Re: [PATCH 08/18] virtiofs: Drain all pending requests during ->remove time
On Fri, Sep 06, 2019 at 10:18:49AM -0400, Michael S. Tsirkin wrote:
> On Fri, Sep 06, 2019 at 10:17:05AM -0400, Vivek Goyal wrote:
> > On Fri, Sep 06, 2019 at 11:52:10AM +0100, Stefan Hajnoczi wrote:
> > > On Thu, Sep 05, 2019 at 03:48:49PM -0400, Vivek Goyal wrote:
> > > > +static void virtio_fs_drain_queue(struct virtio_fs_vq *fsvq)
> > > > +{
> > > > + WARN_ON(fsvq->in_flight < 0);
> > > > +
> > > > + /* Wait for in flight requests to finish.*/
> > > > + while (1) {
> > > > + spin_lock(>lock);
> > > > + if (!fsvq->in_flight) {
> > > > + spin_unlock(>lock);
> > > > + break;
> > > > + }
> > > > + spin_unlock(>lock);
> > > > + usleep_range(1000, 2000);
> > > > + }
> > >
> > > I think all contexts that call this allow sleeping so we could avoid
> > > usleep here.
> >
> > usleep_range() is supposed to be used from non-atomic context.
> >
> > https://github.com/torvalds/linux/blob/master/Documentation/timers/timers-howto.rst
> >
> > What construct you are thinking of?
> >
> > Vivek
>
> completion + signal on vq callback?
Yes. Time-based sleep() is sub-optimal because we could wake up exactly
when in_flight is decremented from the vq callback. This avoids
unnecessary sleep wakeups and the extra time spent sleeping after
in_flight has been decremented.
Stefan
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Re: [PATCH 08/18] virtiofs: Drain all pending requests during ->remove time
On Fri, Sep 06, 2019 at 10:17:05AM -0400, Vivek Goyal wrote:
> On Fri, Sep 06, 2019 at 11:52:10AM +0100, Stefan Hajnoczi wrote:
> > On Thu, Sep 05, 2019 at 03:48:49PM -0400, Vivek Goyal wrote:
> > > +static void virtio_fs_drain_queue(struct virtio_fs_vq *fsvq)
> > > +{
> > > + WARN_ON(fsvq->in_flight < 0);
> > > +
> > > + /* Wait for in flight requests to finish.*/
> > > + while (1) {
> > > + spin_lock(>lock);
> > > + if (!fsvq->in_flight) {
> > > + spin_unlock(>lock);
> > > + break;
> > > + }
> > > + spin_unlock(>lock);
> > > + usleep_range(1000, 2000);
> > > + }
> >
> > I think all contexts that call this allow sleeping so we could avoid
> > usleep here.
>
> usleep_range() is supposed to be used from non-atomic context.
>
> https://github.com/torvalds/linux/blob/master/Documentation/timers/timers-howto.rst
>
> What construct you are thinking of?
>
> Vivek
completion + signal on vq callback?
--
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Re: [PATCH 08/18] virtiofs: Drain all pending requests during ->remove time
On Fri, Sep 06, 2019 at 11:52:10AM +0100, Stefan Hajnoczi wrote:
> On Thu, Sep 05, 2019 at 03:48:49PM -0400, Vivek Goyal wrote:
> > +static void virtio_fs_drain_queue(struct virtio_fs_vq *fsvq)
> > +{
> > + WARN_ON(fsvq->in_flight < 0);
> > +
> > + /* Wait for in flight requests to finish.*/
> > + while (1) {
> > + spin_lock(>lock);
> > + if (!fsvq->in_flight) {
> > + spin_unlock(>lock);
> > + break;
> > + }
> > + spin_unlock(>lock);
> > + usleep_range(1000, 2000);
> > + }
>
> I think all contexts that call this allow sleeping so we could avoid
> usleep here.
usleep_range() is supposed to be used from non-atomic context.
https://github.com/torvalds/linux/blob/master/Documentation/timers/timers-howto.rst
What construct you are thinking of?
