core: always create /user and /machine top-level cgroup dirs

This allows clients to put inotify watches on these trees to watch for
state changes, without having to wait until these dirs are created.

This introduces the new top-level /machine cgroup dir as canonical
location where OS containers and VMs shall be located (as discussed with
the libvirt folks).

diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index b07bd7e6be16556dda6579515d2b71a240cbcdee..a248252bcdb26c1eb12000237410ae200d0587df 100644 (file)
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -40,7 +40,7 @@ int cgroup_bonding_realize(CGroupBonding *b) {
         assert(b->path);
         assert(b->controller);
 
-        r = cg_create(b->controller, b->path);
+        r = cg_create(b->controller, b->path, NULL);
         if (r < 0) {
                 log_warning("Failed to create cgroup %s:%s: %s", b->controller, b->path, strerror(-r));
                 return r;
@@ -319,9 +319,9 @@ int cgroup_bonding_is_empty_list(CGroupBonding *first) {
 }
 
 int manager_setup_cgroup(Manager *m) {
-        char *current = NULL, *path = NULL;
+        _cleanup_free_ char *current = NULL, *path = NULL;
         int r;
-        char suffix[32];
+        char suffix[sizeof("/systemd-") + DECIMAL_STR_MAX(pid_t)];
 
         assert(m);
 
@@ -335,7 +335,7 @@ int manager_setup_cgroup(Manager *m) {
         r = cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, 0, &current);
         if (r < 0) {
                 log_error("Cannot determine cgroup we are running in: %s", strerror(-r));
-                goto finish;
+                return r;
         }
 
         if (m->running_as == SYSTEMD_SYSTEM)
@@ -354,35 +354,35 @@ int manager_setup_cgroup(Manager *m) {
         } else {
                 /* We need a new root cgroup */
                 m->cgroup_hierarchy = NULL;
-                if (asprintf(&m->cgroup_hierarchy, "%s%s", streq(current, "/") ? "" : current, suffix) < 0) {
-                        r = log_oom();
-                        goto finish;
-                }
+                if (asprintf(&m->cgroup_hierarchy, "%s%s", streq(current, "/") ? "" : current, suffix) < 0)
+                        return log_oom();
         }
 
         /* 2. Show data */
         r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, m->cgroup_hierarchy, NULL, &path);
         if (r < 0) {
                 log_error("Cannot find cgroup mount point: %s", strerror(-r));
-                goto finish;
+                return r;
         }
 
         log_debug("Using cgroup controller " SYSTEMD_CGROUP_CONTROLLER ". File system hierarchy is at %s.", path);
 
         /* 3. Install agent */
-        r = cg_install_release_agent(SYSTEMD_CGROUP_CONTROLLER, SYSTEMD_CGROUP_AGENT_PATH);
-        if (r < 0)
-                log_warning("Failed to install release agent, ignoring: %s", strerror(-r));
-        else if (r > 0)
-                log_debug("Installed release agent.");
-        else
-                log_debug("Release agent already installed.");
+        if (m->running_as == SYSTEMD_SYSTEM) {
+                r = cg_install_release_agent(SYSTEMD_CGROUP_CONTROLLER, SYSTEMD_CGROUP_AGENT_PATH);
+                if (r < 0)
+                        log_warning("Failed to install release agent, ignoring: %s", strerror(-r));
+                else if (r > 0)
+                        log_debug("Installed release agent.");
+                else
+                        log_debug("Release agent already installed.");
+        }
 
         /* 4. Realize the group */
         r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, m->cgroup_hierarchy, 0);
         if (r < 0) {
                 log_error("Failed to create root cgroup hierarchy: %s", strerror(-r));
-                goto finish;
+                return r;
         }
 
         /* 5. And pin it, so that it cannot be unmounted */
@@ -392,19 +392,21 @@ int manager_setup_cgroup(Manager *m) {
         m->pin_cgroupfs_fd = open(path, O_RDONLY|O_CLOEXEC|O_DIRECTORY|O_NOCTTY|O_NONBLOCK);
         if (r < 0) {
                 log_error("Failed to open pin file: %m");
-                r = -errno;
-                goto finish;
+                return -errno;
         }
 
-        log_debug("Created root group.");
-
+        /* 6. Remove non-existing controllers from the default controllers list */
         cg_shorten_controllers(m->default_controllers);
 
-finish:
-        free(current);
-        free(path);
+        /* 7. Let's create the user and machine hierarchies
+         * right-away, so that people can inotify on them, if they
+         * wish, without this being racy. */
+        if (m->running_as == SYSTEMD_SYSTEM) {
+                cg_create(SYSTEMD_CGROUP_CONTROLLER, m->cgroup_hierarchy, "../user");
+                cg_create(SYSTEMD_CGROUP_CONTROLLER, m->cgroup_hierarchy, "../machine");
+        }
 
