On Fri, Sep 26, 2008 at 04:47:05PM +0100, Daniel P. Berrange wrote:
> On Fri, Sep 26, 2008 at 05:41:02PM +0200, Guido G?nther wrote:
> > On Fri, Sep 26, 2008 at 09:51:26AM -0400, Cole Robinson wrote:
> > > It's easy to forget, but anytime you update libvirt you will
> > > need to restart libvirtd. Sounds like that could be the problem.
> > The Ubuntu packages are based on the Debian ones and I dropped the
> > daemon restart from the postinst so we don't tear down all running
> > machines - so this is likely the problem.
> > Did anybody work on saving enough state to restart libvirtd while
> > keeping the VMs running? If not I might give it a whirl once I find some
> > time.
>
> We've got this problem sorted in the 'lxc' driver and need to apply
> the same approach to the QEMU driver. The problem was always finding
> the Pseduo-TTY/PID for the monitor after restart, and associating the
> live config with it. We've "solved" that in LXC driver by savingt the
> live XML & PID to /var/run/libvirt/lxc/. It basically needs the same
> approach to be applied to the QEMU daemons. In addition the DNSmasq
> deamon needs adapting for simiarl reasons.
Attached is a very early patch. It keeps the qemu instances running and
writes out their states upon shutdown. Reconnecting (and therefore sending
monitor commands, etc.) works but since stdout/stderr don't get picked
up again yet we don't handle virEventAddhandle. I'll grab them from
/proc/<pid>/fd/{1,2} later. Network state is missing too, but since this
is moving into a separate file it's becoming a different matter anyway.
-- Guido
Subject: [PATCH] let qemu/kvm survive libvirtd restarts
---
src/domain_conf.c | 1 +
src/domain_conf.h | 1 +
src/qemu_conf.h | 1 +
src/qemu_driver.c | 264 +++++++++++++++++++++++++++++++++++++++++++++++++----
src/util.c | 4 +-
src/util.h | 1 +
6 files changed, 254 insertions(+), 18 deletions(-)
diff --git a/src/domain_conf.c b/src/domain_conf.c
index 6a35064..aa102f6 100644
--- a/src/domain_conf.c
+++ b/src/domain_conf.c
@@ -420,6 +420,7 @@ void virDomainObjFree(virDomainObjPtr dom)
virDomainDefFree(dom->def);
virDomainDefFree(dom->newDef);
+ VIR_FREE(dom->monitorpath);
VIR_FREE(dom->vcpupids);
VIR_FREE(dom);
diff --git a/src/domain_conf.h b/src/domain_conf.h
index 632e5ad..1ac1561 100644
--- a/src/domain_conf.h
+++ b/src/domain_conf.h
@@ -448,6 +448,7 @@ struct _virDomainObj {
int stdout_fd;
int stderr_fd;
int monitor;
+ char *monitorpath;
int logfile;
int pid;
int state;
diff --git a/src/qemu_conf.h b/src/qemu_conf.h
index 88dfade..f47582e 100644
--- a/src/qemu_conf.h
+++ b/src/qemu_conf.h
@@ -62,6 +62,7 @@ struct qemud_driver {
char *networkConfigDir;
char *networkAutostartDir;
char *logDir;
+ char *stateDir;
unsigned int vncTLS : 1;
unsigned int vncTLSx509verify : 1;
char *vncTLSx509certdir;
diff --git a/src/qemu_driver.c b/src/qemu_driver.c
index 806608d..87789a9 100644
--- a/src/qemu_driver.c
+++ b/src/qemu_driver.c
@@ -172,6 +172,181 @@ void qemudAutostartConfigs(struct qemud_driver *driver) {
