Re: [Qemu-devel] [PATCH 1/2] qemu-ga: execute script to quiesce the guest on fsfreeze-freeze/thaw

[Lei Li <lilei@linux.vnet.ibm.com>]

Hi Tomoki,

You should use the plain text format to send your patch. Otherwise
people will not be able to apply the patch. :)

On 11/08/2012 08:36 PM, 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 script specified
> in --fsfreeze-script option is executed with "freeze" argument before the
> filesystem is frozen. For fsfreeze-thaw command, the 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   | 34 ++++++++++++++++++++++++++++++++++
>   qga/guest-agent-core.h |  2 ++
>   3 files changed, 77 insertions(+), 1 deletion(-)
>
> diff --git a/qemu-ga.c b/qemu-ga.c
> index 9b59a52..7cb682e 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_SCRIPT_DEFAULT CONFIG_QEMU_CONFDIR "/fsfreeze.sh"
> +#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_script;
> +#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_script\n"
> +"                    specify fsfreeze script (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_SCRIPT_DEFAULT,
> +#endif
>       QGA_STATEDIR_DEFAULT);
>   }
>
> @@ -401,6 +420,13 @@ void ga_unset_frozen(GAState *s)
>       }
>   }
>
> +#ifdef CONFIG_FSFREEZE
> +const char *ga_fsfreeze_script(GAState *s)
> +{
> +    return s->fsfreeze_script;
> +}
> +#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_script = QGA_FSFREEZE_SCRIPT_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-script", 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_script = 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_script = fsfreeze_script;
> +#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..007c0a3 100644
> --- a/qga/commands-posix.c
> +++ b/qga/commands-posix.c
> @@ -13,6 +13,7 @@
>
>   #include <glib.h>
>   #include <sys/types.h>
> +#include <sys/stat.h>
>   #include <sys/ioctl.h>
>   #include <sys/wait.h>
>   #include "qga/guest-agent-core.h"
> @@ -396,6 +397,34 @@ GuestFsfreezeStatus qmp_guest_fsfreeze_status(Error **err)
>       return GUEST_FSFREEZE_STATUS_THAWED;
>   }
>
> +int execute_fsfreeze_script(const char *arg)
> +{
> +    int ret = -1;
> +    const char *fsfreeze_script;
> +    char *cmdline;
> +    struct stat st;
> +
> +    fsfreeze_script = ga_fsfreeze_script(ga_state);
> +    if (fsfreeze_script && stat(fsfreeze_script, &st) == 0) {
> +        if (S_ISREG(st.st_mode) && (st.st_mode & S_IXUSR)) {
> +            slog("executing fsfreeze script with arg `%s'", arg);
> +            cmdline = malloc(strlen(fsfreeze_script) + strlen(arg) + 2);
> +            if (cmdline) {
> +                sprintf(cmdline, "%s %s", fsfreeze_script, arg);
> +                ret = system(cmdline);
> +                free(cmdline);
> +            }
> +            if (ret > 0) {
> +                g_warning("fsfreeze script failed with status=%d", ret);
> +            } else if (ret == -1) {
> +                g_warning("execution of fsfreeze script failed: %s",
> +                          strerror(errno));
> +            }
> +        }
> +    }
> +    return ret;
> +}
> +
>   /*
>    * Walk list of mounted file systems in the guest, and freeze the ones which
>    * are real local file systems.
> @@ -410,6 +439,8 @@ int64_t qmp_guest_fsfreeze_freeze(Error **err)
>
>       slog("guest-fsfreeze called");
>
> +    execute_fsfreeze_script("freeze");
> +
>       QTAILQ_INIT(&mounts);
>       ret = build_fs_mount_list(&mounts);
>       if (ret < 0) {
> @@ -513,6 +544,9 @@ int64_t qmp_guest_fsfreeze_thaw(Error **err)
>
>       ga_unset_frozen(ga_state);
>       free_fs_mount_list(&mounts);
> +
> +    execute_fsfreeze_script("thaw");
> +
>       return i;
>   }
>
> diff --git a/qga/guest-agent-core.h b/qga/guest-agent-core.h
> index 49a7abe..b466bfd 100644
> --- a/qga/guest-agent-core.h
> +++ b/qga/guest-agent-core.h
> @@ -34,6 +34,8 @@ 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_script(GAState *s);
> +int execute_fsfreeze_script(const char *arg);
>
>   #ifndef _WIN32
>   void reopen_fd_to_null(int fd);


-- 
Lei