virtiofs: Set FR_SENT flag only after request has been sent

task #28910367
commit 5dbe190f341206a7896f7e40c1e3a36933d812f3 upstream

FR_SENT flag should be set when request has been sent successfully sent
over virtqueue. This is used by interrupt logic to figure out if interrupt
request should be sent or not.

Also add it to fqp->processing list after sending it successfully.
Signed-off-by: NVivek Goyal <vgoyal@redhat.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NLiu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

fs/fuse/virtio_fs.c

@@ -844,6 +844,7 @@ static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq,
 	unsigned int i;
 	int ret;
 	bool notify;
+	struct fuse_pqueue *fpq;
 
 	/* Does the sglist fit on the stack? */
 	total_sgs = sg_count_fuse_req(req);
@@ -898,6 +899,15 @@ static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq,
 		goto out;
 	}
 
+	/* Request successfully sent. */
+	fpq = &fsvq->fud->pq;
+	spin_lock(&fpq->lock);
+	list_add_tail(&req->list, &fpq->processing);
+	spin_unlock(&fpq->lock);
+	set_bit(FR_SENT, &req->flags);
+	/* matches barrier in request_wait_answer() */
+	smp_mb__after_atomic();
+
 	fsvq->in_flight++;
 	notify = virtqueue_kick_prepare(vq);
 
@@ -926,7 +936,6 @@ __releases(fiq->lock)
 	struct virtio_fs *fs;
 	struct fuse_conn *fc;
 	struct fuse_req *req;
-	struct fuse_pqueue *fpq;
 	struct virtio_fs_vq *fsvq;
 	int ret;
 
@@ -945,14 +954,6 @@ __releases(fiq->lock)
 		 req->in.h.nodeid, req->in.h.len,
 		 fuse_len_args(req->out.numargs, req->out.args));
 
-	fpq = &fs->vqs[queue_id].fud->pq;
-	spin_lock(&fpq->lock);
-	list_add_tail(&req->list, &fpq->processing);
-	spin_unlock(&fpq->lock);
-	set_bit(FR_SENT, &req->flags);
-	/* matches barrier in request_wait_answer() */
-	smp_mb__after_atomic();
-
 retry:
 	fsvq = &fs->vqs[queue_id];
 	ret = virtio_fs_enqueue_req(fsvq, req);
@@ -965,10 +966,6 @@ __releases(fiq->lock)
 		}
 		req->out.h.error = ret;
 		pr_err("virtio-fs: virtio_fs_enqueue_req() failed %d\n", ret);
-		spin_lock(&fpq->lock);
-		clear_bit(FR_SENT, &req->flags);
-		list_del_init(&req->list);
-		spin_unlock(&fpq->lock);
 
 		/* Can't end request in submission context. Use a worker */
 		spin_lock(&fsvq->lock);