qemu: add code for handling virtiofsd

Start virtiofsd for each <filesystem> device using it.

Pre-create the socket for communication with QEMU and pass it
to virtiofsd.

Note that virtiofsd needs to run as root.

https://bugzilla.redhat.com/show_bug.cgi?id=1694166

Introduced by QEMU commit a43efa34c7d7b628cbf1ec0fe60043e5c91043ea

Signed-off-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
Tested-by: Andrea Bolognani <abologna@redhat.com>

po/POTFILES.in

@@ -172,6 +172,7 @@
 @SRCDIR@/src/qemu/qemu_tpm.c
 @SRCDIR@/src/qemu/qemu_vhost_user.c
 @SRCDIR@/src/qemu/qemu_vhost_user_gpu.c
+@SRCDIR@/src/qemu/qemu_virtiofs.c
 @SRCDIR@/src/remote/remote_daemon.c
 @SRCDIR@/src/remote/remote_daemon_config.c
 @SRCDIR@/src/remote/remote_daemon_dispatch.c

src/qemu/Makefile.inc.am

@@ -67,6 +67,8 @@ QEMU_DRIVER_SOURCES = \
 	qemu/qemu_vhost_user.h \
 	qemu/qemu_vhost_user_gpu.c \
 	qemu/qemu_vhost_user_gpu.h \
+	qemu/qemu_virtiofs.c \
+	qemu/qemu_virtiofs.h \
 	qemu/qemu_checkpoint.c \
 	qemu/qemu_checkpoint.h \
 	qemu/qemu_backup.c \

src/qemu/qemu_domain.c

@@ -1433,8 +1433,11 @@ qemuDomainFSPrivateNew(void)
 
 
 static void
-qemuDomainFSPrivateDispose(void *obj G_GNUC_UNUSED)
+qemuDomainFSPrivateDispose(void *obj)
 {
+    qemuDomainFSPrivatePtr priv = obj;
+
+    g_free(priv->vhostuser_fs_sock);
 }
 
 static virClassPtr qemuDomainVideoPrivateClass;

src/qemu/qemu_domain.h

@@ -568,7 +568,7 @@ typedef qemuDomainFSPrivate *qemuDomainFSPrivatePtr;
 struct _qemuDomainFSPrivate {
     virObject parent;
 
-    int dummy;
+    char *vhostuser_fs_sock;
 };
 
 

src/qemu/qemu_extdevice.c

@@ -20,11 +20,13 @@
 
 #include <config.h>
 
+#include "qemu_command.h"
 #include "qemu_extdevice.h"
 #include "qemu_vhost_user_gpu.h"
 #include "qemu_domain.h"
 #include "qemu_tpm.h"
 #include "qemu_slirp.h"
+#include "qemu_virtiofs.h"
 
 #include "viralloc.h"
 #include "virlog.h"
@@ -153,7 +155,7 @@ qemuExtDevicesCleanupHost(virQEMUDriverPtr driver,
 int
 qemuExtDevicesStart(virQEMUDriverPtr driver,
                     virDomainObjPtr vm,
-                    virLogManagerPtr logManager G_GNUC_UNUSED,
+                    virLogManagerPtr logManager,
                     bool incomingMigration)
 {
     virDomainDefPtr def = vm->def;
@@ -183,6 +185,15 @@ qemuExtDevicesStart(virQEMUDriverPtr driver,
             return -1;
     }
 
+    for (i = 0; i < def->nfss; i++) {
+        virDomainFSDefPtr fs = def->fss[i];
+
+        if (fs->fsdriver == VIR_DOMAIN_FS_DRIVER_TYPE_VIRTIOFS) {
+            if (qemuVirtioFSStart(logManager, driver, vm, fs) < 0)
+                return -1;
+        }
+    }
+
     return 0;
 }
 
@@ -214,6 +225,13 @@ qemuExtDevicesStop(virQEMUDriverPtr driver,
         if (slirp)
             qemuSlirpStop(slirp, vm, driver, net, false);
     }
+
+    for (i = 0; i < def->nfss; i++) {
+        virDomainFSDefPtr fs = def->fss[i];
+
+        if (fs->fsdriver == VIR_DOMAIN_FS_DRIVER_TYPE_VIRTIOFS)
+            qemuVirtioFSStop(driver, vm, fs);
+    }
 }
 