}
#ifdef WITH_LIBVIRTD
+
+static int
+qemudFileWriteMonitor(const char *dir,
+ const char *name,
+ const char *path)
+{
+ int rc;
+ int fd;
+ FILE *file = NULL;
+ char *monitorfile = NULL;
+
+ if ((rc = virFileMakePath(dir)))
+ goto cleanup;
+
+ if (asprintf(&monitorfile, "%s/%s.monitor", dir, name) < 0) {
+ rc = ENOMEM;
+ goto cleanup;
+ }
+
+ if ((fd = open(monitorfile,
+ O_WRONLY | O_CREAT | O_TRUNC,
+ S_IRUSR | S_IWUSR)) < 0) {
+ rc = errno;
+ goto cleanup;
+ }
+
+ if (!(file = fdopen(fd, "w"))) {
+ rc = errno;
+ close(fd);
+ goto cleanup;
+ }
+
+ if (fprintf(file, "%s", path) < 0) {
+ rc = errno;
+ goto cleanup;
+ }
+
+ rc = 0;
+
+cleanup:
+ if (file &&
+ fclose(file) < 0) {
+ rc = errno;
+ }
+
+ VIR_FREE(monitorfile);
+ return rc;
+}
+
+static int
+qemudFileReadMonitor(const char *dir,
+ const char *name,
+ char **path)
+{
+ int rc;
+ FILE *file;
+ char *monitorfile = NULL;
+
+ if (asprintf(&monitorfile, "%s/%s.monitor", dir, name) < 0) {
+ rc = ENOMEM;
+ goto cleanup;
+ }
+
+ if (!(file = fopen(monitorfile, "r"))) {
+ rc = errno;
+ goto cleanup;
+ }
+
+ if (fscanf(file, "%as", path) != 1) {
+ rc = EINVAL;
+ goto cleanup;
+ }
+
+ if (fclose(file) < 0) {
+ rc = errno;
+ goto cleanup;
+ }
+
+ rc = 0;
+
+ cleanup:
+ VIR_FREE(monitorfile);
+ return rc;
+}
+
+static int
+qemudFileDeleteMonitor(const char *dir,
+ const char *name)
+{
+ int rc = 0;
+ char *pidfile = NULL;
+
+ if (asprintf(&pidfile, "%s/%s.monitor", dir, name) < 0) {
+ rc = errno;
+ goto cleanup;
+ }
+
+ if (unlink(pidfile) < 0 && errno != ENOENT)
+ rc = errno;
+
+cleanup:
+ VIR_FREE(pidfile);
+ return rc;
+}
+
+
+static int qemudOpenMonitor(virConnectPtr conn,
+ struct qemud_driver *driver,
+ virDomainObjPtr vm,
+ const char *monitor,
+ int reconnect);
+/**
+ * qemudReconnectVMs
+ *
+ * Reconnect running vms to the daemon process
+ */
+static int
+qemudReconnectVMs(struct qemud_driver *driver)
+{
+ virDomainObjPtr vm = driver->domains;
+
+ while (vm) {
+ virDomainDefPtr tmp;
+ char *config = NULL;
+ char *monitor = NULL;
+ int rc;
+
+ /* Read pid */
+ if ((rc = virFileReadPid(driver->stateDir, vm->def->name, &vm->pid)) == 0) {
+ virFileDeletePid(driver->stateDir, vm->def->name);
+ DEBUG("Found pid %d for '%s'", vm->pid, vm->def->name);
+ } else
+ goto next;
+
+ if ((config = virDomainConfigFile(NULL,
+ driver->stateDir,
+ vm->def->name)) == NULL) {
+ qemudLog(QEMUD_ERR, _("Failed to read back domain config for %s\n"),
+ vm->def->name);
+ goto next;
+ }
+
+ /* Try and load the config */
+ tmp = virDomainDefParseFile(NULL, driver->caps, config);
+ unlink(config);
+ if (tmp) {
+ vm->newDef = vm->def;
+ vm->def = tmp;
+ }
+
+ /* read back monitor path */
+ if ((rc = qemudFileReadMonitor(driver->stateDir, vm->def->name, &monitor)) != 0) {
+ qemudLog(QEMUD_ERR, _("Failed to read back monitor path for %s: %s\n"),
+ vm->def->name, strerror(rc));
+ goto next;
+ }
+ qemudFileDeleteMonitor(driver->stateDir, vm->def->name);
+
+ /* FIXME: reconnect stdout/stderr via /proc/pid/fd/ */
