[PATCH] cleanup bio_map_user and helper

Bart did this patch, I changed it a bit. Basically it cleans the mapping
interface up a bit, and adds a little helper to set up the request from
the bio.

In addition, it fixes a long standing bug where bio_map_user() would
call blk_queue_bounce() without the direction bit being set, auch.

 - Abstract out bio request preparation
 - Have bio_map_user() set data direction (fixes bug where blk_queue_bounce()
   is called without it set)
 - Split bio_map_user() in two

2 files changed, 22 insertions, 32 deletions

diff --git a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
index 832189677065..ec0b1e827ae0 100644
--- a/drivers/block/ll_rw_blk.c
+++ b/drivers/block/ll_rw_blk.c
@@ -2196,6 +2196,21 @@ void end_request(struct request *req, int uptodate)
 	}
 }
 
+void blk_rq_bio_prep(request_queue_t *q, struct request *rq, struct bio *bio)
+{
+	/* first three bits are identical in rq->flags and bio->bi_rw */
+	rq->flags |= (bio->bi_rw & 7);
+
+	rq->nr_phys_segments = bio_phys_segments(q, bio);
+	rq->nr_hw_segments = bio_hw_segments(q, bio);
+	rq->current_nr_sectors = bio_cur_sectors(bio);
+	rq->hard_cur_sectors = rq->current_nr_sectors;
+	rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio);
+	rq->buffer = bio_data(bio);
+
+	rq->bio = rq->biotail = bio;
+}
+
 int __init blk_dev_init(void)
 {
 	int total_ram = nr_free_pages() << (PAGE_SHIFT - 10);
@@ -2285,3 +2300,5 @@ EXPORT_SYMBOL(blk_stop_queue);
 EXPORT_SYMBOL(__blk_stop_queue);
 EXPORT_SYMBOL(blk_run_queue);
 EXPORT_SYMBOL(blk_run_queues);
+
+EXPORT_SYMBOL(blk_rq_bio_prep);
diff --git a/drivers/block/scsi_ioctl.c b/drivers/block/scsi_ioctl.c
index 4adc5f7004a9..0e4fd3232c4c 100644
--- a/drivers/block/scsi_ioctl.c
+++ b/drivers/block/scsi_ioctl.c
@@ -193,18 +193,6 @@ static int sg_io(request_queue_t *q, struct block_device *bdev,
 		 * be a write to vm.
 		 */
 		bio = bio_map_user(bdev, uaddr, hdr.dxfer_len, reading);
-		if (bio) {
-			if (writing)
-				bio->bi_rw |= (1 << BIO_RW);
-
-			nr_sectors = (bio->bi_size + 511) >> 9;
-
-			if (bio->bi_size < hdr.dxfer_len) {
-				bio_endio(bio, bio->bi_size, 0);
-				bio_unmap_user(bio, 0);
-				bio = NULL;
-			}
-		}
 
 		/*
 		 * if bio setup failed, fall back to slow approach
@@ -243,21 +231,10 @@ static int sg_io(request_queue_t *q, struct block_device *bdev,
 	rq->hard_nr_sectors = rq->nr_sectors = nr_sectors;
 	rq->hard_cur_sectors = rq->current_nr_sectors = nr_sectors;
 
-	if (bio) {
-		/*
-		 * subtle -- if bio_map_user() ended up bouncing a bio, it
-		 * would normally disappear when its bi_end_io is run.
-		 * however, we need it for the unmap, so grab an extra
-		 * reference to it
-		 */
-		bio_get(bio);
+	rq->bio = rq->biotail = bio;
 
-		rq->nr_phys_segments = bio_phys_segments(q, bio);
-		rq->nr_hw_segments = bio_hw_segments(q, bio);
-		rq->current_nr_sectors = bio_cur_sectors(bio);
-		rq->hard_cur_sectors = rq->current_nr_sectors;
-		rq->buffer = bio_data(bio);
-	}
+	if (bio)
+		blk_rq_bio_prep(q, rq, bio);
 
 	rq->data_len = hdr.dxfer_len;
 	rq->data = buffer;
@@ -268,8 +245,6 @@ static int sg_io(request_queue_t *q, struct block_device *bdev,
 	if (!rq->timeout)
 		rq->timeout = BLK_DEFAULT_TIMEOUT;
 
-	rq->bio = rq->biotail = bio;
-
 	start_time = jiffies;
 
 	/* ignore return value. All information is passed back to caller
@@ -277,11 +252,9 @@ static int sg_io(request_queue_t *q, struct block_device *bdev,
 	 * N.B. a non-zero SCSI status is _not_ necessarily an error.
 	 */
 	blk_do_rq(q, bdev, rq);
-	
-	if (bio) {
+
+	if (bio)
 		bio_unmap_user(bio, reading);
-		bio_put(bio);
-	}
 
 	/* write to all output members */
 	hdr.status = rq->errors;