mirror of https://gitee.com/openkylin/libvirt.git
Replace LXC cgroup mount code with call to virCgroupIsolateMount
The LXC driver currently has code to detect cgroups mounts and then re-mount them inside the new root filesystem. Replace this fragile code with a call to virCgroupIsolateMount. Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
This commit is contained in:
Daniel P. Berrange
parent
1da631ecf3
commit
ff66b45e2b
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@ -35,7 +35,6 @@
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#include <sys/stat.h>
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#include <unistd.h>
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#include <mntent.h>
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#include <dirent.h>
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#include <sys/reboot.h>
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#include <linux/reboot.h>
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@ -1735,227 +1734,6 @@ static int lxcContainerSetupAllHostdevs(virDomainDefPtr vmDef,
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}
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struct lxcContainerCGroup {
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const char *dir;
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const char *linkDest;
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};
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static void lxcContainerCGroupFree(struct lxcContainerCGroup *mounts,
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size_t nmounts)
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{
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size_t i;
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if (!mounts)
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return;
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for (i = 0 ; i < nmounts ; i++) {
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VIR_FREE(mounts[i].dir);
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VIR_FREE(mounts[i].linkDest);
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}
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VIR_FREE(mounts);
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}
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static int lxcContainerIdentifyCGroups(struct lxcContainerCGroup **mountsret,
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size_t *nmountsret,
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char **root)
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{
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FILE *procmnt = NULL;
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struct mntent mntent;
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struct dirent *dent;
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char mntbuf[1024];
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int ret = -1;
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struct lxcContainerCGroup *mounts = NULL;
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size_t nmounts = 0;
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DIR *dh = NULL;
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char *path = NULL;
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*mountsret = NULL;
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*nmountsret = 0;
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*root = NULL;
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VIR_DEBUG("Finding cgroups mount points of type cgroup");
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if (!(procmnt = setmntent("/proc/mounts", "r"))) {
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virReportSystemError(errno, "%s",
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_("Failed to read /proc/mounts"));
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return -1;
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}
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while (getmntent_r(procmnt, &mntent, mntbuf, sizeof(mntbuf)) != NULL) {
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VIR_DEBUG("Got %s", mntent.mnt_dir);
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if (STRNEQ(mntent.mnt_type, "cgroup"))
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continue;
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if (!*root) {
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char *tmp;
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if (!(*root = strdup(mntent.mnt_dir))) {
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virReportOOMError();
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goto cleanup;
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}
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tmp = strrchr(*root, '/');
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*tmp = '\0';
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} else if (!STRPREFIX(mntent.mnt_dir, *root)) {
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virReportError(VIR_ERR_INTERNAL_ERROR,
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_("Cgroup %s is not mounted under %s"),
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mntent.mnt_dir, *root);
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goto cleanup;
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}
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/* Skip named mounts with no controller since they're
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* for application use only ie systemd */
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if (strstr(mntent.mnt_opts, "name="))
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continue;
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if (VIR_EXPAND_N(mounts, nmounts, 1) < 0) {
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virReportOOMError();
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goto cleanup;
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}
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if (!(mounts[nmounts-1].dir = strdup(mntent.mnt_dir))) {
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virReportOOMError();
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goto cleanup;
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}
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VIR_DEBUG("Grabbed '%s'", mntent.mnt_dir);
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}
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if (!*root) {
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VIR_DEBUG("No mounted cgroups found");
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ret = 0;
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goto cleanup;
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}
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VIR_DEBUG("Checking for symlinks in %s", *root);
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if (!(dh = opendir(*root))) {
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virReportSystemError(errno,
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_("Unable to read directory %s"),
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*root);
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goto cleanup;
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}
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while ((dent = readdir(dh)) != NULL) {
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ssize_t rv;
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/* The cgroups links are just relative to the local
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* dir so we don't need a large buf */
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char linkbuf[100];
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if (dent->d_name[0] == '.')
