[PATCH] blk: move threshold unplugging

The 'unplug on queued exceeding unplug threshold' logic only works for file
system requests currently, since it's in __make_request().  Move it where
it belongs, in elv_add_request().  This way it works for queued block sg
requests as well.
Signed-Off-By: Jens Axboe <axboe@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/block/elevator.c

@@ -181,6 +181,14 @@ void __elv_add_request(request_queue_t *q, struct request *rq, int where,
 
 	rq->q = q;
 	q->elevator.elevator_add_req_fn(q, rq, where);
+
+	if (blk_queue_plugged(q)) {
+		int nrq = q->rq.count[READ] + q->rq.count[WRITE] - q->in_flight;
+
+		if (nrq == q->unplug_thresh)
+			__generic_unplug_device(q);
+	}
+
 }
 
 void elv_add_request(request_queue_t *q, struct request *rq, int where,

drivers/block/ll_rw_blk.c

@@ -1123,7 +1123,7 @@ EXPORT_SYMBOL(blk_remove_plug);
 /*
  * remove the plug and let it rip..
  */
-static inline void __generic_unplug_device(request_queue_t *q)
+inline void __generic_unplug_device(request_queue_t *q)
 {
 	if (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags))
 		return;
@@ -1137,6 +1137,7 @@ static inline void __generic_unplug_device(request_queue_t *q)
 	if (elv_next_request(q))
 		q->request_fn(q);
 }
+EXPORT_SYMBOL(__generic_unplug_device);
 
 /**
  * generic_unplug_device - fire a request queue
@@ -2280,13 +2281,9 @@ static int __make_request(request_queue_t *q, struct bio *bio)
 out:
 	if (freereq)
 		__blk_put_request(q, freereq);
+	if (bio_sync(bio))
+		__generic_unplug_device(q);
 
-	if (blk_queue_plugged(q)) {
-		int nrq = q->rq.count[READ] + q->rq.count[WRITE] - q->in_flight;
-
-		if (nrq == q->unplug_thresh || bio_sync(bio))
-			__generic_unplug_device(q);
-	}
 	spin_unlock_irq(q->queue_lock);
 	return 0;
 

include/linux/blkdev.h

@@ -592,6 +592,7 @@ extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bd
 extern int blk_rq_map_sg(request_queue_t *, struct request *, struct scatterlist *);
 extern void blk_dump_rq_flags(struct request *, char *);
 extern void generic_unplug_device(request_queue_t *);
+extern inline void __generic_unplug_device(request_queue_t *);
 extern long nr_blockdev_pages(void);
 
 int blk_get_queue(request_queue_t *);