Orange Pi5 kernel

// SPDX-License-Identifier: GPL-2.0-only
/*
 * 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>
 */
 
#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);
static DEFINE_SPINLOCK(kernfs_rename_lock);	/* kn->parent and ->name */
static char kernfs_pr_cont_buf[PATH_MAX];	/* protected by rename_lock */
static DEFINE_SPINLOCK(kernfs_idr_lock);	/* root->ino_idr */
 
#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
}
 
static int kernfs_name_locked(struct kernfs_node *kn, char *buf, size_t buflen)
{
<------>if (!kn)
<------><------>return strlcpy(buf, "(null)", buflen);
 
<------>return strlcpy(buf, kn->parent ? kn->name : "/", buflen);
}
 
/* kernfs_node_depth - compute depth from @from to @to */
static size_t kernfs_depth(struct kernfs_node *from, struct kernfs_node *to)
{
<------>size_t depth = 0;
 
<------>while (to->parent && to != from) {
<------><------>depth++;
<------><------>to = to->parent;
<------>}
<------>return depth;
}
 
static struct kernfs_node *kernfs_common_ancestor(struct kernfs_node *a,
<------><------><------><------><------><------>  struct kernfs_node *b)
{
<------>size_t da, db;
<------>struct kernfs_root *ra = kernfs_root(a), *rb = kernfs_root(b);
 
<------>if (ra != rb)
<------><------>return NULL;
 
<------>da = kernfs_depth(ra->kn, a);
<------>db = kernfs_depth(rb->kn, b);
 
<------>while (da > db) {
<------><------>a = a->parent;
<------><------>da--;
<------>}
<------>while (db > da) {
<------><------>b = b->parent;
<------><------>db--;
<------>}
 
<------>/* worst case b and a will be the same at root */
<------>while (b != a) {
<------><------>b = b->parent;
<------><------>a = a->parent;
<------>}
 
<------>return a;
}
 
/**
 * kernfs_path_from_node_locked - find a pseudo-absolute path to @kn_to,
 * where kn_from is treated as root of the path.
 * @kn_from: kernfs node which should be treated as root for the path
 * @kn_to: kernfs node to which path is needed
 * @buf: buffer to copy the path into
 * @buflen: size of @buf
 *
 * We need to handle couple of scenarios here:
 * [1] when @kn_from is an ancestor of @kn_to at some level
 * kn_from: /n1/n2/n3
 * kn_to:   /n1/n2/n3/n4/n5
 * result:  /n4/n5
 *
 * [2] when @kn_from is on a different hierarchy and we need to find common
 * ancestor between @kn_from and @kn_to.
 * kn_from: /n1/n2/n3/n4
 * kn_to:   /n1/n2/n5
 * result:  /../../n5
 * OR
 * kn_from: /n1/n2/n3/n4/n5   [depth=5]
 * kn_to:   /n1/n2/n3         [depth=3]
 * result:  /../..
 *
 * [3] when @kn_to is NULL result will be "(null)"
 *
 * Returns the length of the full path.  If the full length is equal to or
 * greater than @buflen, @buf contains the truncated path with the trailing
 * '\0'.  On error, -errno is returned.
 */
static int kernfs_path_from_node_locked(struct kernfs_node *kn_to,
<------><------><------><------><------>struct kernfs_node *kn_from,
<------><------><------><------><------>char *buf, size_t buflen)
{
<------>struct kernfs_node *kn, *common;
<------>const char parent_str[] = "/..";
<------>size_t depth_from, depth_to, len = 0;
<------>int i, j;
 
<------>if (!kn_to)
<------><------>return strlcpy(buf, "(null)", buflen);
 
<------>if (!kn_from)
<------><------>kn_from = kernfs_root(kn_to)->kn;
 
<------>if (kn_from == kn_to)
<------><------>return strlcpy(buf, "/", buflen);
 
<------>if (!buf)
<------><------>return -EINVAL;
 
<------>common = kernfs_common_ancestor(kn_from, kn_to);
<------>if (WARN_ON(!common))
<------><------>return -EINVAL;
 
<------>depth_to = kernfs_depth(common, kn_to);
<------>depth_from = kernfs_depth(common, kn_from);
 
