path_mount(): constify struct path argument

now it finally can be done.

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/internal.h

@@ -84,7 +84,7 @@ void mnt_put_write_access_file(struct file *file);
 extern void dissolve_on_fput(struct vfsmount *);
 extern bool may_mount(void);
 
-int path_mount(const char *dev_name, struct path *path,
+int path_mount(const char *dev_name, const struct path *path,
 		const char *type_page, unsigned long flags, void *data_page);
 int path_umount(struct path *path, int flags);
 

fs/namespace.c

@@ -4012,7 +4012,7 @@ static char *copy_mount_string(const void __user *data)
  * Therefore, if this magic number is present, it carries no information
  * and must be discarded.
  */
-int path_mount(const char *dev_name, struct path *path,
+int path_mount(const char *dev_name, const struct path *path,
 		const char *type_page, unsigned long flags, void *data_page)
 {
 	unsigned int mnt_flags = 0, sb_flags;