28 files changed, 2091 insertions, 503 deletions

diff --git a/arch/s390/include/asm/ccwgroup.h b/arch/s390/include/asm/ccwgroup.h
index 23723ce5ca7..6e670f88d12 100644
--- a/arch/s390/include/asm/ccwgroup.h
+++ b/arch/s390/include/asm/ccwgroup.h
@@ -23,6 +23,7 @@ struct ccwgroup_device {
 	unsigned int count;
 	struct device	dev;
 	struct ccw_device *cdev[0];
+	struct work_struct ungroup_work;
 };
 
 /**
diff --git a/arch/s390/pci/pci_sysfs.c b/arch/s390/pci/pci_sysfs.c
index cf8a12ff733..ab4a9139300 100644
--- a/arch/s390/pci/pci_sysfs.c
+++ b/arch/s390/pci/pci_sysfs.c
@@ -48,29 +48,27 @@ static ssize_t show_pfgid(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR(pfgid, S_IRUGO, show_pfgid, NULL);
 
-static void recover_callback(struct device *dev)
+static ssize_t store_recover(struct device *dev, struct device_attribute *attr,
+			     const char *buf, size_t count)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct zpci_dev *zdev = get_zdev(pdev);
 	int ret;
 
+	if (!device_remove_file_self(dev, attr))
+		return count;
+
 	pci_stop_and_remove_bus_device(pdev);
 	ret = zpci_disable_device(zdev);
 	if (ret)
-		return;
+		return ret;
 
 	ret = zpci_enable_device(zdev);
 	if (ret)
-		return;
+		return ret;
 
 	pci_rescan_bus(zdev->bus);
-}
-
-static ssize_t store_recover(struct device *dev, struct device_attribute *attr,
-			     const char *buf, size_t count)
-{
-	int rc = device_schedule_callback(dev, recover_callback);
-	return rc ? rc : count;
+	return count;
 }
 static DEVICE_ATTR(recover, S_IWUSR, NULL, store_recover);
 
diff --git a/dir.c b/dir.c
new file mode 100644
index 00000000000..d8cfe0d618a
--- /dev/null
+++ b/dir.c
@@ -0,0 +1,1248 @@
+/*
+ * fs/kernfs/dir.c - kernfs directory implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2.
+ */
+
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/idr.h>
+#include <linux/slab.h>
+#include <linux/security.h>
+#include <linux/hash.h>
+
+#include "kernfs-internal.h"
+
+DEFINE_MUTEX(kernfs_mutex);
+
+#define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb)
+
+static bool kernfs_active(struct kernfs_node *kn)
+{
+	lockdep_assert_held(&kernfs_mutex);
+	return atomic_read(&kn->active) >= 0;
+}
+
+static bool kernfs_lockdep(struct kernfs_node *kn)
+{
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	return kn->flags & KERNFS_LOCKDEP;
+#else
+	return false;
+#endif
+}
+
+/**
+ *	kernfs_name_hash
+ *	@name: Null terminated string to hash
+ *	@ns:   Namespace tag to hash
+ *
+ *	Returns 31 bit hash of ns + name (so it fits in an off_t )
+ */
+static unsigned int kernfs_name_hash(const char *name, const void *ns)
+{
+	unsigned long hash = init_name_hash();
+	unsigned int len = strlen(name);
+	while (len--)
+		hash = partial_name_hash(*name++, hash);
+	hash = (end_name_hash(hash) ^ hash_ptr((void *)ns, 31));
+	hash &= 0x7fffffffU;
+	/* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */
+	if (hash < 1)
+		hash += 2;
+	if (hash >= INT_MAX)
+		hash = INT_MAX - 1;
+	return hash;
+}
+
+static int kernfs_name_compare(unsigned int hash, const char *name,
+			       const void *ns, const struct kernfs_node *kn)
+{
+	if (hash != kn->hash)
+		return hash - kn->hash;
+	if (ns != kn->ns)
+		return ns - kn->ns;
+	return strcmp(name, kn->name);
+}
+
+static int kernfs_sd_compare(const struct kernfs_node *left,
+			     const struct kernfs_node *right)
+{
+	return kernfs_name_compare(left->hash, left->name, left->ns, right);
+}
+
+/**
+ *	kernfs_link_sibling - link kernfs_node into sibling rbtree
+ *	@kn: kernfs_node of interest
+ *
+ *	Link @kn into its sibling rbtree which starts from
+ *	@kn->parent->dir.children.
