Merge branch 'efi-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[linux-2.6-block.git] / kernel / cgroup.c

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 909a7d31ffd3d3083c2253aefd4253715bcb2278..86cb5c6e89320f28e17691c6d69e58c9dfde81fb 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1215,6 +1215,41 @@ static void cgroup_destroy_root(struct cgroup_root *root)
        cgroup_free_root(root);
 }
 
+/*
+ * look up cgroup associated with current task's cgroup namespace on the
+ * specified hierarchy
+ */
+static struct cgroup *
+current_cgns_cgroup_from_root(struct cgroup_root *root)
+{
+       struct cgroup *res = NULL;
+       struct css_set *cset;
+
+       lockdep_assert_held(&css_set_lock);
+
+       rcu_read_lock();
+
+       cset = current->nsproxy->cgroup_ns->root_cset;
+       if (cset == &init_css_set) {
+               res = &root->cgrp;
+       } else {
+               struct cgrp_cset_link *link;
+
+               list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
+                       struct cgroup *c = link->cgrp;
+
+                       if (c->root == root) {
+                               res = c;
+                               break;
+                       }
+               }
+       }
+       rcu_read_unlock();
+
+       BUG_ON(!res);
+       return res;
+}
+
 /* look up cgroup associated with given css_set on the specified hierarchy */
 static struct cgroup *cset_cgroup_from_root(struct css_set *cset,
                                            struct cgroup_root *root)
@@ -1593,6 +1628,33 @@ static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
        return 0;
 }
 
+static int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
+                           struct kernfs_root *kf_root)
+{
+       int len = 0;
+       char *buf = NULL;
+       struct cgroup_root *kf_cgroot = cgroup_root_from_kf(kf_root);
+       struct cgroup *ns_cgroup;
+
+       buf = kmalloc(PATH_MAX, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
+       spin_lock_bh(&css_set_lock);
+       ns_cgroup = current_cgns_cgroup_from_root(kf_cgroot);
+       len = kernfs_path_from_node(kf_node, ns_cgroup->kn, buf, PATH_MAX);
+       spin_unlock_bh(&css_set_lock);
+
+       if (len >= PATH_MAX)
+               len = -ERANGE;
+       else if (len > 0) {
+               seq_escape(sf, buf, " \t\n\\");
+               len = 0;
+       }
+       kfree(buf);
+       return len;
+}
+
 static int cgroup_show_options(struct seq_file *seq,
                               struct kernfs_root *kf_root)
 {
@@ -5433,6 +5495,7 @@ static struct kernfs_syscall_ops cgroup_kf_syscall_ops = {
        .mkdir                  = cgroup_mkdir,
        .rmdir                  = cgroup_rmdir,
        .rename                 = cgroup_rename,
+       .show_path              = cgroup_show_path,
 };
 
 static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early)