block: export __make_request

Avoid the hacks need for request based device mappers currently by simply
exporting the symbol instead of trying to get it through the back door.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

block/blk-core.c

@@ -38,8 +38,6 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
 
-static int __make_request(struct request_queue *q, struct bio *bio);
-
 /*
  * For the allocated request tables
  */
@@ -1213,7 +1211,7 @@ void init_request_from_bio(struct request *req, struct bio *bio)
 	blk_rq_bio_prep(req->q, req, bio);
 }
 
-static int __make_request(struct request_queue *q, struct bio *bio)
+int __make_request(struct request_queue *q, struct bio *bio)
 {
 	const bool sync = !!(bio->bi_rw & REQ_SYNC);
 	struct blk_plug *plug;
@@ -1317,6 +1315,7 @@ static int __make_request(struct request_queue *q, struct bio *bio)
 out:
 	return 0;
 }
+EXPORT_SYMBOL_GPL(__make_request);	/* for device mapper only */
 
 /*
  * If bio->bi_dev is a partition, remap the location

drivers/md/dm.c

@@ -180,9 +180,6 @@ struct mapped_device {
 	/* forced geometry settings */
 	struct hd_geometry geometry;
 
-	/* For saving the address of __make_request for request based dm */
-	make_request_fn *saved_make_request_fn;
-
 	/* sysfs handle */
 	struct kobject kobj;
 
@@ -1420,13 +1417,6 @@ static int _dm_request(struct request_queue *q, struct bio *bio)
 	return 0;
 }
 
-static int dm_make_request(struct request_queue *q, struct bio *bio)
-{
-	struct mapped_device *md = q->queuedata;
-
-	return md->saved_make_request_fn(q, bio); /* call __make_request() */
-}
-
 static int dm_request_based(struct mapped_device *md)
 {
 	return blk_queue_stackable(md->queue);
@@ -1437,7 +1427,7 @@ static int dm_request(struct request_queue *q, struct bio *bio)
 	struct mapped_device *md = q->queuedata;
 
 	if (dm_request_based(md))
-		return dm_make_request(q, bio);
+		return __make_request(q, bio);
 
 	return _dm_request(q, bio);
 }
@@ -2172,7 +2162,6 @@ static int dm_init_request_based_queue(struct mapped_device *md)
 		return 0;
 
 	md->queue = q;
-	md->saved_make_request_fn = md->queue->make_request_fn;
 	dm_init_md_queue(md);
 	blk_queue_softirq_done(md->queue, dm_softirq_done);
 	blk_queue_prep_rq(md->queue, dm_prep_fn);

include/linux/blkdev.h

@@ -675,6 +675,8 @@ extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t,
 extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t,
 			 struct scsi_ioctl_command __user *);
 
+extern int __make_request(struct request_queue *q, struct bio *bio);
+
 /*
  * A queue has just exitted congestion.  Note this in the global counter of
  * congested queues, and wake up anyone who was waiting for requests to be