Re: [PATCH 2/4] block: enumify ELEVATOR_*_MERGE

[Sagi Grimberg]

Looks good,

Reviewed-by: Sagi Grimberg 

[PATCH 2/4] block: enumify ELEVATOR_*_MERGE

[Christoph Hellwig]

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 
---
 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 = >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, , 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, , 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);
+