blk_end_request: changing ide-cd (take 4)

This patch converts ide-cd (cdrom_newpc_intr()) to use blk_end_request
interfaces.  Related 'uptodate' arguments are converted to 'error'.

In PIO mode, ide-cd (cdrom_newpc_intr()) needs to defer
end_that_request_last() until the device clears DRQ_STAT and raises
an interrupt after end_that_request_first().
So blk_end_request() has to return without completing request
even if no leftover in the request.

ide-cd uses blk_end_request_callback() and a dummy callback function,
which just returns value '1', to tell blk_end_request_callback()
about that.

Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

drivers/ide/ide-cd.c

@@ -1647,6 +1647,17 @@ static int cdrom_write_check_ireason(ide_drive_t *drive, int len, int ireason)
 	return 1;
 }
 
+/*
+ * Called from blk_end_request_callback() after the data of the request
+ * is completed and before the request is completed.
+ * By returning value '1', blk_end_request_callback() returns immediately
+ * without completing the request.
+ */
+static int cdrom_newpc_intr_dummy_cb(struct request *rq)
+{
+	return 1;
+}
+
 typedef void (xfer_func_t)(ide_drive_t *, void *, u32);
 
 /*
@@ -1685,9 +1696,13 @@ static ide_startstop_t cdrom_newpc_intr(ide_drive_t *drive)
 			return ide_error(drive, "dma error", stat);
 		}
 
-		end_that_request_chunk(rq, 1, rq->data_len);
-		rq->data_len = 0;
-		goto end_request;
+		spin_lock_irqsave(&ide_lock, flags);
+		if (__blk_end_request(rq, 0, rq->data_len))
+			BUG();
+		HWGROUP(drive)->rq = NULL;
+		spin_unlock_irqrestore(&ide_lock, flags);
+
+		return ide_stopped;
 	}
 
 	/*
@@ -1705,8 +1720,15 @@ static ide_startstop_t cdrom_newpc_intr(ide_drive_t *drive)
 	/*
 	 * If DRQ is clear, the command has completed.
 	 */
-	if ((stat & DRQ_STAT) == 0)
-		goto end_request;
+	if ((stat & DRQ_STAT) == 0) {
+		spin_lock_irqsave(&ide_lock, flags);
+		if (__blk_end_request(rq, 0, 0))
+			BUG();
+		HWGROUP(drive)->rq = NULL;
+		spin_unlock_irqrestore(&ide_lock, flags);
+
+		return ide_stopped;
+	}
 
 	/*
 	 * check which way to transfer data
@@ -1759,7 +1781,14 @@ static ide_startstop_t cdrom_newpc_intr(ide_drive_t *drive)
 		rq->data_len -= blen;
 
 		if (rq->bio)
-			end_that_request_chunk(rq, 1, blen);
+			/*
+			 * The request can't be completed until DRQ is cleared.
+			 * So complete the data, but don't complete the request
+			 * using the dummy function for the callback feature
+			 * of blk_end_request_callback().
+			 */
+			blk_end_request_callback(rq, 0, blen,
+						 cdrom_newpc_intr_dummy_cb);
 		else
 			rq->data += blen;
 	}
@@ -1780,14 +1809,6 @@ static ide_startstop_t cdrom_newpc_intr(ide_drive_t *drive)
 
 	ide_set_handler(drive, cdrom_newpc_intr, rq->timeout, NULL);
 	return ide_started;
-
-end_request:
-	spin_lock_irqsave(&ide_lock, flags);
-	blkdev_dequeue_request(rq);
-	end_that_request_last(rq, 1);
-	HWGROUP(drive)->rq = NULL;
-	spin_unlock_irqrestore(&ide_lock, flags);
-	return ide_stopped;
 }
 
 static ide_startstop_t cdrom_write_intr(ide_drive_t *drive)