blob: 246740a741efa3a2441391143612378f9c711504 [file] [log] [blame]
/*
* 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/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(sysfs_mutex);
#define to_sysfs_dirent(X) rb_entry((X), struct sysfs_dirent, s_rb)
static DEFINE_SPINLOCK(sysfs_ino_lock);
static DEFINE_IDA(sysfs_ino_ida);
/**
* sysfs_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 sysfs_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 sysfs_name_compare(unsigned int hash, const char *name,
const void *ns, const struct sysfs_dirent *sd)
{
if (hash != sd->s_hash)
return hash - sd->s_hash;
if (ns != sd->s_ns)
return ns - sd->s_ns;
return strcmp(name, sd->s_name);
}
static int sysfs_sd_compare(const struct sysfs_dirent *left,
const struct sysfs_dirent *right)
{
return sysfs_name_compare(left->s_hash, left->s_name, left->s_ns,
right);
}
/**
* sysfs_link_sibling - link sysfs_dirent into sibling rbtree
* @sd: sysfs_dirent of interest
*
* Link @sd into its sibling rbtree which starts from
* sd->s_parent->s_dir.children.
*
* Locking:
* mutex_lock(sysfs_mutex)
*
* RETURNS:
* 0 on susccess -EEXIST on failure.
*/
static int sysfs_link_sibling(struct sysfs_dirent *sd)
{
struct rb_node **node = &sd->s_parent->s_dir.children.rb_node;
struct rb_node *parent = NULL;
if (sysfs_type(sd) == SYSFS_DIR)
sd->s_parent->s_dir.subdirs++;
while (*node) {
struct sysfs_dirent *pos;
int result;
pos = to_sysfs_dirent(*node);
parent = *node;
result = sysfs_sd_compare(sd, pos);
if (result < 0)
node = &pos->s_rb.rb_left;
else if (result > 0)
node = &pos->s_rb.rb_right;
else
return -EEXIST;
}
/* add new node and rebalance the tree */
rb_link_node(&sd->s_rb, parent, node);
rb_insert_color(&sd->s_rb, &sd->s_parent->s_dir.children);
return 0;
}
/**
* sysfs_unlink_sibling - unlink sysfs_dirent from sibling rbtree
* @sd: sysfs_dirent of interest
*
* Unlink @sd from its sibling rbtree which starts from
* sd->s_parent->s_dir.children.
*
* Locking:
* mutex_lock(sysfs_mutex)
*/
static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
{
if (sysfs_type(sd) == SYSFS_DIR)
sd->s_parent->s_dir.subdirs--;
rb_erase(&sd->s_rb, &sd->s_parent->s_dir.children);
}
/**
* sysfs_get_active - get an active reference to sysfs_dirent
* @sd: sysfs_dirent to get an active reference to
*
* Get an active reference of @sd. This function is noop if @sd
* is NULL.
*
* RETURNS:
* Pointer to @sd on success, NULL on failure.
*/
struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
{
if (unlikely(!sd))
return NULL;
if (!atomic_inc_unless_negative(&sd->s_active))
return NULL;
if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_);
return sd;
}
/**
* sysfs_put_active - put an active reference to sysfs_dirent
* @sd: sysfs_dirent to put an active reference to
*
* Put an active reference to @sd. This function is noop if @sd
* is NULL.
*/
void sysfs_put_active(struct sysfs_dirent *sd)
{
int v;
if (unlikely(!sd))
return;
if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
rwsem_release(&sd->dep_map, 1, _RET_IP_);
v = atomic_dec_return(&sd->s_active);
if (likely(v != SD_DEACTIVATED_BIAS))
return;
/* atomic_dec_return() is a mb(), we'll always see the updated
* sd->u.completion.
*/
complete(sd->u.completion);
}
/**
* sysfs_deactivate - deactivate sysfs_dirent
* @sd: sysfs_dirent to deactivate
*
* Deny new active references and drain existing ones.
*/
static void sysfs_deactivate(struct sysfs_dirent *sd)
{
DECLARE_COMPLETION_ONSTACK(wait);
int v;
BUG_ON(!(sd->s_flags & SYSFS_FLAG_REMOVED));
if (!(sysfs_type(sd) & SYSFS_ACTIVE_REF))
return;
sd->u.completion = (void *)&wait;
rwsem_acquire(&sd->dep_map, 0, 0, _RET_IP_);
/* atomic_add_return() is a mb(), put_active() will always see
* the updated sd->u.completion.
