// SPDX-License-Identifier: GPL-2.0
/*
* inode.c - part of debugfs, a tiny little debug file system
*
* Copyright (C) 2004,2019 Greg Kroah-Hartman <[email protected]>
* Copyright (C) 2004 IBM Inc.
* Copyright (C) 2019 Linux Foundation <[email protected]>
*
* debugfs is for people to use instead of /proc or /sys.
* See ./Documentation/core-api/kernel-api.rst for more details.
*/
#define pr_fmt(fmt) "debugfs: " fmt
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/kobject.h>
#include <linux/namei.h>
#include <linux/debugfs.h>
#include <linux/fsnotify.h>
#include <linux/string.h>
#include <linux/seq_file.h>
#include <linux/magic.h>
#include <linux/slab.h>
#include <linux/security.h>
#include "internal.h"
#define DEBUGFS_DEFAULT_MODE 0700
static struct vfsmount *debugfs_mount;
static int debugfs_mount_count;
static bool debugfs_registered;
static unsigned int debugfs_allow __ro_after_init = DEFAULT_DEBUGFS_ALLOW_BITS;
/*
* Don't allow access attributes to be changed whilst the kernel is locked down
* so that we can use the file mode as part of a heuristic to determine whether
* to lock down individual files.
*/
static int debugfs_setattr(struct mnt_idmap *idmap,
struct dentry *dentry, struct iattr *ia)
{
int ret;
if (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) {
ret = security_locked_down(LOCKDOWN_DEBUGFS);
if (ret)
return ret;
}
return simple_setattr(&nop_mnt_idmap, dentry, ia);
}
static const struct inode_operations debugfs_file_inode_operations = {
.setattr = debugfs_setattr,
};
static const struct inode_operations debugfs_dir_inode_operations = {
.lookup = simple_lookup,
.setattr = debugfs_setattr,
};
static const struct inode_operations debugfs_symlink_inode_operations = {
.get_link = simple_get_link,
.setattr = debugfs_setattr,
};
static struct inode *debugfs_get_inode(struct super_block *sb)
{
struct inode *inode = new_inode(sb);
if (inode) {
inode->i_ino = get_next_ino();
simple_inode_init_ts(inode);
}
return inode;
}
struct debugfs_fs_info {
kuid_t uid;
kgid_t gid;
umode_t mode;
/* Opt_* bitfield. */
unsigned int opts;
};
enum {
Opt_uid,
Opt_gid,
Opt_mode,
Opt_source,
};
static const struct fs_parameter_spec debugfs_param_specs[] = {
fsparam_gid ("gid", Opt_gid),
fsparam_u32oct ("mode", Opt_mode),
fsparam_uid ("uid", Opt_uid),
fsparam_string ("source", Opt_source),
{}
};
static int debugfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
struct debugfs_fs_info *opts = fc->s_fs_info;
struct fs_parse_result result;
int opt;
opt = fs_parse(fc, debugfs_param_specs, param, &result);
if (opt < 0) {
/*
* We might like to report bad mount options here; but
* traditionally debugfs has ignored all mount options
*/
if (opt == -ENOPARAM)
return 0;
return opt;
}
switch (opt) {
case Opt_uid:
opts->uid = result.uid;
break;
case Opt_gid:
opts->gid = result.gid;
break;
case Opt_mode:
opts->mode = result.uint_32 & S_IALLUGO;
break;
case Opt_source:
if (fc->source)
return invalfc(fc, "Multiple sources specified");
fc->source = param->string;
param->string = NULL;
break;
/*
* We might like to report bad mount options here;
* but traditionally debugfs has ignored all mount options
*/
}
opts->opts |= BIT(opt);
return 0;
}
static void _debugfs_apply_options(struct super_block *sb, bool remount)
{
struct debugfs_fs_info *fsi = sb->s_fs_info;
struct inode *inode = d_inode(sb->s_root);
/*
* On remount, only reset mode/uid/gid if they were provided as mount
* options.
