// 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 <[email protected]>
*/
#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"
static DEFINE_RWLOCK(kernfs_rename_lock); /* kn->parent and ->name */
/*
* Don't use rename_lock to piggy back on pr_cont_buf. We don't want to
* call pr_cont() while holding rename_lock. Because sometimes pr_cont()
* will perform wakeups when releasing console_sem. Holding rename_lock
* will introduce deadlock if the scheduler reads the kernfs_name in the
* wakeup path.
*/
static DEFINE_SPINLOCK(kernfs_pr_cont_lock);
static char kernfs_pr_cont_buf[PATH_MAX]; /* protected by pr_cont_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)
{
return atomic_read(&kn->active) >= 0;
}
static bool kernfs_active(struct kernfs_node *kn)
{
lockdep_assert_held(&kernfs_root(kn)->kernfs_rwsem);
return __kernfs_active(kn);
}
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 strscpy(buf, "(null)", buflen);
return strscpy(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)"
*
* Return: the length of the constructed path. If the path would have been
* 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;
ssize_t copied;
int i, j;
if (!kn_to)
return strscpy(buf, "(null)", buflen);
if (!kn_from)
kn_from = kernfs_root(kn_to)->kn;
if (kn_from == kn_to)
return strscpy(buf, "/", buflen);
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++) {
copied = strscpy(buf + len, parent_str, buflen - len);
if (copied < 0)
return copied;
len += copied;
}
/* 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 += scnprintf(buf + len, buflen - len, "/%s", kn->name);
}
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 strscpy().
*
* Fills buffer with "(null)" if @kn is %NULL.
*
* Return: the resulting length of @buf. If @buf isn't long enough,
* it's filled up to @buflen-1 and nul terminated, and returns -E2BIG.
*
* 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;
read_lock_irqsave(&kernfs_rename_lock, flags);
ret = kernfs_name_locked(kn, buf, buflen);
read_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.
*
* Return: the length of the constructed path. If the path would have been
* 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;
read_lock_irqsave(&kernfs_rename_lock, flags);
ret = kernfs_path_from_node_locked(to, from, buf, buflen);
read_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_pr_cont_lock, flags);
kernfs_name(kn, kernfs_pr_cont_buf, sizeof(kernfs_pr_cont_buf));
pr_cont("%s", kernfs_pr_cont_buf);
spin_unlock_irqrestore(&kernfs_pr_cont_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_pr_cont_lock, flags);
sz = kernfs_path_from_node(kn, NULL, kernfs_pr_cont_buf,
sizeof(kernfs_pr_cont_buf));
if (sz < 0) {
if (sz == -E2BIG)
pr_cont("(name too long)");
else
pr_cont("(error)");
goto out;
}
pr_cont("%s", kernfs_pr_cont_buf);
out:
spin_unlock_irqrestore(&kernfs_pr_cont_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.
*
* Return: parent node of @kn
*/
struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn)
{
struct kernfs_node *parent;
unsigned long flags;
read_lock_irqsave(&kernfs_rename_lock, flags);
parent = kn->parent;
kernfs_get(parent);
read_unlock_irqrestore(&kernfs_rename_lock, flags);
return parent;
}
/**
* kernfs_name_hash - calculate hash of @ns + @name
* @name: Null terminated string to hash
* @ns: Namespace tag to hash
*
* Return: 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:
* kernfs_rwsem held exclusive
*
* Return:
* %0 on success, -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 */
down_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
if (kernfs_type(kn) == KERNFS_DIR)
kn->parent->dir.subdirs++;
kernfs_inc_rev(kn->parent);
up_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
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.
*
* Return: %true if @kn was actually removed,
* %false if @kn wasn't on the rbtree.
*
* Locking:
* kernfs_rwsem held exclusive
*/
static bool kernfs_unlink_sibling(struct kernfs_node *kn)
{
if (RB_EMPTY_NODE(&kn->rb))
return false;
down_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
if (kernfs_type(kn) == KERNFS_DIR)
kn->parent->dir.subdirs--;
kernfs_inc_rev(kn->parent);
up_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
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.
*
* Return:
* 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. Multiple
* 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_root(kn)->kernfs_rwsem)
__acquires(&kernfs_root(kn)->kernfs_rwsem)
{
struct kernfs_root *root = kernfs_root(kn);
lockdep_assert_held_write(&root->kernfs_rwsem);
WARN_ON_ONCE(kernfs_active(kn));
/*
* Skip draining if already fully drained. This avoids draining and its
* lockdep annotations for nodes which have never been activated
* allowing embedding kernfs_remove() in create error paths without
* worrying about draining.
