Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

Pull virtio fix from Michael Tsirkin:
 "A last minute revert to fix a regression"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  Revert "virtio-blk: support completion batching for the IRQ path"

Author: torvalds

drivers/block/virtio_blk.c

@@ -348,63 +348,33 @@ static inline void virtblk_request_done(struct request *req)
 	blk_mq_end_request(req, status);
 }
 
-static void virtblk_complete_batch(struct io_comp_batch *iob)
-{
-	struct request *req;
-
-	rq_list_for_each(&iob->req_list, req) {
-		virtblk_unmap_data(req, blk_mq_rq_to_pdu(req));
-		virtblk_cleanup_cmd(req);
-	}
-	blk_mq_end_request_batch(iob);
-}
-
-static int virtblk_handle_req(struct virtio_blk_vq *vq,
-			      struct io_comp_batch *iob)
-{
-	struct virtblk_req *vbr;
-	int req_done = 0;
-	unsigned int len;
-
-	while ((vbr = virtqueue_get_buf(vq->vq, &len)) != NULL) {
-		struct request *req = blk_mq_rq_from_pdu(vbr);
-
-		if (likely(!blk_should_fake_timeout(req->q)) &&
-		    !blk_mq_complete_request_remote(req) &&
-		    !blk_mq_add_to_batch(req, iob, virtblk_vbr_status(vbr),
-					 virtblk_complete_batch))
-			virtblk_request_done(req);
-		req_done++;
-	}
-
-	return req_done;
-}
-
 static void virtblk_done(struct virtqueue *vq)
 {
 	struct virtio_blk *vblk = vq->vdev->priv;
-	struct virtio_blk_vq *vblk_vq = &vblk->vqs[vq->index];
-	int req_done = 0;
+	bool req_done = false;
+	int qid = vq->index;
+	struct virtblk_req *vbr;
 	unsigned long flags;
-	DEFINE_IO_COMP_BATCH(iob);
+	unsigned int len;
 
-	spin_lock_irqsave(&vblk_vq->lock, flags);
+	spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
 	do {
 		virtqueue_disable_cb(vq);
-		req_done += virtblk_handle_req(vblk_vq, &iob);
+		while ((vbr = virtqueue_get_buf(vblk->vqs[qid].vq, &len)) != NULL) {
+			struct request *req = blk_mq_rq_from_pdu(vbr);
 
+			if (likely(!blk_should_fake_timeout(req->q)))
+				blk_mq_complete_request(req);
+			req_done = true;
+		}
 		if (unlikely(virtqueue_is_broken(vq)))
 			break;
 	} while (!virtqueue_enable_cb(vq));
 
-	if (req_done) {
-		if (!rq_list_empty(iob.req_list))
-			iob.complete(&iob);
-
-		/* In case queue is stopped waiting for more buffers. */
+	/* In case queue is stopped waiting for more buffers. */
+	if (req_done)
 		blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
-	}
-	spin_unlock_irqrestore(&vblk_vq->lock, flags);
+	spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
 }
 
 static void virtio_commit_rqs(struct blk_mq_hw_ctx *hctx)
@@ -1283,15 +1253,37 @@ static void virtblk_map_queues(struct blk_mq_tag_set *set)
 	}
 }
 
+static void virtblk_complete_batch(struct io_comp_batch *iob)
+{
+	struct request *req;
+
+	rq_list_for_each(&iob->req_list, req) {
+		virtblk_unmap_data(req, blk_mq_rq_to_pdu(req));
+		virtblk_cleanup_cmd(req);
+	}
+	blk_mq_end_request_batch(iob);
+}
+
 static int virtblk_poll(struct blk_mq_hw_ctx *hctx, struct io_comp_batch *iob)
 {
 	struct virtio_blk *vblk = hctx->queue->queuedata;
 	struct virtio_blk_vq *vq = get_virtio_blk_vq(hctx);
+	struct virtblk_req *vbr;
 	unsigned long flags;
+	unsigned int len;
 	int found = 0;
 
 	spin_lock_irqsave(&vq->lock, flags);
-	found = virtblk_handle_req(vq, iob);
+
+	while ((vbr = virtqueue_get_buf(vq->vq, &len)) != NULL) {
+		struct request *req = blk_mq_rq_from_pdu(vbr);
+
+		found++;
+		if (!blk_mq_complete_request_remote(req) &&
+		    !blk_mq_add_to_batch(req, iob, virtblk_vbr_status(vbr),
+						virtblk_complete_batch))
+			virtblk_request_done(req);
+	}
 
 	if (found)
 		blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);