/*
* Make sure the 'cgroup group' exists, so that we don't have to worry about
* that later.
*
* @lxcgroup: the cgroup group, i.e. 'lxc' by default.
*
* See detailed comments at lxc_cgroup_path_create for more information.
*
* Returns 0 on success, -1 on error.
*/
static int create_lxcgroups(const char *lxcgroup)
{
FILE *file = NULL;
struct mntent *mntent;
int ret, retv = -1;
char path[MAXPATHLEN];
file = setmntent(MTAB, "r");
if (!file) {
SYSERROR("failed to open %s", MTAB);
return -1;
}
while ((mntent = getmntent(file))) {
if (strcmp(mntent->mnt_type, "cgroup"))
continue;
if (!mount_has_subsystem(mntent))
continue;
/*
* TODO - handle case where lxcgroup has subdirs? (i.e. build/l1)
* We probably only want to support that for /users/joe
*/
ret = snprintf(path, MAXPATHLEN, "%s/%s",
mntent->mnt_dir, lxcgroup ? lxcgroup : "lxc");
if (ret < 0 || ret >= MAXPATHLEN)
goto fail;
if (access(path, F_OK)) {
set_clone_children(mntent->mnt_dir);
ret = mkdir(path, 0755);
if (ret == -1 && errno != EEXIST) {
SYSERROR("failed to create '%s' directory", path);
goto fail;
}
}
}
retv = 0;
fail:
endmntent(file);
return retv;
}
/**
* Mount the cgroup filesystems and record the information.
* This should take configuration data from /etc. For now,
* Just mount all controllers, separately just as cgroup-lite
* does, and set the use_hierarchy and clone_children options.
*
* Things which should go into configuration file:
* . which controllers to mount
* . which controllers to co-mount
* . any mount options (per-controller)
* . values for sane_behavior, use_hierarchy, and clone_children
*/
int setup_cgroup_mounts(void)
{
FILE *cgf;
int ret;
char line[400];
if (unshare(CLONE_NEWNS) < 0) {
nih_fatal("Failed to unshare a private mount ns: %s", strerror(errno));
return -1;
}
if (!setup_base_path()) {
nih_fatal("Error setting up base cgroup path");
return -1;
}
if ((cgf = fopen("/proc/cgroups", "r")) == NULL) {
nih_fatal ("Error opening /proc/cgroups: %s", strerror(errno));
return -1;
}
while (fgets(line, 400, cgf)) {
char *p;
struct controller_mounts *tmp;
char dest[MAXPATHLEN];
unsigned long h;
if (line[0] == '#')
continue;
p = index(line, '\t');
if (!p)
continue;
*p = '\0';
h = strtoul(p+1, NULL, 10);
if (h) {
nih_info("%s was already mounted!", line);
#if STRICT
ret = -1;
goto out;
#endif
}
ret = snprintf(dest, MAXPATHLEN, "%s/%s", base_path, line);
if (ret < 0 || ret >= MAXPATHLEN) {
nih_fatal("Error calculating pathname for %s and %s", base_path, line);
goto out;
}
if (mkdir(dest, 0755) < 0 && errno != EEXIST) {
nih_fatal("Failed to create %s: %s", dest, strerror(errno));
ret = -1;
goto out;
}
if ((ret = mount(line, dest, "cgroup", 0, line)) < 0) {
nih_fatal("Failed mounting %s: %s", line, strerror(errno));
goto out;
}
ret = -1;
tmp = realloc(all_mounts, (num_controllers+1) * sizeof(*all_mounts));
if (!tmp) {
nih_fatal("Out of memory mounting controllers");
goto out;
}
all_mounts = tmp;
all_mounts[num_controllers].controller = strdup(line);
if (!all_mounts[num_controllers].controller) {
nih_fatal("Out of memory mounting controllers");
goto out;
}
all_mounts[num_controllers].options = NULL;
all_mounts[num_controllers].path = strdup(dest);
if (!all_mounts[num_controllers].path) {
nih_fatal("Out of memory mounting controllers");
goto out;
}
nih_info("Mounted %s onto %s",
all_mounts[num_controllers].controller,
all_mounts[num_controllers].path);
if (strcmp(all_mounts[num_controllers].controller, "cpuset") == 0) {
set_clone_children(dest); // TODO make this optional?
nih_info("set clone_children");
} else if (strcmp(all_mounts[num_controllers].controller, "memory") == 0) {
set_use_hierarchy(dest); // TODO make this optional?
nih_info("set memory.use_hierarchy");
}
num_controllers++;
}
nih_info("mounted %d controllers", num_controllers);
ret = 0;
out:
fclose(cgf);
return ret;
}