1 files changed, 47 insertions, 13 deletions

diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index f17fcf89e18e..c59f015f386e 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -9,7 +9,7 @@
  *	2 as published by the Free Software Foundation.
  *
  *  debugfs is for people to use instead of /proc or /sys.
- *  See Documentation/DocBook/kernel-api for more details.
+ *  See ./Documentation/core-api/kernel-api.rst for more details.
  *
  */
 
@@ -187,9 +187,9 @@ static const struct super_operations debugfs_super_operations = {
 
 static struct vfsmount *debugfs_automount(struct path *path)
 {
-	struct vfsmount *(*f)(void *);
-	f = (struct vfsmount *(*)(void *))path->dentry->d_fsdata;
-	return f(d_inode(path->dentry)->i_private);
+	debugfs_automount_t f;
+	f = (debugfs_automount_t)path->dentry->d_fsdata;
+	return f(path->dentry, d_inode(path->dentry)->i_private);
 }
 
 static const struct dentry_operations debugfs_dops = {
@@ -199,12 +199,10 @@ static const struct dentry_operations debugfs_dops = {
 
 static int debug_fill_super(struct super_block *sb, void *data, int silent)
 {
-	static struct tree_descr debug_files[] = {{""}};
+	static const struct tree_descr debug_files[] = {{""}};
 	struct debugfs_fs_info *fsi;
 	int err;
 
-	save_mount_options(sb, data);
-
 	fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
 	sb->s_fs_info = fsi;
 	if (!fsi) {
@@ -248,6 +246,42 @@ static struct file_system_type debug_fs_type = {
 };
 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 (IS_ERR(parent))
+		return NULL;
+
+	if (!parent)
+		parent = debugfs_mount->mnt_root;
+
+	inode_lock(d_inode(parent));
+	dentry = lookup_one_len(name, parent, strlen(name));
+	inode_unlock(d_inode(parent));
+
+	if (IS_ERR(dentry))
+		return NULL;
+	if (!d_really_is_positive(dentry)) {
+		dput(dentry);
+		return NULL;
+	}
+	return dentry;
+}
+EXPORT_SYMBOL_GPL(debugfs_lookup);
+
 static struct dentry *start_creating(const char *name, struct dentry *parent)
 {
 	struct dentry *dentry;
@@ -504,7 +538,7 @@ EXPORT_SYMBOL_GPL(debugfs_create_dir);
  */
 struct dentry *debugfs_create_automount(const char *name,
 					struct dentry *parent,
-					struct vfsmount *(*f)(void *),
+					debugfs_automount_t f,
 					void *data)
 {
 	struct dentry *dentry = start_creating(name, parent);
@@ -730,7 +764,7 @@ struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
 {
 	int error;
 	struct dentry *dentry = NULL, *trap;
-	const char *old_name;
+	struct name_snapshot old_name;
 
 	trap = lock_rename(new_dir, old_dir);
 	/* Source or destination directories don't exist? */
@@ -745,19 +779,19 @@ struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
 	if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
 		goto exit;
 
-	old_name = fsnotify_oldname_init(old_dentry->d_name.name);
+	take_dentry_name_snapshot(&old_name, old_dentry);
 
 	error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir),
 			      dentry, 0);
 	if (error) {
-		fsnotify_oldname_free(old_name);
+		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,
+	fsnotify_move(d_inode(old_dir), d_inode(new_dir), old_name.name,
 		d_is_dir(old_dentry),
 		NULL, old_dentry);
-	fsnotify_oldname_free(old_name);
+	release_dentry_name_snapshot(&old_name);
 	unlock_rename(new_dir, old_dir);
 	dput(dentry);
 	return old_dentry;