From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Date: Mon, 27 Jan 2020 19:00:56 +0000

Subject: [PATCH] virtiofsd: Open vhost connection instead of mounting

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When run with vhost-user options we conect to the QEMU instead

via a socket.  Start this off by creating the socket.

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

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

Reviewed-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>

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

(cherry picked from commit d14bf584dd965821e80d14c16d9292a464b1ab85)

---

 tools/virtiofsd/fuse_i.h        |  7 ++-

 tools/virtiofsd/fuse_lowlevel.c | 55 +++--------------------

 tools/virtiofsd/fuse_virtio.c   | 79 +++++++++++++++++++++++++++++++++

 tools/virtiofsd/fuse_virtio.h   | 23 ++++++++++

 4 files changed, 114 insertions(+), 50 deletions(-)

 create mode 100644 tools/virtiofsd/fuse_virtio.c

 create mode 100644 tools/virtiofsd/fuse_virtio.h

diff --git a/tools/virtiofsd/fuse_i.h b/tools/virtiofsd/fuse_i.h

index 26b1a7da88..82d6ac7115 100644

--- a/tools/virtiofsd/fuse_i.h

+++ b/tools/virtiofsd/fuse_i.h

@@ -6,9 +6,10 @@

  * See the file COPYING.LIB

  */

-#define FUSE_USE_VERSION 31

-

+#ifndef FUSE_I_H

+#define FUSE_I_H

+#define FUSE_USE_VERSION 31

 #include "fuse.h"

 #include "fuse_lowlevel.h"

@@ -101,3 +102,5 @@ void fuse_session_process_buf_int(struct fuse_session *se,

 /* room needed in buffer to accommodate header */

 #define FUSE_BUFFER_HEADER_SIZE 0x1000

+

+#endif

diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c

index 17e8718283..5df124e64b 100644

--- a/tools/virtiofsd/fuse_lowlevel.c

+++ b/tools/virtiofsd/fuse_lowlevel.c

@@ -14,6 +14,7 @@

 #include "standard-headers/linux/fuse.h"

 #include "fuse_misc.h"

 #include "fuse_opt.h"

+#include "fuse_virtio.h"

 #include <assert.h>

 #include <errno.h>

@@ -2202,6 +2203,11 @@ struct fuse_session *fuse_session_new(struct fuse_args *args,

         goto out4;

     }

+    if (!se->vu_socket_path) {

+        fprintf(stderr, "fuse: missing -o vhost_user_socket option\n");

+        goto out4;

+    }

+

     se->bufsize = FUSE_MAX_MAX_PAGES * getpagesize() + FUSE_BUFFER_HEADER_SIZE;

     list_init_req(&se->list);

@@ -2224,54 +2230,7 @@ out1:

 int fuse_session_mount(struct fuse_session *se)

 {

-    int fd;

-

-    /*

-     * Make sure file descriptors 0, 1 and 2 are open, otherwise chaos

-     * would ensue.

-     */

-    do {

-        fd = open("/dev/null", O_RDWR);

-        if (fd > 2) {

-            close(fd);

-        }

-    } while (fd >= 0 && fd <= 2);

-

-    /*

-     * To allow FUSE daemons to run without privileges, the caller may open

-     * /dev/fuse before launching the file system and pass on the file

-     * descriptor by specifying /dev/fd/N as the mount point. Note that the

-     * parent process takes care of performing the mount in this case.

-     */

-    fd = fuse_mnt_parse_fuse_fd(mountpoint);

-    if (fd != -1) {

-        if (fcntl(fd, F_GETFD) == -1) {

-            fuse_log(FUSE_LOG_ERR, "fuse: Invalid file descriptor /dev/fd/%u\n",

-                     fd);

-            return -1;

-        }

-        se->fd = fd;

-        return 0;

-    }

-

-    /* Open channel */

-    fd = fuse_kern_mount(mountpoint, se->mo);

-    if (fd == -1) {

-        return -1;

-    }

-    se->fd = fd;

-

-    /* Save mountpoint */

-    se->mountpoint = strdup(mountpoint);

