If virtqueue is full, we put forget requests on a list and these forgets
are dispatched later using a worker. As of now we don't count these
forgets in fsvq->in_flight variable. This means when queue is being drained,
we have to have special logic to first drain these pending requests and
then wait for fsvq->in_flight to go to zero.
By counting pending forgets in fsvq->in_flight, we can get rid of special
logic and just wait for in_flight to go to zero. Worker thread will
kick and drain all the forgets anyway, leading in_flight to zero.
I also need similar logic for normal request queue in next patch where
I am about to defer request submission in the worker context if queue is
full.
This simplifies the code a bit.
Also add two helper functions to inc/dec in_flight. Decrement in_flight
helper will later used to call completion when in_flight reaches zero.
Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---
fs/fuse/virtio_fs.c | 44 ++++++++++++++++++++------------------------
1 file changed, 20 insertions(+), 24 deletions(-)
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index e0fcf3030951..625de45fa471 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -67,6 +67,19 @@ static inline struct fuse_pqueue *vq_to_fpq(struct virtqueue *vq)
return &vq_to_fsvq(vq)->fud->pq;
}
+/* Should be called with fsvq->lock held. */
+static inline void inc_in_flight_req(struct virtio_fs_vq *fsvq)
+{
+ fsvq->in_flight++;
+}
+
+/* Should be called with fsvq->lock held. */
+static inline void dec_in_flight_req(struct virtio_fs_vq *fsvq)
+{
+ WARN_ON(fsvq->in_flight <= 0);
+ fsvq->in_flight--;
+}
+
static void release_virtio_fs_obj(struct kref *ref)
{
struct virtio_fs *vfs = container_of(ref, struct virtio_fs, refcount);
@@ -110,22 +123,6 @@ static void virtio_fs_drain_queue(struct virtio_fs_vq *fsvq)
flush_delayed_work(&fsvq->dispatch_work);
}
-static inline void drain_hiprio_queued_reqs(struct virtio_fs_vq *fsvq)
-{
- struct virtio_fs_forget *forget;
-
- spin_lock(&fsvq->lock);
- while (1) {
- forget = list_first_entry_or_null(&fsvq->queued_reqs,
- struct virtio_fs_forget, list);
- if (!forget)
- break;
- list_del(&forget->list);
- kfree(forget);
- }
- spin_unlock(&fsvq->lock);
-}
-
static void virtio_fs_drain_all_queues(struct virtio_fs *fs)
{
struct virtio_fs_vq *fsvq;
@@ -133,9 +130,6 @@ static void virtio_fs_drain_all_queues(struct virtio_fs *fs)
for (i = 0; i < fs->nvqs; i++) {
fsvq = &fs->vqs[i];
- if (i == VQ_HIPRIO)
- drain_hiprio_queued_reqs(fsvq);
-
virtio_fs_drain_queue(fsvq);
}
}
@@ -254,7 +248,7 @@ static void virtio_fs_hiprio_done_work(struct work_struct *work)
while ((req = virtqueue_get_buf(vq, &len)) != NULL) {
kfree(req);
- fsvq->in_flight--;
+ dec_in_flight_req(fsvq);
}
} while (!virtqueue_enable_cb(vq) && likely(!virtqueue_is_broken(vq)));
spin_unlock(&fsvq->lock);
@@ -306,6 +300,7 @@ static void virtio_fs_hiprio_dispatch_work(struct work_struct *work)
list_del(&forget->list);
if (!fsvq->connected) {
+ dec_in_flight_req(fsvq);
spin_unlock(&fsvq->lock);
kfree(forget);
continue;
@@ -327,13 +322,13 @@ static void virtio_fs_hiprio_dispatch_work(struct work_struct *work)
} else {
pr_debug("virtio-fs: Could not queue FORGET: err=%d. Dropping it.\n",
ret);
+ dec_in_flight_req(fsvq);
kfree(forget);
}
spin_unlock(&fsvq->lock);
return;
}
- fsvq->in_flight++;
notify = virtqueue_kick_prepare(vq);
spin_unlock(&fsvq->lock);
@@ -472,7 +467,7 @@ static void virtio_fs_requests_done_work(struct work_struct *work)
fuse_request_end(fc, req);
spin_lock(&fsvq->lock);
- fsvq->in_flight--;
+ dec_in_flight_req(fsvq);
spin_unlock(&fsvq->lock);
}
}
@@ -730,6 +725,7 @@ __releases(fiq->lock)
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);
@@ -739,7 +735,7 @@ __releases(fiq->lock)
goto out;
}
- fsvq->in_flight++;
+ inc_in_flight_req(fsvq);
notify = virtqueue_kick_prepare(vq);
spin_unlock(&fsvq->lock);
@@ -921,7 +917,7 @@ static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq,
/* matches barrier in request_wait_answer() */
smp_mb__after_atomic();
- fsvq->in_flight++;
+ inc_in_flight_req(fsvq);
notify = virtqueue_kick_prepare(vq);
spin_unlock(&fsvq->lock);
--
2.20.1
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