Switch these constants to an enum, and make let the compiler ensure that
all callers of blk_try_merge and elv_merge handle all potential values.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
block/blk-core.c | 76 +++++++++++++++++++++++++-----------------------
block/blk-merge.c | 2 +-
block/blk-mq-sched.c | 35 +++++++++++-----------
block/blk-mq.c | 32 +++++++++-----------
block/blk.h | 2 +-
block/cfq-iosched.c | 4 +--
block/deadline-iosched.c | 12 +++-----
block/elevator.c | 10 ++++---
block/mq-deadline.c | 2 +-
include/linux/elevator.h | 28 ++++++++++--------
10 files changed, 102 insertions(+), 101 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index d161d4ab7052..75fe534861df 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1513,12 +1513,11 @@ bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
{
struct blk_plug *plug;
struct request *rq;
- bool ret = false;
struct list_head *plug_list;
plug = current->plug;
if (!plug)
- goto out;
+ return false;
*request_count = 0;
if (q->mq_ops)
@@ -1527,7 +1526,7 @@ bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
plug_list = &plug->list;
list_for_each_entry_reverse(rq, plug_list, queuelist) {
- int el_ret;
+ bool merged = false;
if (rq->q == q) {
(*request_count)++;
@@ -1543,19 +1542,22 @@ bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
if (rq->q != q || !blk_rq_merge_ok(rq, bio))
continue;
- el_ret = blk_try_merge(rq, bio);
- if (el_ret == ELEVATOR_BACK_MERGE) {
- ret = bio_attempt_back_merge(q, rq, bio);
- if (ret)
- break;
- } else if (el_ret == ELEVATOR_FRONT_MERGE) {
- ret = bio_attempt_front_merge(q, rq, bio);
- if (ret)
- break;
+ switch (blk_try_merge(rq, bio)) {
+ case ELEVATOR_BACK_MERGE:
+ merged = bio_attempt_back_merge(q, rq, bio);
+ break;
+ case ELEVATOR_FRONT_MERGE:
+ merged = bio_attempt_front_merge(q, rq, bio);
+ break;
+ default:
+ break;
}
+
+ if (merged)
+ return true;
}
-out:
- return ret;
+
+ return false;
}
unsigned int blk_plug_queued_count(struct request_queue *q)
@@ -1597,7 +1599,7 @@ void init_request_from_bio(struct request *req, struct bio *bio)
static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio)
{
struct blk_plug *plug;
- int el_ret, where = ELEVATOR_INSERT_SORT;
+ int where = ELEVATOR_INSERT_SORT;
struct request *req, *free;
unsigned int request_count = 0;
unsigned int wb_acct;
@@ -1635,27 +1637,29 @@ static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio)
spin_lock_irq(q->queue_lock);
- el_ret = elv_merge(q, &req, bio);
- if (el_ret == ELEVATOR_BACK_MERGE) {
- if (bio_attempt_back_merge(q, req, bio)) {
- elv_bio_merged(q, req, bio);
- free = attempt_back_merge(q, req);
- if (!free)
- elv_merged_request(q, req, el_ret);
- else
- __blk_put_request(q, free);
- goto out_unlock;
- }
- } else if (el_ret == ELEVATOR_FRONT_MERGE) {
- if (bio_attempt_front_merge(q, req, bio)) {
- elv_bio_merged(q, req, bio);
- free = attempt_front_merge(q, req);
- if (!free)
- elv_merged_request(q, req, el_ret);
- else
- __blk_put_request(q, free);
- goto out_unlock;
- }
+ switch (elv_merge(q, &req, bio)) {
+ case ELEVATOR_BACK_MERGE:
+ if (!bio_attempt_back_merge(q, req, bio))
+ break;
+ elv_bio_merged(q, req, bio);
+ free = attempt_back_merge(q, req);
+ if (free)
+ __blk_put_request(q, free);
+ else
+ elv_merged_request(q, req, ELEVATOR_BACK_MERGE);
+ goto out_unlock;
+ case ELEVATOR_FRONT_MERGE:
+ if (!bio_attempt_front_merge(q, req, bio))
+ break;
+ elv_bio_merged(q, req, bio);
+ free = attempt_front_merge(q, req);
+ if (free)
+ __blk_put_request(q, free);
+ else
+ elv_merged_request(q, req, ELEVATOR_FRONT_MERGE);
+ goto out_unlock;
+ default:
+ break;
}
get_rq:
diff --git a/block/blk-merge.c b/block/blk-merge.c
index c956d9e7aafd..6cbd90ad5f90 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -801,7 +801,7 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
return true;
}
-int blk_try_merge(struct request *rq, struct bio *bio)
+enum elv_merge blk_try_merge(struct request *rq, struct bio *bio)
{
if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector)
return ELEVATOR_BACK_MERGE;
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index ee455e7cf9d8..72d0d8361175 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -238,30 +238,29 @@ bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
struct request **merged_request)
{
struct request *rq;
- int ret;
- ret = elv_merge(q, &rq, bio);
- if (ret == ELEVATOR_BACK_MERGE) {
+ switch (elv_merge(q, &rq, bio)) {
+ case ELEVATOR_BACK_MERGE:
if (!blk_mq_sched_allow_merge(q, rq, bio))
return false;
- if (bio_attempt_back_merge(q, rq, bio)) {
- *merged_request = attempt_back_merge(q, rq);
- if (!*merged_request)
- elv_merged_request(q, rq, ret);
- return true;
- }
- } else if (ret == ELEVATOR_FRONT_MERGE) {
+ if (!bio_attempt_back_merge(q, rq, bio))
+ return false;