*/
v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active);
if (v != SD_DEACTIVATED_BIAS) {
lock_contended(&sd->dep_map, _RET_IP_);
wait_for_completion(&wait);
}
lock_acquired(&sd->dep_map, _RET_IP_);
rwsem_release(&sd->dep_map, 1, _RET_IP_);
}
static int sysfs_alloc_ino(unsigned int *pino)
{
int ino, rc;
retry:
spin_lock(&sysfs_ino_lock);
rc = ida_get_new_above(&sysfs_ino_ida, 1, &ino);
spin_unlock(&sysfs_ino_lock);
if (rc == -EAGAIN) {
if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL))
goto retry;
rc = -ENOMEM;
}
*pino = ino;
return rc;
}
static void sysfs_free_ino(unsigned int ino)
{
spin_lock(&sysfs_ino_lock);
ida_remove(&sysfs_ino_ida, ino);
spin_unlock(&sysfs_ino_lock);
}
/**
* kernfs_get - get a reference count on a sysfs_dirent
* @sd: the target sysfs_dirent
*/
void kernfs_get(struct sysfs_dirent *sd)
{
if (sd) {
WARN_ON(!atomic_read(&sd->s_count));
atomic_inc(&sd->s_count);
}
}
EXPORT_SYMBOL_GPL(kernfs_get);
/**
* kernfs_put - put a reference count on a sysfs_dirent
* @sd: the target sysfs_dirent
*
* Put a reference count of @sd and destroy it if it reached zero.
*/
void kernfs_put(struct sysfs_dirent *sd)
{
struct sysfs_dirent *parent_sd;
struct kernfs_root *root;
if (!sd || !atomic_dec_and_test(&sd->s_count))
return;
root = kernfs_root(sd);
repeat:
/* Moving/renaming is always done while holding reference.
* sd->s_parent won't change beneath us.
*/
parent_sd = sd->s_parent;
WARN(!(sd->s_flags & SYSFS_FLAG_REMOVED),
"sysfs: free using entry: %s/%s\n",
parent_sd ? parent_sd->s_name : "", sd->s_name);
if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
kernfs_put(sd->s_symlink.target_sd);
if (sysfs_type(sd) & SYSFS_COPY_NAME)
kfree(sd->s_name);
if (sd->s_iattr && sd->s_iattr->ia_secdata)
security_release_secctx(sd->s_iattr->ia_secdata,
sd->s_iattr->ia_secdata_len);
kfree(sd->s_iattr);
sysfs_free_ino(sd->s_ino);
kmem_cache_free(sysfs_dir_cachep, sd);
sd = parent_sd;
if (sd) {
if (atomic_dec_and_test(&sd->s_count))
goto repeat;
} else {
/* just released the root sd, free @root too */
kfree(root);
}
}
EXPORT_SYMBOL_GPL(kernfs_put);
static int sysfs_dentry_delete(const struct dentry *dentry)
{
struct sysfs_dirent *sd = dentry->d_fsdata;
return !(sd && !(sd->s_flags & SYSFS_FLAG_REMOVED));
}
static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags)
{
struct sysfs_dirent *sd;
if (flags & LOOKUP_RCU)
return -ECHILD;
sd = dentry->d_fsdata;
mutex_lock(&sysfs_mutex);
/* The sysfs dirent has been deleted */
if (sd->s_flags & SYSFS_FLAG_REMOVED)
goto out_bad;
/* The sysfs dirent has been moved? */
if (dentry->d_parent->d_fsdata != sd->s_parent)
goto out_bad;
/* The sysfs dirent has been renamed */
if (strcmp(dentry->d_name.name, sd->s_name) != 0)
goto out_bad;
/* The sysfs dirent has been moved to a different namespace */
if (sd->s_parent && (sd->s_parent->s_flags & SYSFS_FLAG_NS) &&
sysfs_info(dentry->d_sb)->ns != sd->s_ns)
goto out_bad;
mutex_unlock(&sysfs_mutex);
out_valid:
return 1;
out_bad:
/* Remove the dentry from the dcache hashes.
* If this is a deleted dentry we use d_drop instead of d_delete
* so sysfs doesn't need to cope with negative dentries.
*
* If this is a dentry that has simply been renamed we
* use d_drop to remove it from the dcache lookup on its
* old parent. If this dentry persists later when a lookup
* is performed at its new name the dentry will be readded
* to the dcache hashes.
*/
mutex_unlock(&sysfs_mutex);
/* 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.
