block: add request submission interface
This patch adds blk_insert_cloned_request(), a generic request
submission interface for request stacking drivers.
Request-based dm will use it to submit their clones to underlying
devices.
blk_rq_check_limits() is also added because it is possible that
the lower queue has stronger limitations than the upper queue
if multiple drivers are stacking at request-level.
Not only for blk_insert_cloned_request()'s internal use, the function
will be used by request-based dm when the queue limitation is
modified (e.g. by replacing dm's table).
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index e82a84c..964c246 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -693,6 +693,9 @@
extern struct request *blk_get_request(struct request_queue *, int, gfp_t);
extern void blk_insert_request(struct request_queue *, struct request *, int, void *);
extern void blk_requeue_request(struct request_queue *, struct request *);
+extern int blk_rq_check_limits(struct request_queue *q, struct request *rq);
+extern int blk_insert_cloned_request(struct request_queue *q,
+ struct request *rq);
extern void blk_plug_device(struct request_queue *);
extern void blk_plug_device_unlocked(struct request_queue *);
extern int blk_remove_plug(struct request_queue *);