Re: [PATCH 17/31] block: Introduce request_queue.initialize_rq_fn()

[Hannes Reinecke]

On 05/24/2017 02:34 AM, Bart Van Assche wrote:
> Several block drivers need to initialize the driver-private data
> after having called blk_get_request() and before .prep_rq_fn() is
> called, e.g. when submitting a REQ_OP_SCSI_* request. Avoid that
> that initialization code has to be repeated after every
> blk_get_request() call by adding a new callback function to struct
> request_queue.
> 
> Signed-off-by: Bart Van Assche 
> Cc: Jens Axboe 
> Cc: Christoph Hellwig 
> Cc: Omar Sandoval 
> Cc: Hannes Reinecke 
> Cc: linux-bl...@vger.kernel.org
> ---
>  block/blk-core.c   | 3 +++
>  block/blk-mq.c | 3 +++
>  include/linux/blkdev.h | 4 
>  3 files changed, 10 insertions(+)
> 
Reviewed-by: Hannes Reinecke 

Cheers,

Hannes
-- 
Dr. Hannes ReineckeTeamlead Storage & Networking
h...@suse.de   +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)

[PATCH 17/31] block: Introduce request_queue.initialize_rq_fn()

[Bart Van Assche]

Several block drivers need to initialize the driver-private data
after having called blk_get_request() and before .prep_rq_fn() is
called, e.g. when submitting a REQ_OP_SCSI_* request. Avoid that
that initialization code has to be repeated after every
blk_get_request() call by adding a new callback function to struct
request_queue.

Signed-off-by: Bart Van Assche 
Cc: Jens Axboe 
Cc: Christoph Hellwig 
Cc: Omar Sandoval 
Cc: Hannes Reinecke 
Cc: linux-bl...@vger.kernel.org
---
 block/blk-core.c   | 3 +++
 block/blk-mq.c | 3 +++
 include/linux/blkdev.h | 4 
 3 files changed, 10 insertions(+)

diff --git a/block/blk-core.c b/block/blk-core.c
index 55a7b76db7c2..8a680f7bb168 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -126,6 +126,9 @@ void blk_rq_init(struct request_queue *q, struct request 
*rq)
rq->start_time = jiffies;
set_start_time_ns(rq);
rq->part = NULL;
+
+   if (q->initialize_rq_fn)
+   q->initialize_rq_fn(rq);
 }
 EXPORT_SYMBOL(blk_rq_init);
 
diff --git a/block/blk-mq.c b/block/blk-mq.c
index a69ad122ed66..2af43d4e5b96 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -241,6 +241,9 @@ void blk_mq_rq_ctx_init(struct request_queue *q, struct 
blk_mq_ctx *ctx,
rq->end_io_data = NULL;
rq->next_rq = NULL;
 
+   if (q->initialize_rq_fn)
+   q->initialize_rq_fn(rq);
+
ctx->rq_dispatched[op_is_sync(op)]++;
 }
 EXPORT_SYMBOL_GPL(blk_mq_rq_ctx_init);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 6416a5834b05..e3c03d429371 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -410,8 +410,12 @@ struct request_queue {
rq_timed_out_fn *rq_timed_out_fn;
dma_drain_needed_fn *dma_drain_needed;
lld_busy_fn *lld_busy_fn;
+   /* Called just after a request is allocated */
init_rq_fn  *init_rq_fn;
+   /* Called just before a request is freed */
exit_rq_fn  *exit_rq_fn;
+   /* Called from inside blk_get_request() */
+   void (*initialize_rq_fn)(struct request *rq);
 
const struct blk_mq_ops *mq_ops;
 
-- 
2.12.2