1 files changed, 52 insertions, 9 deletions

diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 3ea613d5e34f..2de8fc0d6a24 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -55,6 +55,9 @@ struct virtio_fs_forget {
         struct list_head list;
 };
 
+static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq,
+                                 struct fuse_req *req, bool in_flight);
+
 static inline struct virtio_fs_vq *vq_to_fsvq(struct virtqueue *vq)
 {
         struct virtio_fs *fs = vq->vdev->priv;
@@ -260,6 +263,7 @@ static void virtio_fs_request_dispatch_work(struct work_struct *work)
         struct virtio_fs_vq *fsvq = container_of(work, struct virtio_fs_vq,
                                                  dispatch_work.work);
         struct fuse_conn *fc = fsvq->fud->fc;
+        int ret;
 
         pr_debug("virtio-fs: worker %s called.\n", __func__);
         while (1) {
@@ -268,13 +272,45 @@ static void virtio_fs_request_dispatch_work(struct work_struct *work)
                                                list);
                 if (!req) {
                         spin_unlock(&fsvq->lock);
-                        return;
+                        break;
                 }
 
                 list_del_init(&req->list);
                 spin_unlock(&fsvq->lock);
                 fuse_request_end(fc, req);
         }
+
+        /* Dispatch pending requests */
+        while (1) {
+                spin_lock(&fsvq->lock);
+                req = list_first_entry_or_null(&fsvq->queued_reqs,
+                                               struct fuse_req, list);
+                if (!req) {
+                        spin_unlock(&fsvq->lock);
+                        return;
+                }
+                list_del_init(&req->list);
+                spin_unlock(&fsvq->lock);
+
+                ret = virtio_fs_enqueue_req(fsvq, req, true);
+                if (ret < 0) {
+                        if (ret == -ENOMEM || ret == -ENOSPC) {
+                                spin_lock(&fsvq->lock);
+                                list_add_tail(&req->list, &fsvq->queued_reqs);
+                                schedule_delayed_work(&fsvq->dispatch_work,
+                                                      msecs_to_jiffies(1));
+                                spin_unlock(&fsvq->lock);
+                                return;
+                        }
+                        req->out.h.error = ret;
+                        spin_lock(&fsvq->lock);
+                        dec_in_flight_req(fsvq);
+                        spin_unlock(&fsvq->lock);
+                        pr_err("virtio-fs: virtio_fs_enqueue_req() failed %d\n",
+                               ret);
+                        fuse_request_end(fc, req);
+                }
+        }
 }
 
 static void virtio_fs_hiprio_dispatch_work(struct work_struct *work)
@@ -837,7 +873,7 @@ static unsigned int sg_init_fuse_args(struct scatterlist *sg,
 
 /* Add a request to a virtqueue and kick the device */
 static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq,
-                                 struct fuse_req *req)
+                                 struct fuse_req *req, bool in_flight)
 {
         /* requests need at least 4 elements */
         struct scatterlist *stack_sgs[6];
@@ -917,7 +953,8 @@ static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq,
         /* matches barrier in request_wait_answer() */
         smp_mb__after_atomic();
 
-        inc_in_flight_req(fsvq);
+        if (!in_flight)
+                inc_in_flight_req(fsvq);
         notify = virtqueue_kick_prepare(vq);
 
         spin_unlock(&fsvq->lock);
@@ -963,15 +1000,21 @@ __releases(fiq->lock)
                  req->in.h.nodeid, req->in.h.len,
                  fuse_len_args(req->args->out_numargs, req->args->out_args));
 
-retry:
         fsvq = &fs->vqs[queue_id];
-        ret = virtio_fs_enqueue_req(fsvq, req);
+        ret = virtio_fs_enqueue_req(fsvq, req, false);
         if (ret < 0) {
                 if (ret == -ENOMEM || ret == -ENOSPC) {
-                        /* Virtqueue full. Retry submission */
-                        /* TODO use completion instead of timeout */
-                        usleep_range(20, 30);
-                        goto retry;
+                        /*
+                         * Virtqueue full. Retry submission from worker
+                         * context as we might be holding fc->bg_lock.
+                         */
+                        spin_lock(&fsvq->lock);
+                        list_add_tail(&req->list, &fsvq->queued_reqs);
+                        inc_in_flight_req(fsvq);
+                        schedule_delayed_work(&fsvq->dispatch_work,
+                                                msecs_to_jiffies(1));
+                        spin_unlock(&fsvq->lock);
+                        return;
                 }
                 req->out.h.error = ret;
                 pr_err("virtio-fs: virtio_fs_enqueue_req() failed %d\n", ret);