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continue;
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VIR_DEBUG("Checking entry %s", dent->d_name);
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if (virAsprintf(&path, "%s/%s", *root, dent->d_name) < 0) {
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virReportOOMError();
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goto cleanup;
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}
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if ((rv = readlink(path, linkbuf, sizeof(linkbuf)-1)) < 0) {
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if (errno != EINVAL) {
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virReportSystemError(errno,
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_("Unable to resolve link %s"),
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path);
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VIR_FREE(path);
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goto cleanup;
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}
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/* Ok not a link */
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VIR_FREE(path);
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} else {
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linkbuf[rv] = '\0';
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VIR_DEBUG("Got a link %s to %s", path, linkbuf);
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if (VIR_EXPAND_N(mounts, nmounts, 1) < 0) {
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virReportOOMError();
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goto cleanup;
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}
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if (!(mounts[nmounts-1].linkDest = strdup(linkbuf))) {
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virReportOOMError();
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goto cleanup;
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}
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mounts[nmounts-1].dir = path;
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path = NULL;
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}
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}
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*mountsret = mounts;
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*nmountsret = nmounts;
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ret = 0;
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cleanup:
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closedir(dh);
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endmntent(procmnt);
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VIR_FREE(path);
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if (ret < 0) {
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lxcContainerCGroupFree(mounts, nmounts);
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VIR_FREE(*root);
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}
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return ret;
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}
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static int lxcContainerMountCGroups(struct lxcContainerCGroup *mounts,
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size_t nmounts,
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const char *root,
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char *sec_mount_options)
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{
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size_t i;
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char *opts = NULL;
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VIR_DEBUG("Mounting cgroups at '%s'", root);
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if (virFileMakePath(root) < 0) {
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virReportSystemError(errno,
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_("Unable to create directory %s"),
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root);
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return -1;
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}
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if (virAsprintf(&opts,
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"mode=755,size=65536%s", sec_mount_options) < 0) {
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virReportOOMError();
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return -1;
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}
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if (mount("tmpfs", root, "tmpfs", MS_NOSUID|MS_NODEV|MS_NOEXEC, opts) < 0) {
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VIR_FREE(opts);
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virReportSystemError(errno,
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_("Failed to mount %s on %s type %s"),
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"tmpfs", root, "tmpfs");
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return -1;
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}
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VIR_FREE(opts);
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for (i = 0 ; i < nmounts ; i++) {
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if (mounts[i].linkDest) {
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VIR_DEBUG("Link mount point '%s' to '%s'",
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mounts[i].dir, mounts[i].linkDest);
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if (symlink(mounts[i].linkDest, mounts[i].dir) < 0) {
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virReportSystemError(errno,
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_("Unable to symlink directory %s to %s"),
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mounts[i].dir, mounts[i].linkDest);
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return -1;
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}
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} else {
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VIR_DEBUG("Create mount point '%s'", mounts[i].dir);
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if (virFileMakePath(mounts[i].dir) < 0) {
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virReportSystemError(errno,
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_("Unable to create directory %s"),
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mounts[i].dir);
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return -1;
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}
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if (mount("cgroup", mounts[i].dir, "cgroup",
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0, mounts[i].dir + strlen(root) + 1) < 0) {
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virReportSystemError(errno,
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_("Failed to mount cgroup on '%s'"),
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mounts[i].dir);
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return -1;
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}
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}
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}
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return 0;
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}
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/* Got a FS mapped to /, we're going the pivot_root
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* approach to do a better-chroot-than-chroot
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* this is based on this thread http://lkml.org/lkml/2008/3/5/29
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@ -1966,10 +1744,9 @@ static int lxcContainerSetupPivotRoot(virDomainDefPtr vmDef,
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size_t nttyPaths,
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virSecurityManagerPtr securityDriver)
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{
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struct lxcContainerCGroup *mounts = NULL;
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size_t nmounts = 0;
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virCgroupPtr cgroup = NULL;
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int rc;
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int ret = -1;
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char *cgroupRoot = NULL;
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char *sec_mount_options;
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if (!(sec_mount_options = virSecurityManagerGetMountOptions(securityDriver, vmDef)))
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@ -1977,8 +1754,11 @@ static int lxcContainerSetupPivotRoot(virDomainDefPtr vmDef,
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/* Before pivoting we need to identify any
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* cgroups controllers that are mounted */
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if (lxcContainerIdentifyCGroups(&mounts, &nmounts, &cgroupRoot) < 0)
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if ((rc = virCgroupNewSelf(&cgroup)) != 0) {
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virReportSystemError(-rc, "%s",
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_("Cannot identify cgroup placement"));
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goto cleanup;
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}
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/* Ensure the root filesystem is mounted */
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if (lxcContainerPrepareRoot(vmDef, root) < 0)
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@ -2017,8 +1797,7 @@ static int lxcContainerSetupPivotRoot(virDomainDefPtr vmDef,
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/* Now we can re-mount the cgroups controllers in the
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* same configuration as before */
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if (lxcContainerMountCGroups(mounts, nmounts,
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cgroupRoot, sec_mount_options) < 0)
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if (virCgroupIsolateMount(cgroup, "/.oldroot/", sec_mount_options) < 0)
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goto cleanup;
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/* Mounts /dev/pts */
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@ -2048,8 +1827,7 @@ static int lxcContainerSetupPivotRoot(virDomainDefPtr vmDef,
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ret = 0;
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cleanup:
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lxcContainerCGroupFree(mounts, nmounts);
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VIR_FREE(cgroupRoot);
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virCgroupFree(&cgroup);
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VIR_FREE(sec_mount_options);
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return ret;
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}
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