mdmon: --switch-root
For raid rootfs we cannot run the array unmonitored for any length of time. At least XFS will not mount/replay the journal if the underlying block device is readonly (FIXME it also seems that XFS does not always honor the ro status of the backing device as I was able to hit the BUG_ON(mddev->ro == 1) in md_write_start... but I digress). So we need to start mdmon in the initramfs before '/' is mounted and then restart it after the real rootfs is available. Upon seeing the --switch-root option, mdmon will kill any victims in the current /var/run/mdadm directory and then chroot(2) before continuing. The option is deliberately called 'switch-root' instead of 'chroot' to hopefully indicate that this is different than doing "chroot mdmon /dev/imsm". Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams
parent
883a6142e6
commit
13047e4c07
147
mdmon.c
147
mdmon.c
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@ -38,6 +38,7 @@
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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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@ -233,7 +234,11 @@ static int do_fork(void)
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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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@ -245,20 +250,34 @@ int main(int argc, char *argv[])
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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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if (argc != 2) {
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fprintf(stderr, "Usage: md-manage /device/name/for/container\n");
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exit(2);
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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(argv[1], O_RDWR);
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mdfd = open(container_name, O_RDWR);
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if (mdfd < 0) {
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fprintf(stderr, "md-manage: %s: %s\n", argv[1],
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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, "md-manage: %s: Not an md device\n",
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argv[1]);
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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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@ -286,12 +305,53 @@ int main(int argc, char *argv[])
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}
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} else
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pfd[0] = pfd[1] = -1;
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/* hopefully it is a container - we'll check later */
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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 = argv[1];
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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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@ -313,9 +373,28 @@ int main(int argc, char *argv[])
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act.sa_handler = SIG_IGN;
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sigaction(SIGPIPE, &act, NULL);
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/* If this fails, we hope it already exists */
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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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/* pid file lives in /var/run/mdadm/mdXX.pid */
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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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@ -341,50 +420,11 @@ int main(int argc, char *argv[])
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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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container->arrays = NULL;
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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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argv[1]);
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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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argv[1]);
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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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argv[1], 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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if (container->ss->load_super(container, mdfd, argv[1])) {
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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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argv[1]);
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container_name);
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exit(3);
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}
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@ -396,7 +436,6 @@ int main(int argc, char *argv[])
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getppid());
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close(pfd[1]);
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ignore = chdir("/");
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setsid();
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close(0);
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open("/dev/null", O_RDWR);
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