*/
if (!remount || fsi->opts & BIT(Opt_mode)) {
inode->i_mode &= ~S_IALLUGO;
inode->i_mode |= fsi->mode;
}
if (!remount || fsi->opts & BIT(Opt_uid))
inode->i_uid = fsi->uid;
if (!remount || fsi->opts & BIT(Opt_gid))
inode->i_gid = fsi->gid;
}
static void debugfs_apply_options(struct super_block *sb)
{
_debugfs_apply_options(sb, false);
}
static void debugfs_apply_options_remount(struct super_block *sb)
{
_debugfs_apply_options(sb, true);
}
static int debugfs_reconfigure(struct fs_context *fc)
{
struct super_block *sb = fc->root->d_sb;
struct debugfs_fs_info *sb_opts = sb->s_fs_info;
struct debugfs_fs_info *new_opts = fc->s_fs_info;
sync_filesystem(sb);
/* structure copy of new mount options to sb */
*sb_opts = *new_opts;
debugfs_apply_options_remount(sb);
return 0;
}
static int debugfs_show_options(struct seq_file *m, struct dentry *root)
{
struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
if (!uid_eq(fsi->uid, GLOBAL_ROOT_UID))
seq_printf(m, ",uid=%u",
from_kuid_munged(&init_user_ns, fsi->uid));
if (!gid_eq(fsi->gid, GLOBAL_ROOT_GID))
seq_printf(m, ",gid=%u",
from_kgid_munged(&init_user_ns, fsi->gid));
if (fsi->mode != DEBUGFS_DEFAULT_MODE)
seq_printf(m, ",mode=%o", fsi->mode);
return 0;
}
static void debugfs_free_inode(struct inode *inode)
{
if (S_ISLNK(inode->i_mode))
kfree(inode->i_link);
free_inode_nonrcu(inode);
}
static const struct super_operations debugfs_super_operations = {
.statfs = simple_statfs,
.show_options = debugfs_show_options,
.free_inode = debugfs_free_inode,
};
static void debugfs_release_dentry(struct dentry *dentry)
{
struct debugfs_fsdata *fsd = dentry->d_fsdata;
if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
return;
/* check it wasn't a dir (no fsdata) or automount (no real_fops) */
if (fsd && fsd->real_fops) {
WARN_ON(!list_empty(&fsd->cancellations));
mutex_destroy(&fsd->cancellations_mtx);
}
kfree(fsd);
}
static struct vfsmount *debugfs_automount(struct path *path)
{
struct debugfs_fsdata *fsd = path->dentry->d_fsdata;
return fsd->automount(path->dentry, d_inode(path->dentry)->i_private);
}
static const struct dentry_operations debugfs_dops = {
.d_delete = always_delete_dentry,
.d_release = debugfs_release_dentry,
.d_automount = debugfs_automount,
};
static int debugfs_fill_super(struct super_block *sb, struct fs_context *fc)
{
static const struct tree_descr debug_files[] = {{""}};
int err;
err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
if (err)
return err;
sb->s_op = &debugfs_super_operations;
sb->s_d_op = &debugfs_dops;
debugfs_apply_options(sb);
return 0;
}
static int debugfs_get_tree(struct fs_context *fc)
{
if (!(debugfs_allow & DEBUGFS_ALLOW_API))
return -EPERM;
return get_tree_single(fc, debugfs_fill_super);
}
static void debugfs_free_fc(struct fs_context *fc)
{
kfree(fc->s_fs_info);
}
static const struct fs_context_operations debugfs_context_ops = {
.free = debugfs_free_fc,
.parse_param = debugfs_parse_param,
.get_tree = debugfs_get_tree,
.reconfigure = debugfs_reconfigure,
};
static int debugfs_init_fs_context(struct fs_context *fc)
{
struct debugfs_fs_info *fsi;
fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
if (!fsi)
return -ENOMEM;
fsi->mode = DEBUGFS_DEFAULT_MODE;
fc->s_fs_info = fsi;
fc->ops = &debugfs_context_ops;
return 0;
}
static struct file_system_type debug_fs_type = {
.owner = THIS_MODULE,
.name = "debugfs",
.init_fs_context = debugfs_init_fs_context,
.parameters = debugfs_param_specs,
.kill_sb = kill_litter_super,
};
MODULE_ALIAS_FS("debugfs");
/**
* debugfs_lookup() - look up an existing debugfs file
* @name: a pointer to a string containing the name of the file to look up.
* @parent: a pointer to the parent dentry of the file.
*
* This function will return a pointer to a dentry if it succeeds. If the file
* doesn't exist or an error occurs, %NULL will be returned. The returned
* dentry must be passed to dput() when it is no longer needed.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned.
