[PATCH 11/52] fuse: implement FUSE_FORGET for virtio-fs

Vivek Goyal
2018-12-10T17:12:37Z

From: Stefan Hajnoczi <stefanha@redhat.com>

Sent single FUSE_FORGET requests on the hiprio queue. In the future it
may be possible to do FUSE_BATCH_FORGET but that is tricky since
virtio-fs gets called synchronously when forgets are queued.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
fs/fuse/virtio_fs.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 89 insertions(+), 4 deletions(-)

diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index fa99a31ee930..225eb729656f 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -140,10 +140,26 @@ static void virtio_fs_notifications_done_work(struct work_struct *work)
return;
}

-static void virtio_fs_hiprio_done(struct virtqueue *vq)
+/* Work function for hiprio completion */
+static void virtio_fs_hiprio_done_work(struct work_struct *work)
{
- /* TODO */
- dev_dbg(&vq->vdev->dev, "%s\n", __func__);
+ struct virtio_fs_vq *fsvq = container_of(work, struct virtio_fs_vq,
+ done_work);
+ struct fuse_pqueue *fpq = &fsvq->fud->pq;
+ struct virtqueue *vq = fsvq->vq;
+
+ /* Free completed FUSE_FORGET requests */
+ spin_lock(&fpq->lock);
+ do {
+ unsigned len;
+ void *req;
+
+ virtqueue_disable_cb(vq);
+
+ while ((req = virtqueue_get_buf(vq, &len)) != NULL)
+ kfree(req);
+ } while (!virtqueue_enable_cb(vq) && likely(!virtqueue_is_broken(vq)));
+ spin_unlock(&fpq->lock);
}

/* Allocate and copy args into req->argbuf */
@@ -302,6 +318,7 @@ static int virtio_fs_setup_vqs(struct virtio_device *vdev,
callbacks[1] = virtio_fs_vq_done;
snprintf(fs->vqs[1].name, sizeof(fs->vqs[1].name), "hiprio");
names[1] = fs->vqs[1].name;
+ INIT_WORK(&fs->vqs[1].done_work, virtio_fs_hiprio_done_work);

/* Initialize the requests virtqueues */
for (i = 2; i < fs->nvqs; i++) {
@@ -424,11 +441,79 @@ static struct virtio_driver virtio_fs_driver = {
#endif
};

+struct virtio_fs_forget {
+ struct fuse_in_header ih;
+ struct fuse_forget_in arg;
+};
+
static void virtio_fs_wake_forget_and_unlock(struct fuse_iqueue *fiq)
__releases(fiq->waitq.lock)
{
- /* TODO */
+ struct fuse_forget_link *link;
+ struct virtio_fs_forget *forget;
+ struct fuse_pqueue *fpq;
+ struct scatterlist sg;
+ struct scatterlist *sgs[] = {&sg};
+ struct virtio_fs *fs;
+ struct virtqueue *vq;
+ bool notify;
+ u64 unique;
+ int ret;
+
+ BUG_ON(!fiq->forget_list_head.next);
+ link = fiq->forget_list_head.next;
+ BUG_ON(link->next);
+ fiq->forget_list_head.next = NULL;
+ fiq->forget_list_tail = &fiq->forget_list_head;
+
+ unique = fuse_get_unique(fiq);
+
+ fs = fiq->priv;
+
spin_unlock(&fiq->waitq.lock);
+
+ /* Allocate a buffer for the request */
+ forget = kmalloc(sizeof(*forget), GFP_ATOMIC);
+ if (!forget) {
+ pr_err("virtio-fs: dropped FORGET: kmalloc failed\n");
+ goto out; /* TODO avoid dropping it? */
+ }
+
+ forget->ih = (struct fuse_in_header){
+ .opcode = FUSE_FORGET,
+ .nodeid = link->forget_one.nodeid,
+ .unique = unique,
+ .len = sizeof(*forget),
+ };
+ forget->arg = (struct fuse_forget_in){
+ .nlookup = link->forget_one.nlookup,
+ };
+
+ sg_init_one(&sg, forget, sizeof(*forget));
+
+ /* Enqueue the request */
+ vq = fs->vqs[1].vq;
+ dev_dbg(&vq->vdev->dev, "%s\n", __func__);
+ fpq = vq_to_fpq(vq);
+ spin_lock(&fpq->lock);
+
+ ret = virtqueue_add_sgs(vq, sgs, 1, 0, forget, GFP_ATOMIC);
+ if (ret < 0) {
+ pr_err("virtio-fs: dropped FORGET: queue full\n");
+ /* TODO handle full virtqueue */
+ spin_unlock(&fpq->lock);
+ goto out;
+ }
+
+ notify = virtqueue_kick_prepare(vq);
+
+ spin_unlock(&fpq->lock);
+
+ if (notify)
+ virtqueue_notify(vq);
+
+out:
+ kfree(link);
}

static void virtio_fs_wake_interrupt_and_unlock(struct fuse_iqueue *fiq)
--
2.13.6