Merge remote-tracking branch 'remotes/dgilbert-gitlab/tags/pull-virtiofs-20210216' into staging

virtiofsd pull 2021-02-16

Vivek's support for new FUSE KILLPRIV_V2
and some smaller cleanups.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

# gpg: Signature made Tue 16 Feb 2021 18:34:32 GMT
# gpg:                using RSA key 45F5C71B4A0CB7FB977A9FA90516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>" [full]
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert-gitlab/tags/pull-virtiofs-20210216:
  virtiofsd: Do not use a thread pool by default
  viriofsd: Add support for FUSE_HANDLE_KILLPRIV_V2
  virtiofsd: Save error code early at the failure callsite
  tools/virtiofsd: Replace the word 'whitelist'
  virtiofsd: vu_dispatch locking should never fail
  virtiofsd: Allow to build it without the tools

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 35 insertions, 14 deletions

diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
index ddcefee427..523ee64fb7 100644
--- a/tools/virtiofsd/fuse_virtio.c
+++ b/tools/virtiofsd/fuse_virtio.c
@@ -188,6 +188,31 @@ static void copy_iov(struct iovec *src_iov, int src_count,
 }
 
 /*
+ * pthread_rwlock_rdlock() and pthread_rwlock_wrlock can fail if
+ * a deadlock condition is detected or the current thread already
+ * owns the lock. They can also fail, like pthread_rwlock_unlock(),
+ * if the mutex wasn't properly initialized. None of these are ever
+ * expected to happen.
+ */
+static void vu_dispatch_rdlock(struct fv_VuDev *vud)
+{
+    int ret = pthread_rwlock_rdlock(&vud->vu_dispatch_rwlock);
+    assert(ret == 0);
+}
+
+static void vu_dispatch_wrlock(struct fv_VuDev *vud)
+{
+    int ret = pthread_rwlock_wrlock(&vud->vu_dispatch_rwlock);
+    assert(ret == 0);
+}
+
+static void vu_dispatch_unlock(struct fv_VuDev *vud)
+{
+    int ret = pthread_rwlock_unlock(&vud->vu_dispatch_rwlock);
+    assert(ret == 0);
+}
+
+/*
  * Called back by ll whenever it wants to send a reply/message back
  * The 1st element of the iov starts with the fuse_out_header
  * 'unique'==0 means it's a notify message.
@@ -240,12 +265,12 @@ int virtio_send_msg(struct fuse_session *se, struct fuse_chan *ch,
 
     copy_iov(iov, count, in_sg, in_num, tosend_len);
 
-    pthread_rwlock_rdlock(&qi->virtio_dev->vu_dispatch_rwlock);
+    vu_dispatch_rdlock(qi->virtio_dev);
     pthread_mutex_lock(&qi->vq_lock);
     vu_queue_push(dev, q, elem, tosend_len);
     vu_queue_notify(dev, q);
     pthread_mutex_unlock(&qi->vq_lock);
-    pthread_rwlock_unlock(&qi->virtio_dev->vu_dispatch_rwlock);
+    vu_dispatch_unlock(qi->virtio_dev);
 
     req->reply_sent = true;
 
@@ -403,12 +428,12 @@ int virtio_send_data_iov(struct fuse_session *se, struct fuse_chan *ch,
 
     ret = 0;
 
-    pthread_rwlock_rdlock(&qi->virtio_dev->vu_dispatch_rwlock);
+    vu_dispatch_rdlock(qi->virtio_dev);
     pthread_mutex_lock(&qi->vq_lock);
     vu_queue_push(dev, q, elem, tosend_len);
     vu_queue_notify(dev, q);
     pthread_mutex_unlock(&qi->vq_lock);
-    pthread_rwlock_unlock(&qi->virtio_dev->vu_dispatch_rwlock);
+    vu_dispatch_unlock(qi->virtio_dev);
 
 err:
     if (ret == 0) {
@@ -558,12 +583,12 @@ out:
         fuse_log(FUSE_LOG_DEBUG, "%s: elem %d no reply sent\n", __func__,
                  elem->index);
 
-        pthread_rwlock_rdlock(&qi->virtio_dev->vu_dispatch_rwlock);
+        vu_dispatch_rdlock(qi->virtio_dev);
         pthread_mutex_lock(&qi->vq_lock);
         vu_queue_push(dev, q, elem, 0);
         vu_queue_notify(dev, q);
         pthread_mutex_unlock(&qi->vq_lock);
-        pthread_rwlock_unlock(&qi->virtio_dev->vu_dispatch_rwlock);
+        vu_dispatch_unlock(qi->virtio_dev);
     }
 
     pthread_mutex_destroy(&req->ch.lock);
@@ -596,7 +621,6 @@ static void *fv_queue_thread(void *opaque)
              qi->qidx, qi->kick_fd);
     while (1) {
         struct pollfd pf[2];
-        int ret;
 
         pf[0].fd = qi->kick_fd;
         pf[0].events = POLLIN;
@@ -645,8 +669,7 @@ static void *fv_queue_thread(void *opaque)
             break;
         }
         /* Mutual exclusion with virtio_loop() */
-        ret = pthread_rwlock_rdlock(&qi->virtio_dev->vu_dispatch_rwlock);
-        assert(ret == 0); /* there is no possible error case */
+        vu_dispatch_rdlock(qi->virtio_dev);
         pthread_mutex_lock(&qi->vq_lock);
         /* out is from guest, in is too guest */
         unsigned int in_bytes, out_bytes;
@@ -672,7 +695,7 @@ static void *fv_queue_thread(void *opaque)
         }
 
         pthread_mutex_unlock(&qi->vq_lock);
-        pthread_rwlock_unlock(&qi->virtio_dev->vu_dispatch_rwlock);
+        vu_dispatch_unlock(qi->virtio_dev);
 
         /* Process all the requests. */
         if (!se->thread_pool_size && req_list != NULL) {
@@ -799,7 +822,6 @@ int virtio_loop(struct fuse_session *se)
     while (!fuse_session_exited(se)) {
         struct pollfd pf[1];
         bool ok;
-        int ret;
         pf[0].fd = se->vu_socketfd;
         pf[0].events = POLLIN;
         pf[0].revents = 0;
@@ -825,12 +847,11 @@ int virtio_loop(struct fuse_session *se)
         assert(pf[0].revents & POLLIN);
         fuse_log(FUSE_LOG_DEBUG, "%s: Got VU event\n", __func__);
         /* Mutual exclusion with fv_queue_thread() */
-        ret = pthread_rwlock_wrlock(&se->virtio_dev->vu_dispatch_rwlock);
-        assert(ret == 0); /* there is no possible error case */
+        vu_dispatch_wrlock(se->virtio_dev);
 
         ok = vu_dispatch(&se->virtio_dev->dev);
 
-        pthread_rwlock_unlock(&se->virtio_dev->vu_dispatch_rwlock);
+        vu_dispatch_unlock(se->virtio_dev);
 
         if (!ok) {
             fuse_log(FUSE_LOG_ERR, "%s: vu_dispatch failed\n", __func__);