On Fri, Nov 22, 2019 at 05:47:32PM +0000, Dr. David Alan Gilbert wrote:
[..]
> > +static int virtio_send_notify_msg(struct fuse_session *se, struct iovec
> > *iov,
> > + int count)
> > +{
> > + struct fv_QueueInfo *qi;
> > + VuDev *dev = &se->virtio_dev->dev;
> > + VuVirtq *q;
> > + FVRequest *req;
> > + VuVirtqElement *elem;
> > + unsigned int in_num, bad_in_num = 0, bad_out_num = 0;
> > + struct fuse_out_header *out = iov[0].iov_base;
> > + size_t in_len, tosend_len = iov_size(iov, count);
> > + struct iovec *in_sg;
> > + int ret = 0;
> > +
> > + /* Notifications have unique == 0 */
> > + assert (!out->unique);
> > +
> > + if (!se->notify_enabled)
> > + return -EOPNOTSUPP;
> > +
> > + /* If notifications are enabled, queue index 1 is notification queue */
> > + qi = se->virtio_dev->qi[1];
> > + q = vu_get_queue(dev, qi->qidx);
> > +
> > + pthread_rwlock_rdlock(&qi->virtio_dev->vu_dispatch_rwlock);
> > + pthread_mutex_lock(&qi->vq_lock);
> > + /* Pop an element from queue */
> > + req = vu_queue_pop(dev, q, sizeof(FVRequest), &bad_in_num,
> > &bad_out_num);
>
> You don't need bad_in_num/bad_out_num - just pass NULL for both; they're
> only needed if you expect to read/write data that's not mappable (i.e.
> in our direct write case).
Will do.
[..]
> > @@ -1950,21 +1948,54 @@ static void lo_setlk(fuse_req_t req, fuse_ino_t ino,
> >
> > if (!plock) {
> > saverr = ret;
> > + pthread_mutex_unlock(&inode->plock_mutex);
> > goto out;
> > }
> >
> > + /*
> > + * plock is now released when inode is going away. We already have
> > + * a reference on inode, so it is guaranteed that plock->fd is
> > + * still around even after dropping inode->plock_mutex lock
> > + */
> > + ofd = plock->fd;
> > + pthread_mutex_unlock(&inode->plock_mutex);
> > +
> > + /*
> > + * If this lock request can block, request caller to wait for
> > + * notification. Do not access req after this. Once lock is
> > + * available, send a notification instead.
> > + */
> > + if (sleep && lock->l_type != F_UNLCK) {
> > + /*
> > + * If notification queue is not enabled, can't support async
> > + * locks.
> > + */
> > + if (!se->notify_enabled) {
> > + saverr = EOPNOTSUPP;
> > + goto out;
> > + }
> > + async_lock = true;
> > + unique = req->unique;
> > + fuse_reply_wait(req);
> > + }
> > /* TODO: Is it alright to modify flock? */
> > lock->l_pid = 0;
> > - ret = fcntl(plock->fd, F_OFD_SETLK, lock);
> > + if (async_lock)
> > + ret = fcntl(ofd, F_OFD_SETLKW, lock);
> > + else
> > + ret = fcntl(ofd, F_OFD_SETLK, lock);
>
> What happens if the guest is rebooted after it's asked
> for, but not been granted a lock?
I think a regular reboot can't be done till a request is pending, because
virtio-fs can't be unmounted and unmount will wait for all pending
requests to finish.
Destroying qemu will destroy deamon too.
Are there any other reboot paths I have missed.
Thanks
Vivek
