From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Date: Mon, 27 Jan 2020 19:01:00 +0000
Subject: [PATCH] virtiofsd: Start queue threads
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Start a thread for each queue when we get notified it's been started.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
fix by:
Signed-off-by: Jun Piao <piaojun@huawei.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
(cherry picked from commit e4c55a3c144493b436e40031e2eed61a84eca47b)
---
 tools/virtiofsd/fuse_virtio.c | 89 +++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)

diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
index 4819e56568..2a94bb3cca 100644
--- a/tools/virtiofsd/fuse_virtio.c
+++ b/tools/virtiofsd/fuse_virtio.c
@@ -11,6 +11,7 @@
  * See the file COPYING.LIB
  */
 
+#include "qemu/osdep.h"
 #include "fuse_virtio.h"
 #include "fuse_i.h"
 #include "standard-headers/linux/fuse.h"
@@ -30,6 +31,15 @@
 
 #include "contrib/libvhost-user/libvhost-user.h"
 
+struct fv_QueueInfo {
+    pthread_t thread;
+    struct fv_VuDev *virtio_dev;
+
+    /* Our queue index, corresponds to array position */
+    int qidx;
+    int kick_fd;
+};
+
 /*
  * We pass the dev element into libvhost-user
  * and then use it to get back to the outer
@@ -38,6 +48,13 @@
 struct fv_VuDev {
     VuDev dev;
     struct fuse_session *se;
+
+    /*
+     * The following pair of fields are only accessed in the main
+     * virtio_loop
+     */
+    size_t nqueues;
+    struct fv_QueueInfo **qi;
 };
 
 /* From spec */
@@ -83,6 +100,75 @@ static void fv_panic(VuDev *dev, const char *err)
     exit(EXIT_FAILURE);
 }
 
+static void *fv_queue_thread(void *opaque)
+{
+    struct fv_QueueInfo *qi = opaque;
+    fuse_log(FUSE_LOG_INFO, "%s: Start for queue %d kick_fd %d\n", __func__,
+             qi->qidx, qi->kick_fd);
+    while (1) {
+        /* TODO */
+    }
+
+    return NULL;
+}
+
+/* Callback from libvhost-user on start or stop of a queue */
+static void fv_queue_set_started(VuDev *dev, int qidx, bool started)
+{
+    struct fv_VuDev *vud = container_of(dev, struct fv_VuDev, dev);
+    struct fv_QueueInfo *ourqi;
+
+    fuse_log(FUSE_LOG_INFO, "%s: qidx=%d started=%d\n", __func__, qidx,
+             started);
+    assert(qidx >= 0);
+
+    /*
+     * Ignore additional request queues for now.  passthrough_ll.c must be
+     * audited for thread-safety issues first.  It was written with a
+     * well-behaved client in mind and may not protect against all types of
+     * races yet.
+     */
+    if (qidx > 1) {
+        fuse_log(FUSE_LOG_ERR,
+                 "%s: multiple request queues not yet implemented, please only "
+                 "configure 1 request queue\n",
+                 __func__);
+        exit(EXIT_FAILURE);
+    }
+
+    if (started) {
+        /* Fire up a thread to watch this queue */
+        if (qidx >= vud->nqueues) {
+            vud->qi = realloc(vud->qi, (qidx + 1) * sizeof(vud->qi[0]));
+            assert(vud->qi);
+            memset(vud->qi + vud->nqueues, 0,
+                   sizeof(vud->qi[0]) * (1 + (qidx - vud->nqueues)));
+            vud->nqueues = qidx + 1;
+        }
+        if (!vud->qi[qidx]) {
+            vud->qi[qidx] = calloc(sizeof(struct fv_QueueInfo), 1);
+            assert(vud->qi[qidx]);
+            vud->qi[qidx]->virtio_dev = vud;
+            vud->qi[qidx]->qidx = qidx;
+        } else {
+            /* Shouldn't have been started */
+            assert(vud->qi[qidx]->kick_fd == -1);
+        }
+        ourqi = vud->qi[qidx];
+        ourqi->kick_fd = dev->vq[qidx].kick_fd;
+        if (pthread_create(&ourqi->thread, NULL, fv_queue_thread, ourqi)) {
+            fuse_log(FUSE_LOG_ERR, "%s: Failed to create thread for queue %d\n",
+                     __func__, qidx);
+            assert(0);
+        }
+    } else {
+        /* TODO: Kill the thread */
+        assert(qidx < vud->nqueues);
+        ourqi = vud->qi[qidx];
+        ourqi->kick_fd = -1;
+    }
+}
+
 static bool fv_queue_order(VuDev *dev, int qidx)
 {
     return false;
@@ -92,6 +178,9 @@ static const VuDevIface fv_iface = {
     .get_features = fv_get_features,
     .set_features = fv_set_features,
 
+    /* Don't need process message, we've not got any at vhost-user level */
+    .queue_set_started = fv_queue_set_started,
+
     .queue_is_processed_in_order = fv_queue_order,
 };