+ *
+ *	Locking:
+ *	mutex_lock(kernfs_mutex)
+ *
+ *	RETURNS:
+ *	0 on susccess -EEXIST on failure.
+ */
+static int kernfs_link_sibling(struct kernfs_node *kn)
+{
+	struct rb_node **node = &kn->parent->dir.children.rb_node;
+	struct rb_node *parent = NULL;
+
+	if (kernfs_type(kn) == KERNFS_DIR)
+		kn->parent->dir.subdirs++;
+
+	while (*node) {
+		struct kernfs_node *pos;
+		int result;
+
+		pos = rb_to_kn(*node);
+		parent = *node;
+		result = kernfs_sd_compare(kn, pos);
+		if (result < 0)
+			node = &pos->rb.rb_left;
+		else if (result > 0)
+			node = &pos->rb.rb_right;
+		else
+			return -EEXIST;
+	}
+	/* add new node and rebalance the tree */
+	rb_link_node(&kn->rb, parent, node);
+	rb_insert_color(&kn->rb, &kn->parent->dir.children);
+	return 0;
+}
+
+/**
+ *	kernfs_unlink_sibling - unlink kernfs_node from sibling rbtree
+ *	@kn: kernfs_node of interest
+ *
+ *	Try to unlink @kn from its sibling rbtree which starts from
+ *	kn->parent->dir.children.  Returns %true if @kn was actually
+ *	removed, %false if @kn wasn't on the rbtree.
+ *
+ *	Locking:
+ *	mutex_lock(kernfs_mutex)
+ */
+static bool kernfs_unlink_sibling(struct kernfs_node *kn)
+{
+	if (RB_EMPTY_NODE(&kn->rb))
+		return false;
+
+	if (kernfs_type(kn) == KERNFS_DIR)
+		kn->parent->dir.subdirs--;
+
+	rb_erase(&kn->rb, &kn->parent->dir.children);
+	RB_CLEAR_NODE(&kn->rb);
+	return true;
+}
+
+/**
+ *	kernfs_get_active - get an active reference to kernfs_node
+ *	@kn: kernfs_node to get an active reference to
+ *
+ *	Get an active reference of @kn.  This function is noop if @kn
+ *	is NULL.
+ *
+ *	RETURNS:
+ *	Pointer to @kn on success, NULL on failure.
+ */
+struct kernfs_node *kernfs_get_active(struct kernfs_node *kn)
+{
+	if (unlikely(!kn))
+		return NULL;
+
+	if (!atomic_inc_unless_negative(&kn->active))
+		return NULL;
+
+	if (kernfs_lockdep(kn))
+		rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_);
+	return kn;
+}
+
+/**
+ *	kernfs_put_active - put an active reference to kernfs_node
+ *	@kn: kernfs_node to put an active reference to
+ *
+ *	Put an active reference to @kn.  This function is noop if @kn
+ *	is NULL.
+ */
+void kernfs_put_active(struct kernfs_node *kn)
+{
+	struct kernfs_root *root = kernfs_root(kn);
+	int v;
+
+	if (unlikely(!kn))
+		return;
+
+	if (kernfs_lockdep(kn))
+		rwsem_release(&kn->dep_map, 1, _RET_IP_);
+	v = atomic_dec_return(&kn->active);
+	if (likely(v != KN_DEACTIVATED_BIAS))
+		return;
+
+	wake_up_all(&root->deactivate_waitq);
+}
+
+/**
+ * kernfs_drain - drain kernfs_node
+ * @kn: kernfs_node to drain
+ *
+ * Drain existing usages and nuke all existing mmaps of @kn.  Mutiple
+ * removers may invoke this function concurrently on @kn and all will
+ * return after draining is complete.
