block: implement and use [__]blk_end_request_all()

There are many [__]blk_end_request() call sites which call it with
full request length and expect full completion.  Many of them ensure
that the request actually completes by doing BUG_ON() the return
value, which is awkward and error-prone.

This patch adds [__]blk_end_request_all() which takes @rq and @error
and fully completes the request.  BUG_ON() is added to to ensure that
this actually happens.

Most conversions are simple but there are a few noteworthy ones.

* cdrom/viocd: viocd_end_request() replaced with direct calls to
  __blk_end_request_all().

* s390/block/dasd: dasd_end_request() replaced with direct calls to
  __blk_end_request_all().

* s390/char/tape_block: tapeblock_end_request() replaced with direct
  calls to blk_end_request_all().

[ Impact: cleanup ]

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Mike Miller <mike.miller@hp.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Jeff Garzik <jgarzik@pobox.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Alex Dubov <oakad@yahoo.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>

2 files changed, 8 insertions, 24 deletions

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index d181527..fabec95 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -1614,15 +1614,6 @@ void dasd_block_clear_timer(struct dasd_block *block)
 }
 
 /*
- * posts the buffer_cache about a finalized request
- */
-static inline void dasd_end_request(struct request *req, int error)
-{
-	if (__blk_end_request(req, error, blk_rq_bytes(req)))
-		BUG();
-}
-
-/*
  * Process finished error recovery ccw.
  */
 static inline void __dasd_block_process_erp(struct dasd_block *block,
@@ -1676,7 +1667,7 @@ static void __dasd_process_request_queue(struct dasd_block *block)
 				      "Rejecting write request %p",
 				      req);
 			blkdev_dequeue_request(req);
-			dasd_end_request(req, -EIO);
+			__blk_end_request_all(req, -EIO);
 			continue;
 		}
 		cqr = basedev->discipline->build_cp(basedev, block, req);
@@ -1705,7 +1696,7 @@ static void __dasd_process_request_queue(struct dasd_block *block)
 				      "on request %p",
 				      PTR_ERR(cqr), req);
 			blkdev_dequeue_request(req);
-			dasd_end_request(req, -EIO);
+			__blk_end_request_all(req, -EIO);
 			continue;
 		}
 		/*
@@ -1731,7 +1722,7 @@ static void __dasd_cleanup_cqr(struct dasd_ccw_req *cqr)
 	status = cqr->block->base->discipline->free_cp(cqr, req);
 	if (status <= 0)
 		error = status ? status : -EIO;
-	dasd_end_request(req, error);
+	__blk_end_request_all(req, error);
 }
 
 /*
@@ -2040,7 +2031,7 @@ static void dasd_flush_request_queue(struct dasd_block *block)
 	spin_lock_irq(&block->request_queue_lock);
 	while ((req = elv_next_request(block->request_queue))) {
 		blkdev_dequeue_request(req);
-		dasd_end_request(req, -EIO);
+		__blk_end_request_all(req, -EIO);
 	}
 	spin_unlock_irq(&block->request_queue_lock);
 }
diff --git a/drivers/s390/char/tape_block.c b/drivers/s390/char/tape_block.c
index f32e89e..86596d3 100644
--- a/drivers/s390/char/tape_block.c
+++ b/drivers/s390/char/tape_block.c
@@ -74,13 +74,6 @@ tapeblock_trigger_requeue(struct tape_device *device)
  * Post finished request.
  */
 static void
-tapeblock_end_request(struct request *req, int error)
-{
-	if (blk_end_request(req, error, blk_rq_bytes(req)))
-		BUG();
-}
-
-static void
 __tapeblock_end_request(struct tape_request *ccw_req, void *data)
 {
 	struct tape_device *device;
@@ -90,7 +83,7 @@ __tapeblock_end_request(struct tape_request *ccw_req, void *data)
 
 	device = ccw_req->device;
 	req = (struct request *) data;
-	tapeblock_end_request(req, (ccw_req->rc == 0) ? 0 : -EIO);
+	blk_end_request_all(req, (ccw_req->rc == 0) ? 0 : -EIO);
 	if (ccw_req->rc == 0)
 		/* Update position. */
 		device->blk_data.block_position =
@@ -118,7 +111,7 @@ tapeblock_start_request(struct tape_device *device, struct request *req)
 	ccw_req = device->discipline->bread(device, req);
 	if (IS_ERR(ccw_req)) {
 		DBF_EVENT(1, "TBLOCK: bread failed\n");
-		tapeblock_end_request(req, -EIO);
+		blk_end_request_all(req, -EIO);
 		return PTR_ERR(ccw_req);
 	}
 	ccw_req->callback = __tapeblock_end_request;
@@ -131,7 +124,7 @@ tapeblock_start_request(struct tape_device *device, struct request *req)
 		 * Start/enqueueing failed. No retries in
 		 * this case.
 		 */
-		tapeblock_end_request(req, -EIO);
+		blk_end_request_all(req, -EIO);
 		device->discipline->free_bread(ccw_req);
 	}
 
@@ -177,7 +170,7 @@ tapeblock_requeue(struct work_struct *work) {
 			DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
 			blkdev_dequeue_request(req);
 			spin_unlock_irq(&device->blk_data.request_queue_lock);
-			tapeblock_end_request(req, -EIO);
+			blk_end_request_all(req, -EIO);
 			spin_lock_irq(&device->blk_data.request_queue_lock);
 			continue;
 		}