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

Bart Van Assche
2017-05-24T00:34:06Z

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 <bart.vanassche@sandisk.com>
Cc: Jens Axboe <axboe@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: linux-block@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