diff options
Diffstat (limited to 'mdmon.c')
| -rw-r--r-- | mdmon.c | 600 |
1 files changed, 600 insertions, 0 deletions
diff --git a/mdmon.c b/mdmon.c new file mode 100644 index 00000000..27045a12 --- /dev/null +++ b/mdmon.c @@ -0,0 +1,600 @@ +/* + * mdmon - monitor external metadata arrays + * + * Copyright (C) 2007-2009 Neil Brown <neilb@suse.de> + * Copyright (C) 2007-2009 Intel Corporation + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along with + * this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. + */ + +/* + * md array manager. + * When md arrays have user-space managed metadata, this is the program + * that does the managing. + * + * Given one argument: the name of the array (e.g. /dev/md0) that is + * the container. + * We fork off a helper that runs high priority and mlocked. It responds to + * device failures and other events that might stop writeout, or that are + * trivial to deal with. + * The main thread then watches for new arrays being created in the container + * and starts monitoring them too ... along with a few other tasks. + * + * The main thread communicates with the priority thread by writing over + * a pipe. + * Separate programs can communicate with the main thread via Unix-domain + * socket. + * The two threads share address space and open file table. + * + */ + +#ifndef _GNU_SOURCE +#define _GNU_SOURCE +#endif + +#include <unistd.h> +#include <stdlib.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/socket.h> +#include <sys/un.h> +#include <sys/mman.h> +#include <sys/syscall.h> +#include <sys/wait.h> +#include <stdio.h> +#include <errno.h> +#include <string.h> +#include <fcntl.h> +#include <signal.h> +#include <dirent.h> +#ifdef USE_PTHREADS +#include <pthread.h> +#else +#include <sched.h> +#endif + +#include "mdadm.h" +#include "mdmon.h" + +struct active_array *discard_this; +struct active_array *pending_discard; + +int mon_tid, mgr_tid; + +int sigterm; + +#ifdef USE_PTHREADS +static void *run_child(void *v) +{ + struct supertype *c = v; + + mon_tid = syscall(SYS_gettid); + do_monitor(c); + return 0; +} + +static int clone_monitor(struct supertype *container) +{ + pthread_attr_t attr; + pthread_t thread; + int rc; + + mon_tid = -1; + pthread_attr_init(&attr); + pthread_attr_setstacksize(&attr, 4096); + pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); + rc = pthread_create(&thread, &attr, run_child, container); + if (rc) + return rc; + while (mon_tid == -1) + usleep(10); + pthread_attr_destroy(&attr); + + mgr_tid = syscall(SYS_gettid); + + return mon_tid; +} +#else /* USE_PTHREADS */ +static int run_child(void *v) +{ + struct supertype *c = v; + + do_monitor(c); + return 0; +} + +#ifdef __ia64__ +int __clone2(int (*fn)(void *), + void *child_stack_base, size_t stack_size, + int flags, void *arg, ... + /* pid_t *pid, struct user_desc *tls, pid_t *ctid */ ); +#endif +static int clone_monitor(struct supertype *container) +{ + static char stack[4096]; + +#ifdef __ia64__ + mon_tid = __clone2(run_child, stack, sizeof(stack), + CLONE_FS|CLONE_FILES|CLONE_VM|CLONE_SIGHAND|CLONE_THREAD, + container); +#else + mon_tid = clone(run_child, stack+4096-64, + CLONE_FS|CLONE_FILES|CLONE_VM|CLONE_SIGHAND|CLONE_THREAD, + container); +#endif + + mgr_tid = syscall(SYS_gettid); + + return mon_tid; +} +#endif /* USE_PTHREADS */ + +static int make_pidfile(char *devname) +{ + char path[100]; + char pid[10]; + int fd; + int n; + + if (mkdir(MDMON_DIR, 0755) < 0 && + errno != EEXIST) + return -errno; + sprintf(path, "%s/%s.pid", MDMON_DIR, devname); + + fd = open(path, O_RDWR|O_CREAT|O_EXCL, 0600); + if (fd < 0) + return -errno; + sprintf(pid, "%d\n", getpid()); + n = write(fd, pid, strlen(pid)); + close(fd); + if (n < 0) + return -errno; + return 0; +} + +static void try_kill_monitor(pid_t pid, char *devname, int sock) +{ + char buf[100]; + int fd; + int n; + long fl; + + /* first rule of survival... don't off yourself */ + if (pid == getpid()) + return; + + /* kill this process if it is mdmon */ + sprintf(buf, "/proc/%lu/cmdline", (unsigned long) pid); + fd = open(buf, O_RDONLY); + if (fd < 0) + return; + + n = read(fd, buf, sizeof(buf)-1); + buf[sizeof(buf)-1] = 0; + close(fd); + + if (n < 0 || !