+ */
+static void kernfs_drain(struct kernfs_node *kn)
+	__releases(&kernfs_mutex) __acquires(&kernfs_mutex)
+{
+	struct kernfs_root *root = kernfs_root(kn);
+
+	lockdep_assert_held(&kernfs_mutex);
+	WARN_ON_ONCE(kernfs_active(kn));
+
+	mutex_unlock(&kernfs_mutex);
+
+	if (kernfs_lockdep(kn)) {
+		rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_);
+		if (atomic_read(&kn->active) != KN_DEACTIVATED_BIAS)
+			lock_contended(&kn->dep_map, _RET_IP_);
+	}
+
+	/* but everyone should wait for draining */
+	wait_event(root->deactivate_waitq,
+		   atomic_read(&kn->active) == KN_DEACTIVATED_BIAS);
+
+	if (kernfs_lockdep(kn)) {
+		lock_acquired(&kn->dep_map, _RET_IP_);
+		rwsem_release(&kn->dep_map, 1, _RET_IP_);
+	}
+
+	kernfs_unmap_bin_file(kn);
+
+	mutex_lock(&kernfs_mutex);
+}
+
+/**
+ * kernfs_get - get a reference count on a kernfs_node
+ * @kn: the target kernfs_node
+ */
+void kernfs_get(struct kernfs_node *kn)
+{
+	if (kn) {
+		WARN_ON(!atomic_read(&kn->count));
+		atomic_inc(&kn->count);
+	}
+}
+EXPORT_SYMBOL_GPL(kernfs_get);
+
+/**
+ * kernfs_put - put a reference count on a kernfs_node
+ * @kn: the target kernfs_node
+ *
+ * Put a reference count of @kn and destroy it if it reached zero.
+ */
+void kernfs_put(struct kernfs_node *kn)
+{
+	struct kernfs_node *parent;
+	struct kernfs_root *root;
+
+	if (!kn || !atomic_dec_and_test(&kn->count))
+		return;
+	root = kernfs_root(kn);
+ repeat:
+	/*
+	 * Moving/renaming is always done while holding reference.
+	 * kn->parent won't change beneath us.
+	 */
+	parent = kn->parent;
+
+	WARN_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS,
+		  "kernfs_put: %s/%s: released with incorrect active_ref %d\n",
+		  parent ? parent->name : "", kn->name, atomic_read(&kn->active));
+
+	if (kernfs_type(kn) == KERNFS_LINK)
+		kernfs_put(kn->symlink.target_kn);
+	if (!(kn->flags & KERNFS_STATIC_NAME))
+		kfree(kn->name);
+	if (kn->iattr) {
+		if (kn->iattr->ia_secdata)
+			security_release_secctx(kn->iattr->ia_secdata,
+						kn->iattr->ia_secdata_len);
+		simple_xattrs_free(&kn->iattr->xattrs);
+	}
+	kfree(kn->iattr);
+	ida_simple_remove(&root->ino_ida, kn->ino);
+	kmem_cache_free(kernfs_node_cache, kn);
+
+	kn = parent;
+	if (kn) {
+		if (atomic_dec_and_test(&kn->count))
+			goto repeat;
+	} else {
+		/* just released the root kn, free @root too */
+		ida_destroy(&root->ino_ida);
+		kfree(root);
+	}
+}
+EXPORT_SYMBOL_GPL(kernfs_put);
+
+static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
+{
+	struct kernfs_node *kn;
+
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+
+	/* Always perform fresh lookup for negatives */
+	if (!dentry->d_inode)
+		goto out_bad_unlocked;
+
+	kn = dentry->d_fsdata;
+	mutex_lock(&kernfs_mutex);
+
+	/* The kernfs node has been deactivated */
+	if (!kernfs_active(kn))
+		goto out_bad;
+
+	/* The kernfs node has been moved? */
+	if (dentry->d_parent->d_fsdata != kn->parent)
+		goto out_bad;
+
+	/* The kernfs node has been renamed */
+	if (strcmp(dentry->d_name.name, kn->name) != 0)
+		goto out_bad;
+
+	/* The kernfs node has been moved to a different namespace */
+	if (kn->parent && kernfs_ns_enabled(kn->parent) &&
+	    kernfs_info(dentry->d_sb)->ns != kn->ns)
+		goto out_bad;
+
+	mutex_unlock(&kernfs_mutex);
+out_valid:
+	return 1;
+out_bad:
+	mutex_unlock(&kernfs_mutex);
+out_bad_unlocked:
+	/*
+	 * @dentry doesn't match the underlying kernfs node, drop the
+	 * dentry and force lookup.  If we have submounts we must allow the
+	 * vfs caches to lie about the state of the filesystem to prevent
+	 * leaks and other nasty things, so use check_submounts_and_drop()
+	 * instead of d_drop().
