Merge branch 'for-3.15-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup fixes from Tejun Heo:
 "Two patches to fix fallouts from the kernfs conversion:

  Li's patch to stop leaking cgroup_root refs across multiple mounts and
  the other fixes the 90s hang during shutdown caused by always using
  root's uid/gid for new cgroup dirs and files."

* 'for-3.15-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: newly created dirs and files should be owned by the creator
  cgroup: fix top cgroup refcnt leak

1 files changed, 29 insertions, 3 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index fede3d3f28ff..9fcdaa705b6c 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1487,6 +1487,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
         struct cgroup_sb_opts opts;
         struct dentry *dentry;
         int ret;
+        bool new_sb;
 
         /*
          * The first time anyone tries to mount a cgroup, enable the list
@@ -1603,8 +1604,8 @@ out_unlock:
         if (ret)
                 return ERR_PTR(ret);
 
-        dentry = kernfs_mount(fs_type, flags, root->kf_root, NULL);
-        if (IS_ERR(dentry))
+        dentry = kernfs_mount(fs_type, flags, root->kf_root, &new_sb);
+        if (IS_ERR(dentry) || !new_sb)
                 cgroup_put(&root->cgrp);
         return dentry;
 }
@@ -2345,11 +2346,26 @@ static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
         return ret;
 }
 
+/* set uid and gid of cgroup dirs and files to that of the creator */
+static int cgroup_kn_set_ugid(struct kernfs_node *kn)
+{
+        struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID,
+                               .ia_uid = current_fsuid(),
+                               .ia_gid = current_fsgid(), };
+
+        if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) &&
+            gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID))
+                return 0;
+
+        return kernfs_setattr(kn, &iattr);
+}
+
 static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft)
 {
         char name[CGROUP_FILE_NAME_MAX];
         struct kernfs_node *kn;
         struct lock_class_key *key = NULL;
+        int ret;
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
         key = &cft->lockdep_key;
@@ -2357,7 +2373,13 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft)
         kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name),
                                   cgroup_file_mode(cft), 0, cft->kf_ops, cft,
                                   NULL, false, key);
-        return PTR_ERR_OR_ZERO(kn);
+        if (IS_ERR(kn))
+                return PTR_ERR(kn);
+
+        ret = cgroup_kn_set_ugid(kn);
+        if (ret)
+                kernfs_remove(kn);
+        return ret;
 }
 
 /**
@@ -3752,6 +3774,10 @@ static long cgroup_create(struct cgroup *parent, const char *name,
          */
         idr_replace(&root->cgroup_idr, cgrp, cgrp->id);
 
+        err = cgroup_kn_set_ugid(kn);
+        if (err)
+                goto err_destroy;
+
         err = cgroup_addrm_files(cgrp, cgroup_base_files, true);
         if (err)
                 goto err_destroy;