v4.19.13 snapshot.
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
new file mode 100644
index 0000000..feeae80
--- /dev/null
+++ b/fs/sysfs/dir.c
@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * fs/sysfs/dir.c - sysfs core and dir operation implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
+ *
+ * Please see Documentation/filesystems/sysfs.txt for more information.
+ */
+
+#define pr_fmt(fmt) "sysfs: " fmt
+
+#include <linux/fs.h>
+#include <linux/kobject.h>
+#include <linux/slab.h>
+#include "sysfs.h"
+
+DEFINE_SPINLOCK(sysfs_symlink_target_lock);
+
+void sysfs_warn_dup(struct kernfs_node *parent, const char *name)
+{
+ char *buf;
+
+ buf = kzalloc(PATH_MAX, GFP_KERNEL);
+ if (buf)
+ kernfs_path(parent, buf, PATH_MAX);
+
+ pr_warn("cannot create duplicate filename '%s/%s'\n", buf, name);
+ dump_stack();
+
+ kfree(buf);
+}
+
+/**
+ * sysfs_create_dir_ns - create a directory for an object with a namespace tag
+ * @kobj: object we're creating directory for
+ * @ns: the namespace tag to use
+ */
+int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
+{
+ struct kernfs_node *parent, *kn;
+ kuid_t uid;
+ kgid_t gid;
+
+ BUG_ON(!kobj);
+
+ if (kobj->parent)
+ parent = kobj->parent->sd;
+ else
+ parent = sysfs_root_kn;
+
+ if (!parent)
+ return -ENOENT;
+
+ kobject_get_ownership(kobj, &uid, &gid);
+
+ kn = kernfs_create_dir_ns(parent, kobject_name(kobj),
+ S_IRWXU | S_IRUGO | S_IXUGO, uid, gid,
+ kobj, ns);
+ if (IS_ERR(kn)) {
+ if (PTR_ERR(kn) == -EEXIST)
+ sysfs_warn_dup(parent, kobject_name(kobj));
+ return PTR_ERR(kn);
+ }
+
+ kobj->sd = kn;
+ return 0;
+}
+
+/**
+ * sysfs_remove_dir - remove an object's directory.
+ * @kobj: object.
+ *
+ * The only thing special about this is that we remove any files in
+ * the directory before we remove the directory, and we've inlined
+ * what used to be sysfs_rmdir() below, instead of calling separately.
+ */
+void sysfs_remove_dir(struct kobject *kobj)
+{
+ struct kernfs_node *kn = kobj->sd;
+
+ /*
+ * In general, kboject owner is responsible for ensuring removal
+ * doesn't race with other operations and sysfs doesn't provide any
+ * protection; however, when @kobj is used as a symlink target, the
+ * symlinking entity usually doesn't own @kobj and thus has no
+ * control over removal. @kobj->sd may be removed anytime
+ * and symlink code may end up dereferencing an already freed node.
+ *
+ * sysfs_symlink_target_lock synchronizes @kobj->sd
+ * disassociation against symlink operations so that symlink code
+ * can safely dereference @kobj->sd.
+ */
+ spin_lock(&sysfs_symlink_target_lock);
+ kobj->sd = NULL;
+ spin_unlock(&sysfs_symlink_target_lock);
+
+ if (kn) {
+ WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
+ kernfs_remove(kn);
+ }
+}
+
+int sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name,
+ const void *new_ns)
+{
+ struct kernfs_node *parent;
+ int ret;
+
+ parent = kernfs_get_parent(kobj->sd);
+ ret = kernfs_rename_ns(kobj->sd, parent, new_name, new_ns);
+ kernfs_put(parent);
+ return ret;
+}
+
+int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
+ const void *new_ns)
+{
+ struct kernfs_node *kn = kobj->sd;
+ struct kernfs_node *new_parent;
+
+ new_parent = new_parent_kobj && new_parent_kobj->sd ?
+ new_parent_kobj->sd : sysfs_root_kn;
+
+ return kernfs_rename_ns(kn, new_parent, kn->name, new_ns);
+}
+
+/**
+ * sysfs_create_mount_point - create an always empty directory
+ * @parent_kobj: kobject that will contain this always empty directory
+ * @name: The name of the always empty directory to add
+ */
+int sysfs_create_mount_point(struct kobject *parent_kobj, const char *name)
+{
+ struct kernfs_node *kn, *parent = parent_kobj->sd;
+
+ kn = kernfs_create_empty_dir(parent, name);
+ if (IS_ERR(kn)) {
+ if (PTR_ERR(kn) == -EEXIST)
+ sysfs_warn_dup(parent, name);
+ return PTR_ERR(kn);
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(sysfs_create_mount_point);
+
+/**
+ * sysfs_remove_mount_point - remove an always empty directory.
+ * @parent_kobj: kobject that will contain this always empty directory
+ * @name: The name of the always empty directory to remove
+ *
+ */
+void sysfs_remove_mount_point(struct kobject *parent_kobj, const char *name)
+{
+ struct kernfs_node *parent = parent_kobj->sd;
+
+ kernfs_remove_by_name_ns(parent, name, NULL);
+}
+EXPORT_SYMBOL_GPL(sysfs_remove_mount_point);