*/
struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
{
struct dentry *dentry;
if (!debugfs_initialized() || IS_ERR_OR_NULL(name) || IS_ERR(parent))
return NULL;
if (!parent)
parent = debugfs_mount->mnt_root;
dentry = lookup_positive_unlocked(name, parent, strlen(name));
if (IS_ERR(dentry))
return NULL;
return dentry;
}
EXPORT_SYMBOL_GPL(debugfs_lookup);
static struct dentry *start_creating(const char *name, struct dentry *parent)
{
struct dentry *dentry;
int error;
if (!(debugfs_allow & DEBUGFS_ALLOW_API))
return ERR_PTR(-EPERM);
if (!debugfs_initialized())
return ERR_PTR(-ENOENT);
pr_debug("creating file '%s'\n", name);
if (IS_ERR(parent))
return parent;
error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
&debugfs_mount_count);
if (error) {
pr_err("Unable to pin filesystem for file '%s'\n", name);
return ERR_PTR(error);
}
/* If the parent is not specified, we create it in the root.
* We need the root dentry to do this, which is in the super
* block. A pointer to that is in the struct vfsmount that we
* have around.
*/
if (!parent)
parent = debugfs_mount->mnt_root;
inode_lock(d_inode(parent));
if (unlikely(IS_DEADDIR(d_inode(parent))))
dentry = ERR_PTR(-ENOENT);
else
dentry = lookup_one_len(name, parent, strlen(name));
if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
if (d_is_dir(dentry))
pr_err("Directory '%s' with parent '%s' already present!\n",
name, parent->d_name.name);
else
pr_err("File '%s' in directory '%s' already present!\n",
name, parent->d_name.name);
dput(dentry);
dentry = ERR_PTR(-EEXIST);
}
if (IS_ERR(dentry)) {
inode_unlock(d_inode(parent));
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
}
return dentry;
}
static struct dentry *failed_creating(struct dentry *dentry)
{
inode_unlock(d_inode(dentry->d_parent));
dput(dentry);
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
return ERR_PTR(-ENOMEM);
}
static struct dentry *end_creating(struct dentry *dentry)
{
inode_unlock(d_inode(dentry->d_parent));
return dentry;
}
static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
struct dentry *parent, void *data,
const struct file_operations *proxy_fops,
const struct file_operations *real_fops)
{
struct dentry *dentry;
struct inode *inode;
if (!(mode & S_IFMT))
mode |= S_IFREG;
BUG_ON(!S_ISREG(mode));
dentry = start_creating(name, parent);
if (IS_ERR(dentry))
return dentry;
if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
failed_creating(dentry);
return ERR_PTR(-EPERM);
}
inode = debugfs_get_inode(dentry->d_sb);
if (unlikely(!inode)) {
pr_err("out of free dentries, can not create file '%s'\n",
name);
return failed_creating(dentry);
}
inode->i_mode = mode;
inode->i_private = data;
inode->i_op = &debugfs_file_inode_operations;
inode->i_fop = proxy_fops;
dentry->d_fsdata = (void *)((unsigned long)real_fops |
DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
d_instantiate(dentry, inode);
fsnotify_create(d_inode(dentry->d_parent), dentry);
return end_creating(dentry);
}
/**
* debugfs_create_file - create a file in the debugfs filesystem
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have.
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is NULL, then the
* file will be created in the root of the debugfs filesystem.
* @data: a pointer to something that the caller will want to get to later
* on. The inode.i_private pointer will point to this value on
* the open() call.
* @fops: a pointer to a struct file_operations that should be used for
* this file.
*
* This is the basic "create a file" function for debugfs. It allows for a
* wide range of flexibility in creating a file, or a directory (if you want
* to create a directory, the debugfs_create_dir() function is
* recommended to be used instead.)
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be
* returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned.
*
* NOTE: it's expected that most callers should _ignore_ the errors returned
* by this function. Other debugfs functions handle the fact that the "dentry"
* passed to them could be an error and they don't crash in that case.
* Drivers should generally work fine even if debugfs fails to init anyway.
*/
struct dentry *debugfs_create_file(const char *name, umode_t mode,
struct dentry *parent, void *data,
const struct file_operations *fops)
{
return __debugfs_create_file(name, mode, parent, data,
fops ? &debugfs_full_proxy_file_operations :
&debugfs_noop_file_operations,
fops);
}
EXPORT_SYMBOL_GPL(debugfs_create_file);
/**
* debugfs_create_file_unsafe - create a file in the debugfs filesystem
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have.
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is NULL, then the
* file will be created in the root of the debugfs filesystem.
