diff options
Diffstat (limited to 'src/mountfsd/mountfsd-manager.c')
| -rw-r--r-- | src/mountfsd/mountfsd-manager.c | 277 |
1 files changed, 277 insertions, 0 deletions
diff --git a/src/mountfsd/mountfsd-manager.c b/src/mountfsd/mountfsd-manager.c new file mode 100644 index 0000000..b05c6e8 --- /dev/null +++ b/src/mountfsd/mountfsd-manager.c @@ -0,0 +1,277 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +#include <sys/wait.h> + +#include "sd-daemon.h" + +#include "build-path.h" +#include "common-signal.h" +#include "env-util.h" +#include "fd-util.h" +#include "fs-util.h" +#include "mkdir.h" +#include "mountfsd-manager.h" +#include "process-util.h" +#include "set.h" +#include "signal-util.h" +#include "socket-util.h" +#include "stdio-util.h" +#include "umask-util.h" + +#define LISTEN_TIMEOUT_USEC (25 * USEC_PER_SEC) + +static int start_workers(Manager *m, bool explicit_request); + +static size_t manager_current_workers(Manager *m) { + assert(m); + + return set_size(m->workers_fixed) + set_size(m->workers_dynamic); +} + +static int on_worker_exit(sd_event_source *s, const siginfo_t *si, void *userdata) { + Manager *m = ASSERT_PTR(userdata); + + assert(s); + + assert_se(!set_remove(m->workers_dynamic, s) != !set_remove(m->workers_fixed, s)); + sd_event_source_disable_unref(s); + + if (si->si_code == CLD_EXITED) { + if (si->si_status == EXIT_SUCCESS) + log_debug("Worker " PID_FMT " exited successfully.", si->si_pid); + else + log_warning("Worker " PID_FMT " died with a failure exit status %i, ignoring.", si->si_pid, si->si_status); + } else if (si->si_code == CLD_KILLED) + log_warning("Worker " PID_FMT " was killed by signal %s, ignoring.", si->si_pid, signal_to_string(si->si_status)); + else if (si->si_code == CLD_DUMPED) + log_warning("Worker " PID_FMT " dumped core by signal %s, ignoring.", si->si_pid, signal_to_string(si->si_status)); + else + log_warning("Got unexpected exit code via SIGCHLD, ignoring."); + + (void) start_workers(m, /* explicit_request= */ false); /* Fill up workers again if we fell below the low watermark */ + return 0; +} + +static int on_sigusr2(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata) { + Manager *m = ASSERT_PTR(userdata); + + (void) start_workers(m, /* explicit_request= */ true); /* Workers told us there's more work, let's add one more worker as long as we are below the high watermark */ + return 0; +} + +DEFINE_PRIVATE_HASH_OPS_WITH_KEY_DESTRUCTOR( + event_source_hash_ops, + sd_event_source, + (void (*)(const sd_event_source*, struct siphash*)) trivial_hash_func, + (int (*)(const sd_event_source*, const sd_event_source*)) trivial_compare_func, + sd_event_source_disable_unref); + +int manager_new(Manager **ret) { + _cleanup_(manager_freep) Manager *m = NULL; + int r; + + m = new(Manager, 1); + if (!m) + return -ENOMEM; + + *m = (Manager) { + .listen_fd = -EBADF, + .worker_ratelimit = { + .interval = 5 * USEC_PER_SEC, + .burst = 50, + }, + }; + + r = sd_event_new(&m->event); + if (r < 0) + return r; + + r = sd_event_set_signal_exit(m->event, true); + if (r < 0) + return r; + + r = sd_event_add_signal(m->event, NULL, (SIGRTMIN+18)|SD_EVENT_SIGNAL_PROCMASK, sigrtmin18_handler, NULL); + if (r < 0) + return r; + + r = sd_event_add_memory_pressure(m->event, NULL, NULL, NULL); + if (r < 0) + log_debug_errno(r, "Failed allocate memory pressure event source, ignoring: %m"); + + r = sd_event_set_watchdog(m->event, true); + if (r < 0) + log_debug_errno(r, "Failed to enable watchdog handling, ignoring: %m"); + + r = sd_event_add_signal(m->event, NULL, SIGUSR2|SD_EVENT_SIGNAL_PROCMASK, on_sigusr2, m); + if (r < 0) + return r; + + *ret = TAKE_PTR(m); + return 0; +} + +Manager* manager_free(Manager *m) { + if (!m) + return NULL; + + set_free(m->workers_fixed); + set_free(m->workers_dynamic); + + /* Note: we rely on PR_DEATHSIG to kill the workers for us */ + + sd_event_unref(m->event); + + return mfree(m); +} + +static int start_one_worker(Manager *m) { + _cleanup_(sd_event_source_disable_unrefp) sd_event_source *source = NULL; + bool fixed; + pid_t pid; + int r; + + assert(m); + + fixed = set_size(m->workers_fixed) < MOUNTFS_WORKERS_MIN; + + r = safe_fork_full( + "(sd-worker)", + /* stdio_fds= */ NULL, + &m->listen_fd, 1, + FORK_RESET_SIGNALS|FORK_DEATHSIG_SIGTERM|FORK_REOPEN_LOG|FORK_LOG|FORK_CLOSE_ALL_FDS, + &pid); + if (r < 0) + return log_error_errno(r, "Failed to fork new worker child: %m"); + if (r == 0) { + char pids[DECIMAL_STR_MAX(pid_t)]; + /* Child */ + + if (m->listen_fd == 3) { + r = fd_cloexec(3, false); + if (r < 0) { + log_error_errno(r, "Failed to turn off O_CLOEXEC for fd 3: %m"); + _exit(EXIT_FAILURE); + } + } else { + if (dup2(m->listen_fd, 3) < 0) { /* dup2() creates with O_CLOEXEC off */ + log_error_errno(errno, "Failed to move listen fd to 3: %m"); + _exit(EXIT_FAILURE); + } + + safe_close(m->listen_fd); + } + + xsprintf(pids, PID_FMT, pid); + if (setenv("LISTEN_PID", pids, 1) < 0) { + log_error_errno(errno, "Failed to set $LISTEN_PID: %m"); + _exit(EXIT_FAILURE); + } + + if (setenv("LISTEN_FDS", "1", 1) < 0) { + log_error_errno(errno, "Failed to set $LISTEN_FDS: %m"); + _exit(EXIT_FAILURE); + } + + if (setenv("MOUNTFS_FIXED_WORKER", one_zero(fixed), 1) < 0) { + log_error_errno(errno, "Failed to set $MOUNTFS_FIXED_WORKER: %m"); + _exit(EXIT_FAILURE); + } + + r = setenv_systemd_log_level(); + if (r < 0) { + log_error_errno(r, "Failed to set $SYSTEMD_LOG_LEVEL: %m"); + _exit(EXIT_FAILURE); + } + + r = invoke_callout_binary(SYSTEMD_MOUNTWORK_PATH, STRV_MAKE("systemd-mountwork", "xxxxxxxxxxxxxxxx")); /* With some extra space rename_process() can make use of */ + log_error_errno(r, "Failed start worker process: %m"); + _exit(EXIT_FAILURE); + } + + r = sd_event_add_child(m->event, &source, pid, WEXITED, on_worker_exit, m); + if (r < 0) + return log_error_errno(r, "Failed to watch child " PID_FMT ": %m", pid); + + r = set_ensure_put( + fixed ? &m->workers_fixed : &m->workers_dynamic, + &event_source_hash_ops, + source); + if (r < 0) + return log_error_errno(r, "Failed to add child process to set: %m"); + + TAKE_PTR(source); + + return 0; +} + +static int start_workers(Manager *m, bool explicit_request) { + int r; + + assert(m); + + for (;;) { + size_t n; + + n = manager_current_workers(m); + + log_debug("%zu workers running.", n); + + if (n >= MOUNTFS_WORKERS_MIN && (!explicit_request || n >= MOUNTFS_WORKERS_MAX)) + break; + + if (!ratelimit_below(&m->worker_ratelimit)) { + /* If we keep starting workers too often, let's fail the whole daemon, something is wrong */ + sd_event_exit(m->event, EXIT_FAILURE); + + return log_error_errno(SYNTHETIC_ERRNO(EUCLEAN), "Worker threads requested too frequently, something is wrong."); + } + + r = start_one_worker(m); + if (r < 0) + return r; + + explicit_request = false; + } + + return 0; +} + +int manager_startup(Manager *m) { + int n; + + assert(m); + assert(m->listen_fd < 0); + + n = sd_listen_fds(false); + if (n < 0) + return log_error_errno(n, "Failed to determine number of passed file descriptors: %m"); + if (n > 1) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Expected one listening fd, got %i.", n); + if (n == 1) + m->listen_fd = SD_LISTEN_FDS_START; + else { + static const union sockaddr_union sockaddr = { + .un.sun_family = AF_UNIX, + .un.sun_path = "/run/systemd/io.systemd.MountFileSystem", + }; + + m->listen_fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0); + if (m->listen_fd < 0) + return log_error_errno(errno, "Failed to bind on socket: %m"); + + (void) sockaddr_un_unlink(&sockaddr.un); + + WITH_UMASK(0000) + if (bind(m->listen_fd, &sockaddr.sa, SOCKADDR_UN_LEN(sockaddr.un)) < 0) + return log_error_errno(errno, "Failed to bind socket: %m"); + + if (listen(m->listen_fd, SOMAXCONN) < 0) + return log_error_errno(errno, "Failed to listen on socket: %m"); + } + + /* Let's make sure every accept() call on this socket times out after 25s. This allows workers to be + * GC'ed on idle */ + if (setsockopt(m->listen_fd, SOL_SOCKET, SO_RCVTIMEO, TIMEVAL_STORE(LISTEN_TIMEOUT_USEC), sizeof(struct timeval)) < 0) + return log_error_errno(errno, "Failed to se SO_RCVTIMEO: %m"); + + return start_workers(m, /* explicit_request= */ false); +} |