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-rw-r--r--fs/debugfs/inode.c919
1 files changed, 919 insertions, 0 deletions
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
new file mode 100644
index 000000000..08ef68516
--- /dev/null
+++ b/fs/debugfs/inode.c
@@ -0,0 +1,919 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * inode.c - part of debugfs, a tiny little debug file system
+ *
+ * Copyright (C) 2004,2019 Greg Kroah-Hartman <greg@kroah.com>
+ * Copyright (C) 2004 IBM Inc.
+ * Copyright (C) 2019 Linux Foundation <gregkh@linuxfoundation.org>
+ *
+ * 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/mount.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/parser.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 user_namespace *mnt_userns,
+ 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(&init_user_ns, 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();
+ inode->i_atime = inode->i_mtime =
+ inode->i_ctime = current_time(inode);
+ }
+ return inode;
+}
+
+struct debugfs_mount_opts {
+ kuid_t uid;
+ kgid_t gid;
+ umode_t mode;
+ /* Opt_* bitfield. */
+ unsigned int opts;
+};
+
+enum {
+ Opt_uid,
+ Opt_gid,
+ Opt_mode,
+ Opt_err
+};
+
+static const match_table_t tokens = {
+ {Opt_uid, "uid=%u"},
+ {Opt_gid, "gid=%u"},
+ {Opt_mode, "mode=%o"},
+ {Opt_err, NULL}
+};
+
+struct debugfs_fs_info {
+ struct debugfs_mount_opts mount_opts;
+};
+
+static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
+{
+ substring_t args[MAX_OPT_ARGS];
+ int option;
+ int token;
+ kuid_t uid;
+ kgid_t gid;
+ char *p;
+
+ opts->opts = 0;
+ opts->mode = DEBUGFS_DEFAULT_MODE;
+
+ while ((p = strsep(&data, ",")) != NULL) {
+ if (!*p)
+ continue;
+
+ token = match_token(p, tokens, args);
+ switch (token) {
+ case Opt_uid:
+ if (match_int(&args[0], &option))
+ return -EINVAL;
+ uid = make_kuid(current_user_ns(), option);
+ if (!uid_valid(uid))
+ return -EINVAL;
+ opts->uid = uid;
+ break;
+ case Opt_gid:
+ if (match_int(&args[0], &option))
+ return -EINVAL;
+ gid = make_kgid(current_user_ns(), option);
+ if (!gid_valid(gid))
+ return -EINVAL;
+ opts->gid = gid;
+ break;
+ case Opt_mode:
+ if (match_octal(&args[0], &option))
+ return -EINVAL;
+ opts->mode = option & S_IALLUGO;
+ break;
+ /*
+ * We might like to report bad mount options here;
+ * but traditionally debugfs has ignored all mount options
+ */
+ }
+
+ opts->opts |= BIT(token);
+ }
+
+ 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);
+ struct debugfs_mount_opts *opts = &fsi->mount_opts;
+
+ /*
+ * On remount, only reset mode/uid/gid if they were provided as mount
+ * options.
+ */
+
+ if (!remount || opts->opts & BIT(Opt_mode)) {
+ inode->i_mode &= ~S_IALLUGO;
+ inode->i_mode |= opts->mode;
+ }
+
+ if (!remount || opts->opts & BIT(Opt_uid))
+ inode->i_uid = opts->uid;
+
+ if (!remount || opts->opts & BIT(Opt_gid))
+ inode->i_gid = opts->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_remount(struct super_block *sb, int *flags, char *data)
+{
+ int err;
+ struct debugfs_fs_info *fsi = sb->s_fs_info;
+
+ sync_filesystem(sb);
+ err = debugfs_parse_options(data, &fsi->mount_opts);
+ if (err)
+ goto fail;
+
+ debugfs_apply_options_remount(sb);
+
+fail:
+ return err;
+}
+
+static int debugfs_show_options(struct seq_file *m, struct dentry *root)
+{
+ struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
+ struct debugfs_mount_opts *opts = &fsi->mount_opts;
+
+ if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
+ seq_printf(m, ",uid=%u",
+ from_kuid_munged(&init_user_ns, opts->uid));
+ if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
+ seq_printf(m, ",gid=%u",
+ from_kgid_munged(&init_user_ns, opts->gid));
+ if (opts->mode != DEBUGFS_DEFAULT_MODE)
+ seq_printf(m, ",mode=%o", opts->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,
+ .remount_fs = debugfs_remount,
+ .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;
+
+ 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 debug_fill_super(struct super_block *sb, void *data, int silent)
+{
+ static const struct tree_descr debug_files[] = {{""}};
+ struct debugfs_fs_info *fsi;
+ int err;
+
+ fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
+ sb->s_fs_info = fsi;
+ if (!fsi) {
+ err = -ENOMEM;
+ goto fail;
+ }
+
+ err = debugfs_parse_options(data, &fsi->mount_opts);
+ if (err)
+ goto fail;
+
+ err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
+ if (err)
+ goto fail;
+
+ sb->s_op = &debugfs_super_operations;
+ sb->s_d_op = &debugfs_dops;
+
+ debugfs_apply_options(sb);
+
+ return 0;
+
+fail:
+ kfree(fsi);
+ sb->s_fs_info = NULL;
+ return err;
+}
+
+static struct dentry *debug_mount(struct file_system_type *fs_type,
+ int flags, const char *dev_name,
+ void *data)
+{
+ if (!(debugfs_allow & DEBUGFS_ALLOW_API))
+ return ERR_PTR(-EPERM);
+
+ return mount_single(fs_type, flags, data, debug_fill_super);
+}
+
+static struct file_system_type debug_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "debugfs",
+ .mount = debug_mount,
+ .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 (!refcount_dec_and_test(&fsd->active_users))
+ 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, %NULL 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(&init_user_ns, 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);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-30 12:31:59 +0000