Vivek
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Re: [PATCH 08/18] virtiofs: Drain all pending requests during ->remove time
On Thu, Sep 05, 2019 at 03:48:49PM -0400, Vivek Goyal wrote:
> +static void virtio_fs_drain_queue(struct virtio_fs_vq *fsvq)
> +{
> + WARN_ON(fsvq->in_flight < 0);
> +
> + /* Wait for in flight requests to finish.*/
> + while (1) {
> + spin_lock(>lock);
> + if (!fsvq->in_flight) {
> + spin_unlock(>lock);
> + break;
> + }
> + spin_unlock(>lock);
> + usleep_range(1000, 2000);
> + }
I think all contexts that call this allow sleeping so we could avoid
usleep here.
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[PATCH 08/18] virtiofs: Drain all pending requests during ->remove time
When device is going away, drain all pending requests.
Signed-off-by: Vivek Goyal
---
fs/fuse/virtio_fs.c | 83 -
1 file changed, 51 insertions(+), 32 deletions(-)
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 90e7b2f345e5..d5730a50b303 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -63,6 +63,55 @@ static inline struct fuse_pqueue *vq_to_fpq(struct virtqueue
*vq)
return _to_fsvq(vq)->fud->pq;
}
+static void virtio_fs_drain_queue(struct virtio_fs_vq *fsvq)
+{
+ WARN_ON(fsvq->in_flight < 0);
+
+ /* Wait for in flight requests to finish.*/
+ while (1) {
+ spin_lock(>lock);
+ if (!fsvq->in_flight) {
+ spin_unlock(>lock);
+ break;
+ }
+ spin_unlock(>lock);
+ usleep_range(1000, 2000);
+ }
+
+ flush_work(>done_work);
+ flush_delayed_work(>dispatch_work);
+}
+
+static inline void drain_hiprio_queued_reqs(struct virtio_fs_vq *fsvq)
+{
+ struct virtio_fs_forget *forget;
+
+ spin_lock(>lock);
+ while (1) {
+ forget = list_first_entry_or_null(>queued_reqs,
+ struct virtio_fs_forget, list);
+ if (!forget)
+ break;
+ list_del(>list);
+ kfree(forget);
+ }
+ spin_unlock(>lock);
+}
+
+static void virtio_fs_drain_all_queues(struct virtio_fs *fs)
+{
+ struct virtio_fs_vq *fsvq;
+ int i;
+
+ for (i = 0; i < fs->nvqs; i++) {
+ fsvq = >vqs[i];
+ if (i == VQ_HIPRIO)
+ drain_hiprio_queued_reqs(fsvq);
+
+ virtio_fs_drain_queue(fsvq);
+ }
+}
+
/* Add a new instance to the list or return -EEXIST if tag name exists*/
static int virtio_fs_add_instance(struct virtio_fs *fs)
{
@@ -511,6 +560,7 @@ static void virtio_fs_remove(struct virtio_device *vdev)
struct virtio_fs *fs = vdev->priv;
virtio_fs_stop_all_queues(fs);
+ virtio_fs_drain_all_queues(fs);
vdev->config->reset(vdev);
virtio_fs_cleanup_vqs(vdev, fs);
@@ -865,37 +915,6 @@ __releases(fiq->waitq.lock)
}
}
-static void virtio_fs_flush_hiprio_queue(struct virtio_fs_vq *fsvq)
-{
- struct virtio_fs_forget *forget;
-
- WARN_ON(fsvq->in_flight < 0);
-
- /* Go through pending forget requests and free them */
- spin_lock(>lock);
- while (1) {
- forget = list_first_entry_or_null(>queued_reqs,
- struct virtio_fs_forget, list);
- if (!forget)
- break;
- list_del(>list);
- kfree(forget);
- }
-
- spin_unlock(>lock);
-
- /* Wait for in flight requests to finish.*/
- while (1) {
- spin_lock(>lock);
- if (!fsvq->in_flight) {
- spin_unlock(>lock);
- break;
- }
- spin_unlock(>lock);
- usleep_range(1000, 2000);
- }
-}
-
const static struct fuse_iqueue_ops virtio_fs_fiq_ops = {
.wake_forget_and_unlock = virtio_fs_wake_forget_and_unlock,
.wake_interrupt_and_unlock = virtio_fs_wake_interrupt_and_unlock,
@@ -988,7 +1007,7 @@ static void virtio_kill_sb(struct super_block *sb)
spin_lock(>lock);
fsvq->connected = false;
spin_unlock(>lock);
- virtio_fs_flush_hiprio_queue(fsvq);
+ virtio_fs_drain_all_queues(vfs);
fuse_kill_sb_anon(sb);
virtio_fs_free_devs(vfs);
--
2.20.1
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