*/
if (check_submounts_and_drop(dentry) != 0)
goto out_valid;
return 0;
}
static void sysfs_dentry_release(struct dentry *dentry)
{
kernfs_put(dentry->d_fsdata);
}
const struct dentry_operations sysfs_dentry_ops = {
.d_revalidate = sysfs_dentry_revalidate,
.d_delete = sysfs_dentry_delete,
.d_release = sysfs_dentry_release,
};
struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
{
char *dup_name = NULL;
struct sysfs_dirent *sd;
if (type & SYSFS_COPY_NAME) {
name = dup_name = kstrdup(name, GFP_KERNEL);
if (!name)
return NULL;
}
sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
if (!sd)
goto err_out1;
if (sysfs_alloc_ino(&sd->s_ino))
goto err_out2;
atomic_set(&sd->s_count, 1);
atomic_set(&sd->s_active, 0);
sd->s_name = name;
sd->s_mode = mode;
sd->s_flags = type | SYSFS_FLAG_REMOVED;
return sd;
err_out2:
kmem_cache_free(sysfs_dir_cachep, sd);
err_out1:
kfree(dup_name);
return NULL;
}
/**
* sysfs_addrm_start - prepare for sysfs_dirent add/remove
* @acxt: pointer to sysfs_addrm_cxt to be used
*
* This function is called when the caller is about to add or remove
* sysfs_dirent. This function acquires sysfs_mutex. @acxt is used
* to keep and pass context to other addrm functions.
*
* LOCKING:
* Kernel thread context (may sleep). sysfs_mutex is locked on
* return.
*/
void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt)
__acquires(sysfs_mutex)
{
memset(acxt, 0, sizeof(*acxt));
mutex_lock(&sysfs_mutex);
}
/**
* sysfs_add_one - add sysfs_dirent to parent without warning
* @acxt: addrm context to use
* @sd: sysfs_dirent to be added
* @parent_sd: the parent sysfs_dirent to add @sd to
*
* Get @parent_sd and set @sd->s_parent to it and increment nlink of
* the parent inode if @sd is a directory and link into the children
* list of the parent.
*
* This function should be called between calls to
* sysfs_addrm_start() and sysfs_addrm_finish() and should be
* passed the same @acxt as passed to sysfs_addrm_start().
*
* LOCKING:
* Determined by sysfs_addrm_start().
*
* RETURNS:
* 0 on success, -EEXIST if entry with the given name already
* exists.
*/
int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
struct sysfs_dirent *parent_sd)
{
bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
struct sysfs_inode_attrs *ps_iattr;
int ret;
if (has_ns != (bool)sd->s_ns) {
WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
has_ns ? "required" : "invalid",
parent_sd->s_name, sd->s_name);
return -EINVAL;
}
if (sysfs_type(parent_sd) != SYSFS_DIR)
return -EINVAL;
sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
sd->s_parent = parent_sd;
kernfs_get(parent_sd);
ret = sysfs_link_sibling(sd);
if (ret)
return ret;
/* Update timestamps on the parent */
ps_iattr = parent_sd->s_iattr;
if (ps_iattr) {
struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
}
/* Mark the entry added into directory tree */
sd->s_flags &= ~SYSFS_FLAG_REMOVED;
return 0;
}
/**
* sysfs_remove_one - remove sysfs_dirent from parent
* @acxt: addrm context to use
* @sd: sysfs_dirent to be removed
*
* Mark @sd removed and drop nlink of parent inode if @sd is a
* directory. @sd is unlinked from the children list.
*
* This function should be called between calls to
* sysfs_addrm_start() and sysfs_addrm_finish() and should be
* passed the same @acxt as passed to sysfs_addrm_start().
*
* LOCKING:
* Determined by sysfs_addrm_start().
*/
static void sysfs_remove_one(struct sysfs_addrm_cxt *acxt,
struct sysfs_dirent *sd)
{
struct sysfs_inode_attrs *ps_iattr;
/*
* Removal can be called multiple times on the same node. Only the
* first invocation is effective and puts the base ref.