+ *merged_request = attempt_back_merge(q, rq);
+ if (!*merged_request)
+ elv_merged_request(q, rq, ELEVATOR_BACK_MERGE);
+ return true;
+ case ELEVATOR_FRONT_MERGE:
if (!blk_mq_sched_allow_merge(q, rq, bio))
return false;
- if (bio_attempt_front_merge(q, rq, bio)) {
- *merged_request = attempt_front_merge(q, rq);
- if (!*merged_request)
- elv_merged_request(q, rq, ret);
- return true;
- }
+ if (!bio_attempt_front_merge(q, rq, bio))
+ return false;
+ *merged_request = attempt_front_merge(q, rq);
+ if (!*merged_request)
+ elv_merged_request(q, rq, ELEVATOR_FRONT_MERGE);
+ return true;
+ default:
+ return false;
}
-
- return false;
}
EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index be183e6115a1..9294633759d9 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -763,7 +763,7 @@ static bool blk_mq_attempt_merge(struct request_queue *q,
int checked = 8;
list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
- int el_ret;
+ bool merged = false;
if (!checked--)
break;
@@ -771,26 +771,22 @@ static bool blk_mq_attempt_merge(struct request_queue *q,
if (!blk_rq_merge_ok(rq, bio))
continue;
- el_ret = blk_try_merge(rq, bio);
- if (el_ret == ELEVATOR_NO_MERGE)
- continue;
-
- if (!blk_mq_sched_allow_merge(q, rq, bio))
+ switch (blk_try_merge(rq, bio)) {
+ case ELEVATOR_BACK_MERGE:
+ if (blk_mq_sched_allow_merge(q, rq, bio))
+ merged = bio_attempt_back_merge(q, rq, bio);
break;
-
- if (el_ret == ELEVATOR_BACK_MERGE) {
- if (bio_attempt_back_merge(q, rq, bio)) {
- ctx->rq_merged++;
- return true;
- }
- break;
- } else if (el_ret == ELEVATOR_FRONT_MERGE) {
- if (bio_attempt_front_merge(q, rq, bio)) {
- ctx->rq_merged++;
- return true;
- }
+ case ELEVATOR_FRONT_MERGE:
+ if (blk_mq_sched_allow_merge(q, rq, bio))
+ merged = bio_attempt_front_merge(q, rq, bio);
break;
+ default:
+ continue;
}
+
+ if (merged)
+ ctx->rq_merged++;
+ return merged;
}
return false;
diff --git a/block/blk.h b/block/blk.h
index 3e08703902a9..ae82f2ac4019 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -215,7 +215,7 @@ int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
void blk_recalc_rq_segments(struct request *rq);
void blk_rq_set_mixed_merge(struct request *rq);
bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
-int blk_try_merge(struct request *rq, struct bio *bio);
+enum elv_merge blk_try_merge(struct request *rq, struct bio *bio);
void blk_queue_congestion_threshold(struct request_queue *q);
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index f0f29ee731e1..921262770636 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -2528,7 +2528,7 @@ static void cfq_remove_request(struct request *rq)
}
}
-static int cfq_merge(struct request_queue *q, struct request **req,
+static enum elv_merge cfq_merge(struct request_queue *q, struct request **req,
struct bio *bio)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
@@ -2544,7 +2544,7 @@ static int cfq_merge(struct request_queue *q, struct request **req,
}
static void cfq_merged_request(struct request_queue *q, struct request *req,
- int type)
+ enum elv_merge type)
{
if (type == ELEVATOR_FRONT_MERGE) {
struct cfq_queue *cfqq = RQ_CFQQ(req);
diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
index 05fc0ea25a98..c68f6bbc0dcd 100644
--- a/block/deadline-iosched.c
+++ b/block/deadline-iosched.c
@@ -120,12 +120,11 @@ static void deadline_remove_request(struct request_queue *q, struct request *rq)
deadline_del_rq_rb(dd, rq);
}
-static int
+static enum elv_merge
deadline_merge(struct request_queue *q, struct request **req, struct bio *bio)
{
struct deadline_data *dd = q->elevator->elevator_data;
struct request *__rq;
- int ret;
/*
* check for front merge
@@ -138,20 +137,17 @@ deadline_merge(struct request_queue *q, struct request **req, struct bio *bio)
BUG_ON(sector != blk_rq_pos(__rq));
if (elv_bio_merge_ok(__rq, bio)) {
- ret = ELEVATOR_FRONT_MERGE;
- goto out;
+ *req = __rq;
+ return ELEVATOR_FRONT_MERGE;
}
}
}
return ELEVATOR_NO_MERGE;
-out:
- *req = __rq;
- return ret;
}
static void deadline_merged_request(struct request_queue *q,
- struct request *req, int type)
+ struct request *req, enum elv_merge type)
{
struct deadline_data *dd = q->elevator->elevator_data;
diff --git a/block/elevator.c b/block/elevator.c
index 7e4f5880dd64..27ff1ed5a6fa 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -427,11 +427,11 @@ void elv_dispatch_add_tail(struct request_queue *q, struct request *rq)
}
EXPORT_SYMBOL(elv_dispatch_add_tail);
-int elv_merge(struct request_queue *q, struct request **req, struct bio *bio)
+enum elv_merge elv_merge(struct request_queue *q, struct request **req,
+ struct bio *bio)
{
struct elevator_queue *e = q->elevator;
struct request *__rq;
- int ret;
/*
* Levels of merges:
@@ -446,7 +446,8 @@ int elv_merge(struct request_queue *q, struct request **req, struct bio *bio)
* First try one-hit cache.
