1 files changed, 22 insertions, 67 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 72fcd3069a90..79818507e444 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -255,12 +255,17 @@ int cgroup_lock_is_held(void)
 
 EXPORT_SYMBOL_GPL(cgroup_lock_is_held);
 
+static int css_unbias_refcnt(int refcnt)
+{
+	return refcnt >= 0 ? refcnt : refcnt - CSS_DEACT_BIAS;
+}
+
 /* the current nr of refs, always >= 0 whether @css is deactivated or not */
 static int css_refcnt(struct cgroup_subsys_state *css)
 {
 	int v = atomic_read(&css->refcnt);
 
-	return v >= 0 ? v : v - CSS_DEACT_BIAS;
+	return css_unbias_refcnt(v);
 }
 
 /* convenient tests for these bits */
@@ -817,7 +822,7 @@ EXPORT_SYMBOL_GPL(cgroup_unlock);
  */
 
 static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode);
-static struct dentry *cgroup_lookup(struct inode *, struct dentry *, struct nameidata *);
+static struct dentry *cgroup_lookup(struct inode *, struct dentry *, unsigned int);
 static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry);
 static int cgroup_populate_dir(struct cgroup *cgrp);
 static const struct inode_operations cgroup_dir_inode_operations;
@@ -896,13 +901,10 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode)
 		mutex_unlock(&cgroup_mutex);
 
 		/*
-		 * We want to drop the active superblock reference from the
-		 * cgroup creation after all the dentry refs are gone -
-		 * kill_sb gets mighty unhappy otherwise.  Mark
-		 * dentry->d_fsdata with cgroup_diput() to tell
-		 * cgroup_d_release() to call deactivate_super().
+		 * Drop the active superblock reference that we took when we
+		 * created the cgroup
 		 */
-		dentry->d_fsdata = cgroup_diput;
+		deactivate_super(cgrp->root->sb);
 
 		/*
 		 * if we're getting rid of the cgroup, refcount should ensure
@@ -928,13 +930,6 @@ static int cgroup_delete(const struct dentry *d)
 	return 1;
 }
 
-static void cgroup_d_release(struct dentry *dentry)
-{
-	/* did cgroup_diput() tell me to deactivate super? */
-	if (dentry->d_fsdata == cgroup_diput)
-		deactivate_super(dentry->d_sb);
-}
-
 static void remove_dir(struct dentry *d)
 {
 	struct dentry *parent = dget(d->d_parent);
@@ -959,7 +954,7 @@ static int cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
 
 		dget(d);
 		d_delete(d);
-		simple_unlink(d->d_inode, d);
+		simple_unlink(cgrp->dentry->d_inode, d);
 		list_del_init(&cfe->node);
 		dput(d);
 
@@ -1073,28 +1068,24 @@ static int rebind_subsystems(struct cgroupfs_root *root,
 			BUG_ON(cgrp->subsys[i]);
 			BUG_ON(!dummytop->subsys[i]);
 			BUG_ON(dummytop->subsys[i]->cgroup != dummytop);
-			mutex_lock(&ss->hierarchy_mutex);
 			cgrp->subsys[i] = dummytop->subsys[i];
 			cgrp->subsys[i]->cgroup = cgrp;
 			list_move(&ss->sibling, &root->subsys_list);
 			ss->root = root;
 			if (ss->bind)
 				ss->bind(cgrp);
-			mutex_unlock(&ss->hierarchy_mutex);
 			/* refcount was already taken, and we're keeping it */
 		} else if (bit & removed_bits) {
 			/* We're removing this subsystem */
 			BUG_ON(ss == NULL);
 			BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]);
 			BUG_ON(cgrp->subsys[i]->cgroup != cgrp);
-			mutex_lock(&ss->hierarchy_mutex);
 			if (ss->bind)
 				ss->bind(dummytop);
 			dummytop->subsys[i]->cgroup = dummytop;
 			cgrp->subsys[i] = NULL;
 			subsys[i]->root = &rootnode;
 			list_move(&ss->sibling, &rootnode.subsys_list);
-			mutex_unlock(&ss->hierarchy_mutex);
 			/* subsystem is now free - drop reference on module */
 			module_put(ss->module);
 		} else if (bit & final_bits) {
@@ -1542,7 +1533,6 @@ static int cgroup_get_rootdir(struct super_block *sb)
 	static const struct dentry_operations cgroup_dops = {
 		.d_iput = cgroup_diput,
 		.d_delete = cgroup_delete,
-		.d_release = cgroup_d_release,
 	};
 
 	struct inode *inode =
@@ -1593,7 +1583,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
 	opts.new_root = new_root;
 
