8aae4219a2
mdmon cannot remove the pidfile at shutdown becuase it needs to stay running across the "mount -o remount,ro /" event. When it relaunches after a reboot there is a good chance that the pid will match what was there previously. The result is that the "take over for unresponsive mdmon" logic results in self termination. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
465 lines
9.7 KiB
C
465 lines
9.7 KiB
C
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/*
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* md array manager.
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* When md arrays have user-space managed metadata, this is the program
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* that does the managing.
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*
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* Given one argument: the name of the array (e.g. /dev/md0) that is
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* the container.
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* We fork off a helper that runs high priority and mlocked. It responds to
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* device failures and other events that might stop writeout, or that are
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* trivial to deal with.
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* The main thread then watches for new arrays being created in the container
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* and starts monitoring them too ... along with a few other tasks.
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*
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* The main thread communicates with the priority thread by writing over
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* a pipe.
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* Separate programs can communicate with the main thread via Unix-domain
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* socket.
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* The two threads share address space and open file table.
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*
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*/
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#ifndef _GNU_SOURCE
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#define _GNU_SOURCE
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#endif
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#include <unistd.h>
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#include <stdlib.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/socket.h>
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#include <sys/un.h>
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#include <sys/mman.h>
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#include <sys/syscall.h>
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#include <sys/wait.h>
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#include <stdio.h>
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#include <errno.h>
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#include <string.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <dirent.h>
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#include <sched.h>
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#include "mdadm.h"
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#include "mdmon.h"
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struct active_array *discard_this;
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struct active_array *pending_discard;
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int mon_tid, mgr_tid;
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int sigterm;
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int run_child(void *v)
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{
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struct supertype *c = v;
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do_monitor(c);
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return 0;
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}
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int clone_monitor(struct supertype *container)
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{
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static char stack[4096];
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mon_tid = clone(run_child, stack+4096-64,
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CLONE_FS|CLONE_FILES|CLONE_VM|CLONE_SIGHAND|CLONE_THREAD,
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container);
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mgr_tid = syscall(SYS_gettid);
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return mon_tid;
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}
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static struct superswitch *find_metadata_methods(char *vers)
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{
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if (strcmp(vers, "ddf") == 0)
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return &super_ddf;
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if (strcmp(vers, "imsm") == 0)
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return &super_imsm;
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return NULL;
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}
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int make_pidfile(char *devname, int o_excl)
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{
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char path[100];
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char pid[10];
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int fd;
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int n;
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if (sigterm)
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return -1;
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sprintf(path, "/var/run/mdadm/%s.pid", devname);
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fd = open(path, O_RDWR|O_CREAT|o_excl, 0600);
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if (fd < 0)
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return -errno;
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sprintf(pid, "%d\n", getpid());
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n = write(fd, pid, strlen(pid));
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close(fd);
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if (n < 0)
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return -errno;
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return 0;
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}
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int is_container_member(struct mdstat_ent *mdstat, char *container)
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{
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if (mdstat->metadata_version == NULL ||
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strncmp(mdstat->metadata_version, "external:", 9) != 0 ||
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!is_subarray(mdstat->metadata_version+9) ||
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strncmp(mdstat->metadata_version+10, container, strlen(container)) != 0 ||
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mdstat->metadata_version[10+strlen(container)] != '/')
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return 0;
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return 1;
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}
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void remove_pidfile(char *devname);
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static void try_kill_monitor(char *devname)
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{
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char buf[100];
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int fd;
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pid_t pid;
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struct mdstat_ent *mdstat;
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sprintf(buf, "/var/run/mdadm/%s.pid", devname);
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fd = open(buf, O_RDONLY);
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if (fd < 0)
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return;
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if (read(fd, buf, sizeof(buf)) < 0) {
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close(fd);
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return;
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}
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close(fd);
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pid = strtoul(buf, NULL, 10);
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/* first rule of survival... don't off yourself */
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if (pid == getpid())
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return;
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/* kill this process if it is mdmon */
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sprintf(buf, "/proc/%lu/cmdline", (unsigned long) pid);
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fd = open(buf, O_RDONLY);
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if (fd < 0)
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return;
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if (read(fd, buf, sizeof(buf)) < 0) {
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close(fd);
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return;
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}
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if (!strstr(buf, "mdmon"))
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return;
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kill(pid, SIGTERM);
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mdstat = mdstat_read(0, 0);
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for ( ; mdstat; mdstat = mdstat->next)
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if (is_container_member(mdstat, devname)) {
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sprintf(buf, "/dev/%s", mdstat->dev);
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WaitClean(buf, 0);
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}
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free_mdstat(mdstat);
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remove_pidfile(devname);
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}
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void remove_pidfile(char *devname)
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{
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char buf[100];
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if (sigterm)
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return;
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sprintf(buf, "/var/run/mdadm/%s.pid", devname);
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unlink(buf);
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sprintf(buf, "/var/run/mdadm/%s.sock", devname);
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unlink(buf);
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}
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int make_control_sock(char *devname)
