sysfs, kernfs: move sysfs_open_file to include/linux/kernfs.h

sysfs_open_file will be used as the primary handle for kernfs methods.
Move its definition from fs/sysfs/file.c to include/linux/kernfs.h and
mark the public and private fields.

This is pure relocation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/sysfs/file.c

@@ -47,17 +47,6 @@ struct sysfs_open_dirent {
 	struct list_head	files; /* goes through sysfs_open_file.list */
 };
 
-struct sysfs_open_file {
-	struct sysfs_dirent	*sd;
-	struct file		*file;
-	struct mutex		mutex;
-	int			event;
-	struct list_head	list;
-
-	bool			mmapped;
-	const struct vm_operations_struct *vm_ops;
-};
-
 static bool sysfs_is_bin(struct sysfs_dirent *sd)
 {
 	return sysfs_type(sd) == SYSFS_KOBJ_BIN_ATTR;

include/linux/kernfs.h

@@ -9,12 +9,30 @@
 
 #include <linux/kernel.h>
 #include <linux/err.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
 
 struct file;
 struct iattr;
+struct seq_file;
+struct vm_area_struct;
 
 struct sysfs_dirent;
 
+struct sysfs_open_file {
+	/* published fields */
+	struct sysfs_dirent	*sd;
+	struct file		*file;
+
+	/* private fields, do not use outside kernfs proper */
+	struct mutex		mutex;
+	int			event;
+	struct list_head	list;
+
+	bool			mmapped;
+	const struct vm_operations_struct *vm_ops;
+};
+
 #ifdef CONFIG_SYSFS
 
 struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,