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From 3f2044cb5764c6cf568f7b016a5a1e639dcab129 Mon Sep 17 00:00:00 2001
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From: Serge Hallyn <serge.hallyn@ubuntu.com>
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Date: Mon, 17 Feb 2014 15:01:05 -0600
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Subject: [PATCH 1/1] allow passing in extra mounts
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cgroup mounts like the 'none,name=systemd' mount do not show up in
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/proc/cgroups. So allow the user to specify a list of such unbound
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cgroup subsystems to mount. I.e.
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cgmanager -m name=systemd,name=yyy
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Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
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cgmanager.c | 13 +++++-
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fs.c | 149 ++++++++++++++++++++++++++++++++++++++++++------------------
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3 files changed, 117 insertions(+), 47 deletions(-)
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diff --git a/cgmanager.c b/cgmanager.c
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index e203da1..6fe428a 100644
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@@ -604,6 +604,15 @@ int get_tasks_main(void *parent, const char *controller, const char *cgroup,
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return file_read_pids(parent, path, pids);
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+char *extra_cgroup_mounts;
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+my_setter (NihOption *option, const char *arg)
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+ extra_cgroup_mounts = NIH_MUST( strdup(arg) );
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@@ -611,6 +620,8 @@ int get_tasks_main(void *parent, const char *controller, const char *cgroup,
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* Command-line options accepted by this program.
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static NihOption options[] = {
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+ { 'm', "mount", N_("Extra subsystems to mount"),
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+ NULL, "subsystems to mount", NULL, my_setter },
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{ 0, "daemon", N_("Detach and run in the background"),
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NULL, NULL, &daemonise, NULL },
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@@ -708,7 +719,7 @@ main (int argc, char *argv[])
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nih_assert (server != NULL);
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- if (setup_cgroup_mounts() < 0) {
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+ if (setup_cgroup_mounts(extra_cgroup_mounts) < 0) {
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nih_fatal ("Failed to set up cgroup mounts");
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diff --git a/fs.c b/fs.c
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index 313a6c2..b6dd4fd 100644
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@@ -122,6 +122,79 @@ static void set_use_hierarchy(const char *path)
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+static bool do_mount_subsys(char *s)
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+ struct controller_mounts *tmp;
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+ char *src, dest[MAXPATHLEN], *controller;
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+ size_t len = strlen(s);
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+ if (len > MAXPATHLEN) {
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+ nih_fatal("bad controller type: %s", s);
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+ if ((controller = strchr(s, '='))) {
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+ /* this is something like 'name=systemd' */
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+ src = alloca(len+6);
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+ /* so for controller we want 'systemd' */
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+ /* and for source we want "none,name=systemd" */
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+ snprintf(src, len+6, "none,%s", s);
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+ ret = snprintf(dest, MAXPATHLEN, "%s/%s", base_path, src);
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+ if (ret < 0 || ret >= MAXPATHLEN) {
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+ nih_fatal("Error calculating pathname for %s and %s", base_path, src);
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+ if (mkdir(dest, 0755) < 0 && errno != EEXIST) {
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+ nih_fatal("Failed to create %s: %s", dest, strerror(errno));
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+ if ((ret = mount(src, dest, "cgroup", 0, src)) < 0) {
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+ nih_fatal("Failed mounting %s: %s", s, strerror(errno));
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+ tmp = realloc(all_mounts, (num_controllers+1) * sizeof(*all_mounts));
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+ nih_fatal("Out of memory mounting controllers");
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+ all_mounts[num_controllers].controller = strdup(controller);
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+ if (!all_mounts[num_controllers].controller) {
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+ nih_fatal("Out of memory mounting controllers");
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+ all_mounts[num_controllers].options = NULL;
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+ all_mounts[num_controllers].path = strdup(dest);
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+ if (!all_mounts[num_controllers].path) {
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+ nih_fatal("Out of memory mounting controllers");
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+ nih_info(_("Mounted %s onto %s"),
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+ all_mounts[num_controllers].controller,
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+ all_mounts[num_controllers].path);
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+ if (strcmp(all_mounts[num_controllers].controller, "cpuset") == 0) {
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+ set_clone_children(dest); // TODO make this optional?
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+ nih_info(_("set clone_children"));
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+ } else if (strcmp(all_mounts[num_controllers].controller, "memory") == 0) {
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+ set_use_hierarchy(dest); // TODO make this optional?
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+ nih_info(_("set memory.use_hierarchy"));
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* Mount the cgroup filesystems and record the information.