* @data: a pointer to something that the caller will want to get to later
* on. The inode.i_private pointer will point to this value on
* the open() call.
* @fops: a pointer to a struct file_operations that should be used for
* this file.
*
* debugfs_create_file_unsafe() is completely analogous to
* debugfs_create_file(), the only difference being that the fops
* handed it will not get protected against file removals by the
* debugfs core.
*
* It is your responsibility to protect your struct file_operation
* methods against file removals by means of debugfs_file_get()
* and debugfs_file_put(). ->open() is still protected by
* debugfs though.
*
* Any struct file_operations defined by means of
* DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and
* thus, may be used here.
*/
struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
struct dentry *parent, void *data,
const struct file_operations *fops)
{
return __debugfs_create_file(name, mode, parent, data,
fops ? &debugfs_open_proxy_file_operations :
&debugfs_noop_file_operations,
fops);
}
EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe);
/**
* debugfs_create_file_size - create a file in the debugfs filesystem
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have.
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is NULL, then the
* file will be created in the root of the debugfs filesystem.
* @data: a pointer to something that the caller will want to get to later
* on. The inode.i_private pointer will point to this value on
* the open() call.
* @fops: a pointer to a struct file_operations that should be used for
* this file.
* @file_size: initial file size
*
* This is the basic "create a file" function for debugfs. It allows for a
* wide range of flexibility in creating a file, or a directory (if you want
* to create a directory, the debugfs_create_dir() function is
* recommended to be used instead.)
*/
void debugfs_create_file_size(const char *name, umode_t mode,
struct dentry *parent, void *data,
const struct file_operations *fops,
loff_t file_size)
{
struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
if (!IS_ERR(de))
d_inode(de)->i_size = file_size;
}
EXPORT_SYMBOL_GPL(debugfs_create_file_size);
/**
* debugfs_create_dir - create a directory in the debugfs filesystem
* @name: a pointer to a string containing the name of the directory to
* create.
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is NULL, then the
* directory will be created in the root of the debugfs filesystem.
*
* This function creates a directory in debugfs with the given name.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be
* returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned.
*
* NOTE: it's expected that most callers should _ignore_ the errors returned
* by this function. Other debugfs functions handle the fact that the "dentry"
* passed to them could be an error and they don't crash in that case.
* Drivers should generally work fine even if debugfs fails to init anyway.
*/
struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
{
struct dentry *dentry = start_creating(name, parent);
struct inode *inode;
if (IS_ERR(dentry))
return dentry;
if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
failed_creating(dentry);
return ERR_PTR(-EPERM);
}
inode = debugfs_get_inode(dentry->d_sb);
if (unlikely(!inode)) {
pr_err("out of free dentries, can not create directory '%s'\n",
name);
return failed_creating(dentry);
}
inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
inode->i_op = &debugfs_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
/* directory inodes start off with i_nlink == 2 (for "." entry) */
inc_nlink(inode);
d_instantiate(dentry, inode);
inc_nlink(d_inode(dentry->d_parent));
fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
return end_creating(dentry);
}
EXPORT_SYMBOL_GPL(debugfs_create_dir);
/**
* debugfs_create_automount - create automount point in the debugfs filesystem
* @name: a pointer to a string containing the name of the file to create.
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is NULL, then the
* file will be created in the root of the debugfs filesystem.
* @f: function to be called when pathname resolution steps on that one.
* @data: opaque argument to pass to f().
*
* @f should return what ->d_automount() would.
*/
struct dentry *debugfs_create_automount(const char *name,
struct dentry *parent,
debugfs_automount_t f,
void *data)
{
struct dentry *dentry = start_creating(name, parent);
struct debugfs_fsdata *fsd;
struct inode *inode;
if (IS_ERR(dentry))
return dentry;
fsd = kzalloc(sizeof(*fsd), GFP_KERNEL);
if (!fsd) {
failed_creating(dentry);
return ERR_PTR(-ENOMEM);
}
fsd->automount = f;
if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
failed_creating(dentry);
kfree(fsd);
return ERR_PTR(-EPERM);
}
inode = debugfs_get_inode(dentry->d_sb);
if (unlikely(!inode)) {
pr_err("out of free dentries, can not create automount '%s'\n",
name);
kfree(fsd);
return failed_creating(dentry);
}
make_empty_dir_inode(inode);
inode->i_flags |= S_AUTOMOUNT;
inode->i_private = data;
dentry->d_fsdata = fsd;
/* directory inodes start off with i_nlink == 2 (for "." entry) */
inc_nlink(inode);
d_instantiate(dentry, inode);
inc_nlink(d_inode(dentry->d_parent));
fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
return end_creating(dentry);
}
EXPORT_SYMBOL(debugfs_create_automount);
/**
* debugfs_create_symlink- create a symbolic link in the debugfs filesystem
* @name: a pointer to a string containing the name of the symbolic link to
* create.
