There are lots of duplicated code when trying to merge a bio from
plug list and sw queue, we can introduce a new helper to attempt
to merge a bio, which can simplify the blk_bio_list_merge()
and blk_attempt_plug_merge().
Signed-off-by: Baolin Wang <baolin.w...@linux.alibaba.com>
---
block/blk-merge.c | 104 ++++++++++++++++++++++++++-------------------------
block/blk-mq-sched.c | 6 +--
block/blk.h | 21 ++++++++---
3 files changed, 71 insertions(+), 60 deletions(-)
diff --git a/block/blk-merge.c b/block/blk-merge.c
index b09e9fc..80c9744 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -907,13 +907,14 @@ static void blk_account_io_merge_bio(struct request *req)
part_stat_unlock();
}
-bool bio_attempt_back_merge(struct request *req, struct bio *bio,
- unsigned int nr_segs)
+enum bio_merge_status bio_attempt_back_merge(struct request *req,
+ struct bio *bio,
+ unsigned int nr_segs)
{
const int ff = bio->bi_opf & REQ_FAILFAST_MASK;
if (!ll_back_merge_fn(req, bio, nr_segs))
- return false;
+ return BIO_MERGE_FAILED;
trace_block_bio_backmerge(req->q, req, bio);
rq_qos_merge(req->q, req, bio);
@@ -928,16 +929,17 @@ bool bio_attempt_back_merge(struct request *req, struct
bio *bio,
bio_crypt_free_ctx(bio);
blk_account_io_merge_bio(req);
- return true;
+ return BIO_MERGE_OK;
}
-bool bio_attempt_front_merge(struct request *req, struct bio *bio,
- unsigned int nr_segs)
+enum bio_merge_status bio_attempt_front_merge(struct request *req,
+ struct bio *bio,
+ unsigned int nr_segs)
{
const int ff = bio->bi_opf & REQ_FAILFAST_MASK;
if (!ll_front_merge_fn(req, bio, nr_segs))
- return false;
+ return BIO_MERGE_FAILED;
trace_block_bio_frontmerge(req->q, req, bio);
rq_qos_merge(req->q, req, bio);
@@ -954,11 +956,12 @@ bool bio_attempt_front_merge(struct request *req, struct
bio *bio,
bio_crypt_do_front_merge(req, bio);
blk_account_io_merge_bio(req);
- return true;
+ return BIO_MERGE_OK;
}
-bool bio_attempt_discard_merge(struct request_queue *q, struct request *req,
- struct bio *bio)
+enum bio_merge_status bio_attempt_discard_merge(struct request_queue *q,
+ struct request *req,
+ struct bio *bio)
{
unsigned short segments = blk_rq_nr_discard_segments(req);
@@ -976,10 +979,39 @@ bool bio_attempt_discard_merge(struct request_queue *q,
struct request *req,
req->nr_phys_segments = segments + 1;
blk_account_io_merge_bio(req);
- return true;
+ return BIO_MERGE_OK;
no_merge:
req_set_nomerge(q, req);
- return false;
+ return BIO_MERGE_FAILED;
+}
+
+static enum bio_merge_status blk_attempt_bio_merge(struct request_queue *q,
+ struct request *rq,
+ struct bio *bio,
+ unsigned int nr_segs,
+ bool sched_allow_merge)
+{
+ if (!blk_rq_merge_ok(rq, bio))
+ return BIO_MERGE_NONE;
+
+ switch (blk_try_merge(rq, bio)) {
+ case ELEVATOR_BACK_MERGE:
+ if (!sched_allow_merge ||
+ (sched_allow_merge && blk_mq_sched_allow_merge(q, rq, bio)))
+ return bio_attempt_back_merge(rq, bio, nr_segs);
+ break;
+ case ELEVATOR_FRONT_MERGE:
+ if (!sched_allow_merge ||
+ (sched_allow_merge && blk_mq_sched_allow_merge(q, rq, bio)))
+ return bio_attempt_front_merge(rq, bio, nr_segs);
+ break;
+ case ELEVATOR_DISCARD_MERGE:
+ return bio_attempt_discard_merge(q, rq, bio);
+ default:
+ return BIO_MERGE_NONE;
+ }
+
+ return BIO_MERGE_FAILED;
}
/**
@@ -1018,8 +1050,6 @@ bool blk_attempt_plug_merge(struct request_queue *q,
struct bio *bio,
plug_list = &plug->mq_list;
list_for_each_entry_reverse(rq, plug_list, queuelist) {
- bool merged = false;
-
if (rq->q == q && same_queue_rq) {
/*
* Only blk-mq multiple hardware queues case checks the
@@ -1029,24 +1059,11 @@ bool blk_attempt_plug_merge(struct request_queue *q,
struct bio *bio,
*same_queue_rq = rq;
}
- if (rq->q != q || !blk_rq_merge_ok(rq, bio))
+ if (rq->q != q)
continue;
- switch (blk_try_merge(rq, bio)) {
