[PATCH v2 0/5] Reduce code duplication

[PATCH v2 0/5] Reduce code duplication

[Bart Van Assche]

Hello Jens,

This series contains three patches intended to reduce code duplication
and two patches that simplify / optimize I/O priority handling. Please
consider these patches for kernel v4.12.

Thanks,

Bart.

Changes compared to v1:
- Converted ternary operators into an if/then/else-sequence.
- Used EXPORT_SYMBOL_GPL() to export block layer internals.

Bart Van Assche (5):
  block: Export blk_init_request_from_bio()
  null_blk: Use blk_init_request_from_bio() instead of open-coding it
  lightnvm: Use blk_init_request_from_bio() instead of open-coding it
  block: Inline blk_rq_set_prio()
  block: Optimize ioprio_best()

 block/blk-core.c             | 12 +++++++++---
 block/blk-mq.c               |  2 +-
 block/blk.h                  |  1 -
 block/ioprio.c               | 12 +-----------
 drivers/block/null_blk.c     |  9 +--------
 drivers/nvme/host/lightnvm.c |  6 +-----
 include/linux/blkdev.h       | 15 +--------------
 7 files changed, 14 insertions(+), 43 deletions(-)

-- 
2.12.2

[PATCH v2 1/5] block: Export blk_init_request_from_bio()

[Bart Van Assche]

Export this function such that it becomes available to block
drivers.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Matias Bjørling <m@bjorling.me>
Cc: Adam Manzanares <adam.manzanares@wdc.com>
---
 block/blk-core.c       | 5 +++--
 block/blk-mq.c         | 2 +-
 block/blk.h            | 1 -
 include/linux/blkdev.h | 1 +
 4 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 8654aa0cef6d..ec2330113bea 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1628,7 +1628,7 @@ unsigned int blk_plug_queued_count(struct request_queue *q)
 	return ret;
 }
 
-void init_request_from_bio(struct request *req, struct bio *bio)
+void blk_init_request_from_bio(struct request *req, struct bio *bio)
 {
 	if (bio->bi_opf & REQ_RAHEAD)
 		req->cmd_flags |= REQ_FAILFAST_MASK;
@@ -1640,6 +1640,7 @@ void init_request_from_bio(struct request *req, struct bio *bio)
 		req->ioprio = bio_prio(bio);
 	blk_rq_bio_prep(req->q, req, bio);
 }
+EXPORT_SYMBOL_GPL(blk_init_request_from_bio);
 
 static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio)
 {
@@ -1730,7 +1731,7 @@ static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio)
 	 * We don't worry about that case for efficiency. It won't happen
 	 * often, and the elevators are able to handle it.
 	 */
-	init_request_from_bio(req, bio);
+	blk_init_request_from_bio(req, bio);
 
 	if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags))
 		req->cpu = raw_smp_processor_id();
diff --git a/block/blk-mq.c b/block/blk-mq.c
index e2ef7b460924..c496692ecc5b 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1424,7 +1424,7 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
 
 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
 {
-	init_request_from_bio(rq, bio);
+	blk_init_request_from_bio(rq, bio);
 
 	blk_account_io_start(rq, true);
 }
diff --git a/block/blk.h b/block/blk.h
index 07d375183f31..cc8e61cdc229 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -60,7 +60,6 @@ void blk_free_flush_queue(struct blk_flush_queue *q);
 int blk_init_rl(struct request_list *rl, struct request_queue *q,
 		gfp_t gfp_mask);
 void blk_exit_rl(struct request_list *rl);
-void init_request_from_bio(struct request *req, struct bio *bio);
 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
 			struct bio *bio);
 void blk_queue_bypass_start(struct request_queue *q);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index fe9c512cc6fa..be3abaee935e 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -924,6 +924,7 @@ extern int blk_register_queue(struct gendisk *disk);
 extern void blk_unregister_queue(struct gendisk *disk);
 extern blk_qc_t generic_make_request(struct bio *bio);
 extern void blk_rq_init(struct request_queue *q, struct request *rq);
+extern void blk_init_request_from_bio(struct request *req, struct bio *bio);
 extern void blk_put_request(struct request *);
 extern void __blk_put_request(struct request_queue *, struct request *);
 extern struct request *blk_get_request(struct request_queue *, int, gfp_t);
-- 
2.12.2

[PATCH v2 2/5] null_blk: Use blk_init_request_from_bio() instead of open-coding it

[Bart Van Assche]

This patch changes the behavior of the null_blk driver for the
LightNVM mode as follows:
* REQ_FAILFAST_MASK is set for read-ahead requests.
* If no I/O priority has been set in the bio, the I/O priority is
  copied from the I/O context.
* The rq_disk member is initialized if bio->bi_bdev != NULL.
* req->errors is initialized to zero.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Matias Bjørling <m@bjorling.me>
Cc: Adam Manzanares <adam.manzanares@wdc.com>
---
 drivers/block/null_blk.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index f93906ff31e8..e79e3d24e229 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -443,14 +443,7 @@ static int null_lnvm_submit_io(struct nvm_dev *dev, struct nvm_rq *rqd)
 	if (IS_ERR(rq))
 		return -ENOMEM;
 