+	 */
+	if (check_submounts_and_drop(dentry) != 0)
+		goto out_valid;
+
+	return 0;
+}
+
+static void kernfs_dop_release(struct dentry *dentry)
+{
+	kernfs_put(dentry->d_fsdata);
+}
+
+const struct dentry_operations kernfs_dops = {
+	.d_revalidate	= kernfs_dop_revalidate,
+	.d_release	= kernfs_dop_release,
+};
+
+static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
+					     const char *name, umode_t mode,
+					     unsigned flags)
+{
+	char *dup_name = NULL;
+	struct kernfs_node *kn;
+	int ret;
+
+	if (!(flags & KERNFS_STATIC_NAME)) {
+		name = dup_name = kstrdup(name, GFP_KERNEL);
+		if (!name)
+			return NULL;
+	}
+
+	kn = kmem_cache_zalloc(kernfs_node_cache, GFP_KERNEL);
+	if (!kn)
+		goto err_out1;
+
+	ret = ida_simple_get(&root->ino_ida, 1, 0, GFP_KERNEL);
+	if (ret < 0)
+		goto err_out2;
+	kn->ino = ret;
+
+	atomic_set(&kn->count, 1);
+	atomic_set(&kn->active, KN_DEACTIVATED_BIAS);
+	RB_CLEAR_NODE(&kn->rb);
+
+	kn->name = name;
+	kn->mode = mode;
+	kn->flags = flags;
+
+	return kn;
+
+ err_out2:
+	kmem_cache_free(kernfs_node_cache, kn);
+ err_out1:
+	kfree(dup_name);
+	return NULL;
+}
+
+struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
+				    const char *name, umode_t mode,
+				    unsigned flags)
+{
+	struct kernfs_node *kn;
+
+	kn = __kernfs_new_node(kernfs_root(parent), name, mode, flags);
+	if (kn) {
+		kernfs_get(parent);
+		kn->parent = parent;
+	}
+	return kn;
+}
+
+/**
+ *	kernfs_add_one - add kernfs_node to parent without warning
+ *	@kn: kernfs_node to be added
+ *
+ *	The caller must already have initialized @kn->parent.  This
+ *	function increments nlink of the parent's inode if @kn is a
+ *	directory and link into the children list of the parent.
+ *
+ *	RETURNS:
+ *	0 on success, -EEXIST if entry with the given name already
+ *	exists.
+ */
+int kernfs_add_one(struct kernfs_node *kn)
+{
+	struct kernfs_node *parent = kn->parent;
+	struct kernfs_iattrs *ps_iattr;
+	bool has_ns;
+	int ret;
+
+	mutex_lock(&kernfs_mutex);
+
+	ret = -EINVAL;
+	has_ns = kernfs_ns_enabled(parent);
+	if (WARN(has_ns != (bool)kn->ns, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n",
+		 has_ns ? "required" : "invalid", parent->name, kn->name))
+		goto out_unlock;
+
+	if (kernfs_type(parent) != KERNFS_DIR)
+		goto out_unlock;
+
+	ret = -ENOENT;
+	if ((parent->flags & KERNFS_ACTIVATED) && !kernfs_active(parent))
+		goto out_unlock;
+
+	kn->hash = kernfs_name_hash(kn->name, kn->ns);
+
+	ret = kernfs_link_sibling(kn);
+	if (ret)
+		goto out_unlock;
+
+	/* Update timestamps on the parent */
+	ps_iattr = parent->iattr;
+	if (ps_iattr) {
+		struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
+		ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
+	}
+
+	mutex_unlock(&kernfs_mutex);
+
+	/*
+	 * Activate the new node unless CREATE_DEACTIVATED is requested.