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{
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char path[100];
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int sfd;
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long fl;
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struct sockaddr_un addr;
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if (sigterm)
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return -1;
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sprintf(path, "/var/run/mdadm/%s.sock", devname);
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unlink(path);
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sfd = socket(PF_LOCAL, SOCK_STREAM, 0);
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if (sfd < 0)
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return -1;
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addr.sun_family = PF_LOCAL;
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strcpy(addr.sun_path, path);
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if (bind(sfd, &addr, sizeof(addr)) < 0) {
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close(sfd);
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return -1;
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}
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listen(sfd, 10);
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fl = fcntl(sfd, F_GETFL, 0);
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fl |= O_NONBLOCK;
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fcntl(sfd, F_SETFL, fl);
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return sfd;
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}
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int socket_hup_requested;
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static void hup(int sig)
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{
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socket_hup_requested = 1;
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}
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static void term(int sig)
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{
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sigterm = 1;
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}
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static void wake_me(int sig)
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{
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}
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/* if we are debugging and starting mdmon by hand then don't fork */
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static int do_fork(void)
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{
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#ifdef DEBUG
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if (env_no_mdmon())
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return 0;
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#endif
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return 1;
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}
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void usage(void)
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{
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fprintf(stderr, "Usage: mdmon [--switch-root dir] /device/name/for/container\n");
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exit(2);
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}
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int main(int argc, char *argv[])
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{
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int mdfd;
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struct mdinfo *mdi, *di;
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struct supertype *container;
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sigset_t set;
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struct sigaction act;
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int pfd[2];
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int status;
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int ignore;
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char *container_name = NULL;
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char *switchroot = NULL;
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switch (argc) {
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case 2:
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container_name = argv[1];
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break;
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case 4:
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if (strcmp(argv[1], "--switch-root") != 0) {
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fprintf(stderr, "mdmon: unknown argument %s\n", argv[1]);
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usage();
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}
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switchroot = argv[2];
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container_name = argv[3];
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break;
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default:
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usage();
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}
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mdfd = open(container_name, O_RDWR);
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if (mdfd < 0) {
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fprintf(stderr, "mdmon: %s: %s\n", container_name,
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strerror(errno));
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exit(1);
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}
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if (md_get_version(mdfd) < 0) {
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fprintf(stderr, "mdmon: %s: Not an md device\n",
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container_name);
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exit(1);
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}
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/* Fork, and have the child tell us when they are ready */
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if (do_fork()) {
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if (pipe(pfd) != 0) {
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fprintf(stderr, "mdmon: failed to create pipe\n");
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exit(1);
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}
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switch(fork()) {
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case -1:
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fprintf(stderr, "mdmon: failed to fork: %s\n",
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strerror(errno));
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exit(1);
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case 0: /* child */
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close(pfd[0]);
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break;
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default: /* parent */
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close(pfd[1]);
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if (read(pfd[0], &status, sizeof(status)) != sizeof(status)) {
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wait(&status);
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status = WEXITSTATUS(status);
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}
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exit(status);
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}
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} else
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pfd[0] = pfd[1] = -1;
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container = malloc(sizeof(*container));
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container->devnum = fd2devnum(mdfd);
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container->devname = devnum2devname(container->devnum);
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container->device_name = container_name;
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container->arrays = NULL;
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if (!container->devname) {
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fprintf(stderr, "mdmon: failed to allocate container name string\n");
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exit(3);
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}
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mdi = sysfs_read(mdfd, container->devnum,
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GET_VERSION|GET_LEVEL|GET_DEVS);
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if (!mdi) {
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fprintf(stderr, "mdmon: failed to load sysfs info for %s\n",
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container->devname);
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exit(3);
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}
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if (mdi->array.level != UnSet) {
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fprintf(stderr, "mdmon: %s is not a container - cannot monitor\n",
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container_name);
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exit(3);
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}
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if (mdi->array.major_version != -1 ||
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mdi->array.minor_version != -2) {
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fprintf(stderr, "mdmon: %s does not use external metadata - cannot monitor\n",
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container_name);
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exit(3);
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}
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container->ss = find_metadata_methods(mdi->text_version);
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if (container->ss == NULL) {
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fprintf(stderr, "mdmon: %s uses unknown metadata: %s\n",
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container_name, mdi->text_version);
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exit(3);
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}
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container->devs = NULL;
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for (di = mdi->devs; di; di = di->next) {
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struct mdinfo *cd = malloc(sizeof(*cd));
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*cd = *di;
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cd->next = container->devs;
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container->devs = cd;
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}
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sysfs_free(mdi);
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/* SIGUSR is sent between parent and child. So both block it
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* and enable it only with pselect.
