+++ /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,
-};
git.openpandora.org / pandora-kernel.git / commitdiff