*/
if (atomic_read(&kn->active) == KN_DEACTIVATED_BIAS &&
!kernfs_should_drain_open_files(kn))
return;
up_write(&root->kernfs_rwsem);
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_);
}
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_);
}
if (kernfs_should_drain_open_files(kn))
kernfs_drain_open_files(kn);
down_write(&root->kernfs_rwsem);
}
/**
* 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);
static void kernfs_free_rcu(struct rcu_head *rcu)
{
struct kernfs_node *kn = container_of(rcu, struct kernfs_node, rcu);
kfree_const(kn->name);
if (kn->iattr) {
simple_xattrs_free(&kn->iattr->xattrs, NULL);
kmem_cache_free(kernfs_iattrs_cache, kn->iattr);
}
kmem_cache_free(kernfs_node_cache, kn);
}
/**
* 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);
spin_lock(&kernfs_idr_lock);
idr_remove(&root->ino_idr, (u32)kernfs_ino(kn));
spin_unlock(&kernfs_idr_lock);
call_rcu(&kn->rcu, kernfs_free_rcu);
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_rcu(root, rcu);
}
}
EXPORT_SYMBOL_GPL(kernfs_put);
/**
* 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)
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:
spin_lock(&kernfs_idr_lock);
idr_remove(&root->ino_idr, (u32)kernfs_ino(kn));
spin_unlock(&kernfs_idr_lock);
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;
if (parent->mode & S_ISGID) {
/* this code block imitates inode_init_owner() for
* kernfs
*/
if (parent->iattr)
gid = parent->iattr->ia_gid;
if (flags & KERNFS_DIR)
mode |= S_ISGID;
}
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.
*
* Return: %NULL on failure,
* otherwise 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);
rcu_read_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;
}
/*
* We should fail if @kn has never been activated and guarantee success
* if the caller knows that @kn is active. Both can be achieved by
* __kernfs_active() which tests @kn->active without kernfs_rwsem.
*/
if (unlikely(!__kernfs_active(kn) || !atomic_inc_not_zero(&kn->count)))
goto err_unlock;
rcu_read_unlock();
return kn;
err_unlock:
rcu_read_unlock();
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.
*
* Return:
* %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_root *root = kernfs_root(parent);
struct kernfs_iattrs *ps_iattr;
bool has_ns;
int ret;
down_write(&root->kernfs_rwsem);
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_REMOVING | KERNFS_EMPTY_DIR))
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 */
down_write(&root->kernfs_iattr_rwsem);
ps_iattr = parent->iattr;
if (ps_iattr) {
ktime_get_real_ts64(&ps_iattr->ia_ctime);
ps_iattr->ia_mtime = ps_iattr->ia_ctime;
}
up_write(&root->kernfs_iattr_rwsem);
up_write(&root->kernfs_rwsem);
/*
* 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:
up_write(&root->kernfs_rwsem);
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.
*
* Return: 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_root(parent)->kernfs_rwsem);
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)
{
ssize_t len;
char *p, *name;
lockdep_assert_held_read(&kernfs_root(parent)->kernfs_rwsem);
spin_lock_irq(&kernfs_pr_cont_lock);
len = strscpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf));
if (len < 0) {
spin_unlock_irq(&kernfs_pr_cont_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_pr_cont_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.
*
* Return: 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;
struct kernfs_root *root = kernfs_root(parent);
down_read(&root->kernfs_rwsem);
kn = kernfs_find_ns(parent, name, ns);
kernfs_get(kn);
up_read(&root->kernfs_rwsem);
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.
*
* Return: 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;
struct kernfs_root *root = kernfs_root(parent);
down_read(&root->kernfs_rwsem);
kn = kernfs_walk_ns(parent, path, ns);
kernfs_get(kn);
up_read(&root->kernfs_rwsem);
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
*
* Return: 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_rwsem(&root->kernfs_rwsem);
init_rwsem(&root->kernfs_iattr_rwsem);
init_rwsem(&root->kernfs_supers_rwsem);
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 holds kernfs_rwsem from the root so the root
* shouldn't be freed during the operation.
*/
kernfs_get(root->kn);
kernfs_remove(root->kn);
kernfs_put(root->kn); /* will also free @root */
}
/**
* kernfs_root_to_node - return the kernfs_node associated with a kernfs_root
* @root: root to use to lookup
*
* Return: @root's kernfs_node
*/
struct kernfs_node *kernfs_root_to_node(struct kernfs_root *root)
{
return root->kn;
}
/**
* 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
*
* Return: 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
*
* Return: 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 int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
{
struct kernfs_node *kn;
struct kernfs_root *root;
if (flags & LOOKUP_RCU)
return -ECHILD;
/* Negative hashed dentry? */
if (d_really_is_negative(dentry)) {
struct kernfs_node *parent;
/* If the kernfs parent node has changed discard and
* proceed to ->lookup.
