virtiofs: Use a common function to send forget

Currently we are duplicating logic to send forgets at two
places. Consolidate the code by calling one helper function.

This also uses virtqueue_add_outbuf() instead of
virtqueue_add_sgs(). Former is simpler to call.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/fuse/virtio_fs.c

@@ -313,65 +313,85 @@ static void virtio_fs_request_dispatch_work(struct work_struct *work)
 	}
 }
 
-static void virtio_fs_hiprio_dispatch_work(struct work_struct *work)
+/*
+ * Returns 1 if queue is full and sender should wait a bit before sending
+ * next request, 0 otherwise.
+ */
+static int send_forget_request(struct virtio_fs_vq *fsvq,
+			       struct virtio_fs_forget *forget,
+			       bool in_flight)
 {
-	struct virtio_fs_forget *forget;
-	struct virtio_fs_vq *fsvq = container_of(work, struct virtio_fs_vq,
-						 dispatch_work.work);
-	struct virtqueue *vq = fsvq->vq;
 	struct scatterlist sg;
-	struct scatterlist *sgs[] = {&sg};
+	struct virtqueue *vq;
+	int ret = 0;
 	bool notify;
-	int ret;
 
-	pr_debug("virtio-fs: worker %s called.\n", __func__);
-	while (1) {
 	spin_lock(&fsvq->lock);
-		forget = list_first_entry_or_null(&fsvq->queued_reqs,
-					struct virtio_fs_forget, list);
-		if (!forget) {
-			spin_unlock(&fsvq->lock);
-			return;
-		}
-
-		list_del(&forget->list);
 	if (!fsvq->connected) {
+		if (in_flight)
 			dec_in_flight_req(fsvq);
-			spin_unlock(&fsvq->lock);
 		kfree(forget);
-			continue;
+		goto out;
 	}
 
 	sg_init_one(&sg, forget, sizeof(*forget));
-
-		/* Enqueue the request */
+	vq = fsvq->vq;
 	dev_dbg(&vq->vdev->dev, "%s\n", __func__);
-		ret = virtqueue_add_sgs(vq, sgs, 1, 0, forget, GFP_ATOMIC);
+
+	ret = virtqueue_add_outbuf(vq, &sg, 1, forget, GFP_ATOMIC);
 	if (ret < 0) {
 		if (ret == -ENOMEM || ret == -ENOSPC) {
 			pr_debug("virtio-fs: Could not queue FORGET: err=%d. Will try later\n",
 				 ret);
-				list_add_tail(&forget->list,
-						&fsvq->queued_reqs);
+			list_add_tail(&forget->list, &fsvq->queued_reqs);
 			schedule_delayed_work(&fsvq->dispatch_work,
 					      msecs_to_jiffies(1));
+			if (!in_flight)
+				inc_in_flight_req(fsvq);
+			/* Queue is full */
+			ret = 1;
 		} else {
 			pr_debug("virtio-fs: Could not queue FORGET: err=%d. Dropping it.\n",
 				 ret);
-				dec_in_flight_req(fsvq);
 			kfree(forget);
+			if (in_flight)
+				dec_in_flight_req(fsvq);
 		}
-			spin_unlock(&fsvq->lock);
-			return;
+		goto out;
 	}
 
+	if (!in_flight)
+		inc_in_flight_req(fsvq);
 	notify = virtqueue_kick_prepare(vq);
 	spin_unlock(&fsvq->lock);
 
 	if (notify)
 		virtqueue_notify(vq);
-		pr_debug("virtio-fs: worker %s dispatched one forget request.\n",
-			 __func__);
+	return ret;
+out:
+	spin_unlock(&fsvq->lock);
+	return ret;
+}
+
+static void virtio_fs_hiprio_dispatch_work(struct work_struct *work)
+{
+	struct virtio_fs_forget *forget;
+	struct virtio_fs_vq *fsvq = container_of(work, struct virtio_fs_vq,
+						 dispatch_work.work);
+	pr_debug("virtio-fs: worker %s called.\n", __func__);
+	while (1) {
+		spin_lock(&fsvq->lock);
+		forget = list_first_entry_or_null(&fsvq->queued_reqs,
+					struct virtio_fs_forget, list);
+		if (!forget) {
+			spin_unlock(&fsvq->lock);
+			return;
+		}
+
+		list_del(&forget->list);
+		spin_unlock(&fsvq->lock);
+		if (send_forget_request(fsvq, forget, true))
+			return;
 	}
 }
 
@@ -710,14 +730,9 @@ __releases(fiq->lock)
 {
 	struct fuse_forget_link *link;
 	struct virtio_fs_forget *forget;
-	struct scatterlist sg;
-	struct scatterlist *sgs[] = {&sg};
 	struct virtio_fs *fs;
-	struct virtqueue *vq;
 	struct virtio_fs_vq *fsvq;
-	bool notify;
 	u64 unique;
-	int ret;
 
 	link = fuse_dequeue_forget(fiq, 1, NULL);
 	unique = fuse_get_unique(fiq);
@@ -739,46 +754,7 @@ __releases(fiq->lock)
 		.nlookup = link->forget_one.nlookup,
 	};
 
-	sg_init_one(&sg, forget, sizeof(*forget));
-
-	/* Enqueue the request */
-	spin_lock(&fsvq->lock);
-
-	if (!fsvq->connected) {
-		kfree(forget);
-		spin_unlock(&fsvq->lock);
-		goto out;
-	}
-
-	vq = fsvq->vq;
-	dev_dbg(&vq->vdev->dev, "%s\n", __func__);
-
-	ret = virtqueue_add_sgs(vq, sgs, 1, 0, forget, GFP_ATOMIC);
-	if (ret < 0) {
-		if (ret == -ENOMEM || ret == -ENOSPC) {
-			pr_debug("virtio-fs: Could not queue FORGET: err=%d. Will try later.\n",
-				 ret);
-			list_add_tail(&forget->list, &fsvq->queued_reqs);
-			schedule_delayed_work(&fsvq->dispatch_work,
-					msecs_to_jiffies(1));
-			inc_in_flight_req(fsvq);
-		} else {
-			pr_debug("virtio-fs: Could not queue FORGET: err=%d. Dropping it.\n",
-				 ret);
-			kfree(forget);
-		}
-		spin_unlock(&fsvq->lock);
-		goto out;
-	}
-
-	inc_in_flight_req(fsvq);
-	notify = virtqueue_kick_prepare(vq);
-
-	spin_unlock(&fsvq->lock);
-
-	if (notify)
-		virtqueue_notify(vq);
-out:
+	send_forget_request(fsvq, forget, false);
 	kfree(link);
 }