* @parent: a pointer to the parent dentry for this symbolic link. This
* should be a directory dentry if set. If this parameter is NULL,
* then the symbolic link will be created in the root of the debugfs
* filesystem.
* @target: a pointer to a string containing the path to the target of the
* symbolic link.
*
* This function creates a symbolic link with the given name in debugfs that
* links to the given target path.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the symbolic
* link is to be removed (no automatic cleanup happens if your module is
* unloaded, you are responsible here.) If an error occurs, ERR_PTR(-ERROR)
* will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned.
*/
struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
const char *target)
{
struct dentry *dentry;
struct inode *inode;
char *link = kstrdup(target, GFP_KERNEL);
if (!link)
return ERR_PTR(-ENOMEM);
dentry = start_creating(name, parent);
if (IS_ERR(dentry)) {
kfree(link);
return dentry;
}
inode = debugfs_get_inode(dentry->d_sb);
if (unlikely(!inode)) {
pr_err("out of free dentries, can not create symlink '%s'\n",
name);
kfree(link);
return failed_creating(dentry);
}
inode->i_mode = S_IFLNK | S_IRWXUGO;
inode->i_op = &debugfs_symlink_inode_operations;
inode->i_link = link;
d_instantiate(dentry, inode);
return end_creating(dentry);
}
EXPORT_SYMBOL_GPL(debugfs_create_symlink);
static void __debugfs_file_removed(struct dentry *dentry)
{
struct debugfs_fsdata *fsd;
/*
* Paired with the closing smp_mb() implied by a successful
* cmpxchg() in debugfs_file_get(): either
* debugfs_file_get() must see a dead dentry or we must see a
* debugfs_fsdata instance at ->d_fsdata here (or both).
*/
smp_mb();
fsd = READ_ONCE(dentry->d_fsdata);
if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
return;
/* if this was the last reference, we're done */
if (refcount_dec_and_test(&fsd->active_users))
return;
/*
* If there's still a reference, the code that obtained it can
* be in different states:
* - The common case of not using cancellations, or already
* after debugfs_leave_cancellation(), where we just need
* to wait for debugfs_file_put() which signals the completion;
* - inside a cancellation section, i.e. between
* debugfs_enter_cancellation() and debugfs_leave_cancellation(),
* in which case we need to trigger the ->cancel() function,
* and then wait for debugfs_file_put() just like in the
* previous case;
* - before debugfs_enter_cancellation() (but obviously after
* debugfs_file_get()), in which case we may not see the
* cancellation in the list on the first round of the loop,
* but debugfs_enter_cancellation() signals the completion
* after adding it, so this code gets woken up to call the
* ->cancel() function.
*/
while (refcount_read(&fsd->active_users)) {
struct debugfs_cancellation *c;
/*
* Lock the cancellations. Note that the cancellations
* structs are meant to be on the stack, so we need to
* ensure we either use them here or don't touch them,
* and debugfs_leave_cancellation() will wait for this
* to be finished processing before exiting one. It may
* of course win and remove the cancellation, but then
* chances are we never even got into this bit, we only
* do if the refcount isn't zero already.
*/
mutex_lock(&fsd->cancellations_mtx);
while ((c = list_first_entry_or_null(&fsd->cancellations,
typeof(*c), list))) {
list_del_init(&c->list);
c->cancel(dentry, c->cancel_data);
}
mutex_unlock(&fsd->cancellations_mtx);
wait_for_completion(&fsd->active_users_drained);
}
}
static void remove_one(struct dentry *victim)
{
if (d_is_reg(victim))
__debugfs_file_removed(victim);
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
}
/**
* debugfs_remove - recursively removes a directory
* @dentry: a pointer to a the dentry of the directory to be removed. If this
* parameter is NULL or an error value, nothing will be done.
*
* This function recursively removes a directory tree in debugfs that
* was previously created with a call to another debugfs function
* (like debugfs_create_file() or variants thereof.)