*/
if (q->last_merge && elv_bio_merge_ok(q->last_merge, bio)) {
- ret = blk_try_merge(q->last_merge, bio);
+ enum elv_merge ret = blk_try_merge(q->last_merge, bio);
+
if (ret != ELEVATOR_NO_MERGE) {
*req = q->last_merge;
return ret;
@@ -514,7 +515,8 @@ bool elv_attempt_insert_merge(struct request_queue *q, struct request *rq)
return ret;
}
-void elv_merged_request(struct request_queue *q, struct request *rq, int type)
+void elv_merged_request(struct request_queue *q, struct request *rq,
+ enum elv_merge type)
{
struct elevator_queue *e = q->elevator;
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index d68d9c273a66..236121633ca0 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -121,7 +121,7 @@ static void deadline_remove_request(struct request_queue *q, struct request *rq)
}
static void dd_request_merged(struct request_queue *q, struct request *req,
- int type)
+ enum elv_merge type)
{
struct deadline_data *dd = q->elevator->elevator_data;
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index b5825c4f06f7..b38b4e651ea6 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -9,12 +9,21 @@
struct io_cq;
struct elevator_type;
-typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
+/*
+ * Return values from elevator merger
+ */
+enum elv_merge {
+ ELEVATOR_NO_MERGE = 0,
+ ELEVATOR_FRONT_MERGE = 1,
+ ELEVATOR_BACK_MERGE = 2,
+};
+
+typedef enum elv_merge (elevator_merge_fn) (struct request_queue *, struct request **,
struct bio *);
typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
-typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);
+typedef void (elevator_merged_fn) (struct request_queue *, struct request *, enum elv_merge);
typedef int (elevator_allow_bio_merge_fn) (struct request_queue *,
struct request *, struct bio *);
@@ -87,7 +96,7 @@ struct elevator_mq_ops {
bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
bool (*bio_merge)(struct blk_mq_hw_ctx *, struct bio *);
int (*request_merge)(struct request_queue *q, struct request **, struct bio *);
- void (*request_merged)(struct request_queue *, struct request *, int);
+ void (*request_merged)(struct request_queue *, struct request *, enum elv_merge);
void (*requests_merged)(struct request_queue *, struct request *, struct request *);
struct request *(*get_request)(struct request_queue *, unsigned int, struct blk_mq_alloc_data *);
void (*put_request)(struct request *);
@@ -166,10 +175,12 @@ extern void elv_dispatch_sort(struct request_queue *, struct request *);
extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
extern void elv_add_request(struct request_queue *, struct request *, int);
extern void __elv_add_request(struct request_queue *, struct request *, int);
-extern int elv_merge(struct request_queue *, struct request **, struct bio *);
+extern enum elv_merge elv_merge(struct request_queue *, struct request **,
+ struct bio *);
extern void elv_merge_requests(struct request_queue *, struct request *,
struct request *);
-extern void elv_merged_request(struct request_queue *, struct request *, int);
+extern void elv_merged_request(struct request_queue *, struct request *,
+ enum elv_merge);
extern void elv_bio_merged(struct request_queue *q, struct request *,
struct bio *);
extern bool elv_attempt_insert_merge(struct request_queue *, struct request *);
@@ -219,13 +230,6 @@ extern void elv_rb_del(struct rb_root *, struct request *);
extern struct request *elv_rb_find(struct rb_root *, sector_t);
/*
- * Return values from elevator merger
- */
-#define ELEVATOR_NO_MERGE 0
-#define ELEVATOR_FRONT_MERGE 1
-#define ELEVATOR_BACK_MERGE 2
-
-/*
* Insertion selection
*/
#define ELEVATOR_INSERT_FRONT 1
--
2.11.0
