Bogus dir.c file introduced at top level.

deleted file mode 100644
index d8cfe0d..0000000
@@ -1,1248 +0,0 @@
-/*
- * 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 <[email protected]>
- *
- * 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_protection()
- * @kn: the self kernfs_node
- *
- * If kernfs_break_active_protection() was called, this function must be
- * invoked before finishing the kernfs operation.  Note that while this
- * function restores the active reference, it doesn't and can't actually
- * restore the active protection - @kn may already or be in the process of
- * being removed.  Once kernfs_break_active_protection() is invoked, that
- * protection is irreversibly gone for the kernfs operation instance.
- *
- * While this function may be called at any point after
- * kernfs_break_active_protection() is invoked, its most useful location
- * would be right before the enclosing kernfs operation returns.
- */
-void kernfs_unbreak_active_protection(struct kernfs_node *kn)
-{
-	/*
-	 * @kn->active could be in any state; however, the increment we do
-	 * here will be undone as soon as the enclosing kernfs operation
-	 * finishes and this temporary bump can't break anything.  If @kn
-	 * is alive, nothing changes.  If @kn is being deactivated, the
-	 * soon-to-follow put will either finish deactivation or restore
-	 * deactivated state.  If @kn is already removed, the temporary
-	 * bump is guaranteed to be gone before @kn is released.
-	 */
-	atomic_inc(&kn->active);
-	if (kernfs_lockdep(kn))
-		rwsem_acquire(&kn->dep_map, 0, 1, _RET_IP_);
-}
-
-/**
- * kernfs_remove_self - remove a kernfs_node from its own method
- * @kn: the self kernfs_node to remove
- *
- * The caller must be running off of a kernfs operation which is invoked
- * with an active reference - e.g. one of kernfs_ops.  This can be used to
- * implement a file operation which deletes itself.
- *
- * For example, the "delete" file for a sysfs device directory can be
- * implemented by invoking kernfs_remove_self() on the "delete" file
- * itself.  This function breaks the circular dependency of trying to
- * deactivate self while holding an active ref itself.  It isn't necessary
- * to modify the usual removal path to use kernfs_remove_self().  The
- * "delete" implementation can simply invoke kernfs_remove_self() on self
- * before proceeding with the usual removal path.  kernfs will ignore later
- * kernfs_remove() on self.
- *
- * kernfs_remove_self() can be called multiple times concurrently on the
- * same kernfs_node.  Only the first one actually performs removal and
- * returns %true.  All others will wait until the kernfs operation which
- * won self-removal finishes and return %false.  Note that the losers wait
- * for the completion of not only the winning kernfs_remove_self() but also
- * the whole kernfs_ops which won the arbitration.  This can be used to
- * guarantee, for example, all concurrent writes to a "delete" file to
- * finish only after the whole operation is complete.
- */
-bool kernfs_remove_self(struct kernfs_node *kn)
-{
-	bool ret;
-
-	mutex_lock(&kernfs_mutex);
-	kernfs_break_active_protection(kn);
-
-	/*
-	 * SUICIDAL is used to arbitrate among competing invocations.  Only
-	 * the first one will actually perform removal.  When the removal
-	 * is complete, SUICIDED is set and the active ref is restored
-	 * while holding kernfs_mutex.  The ones which lost arbitration
-	 * waits for SUICDED && drained which can happen only after the
-	 * enclosing kernfs operation which executed the winning instance
-	 * of kernfs_remove_self() finished.
-	 */
-	if (!(kn->flags & KERNFS_SUICIDAL)) {
-		kn->flags |= KERNFS_SUICIDAL;
-		__kernfs_remove(kn);
-		kn->flags |= KERNFS_SUICIDED;
-		ret = true;
-	} else {
-		wait_queue_head_t *waitq = &kernfs_root(kn)->deactivate_waitq;
-		DEFINE_WAIT(wait);
-
-		while (true) {
-			prepare_to_wait(waitq, &wait, TASK_UNINTERRUPTIBLE);
-
-			if ((kn->flags & KERNFS_SUICIDED) &&
-			    atomic_read(&kn->active) == KN_DEACTIVATED_BIAS)
-				break;
-
-			mutex_unlock(&kernfs_mutex);
-			schedule();
-			mutex_lock(&kernfs_mutex);
-		}
-		finish_wait(waitq, &wait);
-		WARN_ON_ONCE(!RB_EMPTY_NODE(&kn->rb));
-		ret = false;
-	}
-
-	/*
-	 * This must be done while holding kernfs_mutex; otherwise, waiting
-	 * for SUICIDED && deactivated could finish prematurely.
-	 */
-	kernfs_unbreak_active_protection(kn);
-
-	mutex_unlock(&kernfs_mutex);
-	return ret;
-}
-
-/**
- * kernfs_remove_by_name_ns - find a kernfs_node by name and remove it
- * @parent: parent of the target
- * @name: name of the kernfs_node to remove
- * @ns: namespace tag of the kernfs_node to remove
- *
- * Look for the kernfs_node with @name and @ns under @parent and remove it.
- * Returns 0 on success, -ENOENT if such entry doesn't exist.