*/
if (sd->s_flags & SYSFS_FLAG_REMOVED)
return;
if (sd->s_parent) {
sysfs_unlink_sibling(sd);
/* Update timestamps on the parent */
ps_iattr = sd->s_parent->s_iattr;
if (ps_iattr) {
ps_iattr->ia_iattr.ia_ctime = CURRENT_TIME;
ps_iattr->ia_iattr.ia_mtime = CURRENT_TIME;
}
}
sd->s_flags |= SYSFS_FLAG_REMOVED;
sd->u.removed_list = acxt->removed;
acxt->removed = sd;
}
/**
* sysfs_addrm_finish - finish up sysfs_dirent add/remove
* @acxt: addrm context to finish up
*
* Finish up sysfs_dirent add/remove. Resources acquired by
* sysfs_addrm_start() are released and removed sysfs_dirents are
* cleaned up.
*
* LOCKING:
* sysfs_mutex is released.
*/
void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
__releases(sysfs_mutex)
{
/* release resources acquired by sysfs_addrm_start() */
mutex_unlock(&sysfs_mutex);
/* kill removed sysfs_dirents */
while (acxt->removed) {
struct sysfs_dirent *sd = acxt->removed;
acxt->removed = sd->u.removed_list;
sysfs_deactivate(sd);
sysfs_unmap_bin_file(sd);
kernfs_put(sd);
}
}
/**
* kernfs_find_ns - find sysfs_dirent with the given name
* @parent: sysfs_dirent to search under
* @name: name to look for
* @ns: the namespace tag to use
*
* Look for sysfs_dirent with name @name under @parent. Returns pointer to
* the found sysfs_dirent on success, %NULL on failure.
*/
static struct sysfs_dirent *kernfs_find_ns(struct sysfs_dirent *parent,
const unsigned char *name,
const void *ns)
{
struct rb_node *node = parent->s_dir.children.rb_node;
bool has_ns = parent->s_flags & SYSFS_FLAG_NS;
unsigned int hash;
lockdep_assert_held(&sysfs_mutex);
if (has_ns != (bool)ns) {
WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
has_ns ? "required" : "invalid",
parent->s_name, name);
return NULL;
}
hash = sysfs_name_hash(name, ns);
while (node) {
struct sysfs_dirent *sd;
int result;
sd = to_sysfs_dirent(node);
result = sysfs_name_compare(hash, name, ns, sd);
if (result < 0)
node = node->rb_left;
else if (result > 0)
node = node->rb_right;
else
return sd;
}
return NULL;
}
/**
* kernfs_find_and_get_ns - find and get sysfs_dirent with the given name
* @parent: sysfs_dirent to search under
* @name: name to look for
* @ns: the namespace tag to use
*
* Look for sysfs_dirent with name @name under @parent and get a reference
* if found. This function may sleep and returns pointer to the found
* sysfs_dirent on success, %NULL on failure.
*/
struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
const char *name, const void *ns)
{
struct sysfs_dirent *sd;
mutex_lock(&sysfs_mutex);
sd = kernfs_find_ns(parent, name, ns);
kernfs_get(sd);
mutex_unlock(&sysfs_mutex);
return sd;
}
EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns);
/**
* kernfs_create_root - create a new kernfs 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(void *priv)
{
struct kernfs_root *root;
struct sysfs_dirent *sd;
root = kzalloc(sizeof(*root), GFP_KERNEL);
if (!root)
return ERR_PTR(-ENOMEM);
sd = sysfs_new_dirent("", S_IFDIR | S_IRUGO | S_IXUGO, SYSFS_DIR);
if (!sd) {
kfree(root);
return ERR_PTR(-ENOMEM);
}
sd->s_flags &= ~SYSFS_FLAG_REMOVED;
sd->priv = priv;
sd->s_dir.root = root;
root->sd = sd;
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->sd); /* 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
* @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 sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
const char *name, void *priv,
const void *ns)
{
umode_t mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
struct sysfs_addrm_cxt acxt;
struct sysfs_dirent *sd;
int rc;
/* allocate */
sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
if (!sd)
return ERR_PTR(-ENOMEM);
sd->s_dir.root = parent->s_dir.root;
sd->s_ns = ns;
sd->priv = priv;
/* link in */
sysfs_addrm_start(&acxt);
rc = sysfs_add_one(&acxt, sd, parent);
sysfs_addrm_finish(&acxt);
if (!rc)
return sd;
kernfs_put(sd);
return ERR_PTR(rc);
}
static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
struct dentry *ret = NULL;
struct dentry *parent = dentry->d_parent;
struct sysfs_dirent *parent_sd = parent->d_fsdata;
struct sysfs_dirent *sd;
struct inode *inode;
const void *ns = NULL;
mutex_lock(&sysfs_mutex);
if (parent_sd->s_flags & SYSFS_FLAG_NS)
ns = sysfs_info(dir->i_sb)->ns;
sd = kernfs_find_ns(parent_sd, dentry->d_name.name, ns);
/* no such entry */
if (!sd) {
ret = ERR_PTR(-ENOENT);
goto out_unlock;
}
kernfs_get(sd);
dentry->d_fsdata = sd;
/* attach dentry and inode */
inode = sysfs_get_inode(dir->i_sb, sd);
if (!inode) {
ret = ERR_PTR(-ENOMEM);
goto out_unlock;
}
/* instantiate and hash dentry */
ret = d_materialise_unique(dentry, inode);
out_unlock:
mutex_unlock(&sysfs_mutex);
return ret;
}
const struct inode_operations sysfs_dir_inode_operations = {
.lookup = sysfs_lookup,
.permission = sysfs_permission,
.setattr = sysfs_setattr,
.getattr = sysfs_getattr,
.setxattr = sysfs_setxattr,
};
static struct sysfs_dirent *sysfs_leftmost_descendant(struct sysfs_dirent *pos)
{
struct sysfs_dirent *last;
while (true) {
struct rb_node *rbn;
last = pos;
if (sysfs_type(pos) != SYSFS_DIR)
break;
rbn = rb_first(&pos->s_dir.children);
if (!rbn)
break;
pos = to_sysfs_dirent(rbn);
}
return last;
}
/**
* sysfs_next_descendant_post - find the next descendant for post-order walk
* @pos: the current position (%NULL to initiate traversal)
* @root: sysfs_dirent 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 sysfs_dirent *sysfs_next_descendant_post(struct sysfs_dirent *pos,
struct sysfs_dirent *root)
{
struct rb_node *rbn;
lockdep_assert_held(&sysfs_mutex);
/* if first iteration, visit leftmost descendant which may be root */
if (!pos)
return sysfs_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->s_rb);
if (rbn)
return sysfs_leftmost_descendant(to_sysfs_dirent(rbn));
/* no sibling left, visit parent */
return pos->s_parent;
}
static void __kernfs_remove(struct sysfs_addrm_cxt *acxt,
struct sysfs_dirent *sd)
{
struct sysfs_dirent *pos, *next;
if (!sd)
return;
pr_debug("sysfs %s: removing\n", sd->s_name);
next = NULL;
do {
pos = next;
next = sysfs_next_descendant_post(pos, sd);
if (pos)
sysfs_remove_one(acxt, pos);
} while (next);
}
/**
* kernfs_remove - remove a sysfs_dirent recursively
* @sd: the sysfs_dirent to remove
*
* Remove @sd along with all its subdirectories and files.
*/
void kernfs_remove(struct sysfs_dirent *sd)
{
struct sysfs_addrm_cxt acxt;
sysfs_addrm_start(&acxt);
__kernfs_remove(&acxt, sd);
sysfs_addrm_finish(&acxt);
}
/**
* kernfs_remove_by_name_ns - find a sysfs_dirent by name and remove it
* @dir_sd: parent of the target
* @name: name of the sysfs_dirent to remove
* @ns: namespace tag of the sysfs_dirent to remove
*
* Look for the sysfs_dirent with @name and @ns under @dir_sd and remove
* it. Returns 0 on success, -ENOENT if such entry doesn't exist.
*/
int kernfs_remove_by_name_ns(struct sysfs_dirent *dir_sd, const char *name,
const void *ns)
{
struct sysfs_addrm_cxt acxt;
struct sysfs_dirent *sd;
if (!dir_sd) {
WARN(1, KERN_WARNING "sysfs: can not remove '%s', no directory\n",
name);
return -ENOENT;
}
sysfs_addrm_start(&acxt);
sd = kernfs_find_ns(dir_sd, name, ns);
if (sd)
__kernfs_remove(&acxt, sd);
sysfs_addrm_finish(&acxt);
if (sd)
return 0;
else
return -ENOENT;
}
/**
* kernfs_rename_ns - move and rename a kernfs_node
* @sd: target node
* @new_parent: new parent to put @sd under
* @new_name: new name
* @new_ns: new namespace tag
*/
int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
const char *new_name, const void *new_ns)
{
int error;
mutex_lock(&sysfs_mutex);
error = 0;
if ((sd->s_parent == new_parent) && (sd->s_ns == new_ns) &&
(strcmp(sd->s_name, new_name) == 0))
goto out; /* nothing to rename */
error = -EEXIST;
if (kernfs_find_ns(new_parent, new_name, new_ns))
goto out;
/* rename sysfs_dirent */
if (strcmp(sd->s_name, new_name) != 0) {
error = -ENOMEM;
new_name = kstrdup(new_name, GFP_KERNEL);
if (!new_name)
goto out;
kfree(sd->s_name);
sd->s_name = new_name;
}
/*
* Move to the appropriate place in the appropriate directories rbtree.