(strstr(buf, "mdmon") || + strstr(buf, "@dmon"))) + return; + + kill(pid, SIGTERM); + + if (sock < 0) + return; + + /* Wait for monitor to exit by reading from the socket, after + * clearing the non-blocking flag */ + fl = fcntl(sock, F_GETFL, 0); + fl &= ~O_NONBLOCK; + fcntl(sock, F_SETFL, fl); + n = read(sock, buf, 100); + /* Ignore result, it is just the wait that + * matters + */ +} + +void remove_pidfile(char *devname) +{ + char buf[100]; + + sprintf(buf, "%s/%s.pid", MDMON_DIR, devname); + unlink(buf); + sprintf(buf, "%s/%s.sock", MDMON_DIR, devname); + unlink(buf); +} + +static int make_control_sock(char *devname) +{ + char path[100]; + int sfd; + long fl; + struct sockaddr_un addr; + + if (sigterm) + return -1; + + sprintf(path, "%s/%s.sock", MDMON_DIR, devname); + unlink(path); + sfd = socket(PF_LOCAL, SOCK_STREAM, 0); + if (sfd < 0) + return -1; + + addr.sun_family = PF_LOCAL; + strcpy(addr.sun_path, path); + umask(077); /* ensure no world write access */ + if (bind(sfd, &addr, sizeof(addr)) < 0) { + close(sfd); + return -1; + } + listen(sfd, 10); + fl = fcntl(sfd, F_GETFL, 0); + fl |= O_NONBLOCK; + fcntl(sfd, F_SETFL, fl); + return sfd; +} + +static void term(int sig) +{ + sigterm = 1; +} + +static void wake_me(int sig) +{ + +} + +/* if we are debugging and starting mdmon by hand then don't fork */ +static int do_fork(void) +{ + #ifdef DEBUG + if (check_env("MDADM_NO_MDMON")) + return 0; + #endif + + return 1; +} + +void usage(void) +{ + fprintf(stderr, +"Usage: mdmon [options] CONTAINER\n" +"\n" +"Options are:\n" +" --help -h : This message\n" +" --all -a : All devices\n" +" --foreground -F : Run in foreground (do not fork)\n" +" --takeover -t : Takeover container\n" +); + exit(2); +} + +static int mdmon(char *devnm, int must_fork, int takeover); + +int main(int argc, char *argv[]) +{ + char *container_name = NULL; + char *devnm = NULL; + int status = 0; + int opt; + int all = 0; + int takeover = 0; + int dofork = 1; + static struct option options[] = { + {"all", 0, NULL, 'a'}, + {"takeover", 0, NULL, 't'}, + {"help", 0, NULL, 'h'}, + {"offroot", 0, NULL, OffRootOpt}, + {"foreground", 0, NULL, 'F'}, + {NULL, 0, NULL, 0} + }; + + if (in_initrd()) { + /* + * set first char of argv[0] to @. This is used by + * systemd to signal that the task was launched from + * initrd/initramfs and should be preserved during shutdown + */ + argv[0][0] = '@'; + } + + while ((opt = getopt_long(argc, argv, "thaF", options, NULL)) != -1) { + switch (opt) { + case 'a': + container_name = argv[optind-1]; + all = 1; + break; + case 't': + takeover = 1; + break; + case 'F': + dofork = 0; + break; + case OffRootOpt: + argv[0][0] = '@'; + break; + case 'h': + default: + usage(); + break; + } + } + + if (all == 0 && container_name == NULL) { + if (argv[optind]) + container_name = argv[optind]; + } + + if (container_name == NULL) + usage(); + + if (argc - optind > 1) + usage(); + + if (strcmp(container_name, "/proc/mdstat") == 0) + all = 1; + + if (all) { + struct mdstat_ent *mdstat, *e; + int container_len = strlen(container_name); + + /* launch an mdmon instance for each container found */ + mdstat = mdstat_read(0, 0); + for (e = mdstat; e; e = e->next) { + if (e->metadata_version && + strncmp(e->metadata_version, "external:", 9) == 0 && + !is_subarray(&e->metadata_version[9])) { + /* update cmdline so this mdmon instance can be + * distinguished from others in a call to ps(1) + */ + if (strlen(e->devnm) <= (unsigned)container_len) { + memset(container_name, 0, container_len); + sprintf(container_name, "%s", e->devnm); + } + status |= mdmon(e->devnm, 1, takeover); + } + } + free_mdstat(mdstat); + + return status; + } else if (strncmp(container_name, "md", 2) == 0) { + int id = devnm2devid(container_name); + if (id) + devnm = container_name; + } else { + struct stat st; + + if (stat(container_name, &st) == 0) + devnm = xstrdup(stat2devnm(&st)); + } + + if (!devnm) { + pr_err("%s is not a valid md device name\n", + container_name); + exit(1); + } + return mdmon(devnm, dofork && do_fork(), takeover); +} + +static int mdmon(char *devnm, int must_fork, int takeover) +{ + int mdfd; + struct mdinfo *mdi, *di; + struct supertype *container; + sigset_t set; + struct sigaction act; + int pfd[2]; + int status; + int ignore; + pid_t victim = -1; + int victim_sock = -1; + + dprintf("starting mdmon for %s\n", devnm); + + mdfd = open_dev(devnm); + if (mdfd < 0) { + pr_err("%s: %s\n", devnm, strerror(errno)); + return 1; + } + if (md_get_version(mdfd) < 0) { + pr_err("%s: Not an md