-    if (se->mountpoint == NULL) {

-        goto error_out;

-    }

-

-    return 0;

-

-error_out:

-    fuse_kern_unmount(mountpoint, fd);

-    return -1;

+    return virtio_session_mount(se);

 }

 int fuse_session_fd(struct fuse_session *se)

diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c

new file mode 100644

index 0000000000..cbef6ffdda

--- /dev/null

+++ b/tools/virtiofsd/fuse_virtio.c

@@ -0,0 +1,79 @@

+/*

+ * virtio-fs glue for FUSE

+ * Copyright (C) 2018 Red Hat, Inc. and/or its affiliates

+ *

+ * Authors:

+ *   Dave Gilbert  <dgilbert@redhat.com>

+ *

+ * Implements the glue between libfuse and libvhost-user

+ *

+ * This program can be distributed under the terms of the GNU LGPLv2.

+ * See the file COPYING.LIB

+ */

+

+#include "fuse_i.h"

+#include "standard-headers/linux/fuse.h"

+#include "fuse_misc.h"

+#include "fuse_opt.h"

+#include "fuse_virtio.h"

+

+#include <stdint.h>

+#include <stdio.h>

+#include <string.h>

+#include <sys/socket.h>

+#include <sys/types.h>

+#include <sys/un.h>

+#include <unistd.h>

+

+/* From spec */

+struct virtio_fs_config {

+    char tag[36];

+    uint32_t num_queues;

+};

+

+int virtio_session_mount(struct fuse_session *se)

+{

+    struct sockaddr_un un;

+    mode_t old_umask;

+

+    if (strlen(se->vu_socket_path) >= sizeof(un.sun_path)) {

+        fuse_log(FUSE_LOG_ERR, "Socket path too long\n");

+        return -1;

+    }

+

+    se->fd = -1;

+

+    /*

+     * Create the Unix socket to communicate with qemu

+     * based on QEMU's vhost-user-bridge

+     */

+    unlink(se->vu_socket_path);

+    strcpy(un.sun_path, se->vu_socket_path);

+    size_t addr_len = sizeof(un);

+

+    int listen_sock = socket(AF_UNIX, SOCK_STREAM, 0);

+    if (listen_sock == -1) {

+        fuse_log(FUSE_LOG_ERR, "vhost socket creation: %m\n");

+        return -1;

+    }

+    un.sun_family = AF_UNIX;

+

+    /*

+     * Unfortunately bind doesn't let you set the mask on the socket,

+     * so set umask to 077 and restore it later.

+     */

+    old_umask = umask(0077);

+    if (bind(listen_sock, (struct sockaddr *)&un, addr_len) == -1) {

+        fuse_log(FUSE_LOG_ERR, "vhost socket bind: %m\n");

+        umask(old_umask);

+        return -1;

+    }

+    umask(old_umask);

+

+    if (listen(listen_sock, 1) == -1) {

+        fuse_log(FUSE_LOG_ERR, "vhost socket listen: %m\n");

+        return -1;

+    }

+

+    return -1;

+}

diff --git a/tools/virtiofsd/fuse_virtio.h b/tools/virtiofsd/fuse_virtio.h

new file mode 100644

index 0000000000..8f2edb69ca

--- /dev/null

+++ b/tools/virtiofsd/fuse_virtio.h

@@ -0,0 +1,23 @@

+/*

+ * virtio-fs glue for FUSE

+ * Copyright (C) 2018 Red Hat, Inc. and/or its affiliates

+ *

+ * Authors:

+ *   Dave Gilbert  <dgilbert@redhat.com>

+ *

+ * Implements the glue between libfuse and libvhost-user

+ *

+ * This program can be distributed under the terms of the GNU LGPLv2.

+ *  See the file COPYING.LIB

+ */

+

+#ifndef FUSE_VIRTIO_H

+#define FUSE_VIRTIO_H

+

+#include "fuse_i.h"

+

+struct fuse_session;

+

+int virtio_session_mount(struct fuse_session *se);

+

+#endif