<------>buf[0] = '\0';
 
<------>for (i = 0; i < depth_from; i++)
<------><------>len += strlcpy(buf + len, parent_str,
<------><------><------>       len < buflen ? buflen - len : 0);
 
<------>/* Calculate how many bytes we need for the rest */
<------>for (i = depth_to - 1; i >= 0; i--) {
<------><------>for (kn = kn_to, j = 0; j < i; j++)
<------><------><------>kn = kn->parent;
<------><------>len += strlcpy(buf + len, "/",
<------><------><------>       len < buflen ? buflen - len : 0);
<------><------>len += strlcpy(buf + len, kn->name,
<------><------><------>       len < buflen ? buflen - len : 0);
<------>}
 
<------>return len;
}
 
/**
 * kernfs_name - obtain the name of a given node
 * @kn: kernfs_node of interest
 * @buf: buffer to copy @kn's name into
 * @buflen: size of @buf
 *
 * Copies the name of @kn into @buf of @buflen bytes.  The behavior is
 * similar to strlcpy().  It returns the length of @kn's name and if @buf
 * isn't long enough, it's filled upto @buflen-1 and nul terminated.
 *
 * Fills buffer with "(null)" if @kn is NULL.
 *
 * This function can be called from any context.
 */
int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen)
{
<------>unsigned long flags;
<------>int ret;
 
<------>spin_lock_irqsave(&kernfs_rename_lock, flags);
<------>ret = kernfs_name_locked(kn, buf, buflen);
<------>spin_unlock_irqrestore(&kernfs_rename_lock, flags);
<------>return ret;
}
 
/**
 * kernfs_path_from_node - build path of node @to relative to @from.
 * @from: parent kernfs_node relative to which we need to build the path
 * @to: kernfs_node of interest
 * @buf: buffer to copy @to's path into
 * @buflen: size of @buf
 *
 * Builds @to's path relative to @from in @buf. @from and @to must
 * be on the same kernfs-root. If @from is not parent of @to, then a relative
 * path (which includes '..'s) as needed to reach from @from to @to is
 * returned.
 *
 * Returns the length of the full path.  If the full length is equal to or
 * greater than @buflen, @buf contains the truncated path with the trailing
 * '\0'.  On error, -errno is returned.
 */
int kernfs_path_from_node(struct kernfs_node *to, struct kernfs_node *from,
<------><------><------>  char *buf, size_t buflen)
{
<------>unsigned long flags;
<------>int ret;
 
<------>spin_lock_irqsave(&kernfs_rename_lock, flags);
<------>ret = kernfs_path_from_node_locked(to, from, buf, buflen);
<------>spin_unlock_irqrestore(&kernfs_rename_lock, flags);
<------>return ret;
}
EXPORT_SYMBOL_GPL(kernfs_path_from_node);
 
/**
 * pr_cont_kernfs_name - pr_cont name of a kernfs_node
 * @kn: kernfs_node of interest
 *
 * This function can be called from any context.
 */
void pr_cont_kernfs_name(struct kernfs_node *kn)
{
<------>unsigned long flags;
 
<------>spin_lock_irqsave(&kernfs_rename_lock, flags);
 
<------>kernfs_name_locked(kn, kernfs_pr_cont_buf, sizeof(kernfs_pr_cont_buf));
<------>pr_cont("%s", kernfs_pr_cont_buf);
 
<------>spin_unlock_irqrestore(&kernfs_rename_lock, flags);
}
 
/**
 * pr_cont_kernfs_path - pr_cont path of a kernfs_node
 * @kn: kernfs_node of interest
 *
 * This function can be called from any context.
 */
void pr_cont_kernfs_path(struct kernfs_node *kn)
{
<------>unsigned long flags;
<------>int sz;
 
<------>spin_lock_irqsave(&kernfs_rename_lock, flags);
 
<------>sz = kernfs_path_from_node_locked(kn, NULL, kernfs_pr_cont_buf,
<------><------><------><------><------>  sizeof(kernfs_pr_cont_buf));
<------>if (sz < 0) {
<------><------>pr_cont("(error)");
<------><------>goto out;
<------>}
 