+	 * If not activated here, the kernfs user is responsible for
+	 * activating the node with kernfs_activate().  A node which hasn't
+	 * been activated is not visible to userland and its removal won't
+	 * trigger deactivation.
+	 */
+	if (!(kernfs_root(kn)->flags & KERNFS_ROOT_CREATE_DEACTIVATED))
+		kernfs_activate(kn);
+	return 0;
+
+out_unlock:
+	mutex_unlock(&kernfs_mutex);
+	return ret;
+}
+
+/**
+ * kernfs_find_ns - find kernfs_node with the given name
+ * @parent: kernfs_node to search under
+ * @name: name to look for
+ * @ns: the namespace tag to use
+ *
+ * Look for kernfs_node with name @name under @parent.  Returns pointer to
+ * the found kernfs_node on success, %NULL on failure.
+ */
+static struct kernfs_node *kernfs_find_ns(struct kernfs_node *parent,
+					  const unsigned char *name,
+					  const void *ns)
+{
+	struct rb_node *node = parent->dir.children.rb_node;
+	bool has_ns = kernfs_ns_enabled(parent);
+	unsigned int hash;
+
+	lockdep_assert_held(&kernfs_mutex);
+
+	if (has_ns != (bool)ns) {
+		WARN(1, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n",
+		     has_ns ? "required" : "invalid", parent->name, name);
+		return NULL;
+	}
+
+	hash = kernfs_name_hash(name, ns);
+	while (node) {
+		struct kernfs_node *kn;
+		int result;
+
+		kn = rb_to_kn(node);
+		result = kernfs_name_compare(hash, name, ns, kn);
+		if (result < 0)
+			node = node->rb_left;
+		else if (result > 0)
+			node = node->rb_right;
+		else
+			return kn;
+	}
+	return NULL;
+}
+
+/**
+ * kernfs_find_and_get_ns - find and get kernfs_node with the given name
+ * @parent: kernfs_node to search under
+ * @name: name to look for
+ * @ns: the namespace tag to use
+ *
+ * Look for kernfs_node with name @name under @parent and get a reference
+ * if found.  This function may sleep and returns pointer to the found
+ * kernfs_node on success, %NULL on failure.
+ */
+struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
+					   const char *name, const void *ns)
+{
+	struct kernfs_node *kn;
+
+	mutex_lock(&kernfs_mutex);
+	kn = kernfs_find_ns(parent, name, ns);
+	kernfs_get(kn);
+	mutex_unlock(&kernfs_mutex);
+
+	return kn;
+}
+EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns);
+
+/**
+ * kernfs_create_root - create a new kernfs hierarchy
+ * @scops: optional syscall operations for the hierarchy
+ * @priv: opaque data associated with the new directory
+ *
+ * Returns the root of the new hierarchy on success, ERR_PTR() value on
+ * failure.
+ */
+struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
+				       void *priv)
+{
+	struct kernfs_root *root;
+	struct kernfs_node *kn;
+
+	root = kzalloc(sizeof(*root), GFP_KERNEL);
+	if (!root)
+		return ERR_PTR(-ENOMEM);
+
+	ida_init(&root->ino_ida);
+
+	kn = __kernfs_new_node(root, "", S_IFDIR | S_IRUGO | S_IXUGO,
+			       KERNFS_DIR);
+	if (!kn) {
+		ida_destroy(&root->ino_ida);
+		kfree(root);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	kernfs_activate(kn);
+	kn->priv = priv;
+	kn->dir.root = root;
+
+	root->syscall_ops = scops;
+	root->kn = kn;
+	init_waitqueue_head(&root->deactivate_waitq);
+
+	return root;
+}
+
+/**
+ * kernfs_destroy_root - destroy a kernfs hierarchy
+ * @root: root of the hierarchy to destroy
+ *
+ * Destroy the hierarchy anchored at @root by removing all existing
+ * directories and destroying @root.