*
* This function is required to be called in order for the file to be
* removed, no automatic cleanup of files will happen when a module is
* removed, you are responsible here.
*/
void debugfs_remove(struct dentry *dentry)
{
if (IS_ERR_OR_NULL(dentry))
return;
simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count);
simple_recursive_removal(dentry, remove_one);
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
}
EXPORT_SYMBOL_GPL(debugfs_remove);
/**
* debugfs_lookup_and_remove - lookup a directory or file and recursively remove it
* @name: a pointer to a string containing the name of the item to look up.
* @parent: a pointer to the parent dentry of the item.
*
* This is the equlivant of doing something like
* debugfs_remove(debugfs_lookup(..)) but with the proper reference counting
* handled for the directory being looked up.
*/
void debugfs_lookup_and_remove(const char *name, struct dentry *parent)
{
struct dentry *dentry;
dentry = debugfs_lookup(name, parent);
if (!dentry)
return;
debugfs_remove(dentry);
dput(dentry);
}
EXPORT_SYMBOL_GPL(debugfs_lookup_and_remove);
/**
* debugfs_rename - rename a file/directory in the debugfs filesystem
* @old_dir: a pointer to the parent dentry for the renamed object. This
* should be a directory dentry.
* @old_dentry: dentry of an object to be renamed.
* @new_dir: a pointer to the parent dentry where the object should be
* moved. This should be a directory dentry.
* @new_name: a pointer to a string containing the target name.
*
* This function renames a file/directory in debugfs. The target must not
* exist for rename to succeed.
*
* This function will return a pointer to old_dentry (which is updated to
* reflect renaming) if it succeeds. If an error occurs, ERR_PTR(-ERROR)
* will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned.
*/
struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
struct dentry *new_dir, const char *new_name)
{
int error;
struct dentry *dentry = NULL, *trap;
struct name_snapshot old_name;
if (IS_ERR(old_dir))
return old_dir;
if (IS_ERR(new_dir))
return new_dir;
if (IS_ERR_OR_NULL(old_dentry))
return old_dentry;
trap = lock_rename(new_dir, old_dir);
/* Source or destination directories don't exist? */
if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
goto exit;
/* Source does not exist, cyclic rename, or mountpoint? */
if (d_really_is_negative(old_dentry) || old_dentry == trap ||
d_mountpoint(old_dentry))
goto exit;
dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
/* Lookup failed, cyclic rename or target exists? */
if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
goto exit;
take_dentry_name_snapshot(&old_name, old_dentry);
error = simple_rename(&nop_mnt_idmap, d_inode(old_dir), old_dentry,
d_inode(new_dir), dentry, 0);
if (error) {
release_dentry_name_snapshot(&old_name);
goto exit;
}
d_move(old_dentry, dentry);
fsnotify_move(d_inode(old_dir), d_inode(new_dir), &old_name.name,
d_is_dir(old_dentry),
NULL, old_dentry);
release_dentry_name_snapshot(&old_name);
unlock_rename(new_dir, old_dir);
dput(dentry);
return old_dentry;
exit:
if (dentry && !IS_ERR(dentry))
dput(dentry);
unlock_rename(new_dir, old_dir);
if (IS_ERR(dentry))
return dentry;
return ERR_PTR(-EINVAL);
}
EXPORT_SYMBOL_GPL(debugfs_rename);
/**
* debugfs_initialized - Tells whether debugfs has been registered
*/
bool debugfs_initialized(void)
{
return debugfs_registered;
}
EXPORT_SYMBOL_GPL(debugfs_initialized);
static int __init debugfs_kernel(char *str)
{
if (str) {
if (!strcmp(str, "on"))
debugfs_allow = DEBUGFS_ALLOW_API | DEBUGFS_ALLOW_MOUNT;
else if (!strcmp(str, "no-mount"))
debugfs_allow = DEBUGFS_ALLOW_API;
else if (!strcmp(str, "off"))
debugfs_allow = 0;
}
return 0;
}
early_param("debugfs", debugfs_kernel);
static int __init debugfs_init(void)
{
int retval;
if (!(debugfs_allow & DEBUGFS_ALLOW_MOUNT))
return -EPERM;
retval = sysfs_create_mount_point(kernel_kobj, "debug");
if (retval)
return retval;
retval = register_filesystem(&debug_fs_type);
if (retval)
sysfs_remove_mount_point(kernel_kobj, "debug");
else
debugfs_registered = true;
return retval;
}
core_initcall(debugfs_init);
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