From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Date: Mon, 27 Jan 2020 19:00:58 +0000
Subject: [PATCH] virtiofsd: Add main virtio loop
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Processes incoming requests on the vhost-user fd.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
(cherry picked from commit 204d8ae57b3c57098642c79b3c03d42495149c09)
---
 tools/virtiofsd/fuse_virtio.c | 42 ++++++++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
index 2ae3c764dd..1928a2025c 100644
--- a/tools/virtiofsd/fuse_virtio.c
+++ b/tools/virtiofsd/fuse_virtio.c
@@ -11,12 +11,14 @@
  * See the file COPYING.LIB
  */
 
+#include "fuse_virtio.h"
 #include "fuse_i.h"
 #include "standard-headers/linux/fuse.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)