From ec0f694c11e8e0958d727e40e0759ab99e5908d6 Mon Sep 17 00:00:00 2001 From: Tomoki Sekiyama Date: Wed, 12 Dec 2012 12:55:55 +0900 Subject: qemu-ga: execute hook to quiesce the guest on fsfreeze-freeze/thaw 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. If --fsfreeze-hook option is specified, the hook is executed with "freeze" argument before the filesystem is frozen by fsfreeze-freeze command. As for fsfreeze-thaw command, the hook is executed with "thaw" argument after the filesystem is thawed. This patch depends on patchset to improve error reporting by Luiz Capitulino: http://lists.gnu.org/archive/html/qemu-devel/2012-11/msg03016.html Signed-off-by: Tomoki Sekiyama Reviewed-by: Luiz Capitulino *clarified usage in help output Signed-off-by: Michael Roth --- qga/commands-posix.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++ qga/guest-agent-core.h | 1 + qga/main.c | 48 ++++++++++++++++++++++++++++++++++- 3 files changed, 117 insertions(+), 1 deletion(-) diff --git a/qga/commands-posix.c b/qga/commands-posix.c index 614a421ffd..77f6ee7d5f 100644 --- a/qga/commands-posix.c +++ b/qga/commands-posix.c @@ -410,6 +410,66 @@ static void build_fs_mount_list(FsMountList *mounts, Error **err) #if defined(CONFIG_FSFREEZE) +typedef enum { + FSFREEZE_HOOK_THAW = 0, + FSFREEZE_HOOK_FREEZE, +} FsfreezeHookArg; + +const char *fsfreeze_hook_arg_string[] = { + "thaw", + "freeze", +}; + +static void execute_fsfreeze_hook(FsfreezeHookArg arg, Error **err) +{ + int status; + pid_t pid; + const char *hook; + const char *arg_str = fsfreeze_hook_arg_string[arg]; + Error *local_err = NULL; + + hook = ga_fsfreeze_hook(ga_state); + if (!hook) { + return; + } + if (access(hook, X_OK) != 0) { + error_setg_errno(err, errno, "can't access fsfreeze hook '%s'", hook); + return; + } + + slog("executing fsfreeze hook with arg '%s'", arg_str); + 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_str, NULL, environ); + _exit(EXIT_FAILURE); + } else if (pid < 0) { + error_setg_errno(err, errno, "failed to create child process"); + return; + } + + ga_wait_child(pid, &status, &local_err); + if (error_is_set(&local_err)) { + error_propagate(err, local_err); + return; + } + + if (!WIFEXITED(status)) { + error_setg(err, "fsfreeze hook has terminated abnormally"); + return; + } + + status = WEXITSTATUS(status); + if (status) { + error_setg(err, "fsfreeze hook has failed with status %d", status); + return; + } +} + /* * Return status of freeze/thaw */ @@ -436,6 +496,12 @@ int64_t qmp_guest_fsfreeze_freeze(Error **err) slog("guest-fsfreeze called"); + execute_fsfreeze_hook(FSFREEZE_HOOK_FREEZE, &local_err); + if (error_is_set(&local_err)) { + error_propagate(err, local_err); + return -1; + } + QTAILQ_INIT(&mounts); build_fs_mount_list(&mounts, &local_err); if (error_is_set(&local_err)) { @@ -537,6 +603,9 @@ int64_t qmp_guest_fsfreeze_thaw(Error **err) ga_unset_frozen(ga_state); free_fs_mount_list(&mounts); + + execute_fsfreeze_hook(FSFREEZE_HOOK_THAW, err); + return i; } diff --git a/qga/guest-agent-core.h b/qga/guest-agent-core.h index 8934163375..3354598362 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); diff --git a/qga/main.c b/qga/main.c index ba5fa1c778..a9b968c507 100644 --- a/qga/main.c +++ b/qga/main.c @@ -34,6 +34,12 @@ #include "qga/service-win32.h" #include #endif +#ifdef __linux__ +#include +#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 +165,16 @@ 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" +" enable fsfreeze hook. Accepts an optional argument that\n" +" specifies script to run on freeze/thaw. Script will be\n" +" called with 'freeze'/'thaw' arguments accordingly.\n" +" (default is %s)\n" +" If using -F with an argument, do not follow -F with a\n" +" space.\n" +" (for example: -F/var/run/fsfreezehook.sh)\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 +189,9 @@ static void usage(const char *cmd) "\n" "Report bugs to \n" , cmd, QEMU_VERSION, QGA_VIRTIO_PATH_DEFAULT, QGA_PIDFILE_DEFAULT, +#ifdef CONFIG_FSFREEZE + QGA_FSFREEZE_HOOK_DEFAULT, +#endif QGA_STATEDIR_DEFAULT); } @@ -401,6 +426,13 @@ 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 +710,13 @@ 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 = NULL; +#endif const char *state_dir = QGA_STATEDIR_DEFAULT; #ifdef _WIN32 const char *service = NULL; @@ -691,6 +726,9 @@ int main(int argc, char **argv) { "version", 0, NULL, 'V' }, { "logfile", 1, NULL, 'l' }, { "pidfile", 1, NULL, 'f' }, +#ifdef CONFIG_FSFREEZE + { "fsfreeze-hook", 2, NULL, 'F' }, +#endif { "verbose", 0, NULL, 'v' }, { "method", 1, NULL, 'm' }, { "path", 1, NULL, 'p' }, @@ -723,6 +761,11 @@ int main(int argc, char **argv) case 'f': pid_filepath = optarg; break; +#ifdef CONFIG_FSFREEZE + case 'F': + fsfreeze_hook = optarg ? optarg : QGA_FSFREEZE_HOOK_DEFAULT; + break; +#endif case 't': state_dir = optarg; break; @@ -786,6 +829,9 @@ 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); -- cgit v1.2.3