--- /dev/null
--- /dev/null
++/*
++ * 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,
++};
projects / GitHub / moto-9609 / android_kernel_motorola_exynos9610.git / commitdiff