+
+ if ((rc = qemudOpenMonitor(NULL, driver, vm, monitor, 1)) != 0) {
+ qemudLog(QEMUD_ERR, _("Failed to reconnect to monitor for %s: %d\n"),
+ vm->def->name, rc);
+ goto next;
+ }
+ vm->def->id = driver->nextvmid++;
+ vm->state = VIR_DOMAIN_RUNNING;
+next:
+ VIR_FREE(config);
+ VIR_FREE(monitor);
+ vm = vm->next;
+ }
+ return 0;
+}
+
/**
* qemudStartup:
*
@@ -197,6 +372,10 @@ qemudStartup(void) {
if ((base = strdup (SYSCONF_DIR "/libvirt")) == NULL)
goto out_of_memory;
+
+ if (asprintf (&qemu_driver->stateDir,
+ "%s/run/libvirt/qemu/", LOCAL_STATE_DIR) == -1)
+ goto out_of_memory;
} else {
if (!(pw = getpwuid(uid))) {
qemudLog(QEMUD_ERR, _("Failed to find user record for uid '%d': %s\n"),
@@ -210,6 +389,10 @@ qemudStartup(void) {
if (asprintf (&base, "%s/.libvirt", pw->pw_dir) == -1)
goto out_of_memory;
+
+ if (asprintf (&qemu_driver->stateDir,
+ "%s/run/libvirt/qemu/", base) == -1)
+ goto out_of_memory;
}
/* Configuration paths are either ~/.libvirt/qemu/... (session) or
@@ -250,6 +433,8 @@ qemudStartup(void) {
qemudShutdown();
return -1;
}
+ qemudReconnectVMs(qemu_driver);
+
if (virNetworkLoadAllConfigs(NULL,
&qemu_driver->networks,
qemu_driver->networkConfigDir,
@@ -329,6 +514,34 @@ qemudActive(void) {
return 0;
}
+/**
+ * qemudSaveDomainState
+ *
+ * Save the full state of a running domain to statedir
+ *
+ * Returns 0 on success
+ */
+static int
+qemudSaveDomainState(struct qemud_driver * driver, virDomainObjPtr vm) {
+ int ret;
+
+ if ((ret = virFileWritePid(driver->stateDir, vm->def->name, vm->pid)) != 0) {
+ qemudLog(QEMUD_ERR, _("Unable to safe pidfile for %s: %s\n"),
+ vm->def->name, strerror(ret));
+ return ret;
+ }
+ if ((ret = virDomainSaveConfig(NULL, driver->stateDir, vm->def))) {
+ qemudLog(QEMUD_ERR, _("Unable to save domain %s\n"), vm->def->name);
+ return ret;
+ }
+ if ((ret = qemudFileWriteMonitor(driver->stateDir, vm->def->name, vm->monitorpath)) != 0) {
+ qemudLog(QEMUD_ERR, _("Unable to monitor file for %s: %s\n"),
+ vm->def->name, strerror(ret));
+ return ret;
+ }
+ return 0;
+}
+
/**
* qemudShutdown:
*
@@ -349,10 +562,14 @@ qemudShutdown(void) {
while (vm) {
virDomainObjPtr next = vm->next;
if (virDomainIsActive(vm))
+#if 1
+ qemudSaveDomainState(qemu_driver, vm);
+#else
qemudShutdownVMDaemon(NULL, qemu_driver, vm);
if (!vm->persistent)
virDomainRemoveInactive(&qemu_driver->domains,
vm);
+#endif
vm = next;
}
@@ -389,6 +606,7 @@ qemudShutdown(void) {
VIR_FREE(qemu_driver->networkConfigDir);
VIR_FREE(qemu_driver->networkAutostartDir);
VIR_FREE(qemu_driver->vncTLSx509certdir);
+ VIR_FREE(qemu_driver->stateDir);
if (qemu_driver->brctl)
brShutdown(qemu_driver->brctl);
@@ -499,7 +717,7 @@ qemudCheckMonitorPrompt(virConnectPtr conn ATTRIBUTE_UNUSED,
static int qemudOpenMonitor(virConnectPtr conn,
struct qemud_driver *driver,
virDomainObjPtr vm,
- const char *monitor) {
+ const char *monitor, int reconnect) {
int monfd;
char buf[1024];
int ret = -1;
@@ -520,11 +738,26 @@ static int qemudOpenMonitor(virConnectPtr conn,
goto error;
}