<------>if (sz >= sizeof(kernfs_pr_cont_buf)) {
<------><------>pr_cont("(name too long)");
<------><------>goto out;
<------>}
 
<------>pr_cont("%s", kernfs_pr_cont_buf);
 
out:
<------>spin_unlock_irqrestore(&kernfs_rename_lock, flags);
}
 
/**
 * kernfs_get_parent - determine the parent node and pin it
 * @kn: kernfs_node of interest
 *
 * Determines @kn's parent, pins and returns it.  This function can be
 * called from any context.
 */
struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn)
{
<------>struct kernfs_node *parent;
<------>unsigned long flags;
 
<------>spin_lock_irqsave(&kernfs_rename_lock, flags);
<------>parent = kn->parent;
<------>kernfs_get(parent);
<------>spin_unlock_irqrestore(&kernfs_rename_lock, flags);
 
<------>return parent;
}
 
/**
 *	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(ns);
<------>unsigned int len = strlen(name);
<------>while (len--)
<------><------>hash = partial_name_hash(*name++, hash);
<------>hash = end_name_hash(hash);
<------>hash &= 0x7fffffffU;
<------>/* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */
<------>if (hash < 2)
<------><------>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 -1;
<------>if (hash > kn->hash)
<------><------>return 1;
<------>if (ns < kn->ns)
<------><------>return -1;
<------>if (ns > kn->ns)
<------><------>return 1;
<------>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;
 
<------>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);
 
<------>/* successfully added, account subdir number */
<------>if (kernfs_type(kn) == KERNFS_DIR)
<------><------>kn->parent->dir.subdirs++;
 
<------>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)
{
<------>int v;
 
<------>if (unlikely(!kn))
<------><------>return;
 
<------>if (kernfs_lockdep(kn))
<------><------>rwsem_release(&kn->dep_map, _RET_IP_);
<------>v = atomic_dec_return(&kn->active);
<------>if (likely(v != KN_DEACTIVATED_BIAS))
<------><------>return;
 
<------>wake_up_all(&kernfs_root(kn)->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, _RET_IP_);
<------>}
 
<------>kernfs_drain_open_files(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);
 
<------>kfree_const(kn->name);
 
<------>if (kn->iattr) {
<------><------>simple_xattrs_free(&kn->iattr->xattrs);
<------><------>kmem_cache_free(kernfs_iattrs_cache, kn->iattr);
<------>}
<------>spin_lock(&kernfs_idr_lock);
<------>idr_remove(&root->ino_idr, (u32)kernfs_ino(kn));
<------>spin_unlock(&kernfs_idr_lock);
<------>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 */
<------><------>idr_destroy(&root->ino_idr);
<------><------>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 (d_really_is_negative(dentry))
<------><------>goto out_bad_unlocked;
 
<------>kn = kernfs_dentry_node(dentry);
<------>mutex_lock(&kernfs_mutex);
 
<------>/* The kernfs node has been deactivated */
<------>if (!kernfs_active(kn))
<------><------>goto out_bad;
 
<------>/* The kernfs node has been moved? */
<------>if (kernfs_dentry_node(dentry->d_parent) != 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);
<------>return 1;
out_bad:
<------>mutex_unlock(&kernfs_mutex);
out_bad_unlocked:
<------>return 0;
}
 
const struct dentry_operations kernfs_dops = {
<------>.d_revalidate	= kernfs_dop_revalidate,
};
 
/**
 * kernfs_node_from_dentry - determine kernfs_node associated with a dentry
 * @dentry: the dentry in question
 *
 * Return the kernfs_node associated with @dentry.  If @dentry is not a
 * kernfs one, %NULL is returned.
 *
 * While the returned kernfs_node will stay accessible as long as @dentry
 * is accessible, the returned node can be in any state and the caller is
 * fully responsible for determining what's accessible.
 */
struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
{
<------>if (dentry->d_sb->s_op == &kernfs_sops &&
<------>    !d_really_is_negative(dentry))
<------><------>return kernfs_dentry_node(dentry);
<------>return NULL;
}
 
static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
<------><------><------><------><------>     struct kernfs_node *parent,
<------><------><------><------><------>     const char *name, umode_t mode,
<------><------><------><------><------>     kuid_t uid, kgid_t gid,
<------><------><------><------><------>     unsigned flags)
{
<------>struct kernfs_node *kn;
<------>u32 id_highbits;
<------>int ret;
 
