tools/cgcreate: add support for default systemd delegation slice/scope

Enhance the cgcreate tool to support default systemd delegation
slice/scope, if set in the cgconfig.conf's systemd setting.  Parse the
configuration file and read the systemd::delegate setting, if
any, and set it as the default systemd slice/scope in
systemd_default_cgroup. Setting it appends the slice/scope
name to the constructed default cgroup mount path.

When the user passes the relative cgroup name, its appends to the
sub-tree (delegated slice/scope) by default and if the user wishes to
create a cgroup in another subtree or cgroup root hierarchy, they need
to use the absolute path. For example:

		  cgroup_root
		 /	    \
		/	     \
	 systemd.slice*      cgrp1
		|
	 systemd.scope
		|
	    cgrp-d1

* default system delegation slice/scope - read from cgconfig.conf
$ sudo cgcreate -g cpu:cgrp-d1

will create the cgroup under the cpu controller hirearchy
cgroup_root:systemd_default_cgroup:cgrp-d1

and for creating a cgroup cgrp1, the user can use:
$ sudo cgcreate -g cpu:/cgrp1

or use the newly introduced -b switch to ignore the systemd slice/scope:
$ sudo cgcreate -b -g cpu:cgrp1

Signed-off-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>

diff --git a/src/tools/cgcreate.c b/src/tools/cgcreate.c
index 2ef8d9976639590a0259d139549cbadf91be5bed..5a3e0f48fd3e01091b6c6196d3b03d21b577ce49 100644 (file)
--- a/src/tools/cgcreate.c
+++ b/src/tools/cgcreate.c
@@ -41,6 +41,10 @@ static void usage(int status, const char *program_name)
        info("  -h, --help                      Display this help\n");
        info("  -s, --tperm=mode                Tasks file permissions\n");
        info("  -t <tuid>:<tgid>                Owner of the tasks file\n");
+#ifdef WITH_SYSTEMD
+       info("  -b                              Ignore default systemd ");
+       info("delegate hierarchy\n");
+#endif
 }
 
 int main(int argc, char *argv[])
@@ -59,6 +63,8 @@ int main(int argc, char *argv[])
        uid_t tuid = CGRULE_INVALID, auid = CGRULE_INVALID;
        gid_t tgid = CGRULE_INVALID, agid = CGRULE_INVALID;
 
+       int ignore_default_systemd_delegate_slice = 0;
+
        struct cgroup_group_spec **cgroup_list;
        struct cgroup_controller *cgc;
        struct cgroup *cgroup;
@@ -90,9 +96,17 @@ int main(int argc, char *argv[])
                goto err;
        }
 
+#ifdef WITH_SYSTEMD
        /* parse arguments */
+       while ((c = getopt_long(argc, argv, "a:t:g:hd:f:s:b", long_opts, NULL)) > 0) {
+               switch (c) {
+               case 'b':
+                       ignore_default_systemd_delegate_slice = 1;
+                       break;
+#else
        while ((c = getopt_long(argc, argv, "a:t:g:hd:f:s:", long_opts, NULL)) > 0) {
                switch (c) {
+#endif
                case 'h':
                        usage(0, argv[0]);
                        ret = 0;
@@ -155,6 +169,10 @@ int main(int argc, char *argv[])
                goto err;
        }
 
+       /* this is false always for disable-systemd */
+       if (!ignore_default_systemd_delegate_slice)
+               cgroup_set_default_systemd_cgroup();
+
        /* for each new cgroup */
        for (i = 0; i < capacity; i++) {
                if (!cgroup_list[i])