*
* There's nothing special needed here when getting the
* dentry parent, even if a concurrent rename is in
* progress. That's because the dentry is negative so
* it can only be the target of the rename and it will
* be doing a d_move() not a replace. Consequently the
* dentry d_parent won't change over the d_move().
*
* Also kernfs negative dentries transitioning from
* negative to positive during revalidate won't happen
* because they are invalidated on containing directory
* changes and the lookup re-done so that a new positive
* dentry can be properly created.
*/
root = kernfs_root_from_sb(dentry->d_sb);
down_read(&root->kernfs_rwsem);
parent = kernfs_dentry_node(dentry->d_parent);
if (parent) {
if (kernfs_dir_changed(parent, dentry)) {
up_read(&root->kernfs_rwsem);
return 0;
}
}
up_read(&root->kernfs_rwsem);
/* The kernfs parent node hasn't changed, leave the
* dentry negative and return success.
*/
return 1;
}
kn = kernfs_dentry_node(dentry);
root = kernfs_root(kn);
down_read(&root->kernfs_rwsem);
/* 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;
up_read(&root->kernfs_rwsem);
return 1;
out_bad:
up_read(&root->kernfs_rwsem);
return 0;
}
const struct dentry_operations kernfs_dops = {
.d_revalidate = kernfs_dop_revalidate,
};
static struct dentry *kernfs_iop_lookup(struct inode *dir,
struct dentry *dentry,
unsigned int flags)
{
struct kernfs_node *parent = dir->i_private;
struct kernfs_node *kn;
struct kernfs_root *root;
struct inode *inode = NULL;
const void *ns = NULL;
root = kernfs_root(parent);
down_read(&root->kernfs_rwsem);
if (kernfs_ns_enabled(parent))
ns = kernfs_info(dir->i_sb)->ns;
kn = kernfs_find_ns(parent, dentry->d_name.name, ns);
/* attach dentry and inode */
if (kn) {
/* Inactive nodes are invisible to the VFS so don't
* create a negative.
*/
if (!kernfs_active(kn)) {
up_read(&root->kernfs_rwsem);
return NULL;
}
inode = kernfs_get_inode(dir->i_sb, kn);
if (!inode)
inode = ERR_PTR(-ENOMEM);
}
/*
* Needed for negative dentry validation.
* The negative dentry can be created in kernfs_iop_lookup()
* or transforms from positive dentry in dentry_unlink_inode()
* called from vfs_rmdir().
*/
if (!IS_ERR(inode))
kernfs_set_rev(parent, dentry);
up_read(&root->kernfs_rwsem);
/* instantiate and hash (possibly negative) dentry */
return d_splice_alias(inode, dentry);
}
static int kernfs_iop_mkdir(struct mnt_idmap *idmap,
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 mnt_idmap *idmap,
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.
*
* Return: the next descendant to visit or %NULL when done.
*/
static struct kernfs_node *kernfs_next_descendant_post(struct kernfs_node *pos,
struct kernfs_node *root)
{
struct rb_node *rbn;
lockdep_assert_held_write(&kernfs_root(root)->kernfs_rwsem);
/* 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;
}
static void kernfs_activate_one(struct kernfs_node *kn)
{
lockdep_assert_held_write(&kernfs_root(kn)->kernfs_rwsem);
kn->flags |= KERNFS_ACTIVATED;
if (kernfs_active(kn) || (kn->flags & (KERNFS_HIDDEN | KERNFS_REMOVING)))
return;
WARN_ON_ONCE(kn->parent && RB_EMPTY_NODE(&kn->rb));
WARN_ON_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS);
atomic_sub(KN_DEACTIVATED_BIAS, &kn->active);
}
/**
* 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;
struct kernfs_root *root = kernfs_root(kn);
down_write(&root->kernfs_rwsem);
pos = NULL;
while ((pos = kernfs_next_descendant_post(pos, kn)))
kernfs_activate_one(pos);
up_write(&root->kernfs_rwsem);
}
/**
* kernfs_show - show or hide a node
* @kn: kernfs_node to show or hide
* @show: whether to show or hide
*
* If @show is %false, @kn is marked hidden and deactivated. A hidden node is
* ignored in future activaitons. If %true, the mark is removed and activation
* state is restored. This function won't implicitly activate a new node in a
* %KERNFS_ROOT_CREATE_DEACTIVATED root which hasn't been activated yet.