<------>name = kstrdup_const(name, GFP_KERNEL);
<------>if (!name)
<------><------>return NULL;
 
<------>kn = kmem_cache_zalloc(kernfs_node_cache, GFP_KERNEL);
<------>if (!kn)
<------><------>goto err_out1;
 
<------>idr_preload(GFP_KERNEL);
<------>spin_lock(&kernfs_idr_lock);
<------>ret = idr_alloc_cyclic(&root->ino_idr, kn, 1, 0, GFP_ATOMIC);
<------>if (ret >= 0 && ret < root->last_id_lowbits)
<------><------>root->id_highbits++;
<------>id_highbits = root->id_highbits;
<------>root->last_id_lowbits = ret;
<------>spin_unlock(&kernfs_idr_lock);
<------>idr_preload_end();
<------>if (ret < 0)
<------><------>goto err_out2;
 
<------>kn->id = (u64)id_highbits << 32 | 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;
 
<------>if (!uid_eq(uid, GLOBAL_ROOT_UID) || !gid_eq(gid, GLOBAL_ROOT_GID)) {
<------><------>struct iattr iattr = {
<------><------><------>.ia_valid = ATTR_UID | ATTR_GID,
<------><------><------>.ia_uid = uid,
<------><------><------>.ia_gid = gid,
<------><------>};
 
<------><------>ret = __kernfs_setattr(kn, &iattr);
<------><------>if (ret < 0)
<------><------><------>goto err_out3;
<------>}
 
<------>if (parent) {
<------><------>ret = security_kernfs_init_security(parent, kn);
<------><------>if (ret)
<------><------><------>goto err_out3;
<------>}
 
<------>return kn;
 
 err_out3:
<------>idr_remove(&root->ino_idr, (u32)kernfs_ino(kn));
 err_out2:
<------>kmem_cache_free(kernfs_node_cache, kn);
 err_out1:
<------>kfree_const(name);
<------>return NULL;
}
 
struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
<------><------><------><------>    const char *name, umode_t mode,
<------><------><------><------>    kuid_t uid, kgid_t gid,
<------><------><------><------>    unsigned flags)
{
<------>struct kernfs_node *kn;
 
<------>kn = __kernfs_new_node(kernfs_root(parent), parent,
<------><------><------>       name, mode, uid, gid, flags);
<------>if (kn) {
<------><------>kernfs_get(parent);
<------><------>kn->parent = parent;
<------>}
<------>return kn;
}
 
/*
 * kernfs_find_and_get_node_by_id - get kernfs_node from node id
 * @root: the kernfs root
 * @id: the target node id
 *
 * @id's lower 32bits encode ino and upper gen.  If the gen portion is
 * zero, all generations are matched.
 *
 * RETURNS:
 * NULL on failure. Return a kernfs node with reference counter incremented
 */
struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root,
<------><------><------><------><------><------>   u64 id)
{
<------>struct kernfs_node *kn;
<------>ino_t ino = kernfs_id_ino(id);
<------>u32 gen = kernfs_id_gen(id);
 
<------>spin_lock(&kernfs_idr_lock);
 
<------>kn = idr_find(&root->ino_idr, (u32)ino);
<------>if (!kn)
<------><------>goto err_unlock;
 
<------>if (sizeof(ino_t) >= sizeof(u64)) {
<------><------>/* we looked up with the low 32bits, compare the whole */
<------><------>if (kernfs_ino(kn) != ino)
<------><------><------>goto err_unlock;
<------>} else {
<------><------>/* 0 matches all generations */
<------><------>if (unlikely(gen && kernfs_gen(kn) != gen))
<------><------><------>goto err_unlock;
<------>}
 
<------>/*
<------> * ACTIVATED is protected with kernfs_mutex but it was clear when
<------> * @kn was added to idr and we just wanna see it set.  No need to
<------> * grab kernfs_mutex.
<------> */
<------>if (unlikely(!(kn->flags & KERNFS_ACTIVATED) ||
<------><------>     !atomic_inc_not_zero(&kn->count)))
<------><------>goto err_unlock;
 