 

src/qemu/qemu_virtiofs.c

@@ -0,0 +1,301 @@
+/*
+ * qemu_virtiofs.c: virtiofs support
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include "logging/log_manager.h"
+#include "virlog.h"
+#include "qemu_command.h"
+#include "qemu_conf.h"
+#include "qemu_extdevice.h"
+#include "qemu_security.h"
+#include "qemu_virtiofs.h"
+#include "virpidfile.h"
+#include "virqemu.h"
+#include "virutil.h"
+
+#define VIR_FROM_THIS VIR_FROM_QEMU
+
+
+char *
+qemuVirtioFSCreatePidFilename(virDomainObjPtr vm,
+                              const char *alias)
+{
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+    g_autofree char *shortName = NULL;
+    g_autofree char *name = NULL;
+
+    if (!(shortName = virDomainDefGetShortName(vm->def)))
+        return NULL;
+
+    name = g_strdup_printf("%s-%s-virtiofsd", shortName, alias);
+
+    return virPidFileBuildPath(priv->libDir, name);
+}
+
+
+char *
+qemuVirtioFSCreateSocketFilename(virDomainObjPtr vm,
+                                 const char *alias)
+{
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+
+    return virFileBuildPath(priv->libDir, alias, "-virtiofsd.sock");
+}
+
+
+static char *
+qemuVirtioFSCreateLogFilename(virQEMUDriverConfigPtr cfg,
+                              const virDomainDef *def,
+                              const char *alias)
+{
+    g_autofree char *name = NULL;
+
+    name = g_strdup_printf("%s-%s", def->name, alias);
+
+    return virFileBuildPath(cfg->logDir, name, "-virtiofsd.log");
+}
+
+
+static int
+qemuVirtioFSOpenChardev(virQEMUDriverPtr driver,
+                        virDomainObjPtr vm,
+                        const char *socket_path)
+{
+    virDomainChrSourceDefPtr chrdev = virDomainChrSourceDefNew(NULL);
+    virDomainChrDef chr = { .source = chrdev };
+    VIR_AUTOCLOSE fd = -1;
+    int ret = -1;
+
+    chrdev->type = VIR_DOMAIN_CHR_TYPE_UNIX;
+    chrdev->data.nix.listen = true;
+    chrdev->data.nix.path = g_strdup(socket_path);
+
+    if (qemuSecuritySetDaemonSocketLabel(driver->securityManager, vm->def) < 0)
+        goto cleanup;
+    fd = qemuOpenChrChardevUNIXSocket(chrdev);
+    if (fd < 0) {
+        ignore_value(qemuSecurityClearSocketLabel(driver->securityManager, vm->def));
+        goto cleanup;
+    }
+    if (qemuSecurityClearSocketLabel(driver->securityManager, vm->def) < 0)
+        goto cleanup;
+
+    if (qemuSecuritySetChardevLabel(driver, vm, &chr) < 0)
+        goto cleanup;
+
+    ret = fd;
+    fd = -1;
+
+ cleanup:
+    virObjectUnref(chrdev);
+    return ret;
+}
+
+
+static virCommandPtr
+qemuVirtioFSBuildCommandLine(virQEMUDriverConfigPtr cfg,
+                             virDomainFSDefPtr fs,
+                             int *fd)
+{
+    g_autoptr(virCommand) cmd = NULL;
+    g_auto(virBuffer) opts = VIR_BUFFER_INITIALIZER;
+
+    if (!(cmd = virCommandNew(fs->binary)))
+        return NULL;
+
+    virCommandAddArgFormat(cmd, "--fd=%d", *fd);
+    virCommandPassFD(cmd, *fd, VIR_COMMAND_PASS_FD_CLOSE_PARENT);
+    *fd = -1;
+
+    virCommandAddArg(cmd, "-o");
+    virBufferAddLit(&opts, "source=");
+    virQEMUBuildBufferEscapeComma(&opts, fs->src->path);
+    if (fs->cache)
+        virBufferAsprintf(&opts, ",cache=%s", virDomainFSCacheModeTypeToString(fs->cache));
+
+    if (fs->xattr == VIR_TRISTATE_SWITCH_ON)
+        virBufferAddLit(&opts, ",xattr");
+    else if (fs->xattr == VIR_TRISTATE_SWITCH_OFF)
+        virBufferAddLit(&opts, ",no_xattr");
+
+    if (fs->flock == VIR_TRISTATE_SWITCH_ON)
+        virBufferAddLit(&opts, ",flock");
+    else if (fs->flock == VIR_TRISTATE_SWITCH_OFF)
+        virBufferAddLit(&opts, ",no_flock");
+
+    if (fs->posix_lock == VIR_TRISTATE_SWITCH_ON)
+        virBufferAddLit(&opts, ",posix_lock");
+    else if (fs->posix_lock == VIR_TRISTATE_SWITCH_OFF)
+        virBufferAddLit(&opts, ",no_posix_lock");
+
+    virCommandAddArgBuffer(cmd, &opts);
+    if (cfg->virtiofsdDebug)
+        virCommandAddArg(cmd, "-d");
+
+    return g_steal_pointer(&cmd);
+}
+
+int
+qemuVirtioFSStart(virLogManagerPtr logManager,
+                  virQEMUDriverPtr driver,
+                  virDomainObjPtr vm,
+                  virDomainFSDefPtr fs)
+{
+    g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver);