+ */
+void kernfs_destroy_root(struct kernfs_root *root)
+{
+	kernfs_remove(root->kn);	/* will also free @root */
+}
+
+/**
+ * kernfs_create_dir_ns - create a directory
+ * @parent: parent in which to create a new directory
+ * @name: name of the new directory
+ * @mode: mode of the new directory
+ * @priv: opaque data associated with the new directory
+ * @ns: optional namespace tag of the directory
+ *
+ * Returns the created node on success, ERR_PTR() value on failure.
+ */
+struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
+					 const char *name, umode_t mode,
+					 void *priv, const void *ns)
+{
+	struct kernfs_node *kn;
+	int rc;
+
+	/* allocate */
+	kn = kernfs_new_node(parent, name, mode | S_IFDIR, KERNFS_DIR);
+	if (!kn)
+		return ERR_PTR(-ENOMEM);
+
+	kn->dir.root = parent->dir.root;
+	kn->ns = ns;
+	kn->priv = priv;
+
+	/* link in */
+	rc = kernfs_add_one(kn);
+	if (!rc)
+		return kn;
+
+	kernfs_put(kn);
+	return ERR_PTR(rc);
+}
+
+static struct dentry *kernfs_iop_lookup(struct inode *dir,
+					struct dentry *dentry,
+					unsigned int flags)
+{
+	struct dentry *ret;
+	struct kernfs_node *parent = dentry->d_parent->d_fsdata;
+	struct kernfs_node *kn;
+	struct inode *inode;
+	const void *ns = NULL;
+
+	mutex_lock(&kernfs_mutex);
+
+	if (kernfs_ns_enabled(parent))
+		ns = kernfs_info(dir->i_sb)->ns;
+
+	kn = kernfs_find_ns(parent, dentry->d_name.name, ns);
+
+	/* no such entry */
+	if (!kn || !kernfs_active(kn)) {
+		ret = NULL;
+		goto out_unlock;
+	}
+	kernfs_get(kn);
+	dentry->d_fsdata = kn;
+
+	/* attach dentry and inode */
+	inode = kernfs_get_inode(dir->i_sb, kn);
+	if (!inode) {
+		ret = ERR_PTR(-ENOMEM);
+		goto out_unlock;
+	}
+
+	/* instantiate and hash dentry */
+	ret = d_materialise_unique(dentry, inode);
+ out_unlock:
+	mutex_unlock(&kernfs_mutex);
+	return ret;
+}
+
+static int kernfs_iop_mkdir(struct inode *dir, struct dentry *dentry,
+			    umode_t mode)
+{
+	struct kernfs_node *parent = dir->i_private;
+	struct kernfs_syscall_ops *scops = kernfs_root(parent)->syscall_ops;
+	int ret;
+
+	if (!scops || !scops->mkdir)
+		return -EPERM;
+
+	if (!kernfs_get_active(parent))
+		return -ENODEV;
+
+	ret = scops->mkdir(parent, dentry->d_name.name, mode);
+
+	kernfs_put_active(parent);
+	return ret;
+}
+
+static int kernfs_iop_rmdir(struct inode *dir, struct dentry *dentry)
+{
+	struct kernfs_node *kn  = dentry->d_fsdata;
+	struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops;
+	int ret;
+
+	if (!scops || !scops->rmdir)
+		return -EPERM;
+
+	if (!kernfs_get_active(kn))
+		return -ENODEV;
+
+	ret = scops->rmdir(kn);
+
+	kernfs_put_active(kn);
+	return ret;
+}
+
+static int kernfs_iop_rename(struct inode *old_dir, struct dentry *old_dentry,
+			     struct inode *new_dir, struct dentry *new_dentry)
+{
+	struct kernfs_node *kn  = old_dentry->d_fsdata;