-	rq->__sector = bio->bi_iter.bi_sector;
-	rq->ioprio = bio_prio(bio);
-
-	if (bio_has_data(bio))
-		rq->nr_phys_segments = bio_phys_segments(q, bio);
-
-	rq->__data_len = bio->bi_iter.bi_size;
-	rq->bio = rq->biotail = bio;
+	blk_init_request_from_bio(rq, bio);
 
 	rq->end_io_data = rqd;
 
-- 
2.12.2

[PATCH v2 3/5] lightnvm: Use blk_init_request_from_bio() instead of open-coding it

[Bart Van Assche]

This patch changes the behavior of the lightnvm driver as follows:
* REQ_FAILFAST_MASK is set for read-ahead requests.
* If no I/O priority has been set in the bio, the I/O priority is
  copied from the I/O context.
* The rq_disk member is initialized if bio->bi_bdev != NULL.
* The bio sector offset is copied into req->__sector instead of
  retaining the value -1 set by blk_mq_alloc_request().
* req->errors is initialized to zero.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Matias Bjørling <m@bjorling.me>
Cc: Adam Manzanares <adam.manzanares@wdc.com>
---
 drivers/nvme/host/lightnvm.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/nvme/host/lightnvm.c b/drivers/nvme/host/lightnvm.c
index 4b78090518e1..b76e2e36fef4 100644
--- a/drivers/nvme/host/lightnvm.c
+++ b/drivers/nvme/host/lightnvm.c
@@ -511,11 +511,7 @@ static int nvme_nvm_submit_io(struct nvm_dev *dev, struct nvm_rq *rqd)
 	rq->cmd_flags &= ~REQ_FAILFAST_DRIVER;
 
 	if (bio) {
-		rq->ioprio = bio_prio(bio);
-		rq->__data_len = bio->bi_iter.bi_size;
-		rq->bio = rq->biotail = bio;
-		if (bio_has_data(bio))
-			rq->nr_phys_segments = bio_phys_segments(q, bio);
+		blk_init_request_from_bio(rq, bio);
 	} else {
 		rq->ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
 		rq->__data_len = 0;
-- 
2.12.2

[PATCH v2 4/5] block: Inline blk_rq_set_prio()

[Bart Van Assche]

Since only a single caller remains, inline blk_rq_set_prio(). Initialize
req->ioprio even if no I/O priority has been set in the bio nor in the
I/O context.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Adam Manzanares <adam.manzanares@wdc.com>
Tested-by: Adam Manzanares <adam.manzanares@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Matias Bjørling <m@bjorling.me>
---
 block/blk-core.c       |  7 ++++++-
 include/linux/blkdev.h | 14 --------------
 2 files changed, 6 insertions(+), 15 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index ec2330113bea..4f0fd8f3328d 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1630,14 +1630,19 @@ unsigned int blk_plug_queued_count(struct request_queue *q)
 
 void blk_init_request_from_bio(struct request *req, struct bio *bio)
 {
+	struct io_context *ioc = rq_ioc(bio);
+
 	if (bio->bi_opf & REQ_RAHEAD)
 		req->cmd_flags |= REQ_FAILFAST_MASK;
 
 	req->errors = 0;
 	req->__sector = bio->bi_iter.bi_sector;
-	blk_rq_set_prio(req, rq_ioc(bio));
 	if (ioprio_valid(bio_prio(bio)))
 		req->ioprio = bio_prio(bio);
+	else if (ioc)
+		req->ioprio = ioc->ioprio;
+	else
+		req->ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
 	blk_rq_bio_prep(req->q, req, bio);
 }
 EXPORT_SYMBOL_GPL(blk_init_request_from_bio);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index be3abaee935e..92894995f4b7 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1088,20 +1088,6 @@ static inline unsigned int blk_rq_count_bios(struct request *rq)
 }
 
 /*
- * blk_rq_set_prio - associate a request with prio from ioc
- * @rq: request of interest
- * @ioc: target iocontext
- *
- * Assocate request prio with ioc prio so request based drivers
- * can leverage priority information.
- */
-static inline void blk_rq_set_prio(struct request *rq, struct io_context *ioc)
-{
-	if (ioc)
-		rq->ioprio = ioc->ioprio;
-}
-
-/*
  * Request issue related functions.
  */
 extern struct request *blk_peek_request(struct request_queue *q);
-- 
2.12.2

[PATCH v2 5/5] block: Optimize ioprio_best()

[Bart Van Assche]