+    g_autoptr(virCommand) cmd = NULL;
+    g_autofree char *socket_path = NULL;
+    g_autofree char *pidfile = NULL;
+    g_autofree char *logpath = NULL;
+    pid_t pid = (pid_t) -1;
+    VIR_AUTOCLOSE fd = -1;
+    VIR_AUTOCLOSE logfd = -1;
+    int ret = -1;
+    int rc;
+
+    if (!virFileExists(fs->src->path)) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("the virtiofs export directory '%s' does not exist"),
+                       fs->src->path);
+        return -1;
+    }
+
+    if (!(pidfile = qemuVirtioFSCreatePidFilename(vm, fs->info.alias)))
+        goto cleanup;
+
+    if (!(socket_path = qemuVirtioFSCreateSocketFilename(vm, fs->info.alias)))
+        goto cleanup;
+
+    if ((fd = qemuVirtioFSOpenChardev(driver, vm, socket_path)) < 0)
+        goto cleanup;
+
+    logpath = qemuVirtioFSCreateLogFilename(cfg, vm->def, fs->info.alias);
+
+    if (cfg->stdioLogD) {
+        if ((logfd = virLogManagerDomainOpenLogFile(logManager,
+                                                    "qemu",
+                                                    vm->def->uuid,
+                                                    vm->def->name,
+                                                    logpath,
+                                                    0,
+                                                    NULL, NULL)) < 0)
+            goto cleanup;
+    } else {
+        if ((logfd = open(logpath, O_WRONLY | O_CREAT | O_APPEND, S_IRUSR | S_IWUSR)) < 0) {
+            virReportSystemError(errno, _("failed to create logfile %s"),
+                                 logpath);
+            goto cleanup;
+        }
+        if (virSetCloseExec(logfd) < 0) {
+            virReportSystemError(errno, _("failed to set close-on-exec flag on %s"),
+                                 logpath);
+            goto error;
+        }
+    }
+
+    if (!(cmd = qemuVirtioFSBuildCommandLine(cfg, fs, &fd)))
+        goto cleanup;
+
+    /* so far only running as root is supported */
+    virCommandSetUID(cmd, 0);
+    virCommandSetGID(cmd, 0);
+
+    virCommandSetPidFile(cmd, pidfile);
+    virCommandSetOutputFD(cmd, &logfd);
+    virCommandSetErrorFD(cmd, &logfd);
+    virCommandNonblockingFDs(cmd);
+    virCommandDaemonize(cmd);
+
+    if (qemuExtDeviceLogCommand(driver, vm, cmd, "virtiofsd") < 0)
+        goto cleanup;
+
+    rc = virCommandRun(cmd, NULL);
+
+    if (rc < 0) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("Could not start 'virtiofsd'"));
+        goto error;
+    }
+
+    rc = virPidFileReadPath(pidfile, &pid);
+    if (rc < 0) {
+        virReportSystemError(-rc,
+                             _("Unable to read virtiofsd pidfile '%s'"),
+                             pidfile);
+        goto error;
+    }
+
+    if (virProcessKill(pid, 0) != 0) {
+        virReportSystemError(errno, "%s",
+                             _("virtiofsd died unexpectedly"));
+        goto error;
+    }
+
+    QEMU_DOMAIN_FS_PRIVATE(fs)->vhostuser_fs_sock = g_steal_pointer(&socket_path);
+    ret = 0;
+
+ cleanup:
+    if (socket_path)
+        unlink(socket_path);
+    return ret;
+
+ error:
+    if (pid != -1)
+        virProcessKillPainfully(pid, true);
+    if (pidfile)
+        unlink(pidfile);
+    goto cleanup;
+}
+
+
+void
+qemuVirtioFSStop(virQEMUDriverPtr driver G_GNUC_UNUSED,
+                    virDomainObjPtr vm,
+                    virDomainFSDefPtr fs)
+{
+    g_autofree char *pidfile = NULL;
+    virErrorPtr orig_err;
+    pid_t pid = -1;
+    int rc;
+
+    virErrorPreserveLast(&orig_err);
+
+    if (!(pidfile = qemuVirtioFSCreatePidFilename(vm, fs->info.alias)))
+        goto cleanup;
+
+    rc = virPidFileReadPathIfAlive(pidfile, &pid, NULL);
+    if (rc >= 0 && pid != (pid_t) -1)
+        virProcessKillPainfully(pid, true);
+
+    if (unlink(pidfile) < 0 &&
+        errno != ENOENT) {
+        virReportSystemError(errno,
+                             _("Unable to remove stale pidfile %s"),
+                             pidfile);
+    }
+
+    if (QEMU_DOMAIN_FS_PRIVATE(fs)->vhostuser_fs_sock)
+        unlink(QEMU_DOMAIN_FS_PRIVATE(fs)->vhostuser_fs_sock);
+
+ cleanup:
+    virErrorRestore(&orig_err);
+}

