| Message ID | 20121113045656.2645.88398.stgit@melchior2.sdl.hitachi.co.jp |
|---|---|
| State | New |
| Headers | show |
On Tue, Nov 13, 2012 at 01:56:56PM +0900, Tomoki Sekiyama wrote: > 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.qu@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" Small nit, but can we change this to --fsfreeze-hook? > +" 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 <mdroth@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; > } > Rather than passing freeze/thaw in as a string, I think an enum parameter of the form: typedef enum { FSFREEZE_HOOK_THAW, FSFREEZE_HOOK_FREEZE, } FsfreezeHook; would be better in terms of documenting the interface. > +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"); > + I think if a user configures a pre-freeze hook, it's failure should be treated as a failure of the fsfreeze call in general, otherwise we risk moving forward based on false assumptions that can lead to data loss or other issues. I think the thaw hook is okay the way it is though, they can review the logs for any issues arising after the VM is unfrozen. > 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); >
Hi Michael, Thanks for your review. On 2012/11/21 6:00, mdroth wrote: > On Tue, Nov 13, 2012 at 01:56:56PM +0900, Tomoki Sekiyama wrote: >> 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.qu@hitachi.com> >> --- <snip> >> 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" > > Small nit, but can we change this to --fsfreeze-hook? Ah, sure. >> 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; >> } >> > > Rather than passing freeze/thaw in as a string, I think an enum > parameter of the form: > > typedef enum { > FSFREEZE_HOOK_THAW, > FSFREEZE_HOOK_FREEZE, > } FsfreezeHook; > > would be better in terms of documenting the interface. Okey, I will use enum as the argument. >> +static void execute_fsfreeze_hook(const char *arg) <snip> >> /* >> * 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"); >> + > > I think if a user configures a pre-freeze hook, it's failure should be > treated as a failure of the fsfreeze call in general, otherwise we risk > moving forward based on false assumptions that can lead to data loss or > other issues. I think the thaw hook is okay the way it is though, they > can review the logs for any issues arising after the VM is > unfrozen. I think that is reasonable. It would be better to notify the failure of fsfreeze hook to the host side for investigation of the issue. I will fix these in the next patchset. Thanks,
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 <mdroth@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);
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.qu@hitachi.com> --- qemu-ga.c | 42 +++++++++++++++++++++++++++++++++++++++++- qga/commands-posix.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ qga/guest-agent-core.h | 1 + 3 files changed, 86 insertions(+), 1 deletion(-)