<------>spin_unlock(&kernfs_idr_lock);
<------>return kn;
err_unlock:
<------>spin_unlock(&kernfs_idr_lock);
<------>return NULL;
}
 
/**
 *	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_EMPTY_DIR)
<------><------>goto out_unlock;
 
<------>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) {
<------><------>ktime_get_real_ts64(&ps_iattr->ia_ctime);
<------><------>ps_iattr->ia_mtime = ps_iattr->ia_ctime;
<------>}
 
<------>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;
}
 
static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent,
<------><------><------><------><------>  const unsigned char *path,
<------><------><------><------><------>  const void *ns)
{
<------>size_t len;
<------>char *p, *name;
 
<------>lockdep_assert_held(&kernfs_mutex);
 
<------>/* grab kernfs_rename_lock to piggy back on kernfs_pr_cont_buf */
<------>spin_lock_irq(&kernfs_rename_lock);
 
<------>len = strlcpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf));
 
<------>if (len >= sizeof(kernfs_pr_cont_buf)) {
<------><------>spin_unlock_irq(&kernfs_rename_lock);
<------><------>return NULL;
<------>}
 
<------>p = kernfs_pr_cont_buf;
 
<------>while ((name = strsep(&p, "/")) && parent) {
<------><------>if (*name == '\0')
<------><------><------>continue;
<------><------>parent = kernfs_find_ns(parent, name, ns);
<------>}
 
<------>spin_unlock_irq(&kernfs_rename_lock);
 
<------>return parent;
}
 
/**
 * 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_walk_and_get_ns - find and get kernfs_node with the given path
 * @parent: kernfs_node to search under
 * @path: path to look for
 * @ns: the namespace tag to use
 *
 * Look for kernfs_node with path @path 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_walk_and_get_ns(struct kernfs_node *parent,
<------><------><------><------><------>   const char *path, const void *ns)
{
<------>struct kernfs_node *kn;
 
<------>mutex_lock(&kernfs_mutex);
<------>kn = kernfs_walk_ns(parent, path, ns);
<------>kernfs_get(kn);
<------>mutex_unlock(&kernfs_mutex);
 
<------>return kn;
}
 
/**
 * kernfs_create_root - create a new kernfs hierarchy
 * @scops: optional syscall operations for the hierarchy
 * @flags: KERNFS_ROOT_* flags
 * @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,
<------><------><------><------>       unsigned int flags, void *priv)
{
<------>struct kernfs_root *root;
<------>struct kernfs_node *kn;
 
<------>root = kzalloc(sizeof(*root), GFP_KERNEL);
<------>if (!root)
<------><------>return ERR_PTR(-ENOMEM);
 
<------>idr_init(&root->ino_idr);
<------>INIT_LIST_HEAD(&root->supers);
 
<------>/*
<------> * On 64bit ino setups, id is ino.  On 32bit, low 32bits are ino.
<------> * High bits generation.  The starting value for both ino and
<------> * genenration is 1.  Initialize upper 32bit allocation
<------> * accordingly.
<------> */
<------>if (sizeof(ino_t) >= sizeof(u64))
<------><------>root->id_highbits = 0;
<------>else
<------><------>root->id_highbits = 1;
 
<------>kn = __kernfs_new_node(root, NULL, "", S_IFDIR | S_IRUGO | S_IXUGO,
<------><------><------>       GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
<------><------><------>       KERNFS_DIR);
<------>if (!kn) {
<------><------>idr_destroy(&root->ino_idr);
<------><------>kfree(root);
<------><------>return ERR_PTR(-ENOMEM);
<------>}
 
<------>kn->priv = priv;
<------>kn->dir.root = root;
 
<------>root->syscall_ops = scops;
<------>root->flags = flags;
<------>root->kn = kn;
<------>init_waitqueue_head(&root->deactivate_waitq);
 
<------>if (!(root->flags & KERNFS_ROOT_CREATE_DEACTIVATED))
<------><------>kernfs_activate(kn);
 