src/qemu/qemu_virtiofs.h

@@ -0,0 +1,37 @@
+/*
+ * qemu_virtiofs.h: virtiofs support
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+
+char *
+qemuVirtioFSCreatePidFilename(virDomainObjPtr vm,
+                              const char *alias);
+char *
+qemuVirtioFSCreateSocketFilename(virDomainObjPtr vm,
+                                 const char *alias);
+
+int
+qemuVirtioFSStart(virLogManagerPtr logManager,
+                  virQEMUDriverPtr driver,
+                  virDomainObjPtr vm,
+                  virDomainFSDefPtr fs);
+void
+qemuVirtioFSStop(virQEMUDriverPtr driver,
+                 virDomainObjPtr vm,
+                 virDomainFSDefPtr fs);

tests/qemuxml2argvtest.c

@@ -496,6 +496,17 @@ testCompareXMLToArgv(const void *data)
         }
     }
 
+    for (i = 0; i < vm->def->nfss; i++) {
+        virDomainFSDefPtr fs = vm->def->fss[i];
+        char *s;
+
+        if (fs->fsdriver != VIR_DOMAIN_FS_DRIVER_TYPE_VIRTIOFS)
+            continue;
+
+        s = g_strdup_printf("/tmp/lib/domain--1-guest/fs%zu.vhost-fs.sock", i);
+        QEMU_DOMAIN_FS_PRIVATE(fs)->vhostuser_fs_sock = s;
+    }
+
     if (vm->def->vsock) {
         virDomainVsockDefPtr vsock = vm->def->vsock;
         qemuDomainVsockPrivatePtr vsockPriv =