- case ELEVATOR_BACK_MERGE:
- merged = bio_attempt_back_merge(rq, bio, nr_segs);
- break;
- case ELEVATOR_FRONT_MERGE:
- merged = bio_attempt_front_merge(rq, bio, nr_segs);
- break;
- case ELEVATOR_DISCARD_MERGE:
- merged = bio_attempt_discard_merge(q, rq, bio);
- break;
- default:
- break;
- }
-
- if (merged)
+ if (blk_attempt_bio_merge(q, rq, bio, nr_segs, false) ==
+ BIO_MERGE_OK)
return true;
}
@@ -1064,33 +1081,18 @@ bool blk_bio_list_merge(struct request_queue *q, struct
list_head *list,
int checked = 8;
list_for_each_entry_reverse(rq, list, queuelist) {
- bool merged = false;
-
if (!checked--)
break;
- if (!blk_rq_merge_ok(rq, bio))
- continue;
-
- switch (blk_try_merge(rq, bio)) {
- case ELEVATOR_BACK_MERGE:
- if (blk_mq_sched_allow_merge(q, rq, bio))
- merged = bio_attempt_back_merge(rq, bio,
- nr_segs);
- break;
- case ELEVATOR_FRONT_MERGE:
- if (blk_mq_sched_allow_merge(q, rq, bio))
- merged = bio_attempt_front_merge(rq, bio,
- nr_segs);
- break;
- case ELEVATOR_DISCARD_MERGE:
- merged = bio_attempt_discard_merge(q, rq, bio);
- break;
- default:
+ switch (blk_attempt_bio_merge(q, rq, bio, nr_segs, true)) {
+ case BIO_MERGE_NONE:
continue;
+ case BIO_MERGE_OK:
+ return true;
+ case BIO_MERGE_FAILED:
+ return false;
}
- return merged;
}
return false;
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 82acff9..94db0c9 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -368,7 +368,7 @@ bool blk_mq_sched_try_merge(struct request_queue *q, struct
bio *bio,
case ELEVATOR_BACK_MERGE:
if (!blk_mq_sched_allow_merge(q, rq, bio))
return false;
- if (!bio_attempt_back_merge(rq, bio, nr_segs))
+ if (bio_attempt_back_merge(rq, bio, nr_segs) != BIO_MERGE_OK)
return false;
*merged_request = attempt_back_merge(q, rq);
if (!*merged_request)
@@ -377,14 +377,14 @@ bool blk_mq_sched_try_merge(struct request_queue *q,
struct bio *bio,
case ELEVATOR_FRONT_MERGE:
if (!blk_mq_sched_allow_merge(q, rq, bio))
return false;
- if (!bio_attempt_front_merge(rq, bio, nr_segs))
+ if (bio_attempt_front_merge(rq, bio, nr_segs) != BIO_MERGE_OK)
return false;
*merged_request = attempt_front_merge(q, rq);
if (!*merged_request)
elv_merged_request(q, rq, ELEVATOR_FRONT_MERGE);
return true;
case ELEVATOR_DISCARD_MERGE:
- return bio_attempt_discard_merge(q, rq, bio);
+ return bio_attempt_discard_merge(q, rq, bio) == BIO_MERGE_OK;
default:
return false;
}
diff --git a/block/blk.h b/block/blk.h
index d6152d2..a180443 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -29,6 +29,12 @@ struct blk_flush_queue {
spinlock_t mq_flush_lock;
};
+enum bio_merge_status {
+ BIO_MERGE_OK,
+ BIO_MERGE_NONE,
+ BIO_MERGE_FAILED,
+};
+
extern struct kmem_cache *blk_requestq_cachep;
extern struct kobj_type blk_queue_ktype;
extern struct ida blk_queue_ida;
@@ -169,12 +175,15 @@ static inline void blk_integrity_del(struct gendisk *disk)
unsigned long blk_rq_timeout(unsigned long timeout);
void blk_add_timer(struct request *req);
-bool bio_attempt_front_merge(struct request *req, struct bio *bio,
- unsigned int nr_segs);
-bool bio_attempt_back_merge(struct request *req, struct bio *bio,
- unsigned int nr_segs);
-bool bio_attempt_discard_merge(struct request_queue *q, struct request *req,
- struct bio *bio);
+enum bio_merge_status bio_attempt_front_merge(struct request *req,
+ struct bio *bio,
+ unsigned int nr_segs);
+enum bio_merge_status bio_attempt_back_merge(struct request *req,
+ struct bio *bio,
+ unsigned int nr_segs);
+enum bio_merge_status bio_attempt_discard_merge(struct request_queue *q,
+ struct request *req,
+ struct bio *bio);
bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
unsigned int nr_segs, struct request **same_queue_rq);
bool blk_bio_list_merge(struct request_queue *q, struct list_head *list,
--
1.8.3.1