*
* To avoid recursion complexities, directories aren't supported for now.
*/
void kernfs_show(struct kernfs_node *kn, bool show)
{
struct kernfs_root *root = kernfs_root(kn);
if (WARN_ON_ONCE(kernfs_type(kn) == KERNFS_DIR))
return;
down_write(&root->kernfs_rwsem);
if (show) {
kn->flags &= ~KERNFS_HIDDEN;
if (kn->flags & KERNFS_ACTIVATED)
kernfs_activate_one(kn);
} else {
kn->flags |= KERNFS_HIDDEN;
if (kernfs_active(kn))
atomic_add(KN_DEACTIVATED_BIAS, &kn->active);
kernfs_drain(kn);
}
up_write(&root->kernfs_rwsem);
}
static void __kernfs_remove(struct kernfs_node *kn)
{
struct kernfs_node *pos;
/* Short-circuit if non-root @kn has already finished removal. */
if (!kn)
return;
lockdep_assert_held_write(&kernfs_root(kn)->kernfs_rwsem);
/*
* This is for kernfs_remove_self() which plays with active ref
* after removal.
*/
if (kn->parent && RB_EMPTY_NODE(&kn->rb))
return;
pr_debug("kernfs %s: removing\n", kn->name);
/* prevent new usage by marking all nodes removing and deactivating */
pos = NULL;
while ((pos = kernfs_next_descendant_post(pos, kn))) {
pos->flags |= KERNFS_REMOVING;
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() may drop kernfs_rwsem 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);
kernfs_drain(pos);
/*
* 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 */
down_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
if (ps_iattr) {
ktime_get_real_ts64(&ps_iattr->ia_ctime);
ps_iattr->ia_mtime = ps_iattr->ia_ctime;
}
up_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
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)
{
struct kernfs_root *root;
if (!kn)
return;
root = kernfs_root(kn);
down_write(&root->kernfs_rwsem);
__kernfs_remove(kn);
up_write(&root->kernfs_rwsem);
}
/**
* 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.
*
* Return: %true if @kn is removed by this call, otherwise %false.
*/
bool kernfs_remove_self(struct kernfs_node *kn)
{
bool ret;
struct kernfs_root *root = kernfs_root(kn);
down_write(&root->kernfs_rwsem);
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 kernfs_rwsem for held exclusive. The ones which lost
* arbitration waits for SUICIDED && 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;
up_write(&root->kernfs_rwsem);
schedule();
down_write(&root->kernfs_rwsem);
}
finish_wait(waitq, &wait);
WARN_ON_ONCE(!RB_EMPTY_NODE(&kn->rb));
ret = false;
}
/*
* This must be done while kernfs_rwsem held exclusive; otherwise,
* waiting for SUICIDED && deactivated could finish prematurely.
*/
kernfs_unbreak_active_protection(kn);
up_write(&root->kernfs_rwsem);
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.
*
* Return: %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;
struct kernfs_root *root;
if (!parent) {
WARN(1, KERN_WARNING "kernfs: can not remove '%s', no directory\n",
name);
return -ENOENT;
}
root = kernfs_root(parent);
down_write(&root->kernfs_rwsem);
kn = kernfs_find_ns(parent, name, ns);
if (kn) {
kernfs_get(kn);
__kernfs_remove(kn);
kernfs_put(kn);
}
up_write(&root->kernfs_rwsem);
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
*
* Return: %0 on success, -errno on failure.
*/
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;
struct kernfs_root *root;
const char *old_name = NULL;
int error;
/* can't move or rename root */
if (!kn->parent)
return -EINVAL;
root = kernfs_root(kn);
down_write(&root->kernfs_rwsem);
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 */
write_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;
}
write_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:
up_write(&root->kernfs_rwsem);
return error;
}
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;
struct kernfs_root *root;
const void *ns = NULL;
if (!dir_emit_dots(file, ctx))
return 0;
root = kernfs_root(parent);
down_read(&root->kernfs_rwsem);
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 = fs_umode_to_dtype(pos->mode);
int len = strlen(name);
ino_t ino = kernfs_ino(pos);
ctx->pos = pos->hash;
file->private_data = pos;
kernfs_get(pos);
up_read(&root->kernfs_rwsem);
if (!dir_emit(ctx, name, len, ino, type))
return 0;
down_read(&root->kernfs_rwsem);
}
up_read(&root->kernfs_rwsem);
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,
};
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