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* This should take configuration data from /etc. For now,
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@@ -134,7 +207,7 @@ static void set_use_hierarchy(const char *path)
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* . any mount options (per-controller)
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* . values for sane_behavior, use_hierarchy, and clone_children
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-int setup_cgroup_mounts(void)
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+int setup_cgroup_mounts(char *extra_mounts)
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@@ -148,14 +221,23 @@ int setup_cgroup_mounts(void)
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nih_fatal("Error setting up base cgroup path");
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+ if (extra_mounts) {
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+ for (e = strtok(extra_mounts, ","); e; e = strtok(NULL, ",")) {
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+ if (!do_mount_subsys(e)) {
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+ nih_fatal("Error loading subsystem \"%s\"", e);
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if ((cgf = fopen("/proc/cgroups", "r")) == NULL) {
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nih_fatal ("Error opening /proc/cgroups: %s", strerror(errno));
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while (fgets(line, 400, cgf)) {
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- struct controller_mounts *tmp;
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- char dest[MAXPATHLEN];
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@@ -172,50 +254,12 @@ int setup_cgroup_mounts(void)
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- ret = snprintf(dest, MAXPATHLEN, "%s/%s", base_path, line);
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- if (ret < 0 || ret >= MAXPATHLEN) {
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- nih_fatal("Error calculating pathname for %s and %s", base_path, line);
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- if (mkdir(dest, 0755) < 0 && errno != EEXIST) {
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- nih_fatal("Failed to create %s: %s", dest, strerror(errno));
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+ if (!do_mount_subsys(line)) {
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+ nih_fatal("Error mounting subsystem %s", line);
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- if ((ret = mount(line, dest, "cgroup", 0, line)) < 0) {
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- nih_fatal("Failed mounting %s: %s", line, strerror(errno));
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- tmp = realloc(all_mounts, (num_controllers+1) * sizeof(*all_mounts));
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- nih_fatal("Out of memory mounting controllers");
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- all_mounts[num_controllers].controller = strdup(line);
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- if (!all_mounts[num_controllers].controller) {
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- nih_fatal("Out of memory mounting controllers");
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- all_mounts[num_controllers].options = NULL;
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- all_mounts[num_controllers].path = strdup(dest);
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- if (!all_mounts[num_controllers].path) {
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- nih_fatal("Out of memory mounting controllers");
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- nih_info(_("Mounted %s onto %s"),
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- all_mounts[num_controllers].controller,
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- all_mounts[num_controllers].path);
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- if (strcmp(all_mounts[num_controllers].controller, "cpuset") == 0) {
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- set_clone_children(dest); // TODO make this optional?
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- nih_info(_("set clone_children"));
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- } else if (strcmp(all_mounts[num_controllers].controller, "memory") == 0) {
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- set_use_hierarchy(dest); // TODO make this optional?
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- nih_info(_("set memory.use_hierarchy"));
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nih_info(_("mounted %d controllers"), num_controllers);
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@@ -233,6 +277,21 @@ static inline void drop_newlines(char *s)
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+ * The user will pass in 'cpuset' or 'systemd'. /proc/self/cgroup will
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+ * show 'cpuset:' or 'name=systemd:'. We have to account for that.
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+static bool is_same_controller(const char *cmp, const char *cnt)
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+ if (strcmp(cmp, cnt) == 0)
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+ if (strncmp(cmp, "name=", 5) != 0)
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+ if (strcmp(cmp+5, cnt) == 0)
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* pid_cgroup: return the cgroup of @pid for @controller.
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* retv must be a (at least) MAXPATHLEN size buffer into
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* which the answer will be copied.
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@@ -258,7 +317,7 @@ static inline char *pid_cgroup(pid_t pid, const char *controller, char *retv)
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for (; (token = strtok_r(c1, ",", &saveptr)); c1 = NULL) {
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- if (strcmp(token, controller) != 0)
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+ if (!is_same_controller(token, controller))
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if (strlen(c2+1) + 1 > MAXPATHLEN) {
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nih_error("cgroup name too long");
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diff --git a/fs.h b/fs.h
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index 3322e62..b5d3868 100644
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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-int setup_cgroup_mounts(void);
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+int setup_cgroup_mounts(char *extra_mounts);
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bool compute_pid_cgroup(pid_t pid, const char *controller, const char *cgroup, char *path);
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bool may_access(pid_t pid, uid_t uid, gid_t gid, const char *path, int mode);
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void get_pid_creds(pid_t pid, uid_t *uid, gid_t *gid);
added
removed
debian/patches/0005-allow-passing-in-extra-mounts.patch