- ret = qemudReadMonitorOutput(conn,
- driver, vm, monfd,
- buf, sizeof(buf),
- qemudCheckMonitorPrompt,
- "monitor");
+ if (!reconnect) {
+ ret = qemudReadMonitorOutput(conn,
+ driver, vm, monfd,
+ buf, sizeof(buf),
+ qemudCheckMonitorPrompt,
+ "monitor");
+
+ } else {
+ vm->monitor = monfd;
+ ret = 0;
+ }
+
+ if (ret != 0)
+ goto error;
+
+ if (!(vm->monitorpath = strdup(monitor))) {
+ qemudReportError(conn, NULL, NULL, VIR_ERR_NO_MEMORY,
+ "%s", _("failed to allocate space for monitor path"));
+ goto error;
+ }
/* Keep monitor open upon success */
if (ret == 0)
@@ -623,7 +856,7 @@ qemudFindCharDevicePTYs(virConnectPtr conn,
}
/* Got them all, so now open the monitor console */
- ret = qemudOpenMonitor(conn, driver, vm, monitor);
+ ret = qemudOpenMonitor(conn, driver, vm, monitor, 0);
cleanup:
VIR_FREE(monitor);
@@ -966,12 +1199,11 @@ static int qemudStartVMDaemon(virConnectPtr conn,
ret = virExec(conn, argv, NULL, &keepfd, &vm->pid,
vm->stdin_fd, &vm->stdout_fd, &vm->stderr_fd,
- VIR_EXEC_NONBLOCK);
+ VIR_EXEC_NONBLOCK | VIR_EXEC_SETSID);
if (ret == 0) {
vm->def->id = driver->nextvmid++;
vm->state = migrateFrom ? VIR_DOMAIN_PAUSED : VIR_DOMAIN_RUNNING;
}
-
for (i = 0 ; argv[i] ; i++)
VIR_FREE(argv[i]);
VIR_FREE(argv);
@@ -1037,7 +1269,9 @@ static void qemudShutdownVMDaemon(virConnectPtr conn ATTRIBUTE_UNUSED,
qemudLog(QEMUD_INFO, _("Shutting down VM '%s'\n"), vm->def->name);
- kill(vm->pid, SIGTERM);
+ if (kill(vm->pid, SIGTERM) < 0)
+ qemudLog(QEMUD_ERROR, _("Failed to send SIGTERM to %s (%d): %s\n"),
+ vm->def->name, vm->pid, strerror(errno));
qemudVMData(driver, vm, vm->stdout_fd);
qemudVMData(driver, vm, vm->stderr_fd);
@@ -1057,13 +1291,9 @@ static void qemudShutdownVMDaemon(virConnectPtr conn ATTRIBUTE_UNUSED,
vm->stderr_fd = -1;
vm->monitor = -1;
- if (waitpid(vm->pid, NULL, WNOHANG) != vm->pid) {
- kill(vm->pid, SIGKILL);
- if (waitpid(vm->pid, NULL, 0) != vm->pid) {
- qemudLog(QEMUD_WARN,
- "%s", _("Got unexpected pid, damn\n"));
- }
- }
+ /* shut if off for sure */
+ kill(vm->pid, SIGKILL);
+ virFileDeletePid(driver->stateDir, vm->def->name);
vm->pid = -1;
vm->def->id = -1;
diff --git a/src/util.c b/src/util.c
index ca14be1..442c810 100644
--- a/src/util.c
+++ b/src/util.c
@@ -299,14 +299,16 @@ virExec(virConnectPtr conn,
!FD_ISSET(i, keepfd)))
close(i);
- if (flags & VIR_EXEC_DAEMON) {
+ if (flags & VIR_EXEC_DAEMON || flags & VIR_EXEC_SETSID) {
if (setsid() < 0) {
ReportError(conn, VIR_ERR_INTERNAL_ERROR,
_("cannot become session leader: %s"),
strerror(errno));
_exit(1);
}
+ }
+ if (flags & VIR_EXEC_DAEMON) {
if (chdir("/") < 0) {
ReportError(conn, VIR_ERR_INTERNAL_ERROR,
_("cannot change to root directory: %s"),
diff --git a/src/util.h b/src/util.h
index 093ef46..8fbe2cd 100644
--- a/src/util.h
+++ b/src/util.h
@@ -32,6 +32,7 @@ enum {
VIR_EXEC_NONE = 0,
VIR_EXEC_NONBLOCK = (1 << 0),
VIR_EXEC_DAEMON = (1 << 1),
+ VIR_EXEC_SETSID = (1 << 2),
};
int virExec(virConnectPtr conn,
--
1.5.6.5
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