	    (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio))
+	     && !BIOVEC_VIRT_OVERSIZE(len))) {
 		int mergeable =  ll_new_mergeable(q, req, bio);
 
 		if (mergeable) {
@@ -356,8 +357,9 @@ int ll_front_merge_fn(struct request_queue *q, struct request *req,
 		blk_recount_segments(q, bio);
 	if (!bio_flagged(req->bio, BIO_SEG_VALID))
 		blk_recount_segments(q, req->bio);
-	if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) &&
-	    !BIOVEC_VIRT_OVERSIZE(len)) {
+	if (!bio_has_data(bio) || 
+	    (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) &&
+	     !BIOVEC_VIRT_OVERSIZE(len))) {
 		int mergeable =  ll_new_mergeable(q, req, bio);
 
 		if (mergeable) {
diff --git a/block/elevator.c b/block/elevator.c
index 17ae417..4e27daa 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -444,6 +444,8 @@ void elv_dispatch_sort(struct request_queue *q, struct request *rq)
 	list_for_each_prev(entry, &q->queue_head) {
 		struct request *pos = list_entry_rq(entry);
 
+		if (blk_discard_rq(rq) != blk_discard_rq(pos))
+			break;
 		if (rq_data_dir(rq) != rq_data_dir(pos))
 			break;
 		if (pos->cmd_flags & stop_flags)
@@ -698,7 +700,7 @@ void __elv_add_request(struct request_queue *q, struct request *rq, int where,
 		 * this request is scheduling boundary, update
 		 * end_sector
 		 */
-		if (blk_fs_request(rq)) {
+		if (blk_fs_request(rq) || blk_discard_rq(rq)) {
 			q->end_sector = rq_end_sector(rq);
 			q->boundary_rq = rq;
 		}
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index f8957c5..b9cb7e1 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -531,7 +531,7 @@ enum {
 #define blk_noretry_request(rq)	((rq)->cmd_flags & REQ_FAILFAST)
 #define blk_rq_started(rq)	((rq)->cmd_flags & REQ_STARTED)
 
-#define blk_account_rq(rq)	(blk_rq_started(rq) && blk_fs_request(rq))
+#define blk_account_rq(rq)	(blk_rq_started(rq) && (blk_fs_request(rq) || blk_discard_rq(rq))) 
 
 #define blk_pm_suspend_request(rq)	((rq)->cmd_type == REQ_TYPE_PM_SUSPEND)
 #define blk_pm_resume_request(rq)	((rq)->cmd_type == REQ_TYPE_PM_RESUME)
@@ -588,7 +588,8 @@ static inline void blk_clear_queue_full(struct request_queue *q, int rw)
 #define RQ_NOMERGE_FLAGS	\
 	(REQ_NOMERGE | REQ_STARTED | REQ_HARDBARRIER | REQ_SOFTBARRIER)
 #define rq_mergeable(rq)	\
-	(!((rq)->cmd_flags & RQ_NOMERGE_FLAGS) && blk_fs_request((rq)))
+	(!((rq)->cmd_flags & RQ_NOMERGE_FLAGS) && \
+	 (blk_discard_rq(rq) || blk_fs_request((rq))))
 
 /*
  * q->prep_rq_fn return values
-- 
1.5.5.1


-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse@intel.com                              Intel Corporation