<------>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
 * @uid: uid of the new directory
 * @gid: gid 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,
<------><------><------><------><------> kuid_t uid, kgid_t gid,
<------><------><------><------><------> void *priv, const void *ns)
{
<------>struct kernfs_node *kn;
<------>int rc;
 
<------>/* allocate */
<------>kn = kernfs_new_node(parent, name, mode | S_IFDIR,
<------><------><------>     uid, gid, 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);
}
 
/**
 * kernfs_create_empty_dir - create an always empty directory
 * @parent: parent in which to create a new directory
 * @name: name of the new directory
 *
 * Returns the created node on success, ERR_PTR() value on failure.
 */
struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent,
<------><------><------><------><------>    const char *name)
{
<------>struct kernfs_node *kn;
<------>int rc;
 
<------>/* allocate */
<------>kn = kernfs_new_node(parent, name, S_IRUGO|S_IXUGO|S_IFDIR,
<------><------><------>     GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, KERNFS_DIR);
<------>if (!kn)
<------><------>return ERR_PTR(-ENOMEM);
 
<------>kn->flags |= KERNFS_EMPTY_DIR;
<------>kn->dir.root = parent->dir.root;
<------>kn->ns = NULL;
<------>kn->priv = NULL;
 
<------>/* 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 = dir->i_private;
<------>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;
<------>}
 
<------>/* 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_splice_alias(inode, dentry);
 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  = kernfs_dentry_node(dentry);
<------>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,
<------><------><------>     unsigned int flags)
{
<------>struct kernfs_node *kn = kernfs_dentry_node(old_dentry);
<------>struct kernfs_node *new_parent = new_dir->i_private;
<------>struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops;
<------>int ret;
 
<------>if (flags)
<------><------>return -EINVAL;
 
<------>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,
<------>.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->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 non-root @kn has already finished removal.
<------> * This is for kernfs_remove_self() which plays with active ref
<------> * after removal.
<------> */
<------>if (!kn || (kn->parent && 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) {
<------><------><------><------>ktime_get_real_ts64(&ps_iattr->ia_ctime);
<------><------><------><------>ps_iattr->ia_mtime = ps_iattr->ia_ctime;
<------><------><------>}
 
<------><------><------>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)
{
<------>struct kernfs_node *old_parent;
<------>const char *old_name = NULL;
<------>int error;
 
<------>/* can't move or rename root */
<------>if (!kn->parent)
<------><------>return -EINVAL;
 
<------>mutex_lock(&kernfs_mutex);
 
<------>error = -ENOENT;
<------>if (!kernfs_active(kn) || !kernfs_active(new_parent) ||
<------>    (new_parent->flags & KERNFS_EMPTY_DIR))
<------><------>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_const(new_name, GFP_KERNEL);
<------><------>if (!new_name)
<------><------><------>goto out;
<------>} else {
<------><------>new_name = NULL;
<------>}
 
<------>/*
<------> * Move to the appropriate place in the appropriate directories rbtree.
<------> */
<------>kernfs_unlink_sibling(kn);
<------>kernfs_get(new_parent);
 
<------>/* rename_lock protects ->parent and ->name accessors */
<------>spin_lock_irq(&kernfs_rename_lock);
 
<------>old_parent = kn->parent;
<------>kn->parent = new_parent;
 
<------>kn->ns = new_ns;
<------>if (new_name) {
<------><------>old_name = kn->name;
<------><------>kn->name = new_name;
<------>}
 
<------>spin_unlock_irq(&kernfs_rename_lock);
 
<------>kn->hash = kernfs_name_hash(kn->name, kn->ns);
<------>kernfs_link_sibling(kn);
 
<------>kernfs_put(old_parent);
<------>kfree_const(old_name);
 
<------>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 = kernfs_dentry_node(dentry);
<------>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 = kernfs_ino(pos);
 
<------><------>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;
}
 
const struct file_operations kernfs_dir_fops = {
<------>.read		= generic_read_dir,
<------>.iterate_shared	= kernfs_fop_readdir,
<------>.release	= kernfs_dir_fop_release,
<------>.llseek		= generic_file_llseek,
};