device\n", devnm); + return 1; + } + + /* Fork, and have the child tell us when they are ready */ + if (must_fork) { + if (pipe(pfd) != 0) { + pr_err("failed to create pipe\n"); + return 1; + } + switch(fork()) { + case -1: + pr_err("failed to fork: %s\n", strerror(errno)); + return 1; + case 0: /* child */ + close(pfd[0]); + break; + default: /* parent */ + close(pfd[1]); + if (read(pfd[0], &status, sizeof(status)) != sizeof(status)) { + wait(&status); + status = WEXITSTATUS(status); + } + close(pfd[0]); + return status; + } + } else + pfd[0] = pfd[1] = -1; + + container = xcalloc(1, sizeof(*container)); + strcpy(container->devnm, devnm); + container->arrays = NULL; + container->sock = -1; + + mdi = sysfs_read(mdfd, container->devnm, GET_VERSION|GET_LEVEL|GET_DEVS); + + if (!mdi) { + pr_err("failed to load sysfs info for %s\n", container->devnm); + exit(3); + } + if (mdi->array.level != UnSet) { + pr_err("%s is not a container - cannot monitor\n", devnm); + exit(3); + } + if (mdi->array.major_version != -1 || + mdi->array.minor_version != -2) { + pr_err("%s does not use external metadata - cannot monitor\n", + devnm); + exit(3); + } + + container->ss = version_to_superswitch(mdi->text_version); + if (container->ss == NULL) { + pr_err("%s uses unsupported metadata: %s\n", + devnm, mdi->text_version); + exit(3); + } + + container->devs = NULL; + for (di = mdi->devs; di; di = di->next) { + struct mdinfo *cd = xmalloc(sizeof(*cd)); + *cd = *di; + cd->next = container->devs; + container->devs = cd; + } + sysfs_free(mdi); + + /* SIGUSR is sent between parent and child. So both block it + * and enable it only with pselect. + */ + sigemptyset(&set); + sigaddset(&set, SIGUSR1); + sigaddset(&set, SIGTERM); + sigprocmask(SIG_BLOCK, &set, NULL); + act.sa_handler = wake_me; + act.sa_flags = 0; + sigaction(SIGUSR1, &act, NULL); + act.sa_handler = term; + sigaction(SIGTERM, &act, NULL); + act.sa_handler = SIG_IGN; + sigaction(SIGPIPE, &act, NULL); + + victim = mdmon_pid(container->devnm); + if (victim >= 0) + victim_sock = connect_monitor(container->devnm); + + ignore = chdir("/"); + if (!takeover && victim > 0 && victim_sock >= 0) { + if (fping_monitor(victim_sock) == 0) { + pr_err("%s already managed\n", container->devnm); + exit(3); + } + close(victim_sock); + victim_sock = -1; + } + if (container->ss->load_container(container, mdfd, devnm)) { + pr_err("Cannot load metadata for %s\n", devnm); + exit(3); + } + close(mdfd); + + /* Ok, this is close enough. We can say goodbye to our parent now. + */ + if (victim > 0) + remove_pidfile(devnm); + if (make_pidfile(devnm) < 0) { + exit(3); + } + container->sock = make_control_sock(devnm); + + status = 0; + if (pfd[1] >= 0) { + if (write(pfd[1], &status, sizeof(status)) < 0) + pr_err("failed to notify our parent: %d\n", + getppid()); + close(pfd[1]); + } + + mlockall(MCL_CURRENT | MCL_FUTURE); + + if (clone_monitor(container) < 0) { + pr_err("failed to start monitor process: %s\n", + strerror(errno)); + exit(2); + } + + if (victim > 0) { + try_kill_monitor(victim, container->devnm, victim_sock); + if (victim_sock >= 0) + close(victim_sock); + } + + setsid(); + close(0); + open("/dev/null", O_RDWR); + close(1); + ignore = dup(0); +#ifndef DEBUG + close(2); + ignore = dup(0); +#endif + + /* This silliness is to stop the compiler complaining + * that we ignore 'ignore' + */ + if (ignore) + ignore++; + + do_manager(container); + + exit(0); +} + +/* Some stub functions so super-* can link with us */ +int child_monitor(int afd, struct mdinfo *sra, struct reshape *reshape, + struct supertype *st, unsigned long blocks, + int *fds, unsigned long long *offsets, + int dests, int *destfd, unsigned long long *destoffsets) +{ + return 0; +} + +int restore_stripes(int *dest, unsigned long long *offsets, + int raid_disks, int chunk_size, int level, int layout, + int source, unsigned long long read_offset, + unsigned long long start, unsigned long long length, + char *src_buf) +{ + return 1; +} + +void abort_reshape(struct mdinfo *sra) +{ + return; +} + +int save_stripes(int *source, unsigned long long *offsets, + int raid_disks, int chunk_size, int level, int layout, + int nwrites, int *dest, + unsigned long long start, unsigned long long length, + char *buf) +{ + return 0; +} + +struct superswitch super0 = { + .name = "0.90", +}; +struct superswitch super1 = { + .name = "1.x", +}; |