Re: [PATCH 17/30] virtiofsd: Add main virtio loop

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Marc-André Lureau (marcandre.lureau@gmail.com) wrote:
> On Mon, Oct 21, 2019 at 1:26 PM Dr. David Alan Gilbert (git)
> <dgilbert@redhat.com> wrote:
> >
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> >
> > Processes incoming requests on the vhost-user fd.
> 
> Is there a reason to avoid using glib & its main loop?

Not particularly;  would it actually work out any easier?
Is there an easy way to get the glib loop to check something like
the fuse_session_exited at each iteration.

I probably didn't originally because I wasn't sure if this code
was going back into libfuse or staying here; and libfuse doesn't
use glib.

Dave

> >
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > ---
> >  contrib/virtiofsd/fuse_virtio.c | 42 ++++++++++++++++++++++++++++++---
> >  1 file changed, 39 insertions(+), 3 deletions(-)
> >
> > diff --git a/contrib/virtiofsd/fuse_virtio.c b/contrib/virtiofsd/fuse_virtio.c
> > index 22f71d260f..9c58f11634 100644
> > --- a/contrib/virtiofsd/fuse_virtio.c
> > +++ b/contrib/virtiofsd/fuse_virtio.c
> > @@ -11,12 +11,14 @@
> >   * See the file COPYING.LIB
> >   */
> >
> > +#include "fuse_virtio.h"
> >  #include "fuse_i.h"
> >  #include "fuse_kernel.h"
> >  #include "fuse_misc.h"
> >  #include "fuse_opt.h"
> > -#include "fuse_virtio.h"
> >
> > +#include <assert.h>
> > +#include <errno.h>
> >  #include <stdint.h>
> >  #include <stdio.h>
> >  #include <stdlib.h>
> > @@ -80,15 +82,49 @@ static const VuDevIface fv_iface = {
> >      .queue_is_processed_in_order = fv_queue_order,
> >  };
> >
> > +/*
> > + * Main loop; this mostly deals with events on the vhost-user
> > + * socket itself, and not actual fuse data.
> > + */
> >  int virtio_loop(struct fuse_session *se)
> >  {
> >      fuse_log(FUSE_LOG_INFO, "%s: Entry\n", __func__);
> >
> > -    while (1) {
> > -        /* TODO: Add stuffing */
> > +    while (!fuse_session_exited(se)) {
> > +        struct pollfd pf[1];
> > +        pf[0].fd = se->vu_socketfd;
> > +        pf[0].events = POLLIN;
> > +        pf[0].revents = 0;
> > +
> > +        fuse_log(FUSE_LOG_DEBUG, "%s: Waiting for VU event\n", __func__);
> > +        int poll_res = ppoll(pf, 1, NULL, NULL);
> > +
> > +        if (poll_res == -1) {
> > +            if (errno == EINTR) {
> > +                fuse_log(FUSE_LOG_INFO, "%s: ppoll interrupted, going around\n",
> > +                         __func__);
> > +                continue;
> > +            }
> > +            fuse_log(FUSE_LOG_ERR, "virtio_loop ppoll: %m\n");
> > +            break;
> > +        }
> > +        assert(poll_res == 1);
> > +        if (pf[0].revents & (POLLERR | POLLHUP | POLLNVAL)) {
> > +            fuse_log(FUSE_LOG_ERR, "%s: Unexpected poll revents %x\n", __func__,
> > +                     pf[0].revents);
> > +            break;
> > +        }
> > +        assert(pf[0].revents & POLLIN);
> > +        fuse_log(FUSE_LOG_DEBUG, "%s: Got VU event\n", __func__);
> > +        if (!vu_dispatch(&se->virtio_dev->dev)) {
> > +            fuse_log(FUSE_LOG_ERR, "%s: vu_dispatch failed\n", __func__);
> > +            break;
> > +        }
> >      }
> >
> >      fuse_log(FUSE_LOG_INFO, "%s: Exit\n", __func__);
> > +
> > +    return 0;
> >  }
> >
> >  int virtio_session_mount(struct fuse_session *se)
> > --
> > 2.23.0
> >
> >
> 
> 
> -- 
> Marc-André Lureau
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK