cgroups: fix broken support for deprecated ns cgroup

when using ns cgroup, use /cgroup/<init-cgroup> rather than
/cgroup/<init-cgroup>/lxc

At least lxc-start, lxc-stop, lxc-cgroup, lxc-console and lxc-ls work
with this patch.  I've tested this in a 2.6.35 kernel with ns cgroup,
and in a 3.2 kernel without ns cgroup.

Note also that because of the check for container reboot support,
if we're using the ns cgroup we now end up with a /cgroup/<container>/2
cgroup created, empty, by the clone(CLONE_NEWPID).  I'm really not
sure how much time we want to spend cleaning such things up since
ns cgroup is deprecated in kernel.

Signed-off-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>

diff --git a/src/lxc/cgroup.c b/src/lxc/cgroup.c
index cc3910a4c37ef977ea0946dc8299a4b0c2b5fab9..9af199d320713a4dd035112af51d20f34edf5581 100644 (file)
--- a/src/lxc/cgroup.c
+++ b/src/lxc/cgroup.c
@@ -137,6 +137,21 @@ found:
        return dsg;
 }
 
+static int get_cgroup_flags(struct mntent *mntent)
+{
+       int flags = 0;
+
+
+       if (hasmntopt(mntent, "ns"))
+               flags |= CGROUP_NS_CGROUP;
+
+       if (hasmntopt(mntent, "clone_children"))
+               flags |= CGROUP_CLONE_CHILDREN;
+
+       DEBUG("cgroup %s has flags 0x%x", mntent->mnt_dir, flags);
+       return flags;
+}
+
 static int get_cgroup_mount(const char *subsystem, char *mnt)
 {
        struct mntent *mntent;
@@ -155,10 +170,12 @@ static int get_cgroup_mount(const char *subsystem, char *mnt)
                        continue;
                if (!subsystem || hasmntopt_multiple(mntent, subsystem)) {
                        int ret;
-                       ret = snprintf(mnt, MAXPATHLEN, "%s%s/lxc",
+                       int flags = get_cgroup_flags(mntent);
+                       ret = snprintf(mnt, MAXPATHLEN, "%s%s%s",
                                       mntent->mnt_dir,
                                       get_init_cgroup(subsystem, NULL,
-                                                      initcgroup));
+                                                      initcgroup),
+                                      (flags & CGROUP_NS_CGROUP) ? "" : "/lxc");
                        if (ret < 0 || ret >= MAXPATHLEN)
                                goto fail;
                        fclose(file);
@@ -183,33 +200,26 @@ int lxc_ns_is_mounted(void)
        return (get_cgroup_mount("ns", buf) == 0);
 }
 
-static int get_cgroup_flags(struct mntent *mntent)
-{
-       int flags = 0;
-
-
-       if (hasmntopt(mntent, "ns"))
-               flags |= CGROUP_NS_CGROUP;
-
-       if (hasmntopt(mntent, "clone_children"))
-               flags |= CGROUP_CLONE_CHILDREN;
-
-       DEBUG("cgroup %s has flags 0x%x", mntent->mnt_dir, flags);
-       return flags;
-}
-
 static int cgroup_rename_nsgroup(const char *mnt, const char *name, pid_t pid)
 {
        char oldname[MAXPATHLEN];
+       char newname[MAXPATHLEN];
+       int ret;
+
+       ret = snprintf(oldname, MAXPATHLEN, "%s/%d", mnt, pid);
+       if (ret >= MAXPATHLEN)
+               return -1;
 
-       snprintf(oldname, MAXPATHLEN, "%s/%d", mnt, pid);
+       ret = snprintf(newname, MAXPATHLEN, "%s/%s", mnt, name);
+       if (ret >= MAXPATHLEN)
+               return -1;
 
-       if (rename(oldname, name)) {
-               SYSERROR("failed to rename cgroup %s->%s", oldname, name);
+       if (rename(oldname, newname)) {
+               SYSERROR("failed to rename cgroup %s->%s", oldname, newname);
                return -1;
        }
 
-       DEBUG("'%s' renamed to '%s'", oldname, name);
+       DEBUG("'%s' renamed to '%s'", oldname, newname);
 
        return 0;
 }
@@ -321,7 +331,7 @@ static int lxc_one_cgroup_create(const char *name,
        /* Do we have the deprecated ns_cgroup subsystem? */
        if (flags & CGROUP_NS_CGROUP) {
                WARN("using deprecated ns_cgroup");
-               return cgroup_rename_nsgroup(cgparent, cgname, pid);
+               return cgroup_rename_nsgroup(cginit, name, pid);
        }
 
        ret = snprintf(clonechild, MAXPATHLEN, "%s/cgroup.clone_children",
@@ -464,9 +474,11 @@ int lxc_one_cgroup_destroy(struct mntent *mntent, const char *name)
 {
        char cgname[MAXPATHLEN], initcgroup[MAXPATHLEN];
        char *cgmnt = mntent->mnt_dir;
+       int flags = get_cgroup_flags(mntent);
 
-       snprintf(cgname, MAXPATHLEN, "%s%s/lxc/%s", cgmnt,
-               get_init_cgroup(NULL, mntent, initcgroup), name);
+       snprintf(cgname, MAXPATHLEN, "%s%s%s/%s", cgmnt,
+               get_init_cgroup(NULL, mntent, initcgroup),
+               (flags & CGROUP_NS_CGROUP) ? "" : "/lxc", name);
        DEBUG("destroying %s\n", cgname);
        if (recursive_rmdir(cgname)) {
                SYSERROR("failed to remove cgroup '%s'", cgname);

diff --git a/src/lxc/lxc-ls.in b/src/lxc/lxc-ls.in
index d200509d09ef08d8d80fc005e04a16718fae68f0..a1ad6423c182988087c1165f44913e63755512ad 100644 (file)
--- a/src/lxc/lxc-ls.in
+++ b/src/lxc/lxc-ls.in
@@ -33,7 +33,11 @@ if test -n "$active"; then
        if test -n "$mount_point"; then
                # get cgroup for init
                init_cgroup=`cat /proc/1/cgroup | awk -F: '{ print $3 }' | head -1`
-               cd $mount_point/$init_cgroup/lxc
+               if [ ! -d $mount_point/$init_cgroup/lxc  ]; then
+                       cd $mount_point/$init_cgroup
+               else
+                       cd $mount_point/$init_cgroup/lxc
+               fi
                ls "$@" -d $active
        fi
 fi