-        return r;
+        return 0;
 }
 
 void manager_shutdown_cgroup(Manager *m, bool delete) {

diff --git a/src/login/logind-session.c b/src/login/logind-session.c
index e2f41d3e575e81d988d1cb216cbb814edaf1a6a6..da7ce42015cac814cbf7e22d86ee545ae97dbce8 100644 (file)
--- a/src/login/logind-session.c
+++ b/src/login/logind-session.c
@@ -442,9 +442,9 @@ static int session_create_one_group(Session *s, const char *controller, const ch
         if (s->leader > 0) {
                 r = cg_create_and_attach(controller, path, s->leader);
                 if (r < 0)
-                        r = cg_create(controller, path);
+                        r = cg_create(controller, path, NULL);
         } else
-                r = cg_create(controller, path);
+                r = cg_create(controller, path, NULL);
 
         if (r < 0)
                 return r;

diff --git a/src/login/logind-user.c b/src/login/logind-user.c
index 411215a92534cbbb466115840e5967ba6b778640..4b0ac5e7370335fe13411bb285508c3340ce2670 100644 (file)
--- a/src/login/logind-user.c
+++ b/src/login/logind-user.c
@@ -320,7 +320,7 @@ static int user_create_cgroup(User *u) {
         } else
                 p = u->cgroup_path;
 
-        r = cg_create(SYSTEMD_CGROUP_CONTROLLER, p);
+        r = cg_create(SYSTEMD_CGROUP_CONTROLLER, p, NULL);
         if (r < 0) {
                 log_error("Failed to create cgroup "SYSTEMD_CGROUP_CONTROLLER":%s: %s", p, strerror(-r));
                 free(p);
@@ -335,7 +335,7 @@ static int user_create_cgroup(User *u) {
                 if (strv_contains(u->manager->reset_controllers, *k))
                         continue;
 
-                r = cg_create(*k, p);
+                r = cg_create(*k, p, NULL);
                 if (r < 0)
                         log_warning("Failed to create cgroup %s:%s: %s", *k, p, strerror(-r));
         }

diff --git a/src/shared/cgroup-label.c b/src/shared/cgroup-label.c
index 995e4c57cd4fa3f745b0dafa6e6d155c039e6222..a0b486e51ef8dab8fb83ff09e3eba016a8bc8960 100644 (file)
--- a/src/shared/cgroup-label.c
+++ b/src/shared/cgroup-label.c
@@ -36,14 +36,14 @@
 #include "util.h"
 #include "mkdir.h"
 
-int cg_create(const char *controller, const char *path) {
+int cg_create(const char *controller, const char *path, const char *suffix) {
         _cleanup_free_ char *fs = NULL;
         int r;
 
         assert(controller);
         assert(path);
 
-        r = cg_get_path_and_check(controller, path, NULL, &fs);
+        r = cg_get_path_and_check(controller, path, suffix, &fs);
         if (r < 0)
                 return r;
 
@@ -69,7 +69,7 @@ int cg_create_and_attach(const char *controller, const char *path, pid_t pid) {
         assert(path);
         assert(pid >= 0);
 
-        r = cg_create(controller, path);
+        r = cg_create(controller, path, NULL);
         if (r < 0)
                 return r;
 

diff --git a/src/shared/cgroup-util.h b/src/shared/cgroup-util.h
index 123f72c69ffc875fe40bcbe416f3bfbf467c15c6..274380aa2df54c284ea4a75653f9662a0eab8fbc 100644 (file)
--- a/src/shared/cgroup-util.h
+++ b/src/shared/cgroup-util.h
@@ -55,7 +55,7 @@ int cg_trim(const char *controller, const char *path, bool delete_root);
 int cg_rmdir(const char *controller, const char *path, bool honour_sticky);
 int cg_delete(const char *controller, const char *path);
 
-int cg_create(const char *controller, const char *path);
+int cg_create(const char *controller, const char *path, const char *suffix);
 int cg_attach(const char *controller, const char *path, pid_t pid);
 int cg_create_and_attach(const char *controller, const char *path, pid_t pid);
 

diff --git a/src/test/test-cgroup.c b/src/test/test-cgroup.c
index 96aca1f7de8127930197b5ffc965fd41eb5a054f..2f7cc9be0a5d5744272c16c4b3c7245e6030a2e7 100644 (file)
--- a/src/test/test-cgroup.c
+++ b/src/test/test-cgroup.c
@@ -31,10 +31,10 @@ int main(int argc, char*argv[]) {
         char *path;
         char *c, *p;
 
-        assert_se(cg_create(SYSTEMD_CGROUP_CONTROLLER, "/test-a") == 0);
-        assert_se(cg_create(SYSTEMD_CGROUP_CONTROLLER, "/test-a") == 0);
-        assert_se(cg_create(SYSTEMD_CGROUP_CONTROLLER, "/test-b") == 0);
-        assert_se(cg_create(SYSTEMD_CGROUP_CONTROLLER, "/test-b/test-c") == 0);
+        assert_se(cg_create(SYSTEMD_CGROUP_CONTROLLER, "/test-a", NULL) == 0);
+        assert_se(cg_create(SYSTEMD_CGROUP_CONTROLLER, "/test-a", NULL) == 0);
+        assert_se(cg_create(SYSTEMD_CGROUP_CONTROLLER, "/test-b", NULL) == 0);
+        assert_se(cg_create(SYSTEMD_CGROUP_CONTROLLER, "/test-b/test-c", NULL) == 0);
         assert_se(cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, "/test-b", 0) == 0);
 
         assert_se(cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, getpid(), &path) == 0);