- */
-int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
-			     const void *ns)
-{
-	struct kernfs_node *kn;
-
-	if (!parent) {
-		WARN(1, KERN_WARNING "kernfs: can not remove '%s', no directory\n",
-			name);
-		return -ENOENT;
-	}
-
-	mutex_lock(&kernfs_mutex);
-
-	kn = kernfs_find_ns(parent, name, ns);
-	if (kn)
-		__kernfs_remove(kn);
-
-	mutex_unlock(&kernfs_mutex);
-
-	if (kn)
-		return 0;
-	else
-		return -ENOENT;
-}
-
-/**
- * kernfs_rename_ns - move and rename a kernfs_node
- * @kn: target node
- * @new_parent: new parent to put @sd under
- * @new_name: new name
- * @new_ns: new namespace tag
- */
-int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
-		     const char *new_name, const void *new_ns)
-{
-	int error;
-
-	mutex_lock(&kernfs_mutex);
-
-	error = -ENOENT;
-	if (!kernfs_active(kn) || !kernfs_active(new_parent))
-		goto out;
-
-	error = 0;
-	if ((kn->parent == new_parent) && (kn->ns == new_ns) &&
-	    (strcmp(kn->name, new_name) == 0))
-		goto out;	/* nothing to rename */
-
-	error = -EEXIST;
-	if (kernfs_find_ns(new_parent, new_name, new_ns))
-		goto out;
-
-	/* rename kernfs_node */
-	if (strcmp(kn->name, new_name) != 0) {
-		error = -ENOMEM;
-		new_name = kstrdup(new_name, GFP_KERNEL);
-		if (!new_name)
-			goto out;
-
-		if (kn->flags & KERNFS_STATIC_NAME)
-			kn->flags &= ~KERNFS_STATIC_NAME;
-		else
-			kfree(kn->name);
-
-		kn->name = new_name;
-	}
-
-	/*
-	 * Move to the appropriate place in the appropriate directories rbtree.
-	 */
-	kernfs_unlink_sibling(kn);
-	kernfs_get(new_parent);
-	kernfs_put(kn->parent);
-	kn->ns = new_ns;
-	kn->hash = kernfs_name_hash(kn->name, kn->ns);
-	kn->parent = new_parent;
-	kernfs_link_sibling(kn);
-
-	error = 0;
- out:
-	mutex_unlock(&kernfs_mutex);
-	return error;
-}
-
-/* Relationship between s_mode and the DT_xxx types */
-static inline unsigned char dt_type(struct kernfs_node *kn)
-{
-	return (kn->mode >> 12) & 15;
-}
-
-static int kernfs_dir_fop_release(struct inode *inode, struct file *filp)
-{
-	kernfs_put(filp->private_data);
-	return 0;
-}
-
-static struct kernfs_node *kernfs_dir_pos(const void *ns,
-	struct kernfs_node *parent, loff_t hash, struct kernfs_node *pos)
-{
-	if (pos) {
-		int valid = kernfs_active(pos) &&
-			pos->parent == parent && hash == pos->hash;
-		kernfs_put(pos);
-		if (!valid)
-			pos = NULL;
-	}
-	if (!pos && (hash > 1) && (hash < INT_MAX)) {
-		struct rb_node *node = parent->dir.children.rb_node;
-		while (node) {
-			pos = rb_to_kn(node);
-
-			if (hash < pos->hash)
-				node = node->rb_left;
-			else if (hash > pos->hash)
-				node = node->rb_right;
-			else
-				break;
-		}
-	}
-	/* Skip over entries which are dying/dead or in the wrong namespace */
-	while (pos && (!kernfs_active(pos) || pos->ns != ns)) {
-		struct rb_node *node = rb_next(&pos->rb);
-		if (!node)
-			pos = NULL;
-		else
-			pos = rb_to_kn(node);
-	}
-	return pos;
-}
-
-static struct kernfs_node *kernfs_dir_next_pos(const void *ns,
-	struct kernfs_node *parent, ino_t ino, struct kernfs_node *pos)
-{
-	pos = kernfs_dir_pos(ns, parent, ino, pos);
-	if (pos)
-		do {
-			struct rb_node *node = rb_next(&pos->rb);
-			if (!node)
-				pos = NULL;
-			else
-				pos = rb_to_kn(node);
-		} while (pos && (!kernfs_active(pos) || pos->ns != ns));
-	return pos;
-}
-
-static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx)
-{
-	struct dentry *dentry = file->f_path.dentry;
-	struct kernfs_node *parent = dentry->d_fsdata;
-	struct kernfs_node *pos = file->private_data;
-	const void *ns = NULL;
-
-	if (!dir_emit_dots(file, ctx))
-		return 0;
-	mutex_lock(&kernfs_mutex);
-
-	if (kernfs_ns_enabled(parent))
-		ns = kernfs_info(dentry->d_sb)->ns;
-
-	for (pos = kernfs_dir_pos(ns, parent, ctx->pos, pos);
-	     pos;
-	     pos = kernfs_dir_next_pos(ns, parent, ctx->pos, pos)) {
-		const char *name = pos->name;
-		unsigned int type = dt_type(pos);
-		int len = strlen(name);
-		ino_t ino = pos->ino;
-
-		ctx->pos = pos->hash;
-		file->private_data = pos;
-		kernfs_get(pos);
-
-		mutex_unlock(&kernfs_mutex);
-		if (!dir_emit(ctx, name, len, ino, type))
-			return 0;
-		mutex_lock(&kernfs_mutex);
-	}
-	mutex_unlock(&kernfs_mutex);
-	file->private_data = NULL;
-	ctx->pos = INT_MAX;
-	return 0;
-}
-
-static loff_t kernfs_dir_fop_llseek(struct file *file, loff_t offset,
-				    int whence)
-{
-	struct inode *inode = file_inode(file);
-	loff_t ret;
-
-	mutex_lock(&inode->i_mutex);
-	ret = generic_file_llseek(file, offset, whence);
-	mutex_unlock(&inode->i_mutex);
-
-	return ret;
-}
-
-const struct file_operations kernfs_dir_fops = {
-	.read		= generic_read_dir,
-	.iterate	= kernfs_fop_readdir,
-	.release	= kernfs_dir_fop_release,
-	.llseek		= kernfs_dir_fop_llseek,
-};