+	struct kernfs_node *new_parent = new_dir->i_private;
+	struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops;
+	int ret;
+
+	if (!scops || !scops->rename)
+		return -EPERM;
+
+	if (!kernfs_get_active(kn))
+		return -ENODEV;
+
+	if (!kernfs_get_active(new_parent)) {
+		kernfs_put_active(kn);
+		return -ENODEV;
+	}
+
+	ret = scops->rename(kn, new_parent, new_dentry->d_name.name);
+
+	kernfs_put_active(new_parent);
+	kernfs_put_active(kn);
+	return ret;
+}
+
+const struct inode_operations kernfs_dir_iops = {
+	.lookup		= kernfs_iop_lookup,
+	.permission	= kernfs_iop_permission,
+	.setattr	= kernfs_iop_setattr,
+	.getattr	= kernfs_iop_getattr,
+	.setxattr	= kernfs_iop_setxattr,
+	.removexattr	= kernfs_iop_removexattr,
+	.getxattr	= kernfs_iop_getxattr,
+	.listxattr	= kernfs_iop_listxattr,
+
+	.mkdir		= kernfs_iop_mkdir,
+	.rmdir		= kernfs_iop_rmdir,
+	.rename		= kernfs_iop_rename,
+};
+
+static struct kernfs_node *kernfs_leftmost_descendant(struct kernfs_node *pos)
+{
+	struct kernfs_node *last;
+
+	while (true) {
+		struct rb_node *rbn;
+
+		last = pos;
+
+		if (kernfs_type(pos) != KERNFS_DIR)
+			break;
+
+		rbn = rb_first(&pos->dir.children);
+		if (!rbn)
+			break;
+
+		pos = rb_to_kn(rbn);
+	}
+
+	return last;
+}
+
+/**
+ * kernfs_next_descendant_post - find the next descendant for post-order walk
+ * @pos: the current position (%NULL to initiate traversal)
+ * @root: kernfs_node whose descendants to walk
+ *
+ * Find the next descendant to visit for post-order traversal of @root's
+ * descendants.  @root is included in the iteration and the last node to be
+ * visited.
+ */
+static struct kernfs_node *kernfs_next_descendant_post(struct kernfs_node *pos,
+						       struct kernfs_node *root)
+{
+	struct rb_node *rbn;
+
+	lockdep_assert_held(&kernfs_mutex);
+
+	/* if first iteration, visit leftmost descendant which may be root */
+	if (!pos)
+		return kernfs_leftmost_descendant(root);
+
+	/* if we visited @root, we're done */
+	if (pos == root)
+		return NULL;
+
+	/* if there's an unvisited sibling, visit its leftmost descendant */
+	rbn = rb_next(&pos->rb);
+	if (rbn)
+		return kernfs_leftmost_descendant(rb_to_kn(rbn));
+
+	/* no sibling left, visit parent */
+	return pos->parent;
+}
+
+/**
+ * kernfs_activate - activate a node which started deactivated
+ * @kn: kernfs_node whose subtree is to be activated
+ *
+ * If the root has KERNFS_ROOT_CREATE_DEACTIVATED set, a newly created node
+ * needs to be explicitly activated.  A node which hasn't been activated
+ * isn't visible to userland and deactivation is skipped during its
+ * removal.  This is useful to construct atomic init sequences where
+ * creation of multiple nodes should either succeed or fail atomically.
+ *
+ * The caller is responsible for ensuring that this function is not called
+ * after kernfs_remove*() is invoked on @kn.