*/
sysfs_unlink_sibling(sd);
kernfs_get(new_parent);
kernfs_put(sd->s_parent);
sd->s_ns = new_ns;
sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
sd->s_parent = new_parent;
sysfs_link_sibling(sd);
error = 0;
out:
mutex_unlock(&sysfs_mutex);
return error;
}
/**
* kernfs_enable_ns - enable namespace under a directory
* @sd: directory of interest, should be empty
*
* This is to be called right after @sd is created to enable namespace
* under it. All children of @sd must have non-NULL namespace tags and
* only the ones which match the super_block's tag will be visible.
*/
void kernfs_enable_ns(struct sysfs_dirent *sd)
{
WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
sd->s_flags |= SYSFS_FLAG_NS;
}
/* Relationship between s_mode and the DT_xxx types */
static inline unsigned char dt_type(struct sysfs_dirent *sd)
{
return (sd->s_mode >> 12) & 15;
}
static int sysfs_dir_release(struct inode *inode, struct file *filp)
{
kernfs_put(filp->private_data);
return 0;
}
static struct sysfs_dirent *sysfs_dir_pos(const void *ns,
struct sysfs_dirent *parent_sd, loff_t hash, struct sysfs_dirent *pos)
{
if (pos) {
int valid = !(pos->s_flags & SYSFS_FLAG_REMOVED) &&
pos->s_parent == parent_sd &&
hash == pos->s_hash;
kernfs_put(pos);
if (!valid)
pos = NULL;
}
if (!pos && (hash > 1) && (hash < INT_MAX)) {
struct rb_node *node = parent_sd->s_dir.children.rb_node;
while (node) {
pos = to_sysfs_dirent(node);
if (hash < pos->s_hash)
node = node->rb_left;
else if (hash > pos->s_hash)
node = node->rb_right;
else
break;
}
}
/* Skip over entries in the wrong namespace */
while (pos && pos->s_ns != ns) {
struct rb_node *node = rb_next(&pos->s_rb);
if (!node)
pos = NULL;
else
pos = to_sysfs_dirent(node);
}
return pos;
}
static struct sysfs_dirent *sysfs_dir_next_pos(const void *ns,
struct sysfs_dirent *parent_sd, ino_t ino, struct sysfs_dirent *pos)
{
pos = sysfs_dir_pos(ns, parent_sd, ino, pos);
if (pos)
do {
struct rb_node *node = rb_next(&pos->s_rb);
if (!node)
pos = NULL;
else
pos = to_sysfs_dirent(node);
} while (pos && pos->s_ns != ns);
return pos;
}
static int sysfs_readdir(struct file *file, struct dir_context *ctx)
{
struct dentry *dentry = file->f_path.dentry;
struct sysfs_dirent *parent_sd = dentry->d_fsdata;
struct sysfs_dirent *pos = file->private_data;
const void *ns = NULL;
if (!dir_emit_dots(file, ctx))
return 0;
mutex_lock(&sysfs_mutex);
if (parent_sd->s_flags & SYSFS_FLAG_NS)
ns = sysfs_info(dentry->d_sb)->ns;
for (pos = sysfs_dir_pos(ns, parent_sd, ctx->pos, pos);
pos;
pos = sysfs_dir_next_pos(ns, parent_sd, ctx->pos, pos)) {
const char *name = pos->s_name;
unsigned int type = dt_type(pos);
int len = strlen(name);
ino_t ino = pos->s_ino;
ctx->pos = pos->s_hash;
file->private_data = pos;
kernfs_get(pos);
mutex_unlock(&sysfs_mutex);
if (!dir_emit(ctx, name, len, ino, type))
return 0;
mutex_lock(&sysfs_mutex);
}
mutex_unlock(&sysfs_mutex);
file->private_data = NULL;
ctx->pos = INT_MAX;
return 0;
}
static loff_t sysfs_dir_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 sysfs_dir_operations = {
.read = generic_read_dir,
.iterate = sysfs_readdir,
.release = sysfs_dir_release,
.llseek = sysfs_dir_llseek,
};