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*/
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sigemptyset(&set);
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sigaddset(&set, SIGUSR1);
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sigaddset(&set, SIGHUP);
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sigaddset(&set, SIGALRM);
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sigaddset(&set, SIGTERM);
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sigprocmask(SIG_BLOCK, &set, NULL);
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act.sa_handler = wake_me;
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act.sa_flags = 0;
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sigaction(SIGUSR1, &act, NULL);
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sigaction(SIGALRM, &act, NULL);
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act.sa_handler = hup;
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sigaction(SIGHUP, &act, NULL);
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act.sa_handler = term;
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sigaction(SIGTERM, &act, NULL);
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act.sa_handler = SIG_IGN;
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sigaction(SIGPIPE, &act, NULL);
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if (switchroot) {
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/* we assume we assume that /sys /proc /dev are available in
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* the new root (see nash:setuproot)
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*
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* kill any monitors in the current namespace and change
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* to the new one
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*/
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try_kill_monitor(container->devname);
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if (chroot(switchroot) != 0) {
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fprintf(stderr, "mdmon: failed to chroot to '%s': %s\n",
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switchroot, strerror(errno));
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exit(4);
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}
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}
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/* If this fails, we hope it already exists
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* pid file lives in /var/run/mdadm/mdXX.pid
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*/
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mkdir("/var", 0600);
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mkdir("/var/run", 0600);
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mkdir("/var/run/mdadm", 0600);
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ignore = chdir("/");
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if (make_pidfile(container->devname, O_EXCL) < 0) {
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if (ping_monitor(container->devname) == 0) {
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fprintf(stderr, "mdmon: %s already managed\n",
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container->devname);
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exit(3);
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} else {
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int err;
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/* cleanup the old monitor, this one is taking over */
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try_kill_monitor(container->devname);
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err = make_pidfile(container->devname, 0);
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if (err < 0) {
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fprintf(stderr, "mdmon: %s Cannot create pidfile\n",
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container->devname);
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if (err == -EROFS) {
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/* FIXME implement a mechanism to
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* prevent duplicate monitor instances
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*/
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fprintf(stderr,
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"mdmon: continuing on read-only file system\n");
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} else
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exit(3);
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}
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}
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}
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container->sock = make_control_sock(container->devname);
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if (container->ss->load_super(container, mdfd, container_name)) {
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fprintf(stderr, "mdmon: Cannot load metadata for %s\n",
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container_name);
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exit(3);
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}
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/* Ok, this is close enough. We can say goodbye to our parent now.
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*/
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status = 0;
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if (write(pfd[1], &status, sizeof(status)) < 0)
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fprintf(stderr, "mdmon: failed to notify our parent: %d\n",
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getppid());
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close(pfd[1]);
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setsid();
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close(0);
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open("/dev/null", O_RDWR);
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close(1);
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ignore = dup(0);
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#ifndef DEBUG
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close(2);
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ignore = dup(0);
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#endif
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mlockall(MCL_FUTURE);
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if (clone_monitor(container) < 0) {
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fprintf(stderr, "mdmon: failed to start monitor process: %s\n",
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strerror(errno));
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exit(2);
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}
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do_manager(container);
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exit(0);
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}
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