To use the online disk snapshot for online-backup, application-level
consistency of the snapshot image is required. However, currently the
guest agent can provide only filesystem-level consistency, and the
snapshot may contain dirty data, for example, incomplete transactions.
This patch provides the opportunity to quiesce applications before
snapshot is taken.
When the qemu-ga receives fsfreeze-freeze command, the hook script
specified in --fsfreeze-hook option is executed with "freeze" argument
before the filesystem is frozen. For fsfreeze-thaw command, the hook
script is executed with "thaw" argument after the filesystem is thawed.
Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama...@hitachi.com>
---
qemu-ga.c | 42 +++++++++++++++++++++++++++++++++++++++++-
qga/commands-posix.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
qga/guest-agent-core.h | 1 +
3 files changed, 86 insertions(+), 1 deletion(-)
diff --git a/qemu-ga.c b/qemu-ga.c
index 9b59a52..d1d9b89 100644
--- a/qemu-ga.c
+++ b/qemu-ga.c
@@ -34,6 +34,12 @@
#include "qga/service-win32.h"
#include <windows.h>
#endif
+#ifdef __linux__
+#include <linux/fs.h>
+#ifdef FIFREEZE
+#define CONFIG_FSFREEZE
+#endif
+#endif
#ifndef _WIN32
#define QGA_VIRTIO_PATH_DEFAULT "/dev/virtio-ports/org.qemu.guest_agent.0"
@@ -42,6 +48,9 @@
#endif
#define QGA_STATEDIR_DEFAULT CONFIG_QEMU_LOCALSTATEDIR "/run"
#define QGA_PIDFILE_DEFAULT QGA_STATEDIR_DEFAULT "/qemu-ga.pid"
+#ifdef CONFIG_FSFREEZE
+#define QGA_FSFREEZE_HOOK_DEFAULT CONFIG_QEMU_CONFDIR "/fsfreeze-hook"
+#endif
#define QGA_SENTINEL_BYTE 0xFF
struct GAState {
@@ -64,6 +73,9 @@ struct GAState {
const char *log_filepath;
const char *pid_filepath;
} deferred_options;
+#ifdef CONFIG_FSFREEZE
+ const char *fsfreeze_hook;
+#endif
};
struct GAState *ga_state;
@@ -153,6 +165,10 @@ static void usage(const char *cmd)
" %s)\n"
" -l, --logfile set logfile path, logs to stderr by default\n"
" -f, --pidfile specify pidfile (default is %s)\n"
+#ifdef CONFIG_FSFREEZE
+" -F, --fsfreeze_hook\n"
+" specify fsfreeze hook (default is %s)\n"
+#endif
" -t, --statedir specify dir to store state information (absolute paths\n"
" only, default is %s)\n"
" -v, --verbose log extra debugging information\n"
@@ -167,6 +183,9 @@ static void usage(const char *cmd)
"\n"
"Report bugs to <mdr...@linux.vnet.ibm.com>\n"
, cmd, QEMU_VERSION, QGA_VIRTIO_PATH_DEFAULT, QGA_PIDFILE_DEFAULT,
+#ifdef CONFIG_FSFREEZE
+ QGA_FSFREEZE_HOOK_DEFAULT,
+#endif
QGA_STATEDIR_DEFAULT);
}
@@ -401,6 +420,13 @@ void ga_unset_frozen(GAState *s)
}
}
+#ifdef CONFIG_FSFREEZE
+const char *ga_fsfreeze_hook(GAState *s)
+{
+ return s->fsfreeze_hook;
+}
+#endif
+
static void become_daemon(const char *pidfile)
{
#ifndef _WIN32
@@ -678,10 +704,13 @@ VOID WINAPI service_main(DWORD argc, TCHAR *argv[])
int main(int argc, char **argv)
{
- const char *sopt = "hVvdm:p:l:f:b:s:t:";
+ const char *sopt = "hVvdm:p:l:f:F:b:s:t:";
const char *method = NULL, *path = NULL;
const char *log_filepath = NULL;
const char *pid_filepath = QGA_PIDFILE_DEFAULT;
