[PATCH] update blk_execute_rq to take an at_head parameter

Original From: Mike Christie <michaelc@cs.wisc.edu>

Modified to split out block changes (this patch) and SCSI pieces.
Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/block/ll_rw_blk.c

@@ -2269,13 +2269,14 @@ void blk_execute_rq_nowait(request_queue_t *q, struct gendisk *bd_disk,
  * @q:		queue to insert the request in
  * @bd_disk:	matching gendisk
  * @rq:		request to insert
+ * @at_head:    insert request at head or tail of queue
  *
  * Description:
  *    Insert a fully prepared request at the back of the io scheduler queue
  *    for execution.
  */
 int blk_execute_rq(request_queue_t *q, struct gendisk *bd_disk,
-		   struct request *rq)
+		   struct request *rq, int at_head)
 {
 	DECLARE_COMPLETION(wait);
 	char sense[SCSI_SENSE_BUFFERSIZE];
@@ -2294,7 +2295,7 @@ int blk_execute_rq(request_queue_t *q, struct gendisk *bd_disk,
 	}
 
 	rq->waiting = &wait;
-	blk_execute_rq_nowait(q, bd_disk, rq, 0, blk_end_sync_rq);
+	blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
 	wait_for_completion(&wait);
 	rq->waiting = NULL;
 
@@ -2361,7 +2362,7 @@ int blkdev_scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk,
 	rq->data_len = 0;
 	rq->timeout = 60 * HZ;
 
-	ret = blk_execute_rq(q, disk, rq);
+	ret = blk_execute_rq(q, disk, rq, 0);
 
 	if (ret && error_sector)
 		*error_sector = rq->sector;

drivers/block/scsi_ioctl.c

@@ -308,7 +308,7 @@ static int sg_io(struct file *file, request_queue_t *q,
 	 * (if he doesn't check that is his problem).
 	 * N.B. a non-zero SCSI status is _not_ necessarily an error.
 	 */
-	blk_execute_rq(q, bd_disk, rq);
+	blk_execute_rq(q, bd_disk, rq, 0);
 
 	/* write to all output members */
 	hdr->status = 0xff & rq->errors;
@@ -420,7 +420,7 @@ static int sg_scsi_ioctl(struct file *file, request_queue_t *q,
 	rq->data_len = bytes;
 	rq->flags |= REQ_BLOCK_PC;
 
-	blk_execute_rq(q, bd_disk, rq);
+	blk_execute_rq(q, bd_disk, rq, 0);
 	err = rq->errors & 0xff;	/* only 8 bit SCSI status */
 	if (err) {
 		if (rq->sense_len && rq->sense) {
@@ -573,7 +573,7 @@ int scsi_cmd_ioctl(struct file *file, struct gendisk *bd_disk, unsigned int cmd,
 			rq->cmd[0] = GPCMD_START_STOP_UNIT;
 			rq->cmd[4] = 0x02 + (close != 0);
 			rq->cmd_len = 6;
-			err = blk_execute_rq(q, bd_disk, rq);
+			err = blk_execute_rq(q, bd_disk, rq, 0);
 			blk_put_request(rq);
 			break;
 		default:

drivers/cdrom/cdrom.c

@@ -2136,7 +2136,7 @@ static int cdrom_read_cdda_bpc(struct cdrom_device_info *cdi, __u8 __user *ubuf,
 		if (rq->bio)
 			blk_queue_bounce(q, &rq->bio);
 
-		if (blk_execute_rq(q, cdi->disk, rq)) {
+		if (blk_execute_rq(q, cdi->disk, rq, 0)) {
 			struct request_sense *s = rq->sense;
 			ret = -EIO;
 			cdi->last_sense = s->sense_key;

drivers/ide/ide-disk.c

@@ -750,7 +750,7 @@ static int idedisk_issue_flush(request_queue_t *q, struct gendisk *disk,
 
 	idedisk_prepare_flush(q, rq);
 
-	ret = blk_execute_rq(q, disk, rq);
+	ret = blk_execute_rq(q, disk, rq, 0);
 
 	/*
 	 * if we failed and caller wants error offset, get it

include/linux/blkdev.h

@@ -562,8 +562,8 @@ extern int blk_rq_map_user(request_queue_t *, struct request *, void __user *, u
 extern int blk_rq_unmap_user(struct bio *, unsigned int);
 extern int blk_rq_map_kern(request_queue_t *, struct request *, void *, unsigned int, unsigned int);
 extern int blk_rq_map_user_iov(request_queue_t *, struct request *, struct sg_iovec *, int);
-extern int blk_execute_rq(request_queue_t *, struct gendisk *, struct request *);
-
+extern int blk_execute_rq(request_queue_t *, struct gendisk *,
+			  struct request *, int);
 static inline request_queue_t *bdev_get_queue(struct block_device *bdev)
 {
 	return bdev->bd_disk->queue;