 	/* Locate an existing or new sb for this hierarchy */
-	sb = sget(fs_type, cgroup_test_super, cgroup_set_super, &opts);
+	sb = sget(fs_type, cgroup_test_super, cgroup_set_super, 0, &opts);
 	if (IS_ERR(sb)) {
 		ret = PTR_ERR(sb);
 		cgroup_drop_root(opts.new_root);
@@ -2576,7 +2566,7 @@ static const struct inode_operations cgroup_dir_inode_operations = {
 	.rename = cgroup_rename,
 };
 
-static struct dentry *cgroup_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
+static struct dentry *cgroup_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
 {
 	if (dentry->d_name.len > NAME_MAX)
 		return ERR_PTR(-ENAMETOOLONG);
@@ -3889,8 +3879,12 @@ static void css_dput_fn(struct work_struct *work)
 {
 	struct cgroup_subsys_state *css =
 		container_of(work, struct cgroup_subsys_state, dput_work);
+	struct dentry *dentry = css->cgroup->dentry;
+	struct super_block *sb = dentry->d_sb;
 
-	dput(css->cgroup->dentry);
+	atomic_inc(&sb->s_active);
+	dput(dentry);
+	deactivate_super(sb);
 }
 
 static void init_cgroup_css(struct cgroup_subsys_state *css,
@@ -3917,37 +3911,6 @@ static void init_cgroup_css(struct cgroup_subsys_state *css,
 		set_bit(CSS_CLEAR_CSS_REFS, &css->flags);
 }
 
-static void cgroup_lock_hierarchy(struct cgroupfs_root *root)
-{
-	/* We need to take each hierarchy_mutex in a consistent order */
-	int i;
-
-	/*
-	 * No worry about a race with rebind_subsystems that might mess up the
-	 * locking order, since both parties are under cgroup_mutex.
-	 */
-	for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
-		struct cgroup_subsys *ss = subsys[i];
-		if (ss == NULL)
-			continue;
-		if (ss->root == root)
-			mutex_lock(&ss->hierarchy_mutex);
-	}
-}
-
-static void cgroup_unlock_hierarchy(struct cgroupfs_root *root)
-{
-	int i;
-
-	for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
-		struct cgroup_subsys *ss = subsys[i];
-		if (ss == NULL)
-			continue;
-		if (ss->root == root)
-			mutex_unlock(&ss->hierarchy_mutex);
-	}
-}
-
 /*
  * cgroup_create - create a cgroup
  * @parent: cgroup that will be parent of the new cgroup
@@ -4008,9 +3971,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
 			ss->post_clone(cgrp);
 	}
 
-	cgroup_lock_hierarchy(root);
 	list_add(&cgrp->sibling, &cgrp->parent->children);
-	cgroup_unlock_hierarchy(root);
 	root->number_of_cgroups++;
 
 	err = cgroup_create_dir(cgrp, dentry, mode);
@@ -4037,9 +3998,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
 
  err_remove:
 
-	cgroup_lock_hierarchy(root);
 	list_del(&cgrp->sibling);
-	cgroup_unlock_hierarchy(root);
 	root->number_of_cgroups--;
 
  err_destroy:
@@ -4247,10 +4206,8 @@ again:
 		list_del_init(&cgrp->release_list);
 	raw_spin_unlock(&release_list_lock);
 
-	cgroup_lock_hierarchy(cgrp->root);
 	/* delete this cgroup from parent->children */
 	list_del_init(&cgrp->sibling);
-	cgroup_unlock_hierarchy(cgrp->root);
 
 	list_del_init(&cgrp->allcg_node);
 
@@ -4324,8 +4281,6 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
 	 * need to invoke fork callbacks here. */
 	BUG_ON(!list_empty(&init_task.tasks));
 
-	mutex_init(&ss->hierarchy_mutex);
-	lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key);
 	ss->active = 1;
 
 	/* this function shouldn't be used with modular subsystems, since they
@@ -4452,8 +4407,6 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
 	}
 	write_unlock(&css_set_lock);
 
-	mutex_init(&ss->hierarchy_mutex);
-	lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key);
 	ss->active = 1;
 
 	/* success! */
@@ -4982,10 +4935,12 @@ EXPORT_SYMBOL_GPL(__css_tryget);
 void __css_put(struct cgroup_subsys_state *css)
 {
 	struct cgroup *cgrp = css->cgroup;
+	int v;
 
 	rcu_read_lock();
-	atomic_dec(&css->refcnt);
-	switch (css_refcnt(css)) {
+	v = css_unbias_refcnt(atomic_dec_return(&css->refcnt));
+
+	switch (v) {
 	case 1:
 		if (notify_on_release(cgrp)) {
 			set_bit(CGRP_RELEASABLE, &cgrp->flags);