+ */
+void kernfs_activate(struct kernfs_node *kn)
+{
+	struct kernfs_node *pos;
+
+	mutex_lock(&kernfs_mutex);
+
+	pos = NULL;
+	while ((pos = kernfs_next_descendant_post(pos, kn))) {
+		if (!pos || (pos->flags & KERNFS_ACTIVATED))
+			continue;
+
+		WARN_ON_ONCE(pos->parent && RB_EMPTY_NODE(&pos->rb));
+		WARN_ON_ONCE(atomic_read(&pos->active) != KN_DEACTIVATED_BIAS);
+
+		atomic_sub(KN_DEACTIVATED_BIAS, &pos->active);
+		pos->flags |= KERNFS_ACTIVATED;
+	}
+
+	mutex_unlock(&kernfs_mutex);
+}
+
+static void __kernfs_remove(struct kernfs_node *kn)
+{
+	struct kernfs_node *pos;
+
+	lockdep_assert_held(&kernfs_mutex);
+
+	/*
+	 * Short-circuit if @kn has already finished removal.  This is for
+	 * kernfs_remove_self() which plays with active ref after removal.
+	 */
+	if (!kn || RB_EMPTY_NODE(&kn->rb))
+		return;
+
+	pr_debug("kernfs %s: removing\n", kn->name);
+
+	/* prevent any new usage under @kn by deactivating all nodes */
+	pos = NULL;
+	while ((pos = kernfs_next_descendant_post(pos, kn)))
+		if (kernfs_active(pos))
+			atomic_add(KN_DEACTIVATED_BIAS, &pos->active);
+
+	/* deactivate and unlink the subtree node-by-node */
+	do {
+		pos = kernfs_leftmost_descendant(kn);
+
+		/*
+		 * kernfs_drain() drops kernfs_mutex temporarily and @pos's
+		 * base ref could have been put by someone else by the time
+		 * the function returns.  Make sure it doesn't go away
+		 * underneath us.
+		 */
+		kernfs_get(pos);
+
+		/*
+		 * Drain iff @kn was activated.  This avoids draining and
+		 * its lockdep annotations for nodes which have never been
+		 * activated and allows embedding kernfs_remove() in create
+		 * error paths without worrying about draining.
+		 */
+		if (kn->flags & KERNFS_ACTIVATED)
+			kernfs_drain(pos);
+		else
+			WARN_ON_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS);
+
+		/*
+		 * kernfs_unlink_sibling() succeeds once per node.  Use it
+		 * to decide who's responsible for cleanups.
+		 */
+		if (!pos->parent || kernfs_unlink_sibling(pos)) {
+			struct kernfs_iattrs *ps_iattr =
+				pos->parent ? pos->parent->iattr : NULL;
+
+			/* update timestamps on the parent */
+			if (ps_iattr) {
+				ps_iattr->ia_iattr.ia_ctime = CURRENT_TIME;
+				ps_iattr->ia_iattr.ia_mtime = CURRENT_TIME;
+			}
+
+			kernfs_put(pos);
+		}
+
+		kernfs_put(pos);
+	} while (pos != kn);
+}
+
+/**
+ * kernfs_remove - remove a kernfs_node recursively
+ * @kn: the kernfs_node to remove
+ *
+ * Remove @kn along with all its subdirectories and files.
+ */
+void kernfs_remove(struct kernfs_node *kn)
+{
+	mutex_lock(&kernfs_mutex);
+	__kernfs_remove(kn);
+	mutex_unlock(&kernfs_mutex);
+}
+
+/**
+ * kernfs_break_active_protection - break out of active protection
+ * @kn: the self kernfs_node
+ *
+ * The caller must be running off of a kernfs operation which is invoked
+ * with an active reference - e.g. one of kernfs_ops.  Each invocation of
+ * this function must also be matched with an invocation of
+ * kernfs_unbreak_active_protection().
+ *
+ * This function releases the active reference of @kn the caller is
+ * holding.  Once this function is called, @kn may be removed at any point
+ * and the caller is solely responsible for ensuring that the objects it
+ * dereferences are accessible.
+ */
+void kernfs_break_active_protection(struct kernfs_node *kn)
+{
+	/*
+	 * Take out ourself out of the active ref dependency chain.  If
+	 * we're called without an active ref, lockdep will complain.
+	 */
+	kernfs_put_active(kn);
+}
+
+/**
+ * kernfs_unbreak_active_protection - undo kernfs_break_active_prot