+#ifdef CONFIG_FSFREEZE
+ const char *fsfreeze_hook = QGA_FSFREEZE_HOOK_DEFAULT;
+#endif
const char *state_dir = QGA_STATEDIR_DEFAULT;
#ifdef _WIN32
const char *service = NULL;
@@ -691,6 +720,9 @@ int main(int argc, char **argv)
{ "version", 0, NULL, 'V' },
{ "logfile", 1, NULL, 'l' },
{ "pidfile", 1, NULL, 'f' },
+#ifdef CONFIG_FSFREEZE
+ { "fsfreeze-hook", 1, NULL, 'F' },
+#endif
{ "verbose", 0, NULL, 'v' },
{ "method", 1, NULL, 'm' },
{ "path", 1, NULL, 'p' },
@@ -723,6 +755,11 @@ int main(int argc, char **argv)
case 'f':
pid_filepath = optarg;
break;
+#ifdef CONFIG_FSFREEZE
+ case 'F':
+ fsfreeze_hook = optarg;
+ break;
+#endif
case 't':
state_dir = optarg;
break;
@@ -786,6 +823,9 @@ int main(int argc, char **argv)
s = g_malloc0(sizeof(GAState));
s->log_level = log_level;
s->log_file = stderr;
+#ifdef CONFIG_FSFREEZE
+ s->fsfreeze_hook = fsfreeze_hook;
+#endif
g_log_set_default_handler(ga_log, s);
g_log_set_fatal_mask(NULL, G_LOG_LEVEL_ERROR);
ga_enable_logging(s);
diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index 726930a..8c3e341 100644
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -396,6 +396,45 @@ GuestFsfreezeStatus qmp_guest_fsfreeze_status(Error **err)
return GUEST_FSFREEZE_STATUS_THAWED;
}
+static void execute_fsfreeze_hook(const char *arg)
+{
+ int status;
+ pid_t pid, rpid;
+ const char *hook;
+
+ hook = ga_fsfreeze_hook(ga_state);
+ if (!hook || access(hook, X_OK) != 0) {
+ return;
+ }
+
+ slog("executing fsfreeze hook with arg `%s'", arg);
+ pid = fork();
+ if (pid == 0) {
+ setsid();
+ reopen_fd_to_null(0);
+ reopen_fd_to_null(1);
+ reopen_fd_to_null(2);
+
+ execle(hook, hook, arg, NULL, environ);
+ _exit(EXIT_FAILURE);
+ } else if (pid < 0) {
+ slog("execution of fsfreeze hook failed: %s", strerror(errno));
+ return;
+ }
+
+ do {
+ rpid = waitpid(pid, &status, 0);
+ } while (rpid == -1 && errno == EINTR);
+ if (rpid == pid && WIFEXITED(status)) {
+ int st = WEXITSTATUS(status);
+ if (st) {
+ slog("fsfreeze hook failed with status %d", st);
+ }
+ } else if (rpid == pid && WIFSIGNALED(status)) {
+ slog("fsfreeze hook killed by signal %d", WTERMSIG(status));
+ }
+}
+
/*
* Walk list of mounted file systems in the guest, and freeze the ones which
* are real local file systems.
@@ -410,6 +449,8 @@ int64_t qmp_guest_fsfreeze_freeze(Error **err)
slog("guest-fsfreeze called");
+ execute_fsfreeze_hook("freeze");
+
QTAILQ_INIT(&mounts);
ret = build_fs_mount_list(&mounts);
if (ret < 0) {
@@ -513,6 +554,9 @@ int64_t qmp_guest_fsfreeze_thaw(Error **err)
ga_unset_frozen(ga_state);
free_fs_mount_list(&mounts);
+
+ execute_fsfreeze_hook("thaw");
+
return i;
}
diff --git a/qga/guest-agent-core.h b/qga/guest-agent-core.h
index 49a7abe..c6e8de0 100644
--- a/qga/guest-agent-core.h
+++ b/qga/guest-agent-core.h
@@ -34,6 +34,7 @@ void ga_set_response_delimited(GAState *s);
bool ga_is_frozen(GAState *s);
void ga_set_frozen(GAState *s);
void ga_unset_frozen(GAState *s);
+const char *ga_fsfreeze_hook(GAState *s);
#ifndef _WIN32
void reopen_fd_to_null(int fd);
