From: Tejun Heo <tj@kernel.org>
Date: Tue, 11 Feb 2014 00:34:30 +0000 (-0500)
Subject: Merge branch 'master' into driver-core-next-test-merge-rc2
X-Git-Tag: firefly_0821_release~176^2~4194^2~19
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=a8fa94e0f2ab665f9aa665195618178b61ed8304;p=firefly-linux-kernel-4.4.55.git

Merge branch 'master' into driver-core-next-test-merge-rc2

da9846ae1518 ("kernfs: make kernfs_deactivate() honor KERNFS_LOCKDEP
flag") in driver-core-linus conflicts with kernfs_drain() updates in
driver-core-next.  The former just adds the missing KERNFS_LOCKDEP
checks which are already handled by kernfs_lockdep() checks in
driver-core-next.  The conflict can be resolved by taking code from
driver-core-next.

Conflicts:
	fs/kernfs/dir.c
---

a8fa94e0f2ab665f9aa665195618178b61ed8304
diff --cc dir.c
index 000000000000,000000000000..d8cfe0d618a9
new file mode 100644
--- /dev/null
+++ b/dir.c
@@@ -1,0 -1,0 +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_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,
++};