[GIT PULL] cgroup fixes for v3.15-rc1

[Tejun Heo]

Hello, Linus.

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.

The following changes since commit 4a4389abdd9822fdf3cc2ac6ed87eb811fd43acc:

  Merge branch 'linux_next' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-edac (2014-04-03 17:07:17 -0700)

are available in the git repository at:


  git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git for-3.15-fixes

for you to fetch changes up to 49957f8e2a43035a97d05bddefa394492a969c0d:

  cgroup: newly created dirs and files should be owned by the creator (2014-04-07 16:44:47 -0400)

Thanks.

----------------------------------------------------------------
Li Zefan (1):
      cgroup: fix top cgroup refcnt leak

Tejun Heo (1):
      cgroup: newly created dirs and files should be owned by the creator

 kernel/cgroup.c | 32 +++++++++++++++++++++++++++++---
 1 file changed, 29 insertions(+), 3 deletions(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index fede3d3..9fcdaa7 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;
--
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