From 26de229657b943b7a59ad79c387506f6f33ff963 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Fri, 6 Jan 2017 15:29:30 +0000 Subject: qga: add systemd socket activation support AF_UNIX and AF_VSOCK listen sockets can be passed in by systemd on startup. This allows systemd to manage the listen socket until the first client connects and between restarts. Advantages of socket activation are that parallel startup of network services becomes possible and that unused daemons do not consume memory. The key to achieving this is the LISTEN_FDS environment variable, which is a stable ABI as shown here: https://www.freedesktop.org/wiki/Software/systemd/InterfacePortabilityAndStabilityChart/ We could link against libsystemd and use sd_listen_fds(3) but it's easy to implement the tiny LISTEN_FDS ABI so that qemu-ga does not depend on libsystemd. Some systems may not have systemd installed and wish to avoid the dependency. Other init systems or socket activation servers may implement the same ABI without systemd involvement. Test as follows: $ cat ~/.config/systemd/user/qga.service [Unit] Description=qga [Service] WorkingDirectory=/tmp ExecStart=/path/to/qemu-ga --logfile=/tmp/qga.log --pidfile=/tmp/qga.pid --statedir=/tmp $ cat ~/.config/systemd/user/qga.socket [Socket] ListenStream=/tmp/qga.sock [Install] WantedBy=default.target $ systemctl --user daemon-reload $ systemctl --user start qga.socket $ nc -U /tmp/qga.sock Signed-off-by: Stefan Hajnoczi Reviewed-by: Daniel P. Berrange Signed-off-by: Michael Roth --- qga/channel-posix.c | 68 ++++++++++++++++++++++++++---------------------- qga/channel-win32.c | 2 +- qga/channel.h | 3 ++- qga/main.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++++---- 4 files changed, 110 insertions(+), 37 deletions(-) diff --git a/qga/channel-posix.c b/qga/channel-posix.c index 71582e0..3f34465 100644 --- a/qga/channel-posix.c +++ b/qga/channel-posix.c @@ -118,14 +118,16 @@ static int ga_channel_client_add(GAChannel *c, int fd) return 0; } -static gboolean ga_channel_open(GAChannel *c, const gchar *path, GAChannelMethod method) +static gboolean ga_channel_open(GAChannel *c, const gchar *path, + GAChannelMethod method, int fd) { int ret; c->method = method; switch (c->method) { case GA_CHANNEL_VIRTIO_SERIAL: { - int fd = qemu_open(path, O_RDWR | O_NONBLOCK + assert(fd < 0); + fd = qemu_open(path, O_RDWR | O_NONBLOCK #ifndef CONFIG_SOLARIS | O_ASYNC #endif @@ -153,7 +155,9 @@ static gboolean ga_channel_open(GAChannel *c, const gchar *path, GAChannelMethod } case GA_CHANNEL_ISA_SERIAL: { struct termios tio; - int fd = qemu_open(path, O_RDWR | O_NOCTTY | O_NONBLOCK); + + assert(fd < 0); + fd = qemu_open(path, O_RDWR | O_NOCTTY | O_NONBLOCK); if (fd == -1) { g_critical("error opening channel: %s", strerror(errno)); return false; @@ -183,37 +187,41 @@ static gboolean ga_channel_open(GAChannel *c, const gchar *path, GAChannelMethod break; } case GA_CHANNEL_UNIX_LISTEN: { - Error *local_err = NULL; - int fd = unix_listen(path, NULL, strlen(path), &local_err); - if (local_err != NULL) { - g_critical("%s", error_get_pretty(local_err)); - error_free(local_err); - return false; + if (fd < 0) { + Error *local_err = NULL; + + fd = unix_listen(path, NULL, strlen(path), &local_err); + if (local_err != NULL) { + g_critical("%s", error_get_pretty(local_err)); + error_free(local_err); + return false; + } } ga_channel_listen_add(c, fd, true); break; } case GA_CHANNEL_VSOCK_LISTEN: { - Error *local_err = NULL; - SocketAddress *addr; - char *addr_str; - int fd; - - addr_str = g_strdup_printf("vsock:%s", path); - addr = socket_parse(addr_str, &local_err); - g_free(addr_str); - if (local_err != NULL) { - g_critical("%s", error_get_pretty(local_err)); - error_free(local_err); - return false; - } + if (fd < 0) { + Error *local_err = NULL; + SocketAddress *addr; + char *addr_str; - fd = socket_listen(addr, &local_err); - qapi_free_SocketAddress(addr); - if (local_err != NULL) { - g_critical("%s", error_get_pretty(local_err)); - error_free(local_err); - return false; + addr_str = g_strdup_printf("vsock:%s", path); + addr = socket_parse(addr_str, &local_err); + g_free(addr_str); + if (local_err != NULL) { + g_critical("%s", error_get_pretty(local_err)); + error_free(local_err); + return