Since ioprio_best() translates IOPRIO_CLASS_NONE into IOPRIO_CLASS_BE
and since lower numerical priority values represent a higher priority
a simple numerical comparison is sufficient.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Adam Manzanares <adam.manzanares@wdc.com>
Tested-by: Adam Manzanares <adam.manzanares@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Matias Bjørling <m@bjorling.me>
---
 block/ioprio.c | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/block/ioprio.c b/block/ioprio.c
index 0c47a00f92a8..4b120c9cf7e8 100644
--- a/block/ioprio.c
+++ b/block/ioprio.c
@@ -163,22 +163,12 @@ static int get_task_ioprio(struct task_struct *p)
 
 int ioprio_best(unsigned short aprio, unsigned short bprio)
 {
-	unsigned short aclass;
-	unsigned short bclass;
-
 	if (!ioprio_valid(aprio))
 		aprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
 	if (!ioprio_valid(bprio))
 		bprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
 
-	aclass = IOPRIO_PRIO_CLASS(aprio);
-	bclass = IOPRIO_PRIO_CLASS(bprio);
-	if (aclass == bclass)
-		return min(aprio, bprio);
-	if (aclass > bclass)
-		return bprio;
-	else
-		return aprio;
+	return min(aprio, bprio);
 }
 
 SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
-- 
2.12.2

Re: [PATCH v2 0/5] Reduce code duplication

[Jens Axboe]

On 04/19/2017 03:01 PM, Bart Van Assche wrote:
> Hello Jens,
> 
> This series contains three patches intended to reduce code duplication
> and two patches that simplify / optimize I/O priority handling. Please
> consider these patches for kernel v4.12.

Applied, thanks Bart.

-- 
Jens Axboe

Re: [PATCH v2 1/5] block: Export blk_init_request_from_bio()

[Johannes Thumshirn]

On Wed, Apr 19, 2017 at 02:01:24PM -0700, Bart Van Assche wrote:
> Export this function such that it becomes available to block
> drivers.
> 
> Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Cc: Matias Bj�rling <m@bjorling.me>
> Cc: Adam Manzanares <adam.manzanares@wdc.com>
> ---

Looks good,
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>

-- 
Johannes Thumshirn                                          Storage
jthumshirn@suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: Felix Imend�rffer, Jane Smithard, Graham Norton
HRB 21284 (AG N�rnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

Re: [PATCH v2 2/5] null_blk: Use blk_init_request_from_bio() instead of open-coding it

[Johannes Thumshirn]

On Wed, Apr 19, 2017 at 02:01:25PM -0700, Bart Van Assche wrote:
> This patch changes the behavior of the null_blk driver for the
> LightNVM mode as follows:
> * REQ_FAILFAST_MASK is set for read-ahead requests.
> * If no I/O priority has been set in the bio, the I/O priority is
>   copied from the I/O context.
> * The rq_disk member is initialized if bio->bi_bdev != NULL.
> * req->errors is initialized to zero.
> 
> Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Cc: Matias Bj�rling <m@bjorling.me>
> Cc: Adam Manzanares <adam.manzanares@wdc.com>
> ---

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
-- 
Johannes Thumshirn                                          Storage
jthumshirn@suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: Felix Imend�rffer, Jane Smithard, Graham Norton
HRB 21284 (AG N�rnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

Re: [PATCH v2 3/5] lightnvm: Use blk_init_request_from_bio() instead of open-coding it

[Johannes Thumshirn]

On Wed, Apr 19, 2017 at 02:01:26PM -0700, Bart Van Assche wrote:
> This patch changes the behavior of the lightnvm driver as follows:
> * REQ_FAILFAST_MASK is set for read-ahead requests.
> * If no I/O priority has been set in the bio, the I/O priority is
>   copied from the I/O context.
> * The rq_disk member is initialized if bio->bi_bdev != NULL.
> * The bio sector offset is copied into req->__sector instead of
>   retaining the value -1 set by blk_mq_alloc_request().
> * req->errors is initialized to zero.
> 
> Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Cc: Matias Bj�rling <m@bjorling.me>
> Cc: Adam Manzanares <adam.manzanares@wdc.com>
> ---

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
-- 
Johannes Thumshirn                                          Storage
jthumshirn@suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: Felix Imend�rffer, Jane Smithard, Graham Norton
HRB 21284 (AG N�rnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

Re: [PATCH v2 4/5] block: Inline blk_rq_set_prio()

[Johannes Thumshirn]

On Wed, Apr 19, 2017 at 02:01:27PM -0700, Bart Van Assche wrote:
> Since only a single caller remains, inline blk_rq_set_prio(). Initialize
> req->ioprio even if no I/O priority has been set in the bio nor in the
> I/O context.
> 
> Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
> Reviewed-by: Adam Manzanares <adam.manzanares@wdc.com>
> Tested-by: Adam Manzanares <adam.manzanares@wdc.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Cc: Matias Bj�rling <m@bjorling.me>
> ---

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
-- 
Johannes Thumshirn                                          Storage
jthumshirn@suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: Felix Imend�rffer, Jane Smithard, Graham Norton
HRB 21284 (AG N�rnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850