false; + } + + fd = socket_listen(addr, &local_err); + qapi_free_SocketAddress(addr); + if (local_err != NULL) { + g_critical("%s", error_get_pretty(local_err)); + error_free(local_err); + return false; + } } ga_channel_listen_add(c, fd, true); break; @@ -262,13 +270,13 @@ GIOStatus ga_channel_read(GAChannel *c, gchar *buf, gsize size, gsize *count) } GAChannel *ga_channel_new(GAChannelMethod method, const gchar *path, - GAChannelCallback cb, gpointer opaque) + int listen_fd, GAChannelCallback cb, gpointer opaque) { GAChannel *c = g_new0(GAChannel, 1); c->event_cb = cb; c->user_data = opaque; - if (!ga_channel_open(c, path, method)) { + if (!ga_channel_open(c, path, method, listen_fd)) { g_critical("error opening channel"); ga_channel_free(c); return NULL; diff --git a/qga/channel-win32.c b/qga/channel-win32.c index 21f9dee..7e6dc4d 100644 --- a/qga/channel-win32.c +++ b/qga/channel-win32.c @@ -316,7 +316,7 @@ static gboolean ga_channel_open(GAChannel *c, GAChannelMethod method, } GAChannel *ga_channel_new(GAChannelMethod method, const gchar *path, - GAChannelCallback cb, gpointer opaque) + int listen_fd, GAChannelCallback cb, gpointer opaque) { GAChannel *c = g_new0(GAChannel, 1); SECURITY_ATTRIBUTES sec_attrs; diff --git a/qga/channel.h b/qga/channel.h index 8fd0c8f..1778416 100644 --- a/qga/channel.h +++ b/qga/channel.h @@ -25,7 +25,8 @@ typedef enum { typedef gboolean (*GAChannelCallback)(GIOCondition condition, gpointer opaque); GAChannel *ga_channel_new(GAChannelMethod method, const gchar *path, - GAChannelCallback cb, gpointer opaque); + int listen_fd, GAChannelCallback cb, + gpointer opaque); void ga_channel_free(GAChannel *c); GIOStatus ga_channel_read(GAChannel *c, gchar *buf, gsize size, gsize *count); GIOStatus ga_channel_write_all(GAChannel *c, const gchar *buf, gsize size); diff --git a/qga/main.c b/qga/main.c index 538e4ee..675ef81 100644 --- a/qga/main.c +++ b/qga/main.c @@ -28,6 +28,7 @@ #include "qga/channel.h" #include "qemu/bswap.h" #include "qemu/help_option.h" +#include "qemu/sockets.h" #ifdef _WIN32 #include "qga/service-win32.h" #include "qga/vss-win32.h" @@ -184,6 +185,37 @@ void reopen_fd_to_null(int fd) } #endif +/** + * get_listen_fd: + * @consume: true to prevent future calls from succeeding + * + * Fetch a listen file descriptor that was passed via systemd socket + * activation. Use @consume to prevent child processes from thinking a file + * descriptor was passed. + * + * Returns: file descriptor or -1 if no fd was passed + */ +static int get_listen_fd(bool consume) +{ +#ifdef _WIN32 + return -1; /* no fd passing expected, unsetenv(3) not available */ +#else + const char *listen_fds = getenv("LISTEN_FDS"); + int fd = STDERR_FILENO + 1; + + if (!listen_fds || strcmp(listen_fds, "1") != 0) { + return -1; + } + + if (consume) { + unsetenv("LISTEN_FDS"); + } + + qemu_set_cloexec(fd); + return fd; +#endif /* !_WIN32 */ +} + static void usage(const char *cmd) { printf( @@ -648,7 +680,8 @@ static gboolean channel_event_cb(GIOCondition condition, gpointer data) return true; } -static gboolean channel_init(GAState *s, const gchar *method, const gchar *path) +static gboolean channel_init(GAState *s, const gchar *method, const gchar *path, + int listen_fd) { GAChannelMethod channel_method; @@ -666,7 +699,8 @@ static gboolean channel_init(GAState *s, const gchar *method, const gchar *path) return false; } - s->channel = ga_channel_new(channel_method, path, channel_event_cb, s); + s->channel = ga_channel_new(channel_method, path, listen_fd, + channel_event_cb, s); if (!s->channel) { g_critical("failed to create guest agent channel"); return false; @@ -1025,7 +1059,9 @@ static void config_dump(GAConfig *config) g_key_file_set_boolean(keyfile, "general", "daemon", config->daemonize); g_key_file_set_string(keyfile, "general", "method", config->method); - g_key_file_set_string(keyfile, "general", "path", config->channel_path); + if (config->channel_path) { + g_key_file_set_string(keyfile, "general", "path", config->channel_path); + } if (config->log_filepath) { g_key_file_set_string(keyfile, "general", "logfile", config->log_filepath); @@ -1294,7 +1330,9 @@ static int run_agent(GAState *s, GAConfig *config) #endif s->main_loop = g_main_loop_new(NULL, false); - if (!channel_init(ga_state, config->method, config->channel_path)) { + + if (!channel_init(ga_state, config->method, config->channel_path, + get_listen_fd(true))) { g_critical("failed to initialize guest agent channel"); return EXIT_FAILURE; } @@ -1318,6 +1356,7 @@ int main(int argc, char **argv) int ret = EXIT_SUCCESS; GAState *s = g_new0(GAState, 1); GAConfig *config = g_new0(GAConfig, 1); + int listen_fd; config->log_level = G_LOG_LEVEL_ERROR | G_LOG_LEVEL_CRITICAL; @@ -1339,7 +1378,32 @@ int main(int argc, char **argv) config->method = g_strdup("virtio-serial"); } - if (config->channel_path == NULL) { + listen_fd = get_listen_fd(false); + if (listen_fd >= 0) { + SocketAddress *addr; + + g_free(config->method); + g_free(config->channel_path); + config->method = NULL; + config->channel_path = NULL; + + addr = socket_local_address(listen_fd, NULL); + if (addr) { + if (addr->type == SOCKET_ADDRESS_KIND_UNIX) { + config->method = g_strdup("unix-listen"); + } else if (addr->type == SOCKET_ADDRESS_KIND_VSOCK) { + config->method = g_strdup("vsock-listen"); + } + + qapi_free_SocketAddress(addr); + } + + if (!config->method) { + g_critical("unsupported listen fd type"); + ret = EXIT_FAILURE; + goto end; + } + } else if (config->channel_path == NULL) { if (strcmp(config->method, "virtio-serial") == 0) { /* try the default path for the virtio-serial port */ config->channel_path = g_strdup(QGA_VIRTIO_PATH_DEFAULT); -- cgit v1.1 From ce2eb6c4a044d809caf4dc4e08aed77678f9760e Mon Sep 17 00:00:00 2001 From: Peter Lieven Date: Tue, 31 Jan 2017 16:36:34 +0100 Subject: qga: ignore EBUSY when freezing a filesystem the current implementation fails if we try to freeze an already frozen filesystem. This can happen if a filesystem is mounted more than once (e.g. with a bind mount). Suggested-by: Christian Theune Cc: qemu-stable@nongnu.org Signed-off-by: Peter Lieven Reviewed-by: Paolo Bonzini Signed-off-by: Michael Roth --- qga/commands-posix.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/qga/commands-posix.c b/qga/commands-posix.c index ea37c09..73d93eb 100644 --- a/qga/commands-posix.c +++ b/qga/commands-posix.c @@ -1243,6 +1243,9 @@ int64_t qmp_guest_fsfreeze_freeze_list(bool has_mountpoints, * filesystems may not implement fsfreeze for less obvious reasons. * these will report EOPNOTSUPP. we simply ignore these when tallying * the number of frozen filesystems. + * if a filesystem is mounted more than once (aka bind mount) a + * consecutive attempt to freeze an already frozen filesystem will + * return EBUSY. * * any other error means a failure to freeze a filesystem we * expect to be freezable, so return an error in those cases @@ -1250,7 +1253,7 @@ int64_t qmp_guest_fsfreeze_freeze_list(bool has_mountpoints, */ ret = ioctl(fd, FIFREEZE); if (ret == -1) { - if (errno != EOPNOTSUPP) { + if (errno != EOPNOTSUPP && errno != EBUSY) { error_setg_errno(errp, errno, "failed to freeze %s", mount->dirname); close(fd); -- cgit v1.1 From ec72c0e271f2b13953079a4f4dadb49ac5910b54 Mon Sep 17 00:00:00 2001 From: Bruce Rogers Date: Thu, 2 Mar 2017 12:44:37 -0700 Subject: tests: check path to avoid a failing qga/get-vcpus test MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The qga/get-vcpus test fails in a simple chroot environment, as used in an openSUSE Build Service local build, so first check that the sysfs based path exists in order to avoid calling this test in an environment where it won't work right. Signed-off-by: Bruce Rogers Reviewed-by: Marc-André Lureau Signed-off-by: Michael Roth --- tests/test-qga.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/tests/test-qga.c b/tests/test-qga.c index 868b02a..9e6d19a 100644 --- a/tests/test-qga.c +++ b/tests/test-qga.c @@ -924,7 +924,9 @@ int main(int argc, char **argv) g_test_add_data_func("/qga/info", &fix, test_qga_info); g_test_add_data_func("/qga/network-get-interfaces", &fix, test_qga_network_get_interfaces); - g_test_add_data_func("/qga/get-vcpus", &fix, test_qga_get_vcpus); + if (!access("/sys/devices/system/cpu/cpu0", F_OK)) { + g_test_add_data_func("/qga/get-vcpus", &fix, test_qga_get_vcpus); + } g_test_add_data_func("/qga/get-fsinfo", &fix, test_qga_get_fsinfo); g_test_add_data_func("/qga/get-memory-block-info", &fix, test_qga_get_memory_block_info); -- cgit v1.1