init: export name_to_dev_t and mark name argument as const

DM will switch its device lookup code to using name_to_dev_t() so it
must be exported.  Also, the @name argument should be marked const.
Signed-off-by: Dan Ehrenberg <dehrenberg@chromium.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

include/linux/mount.h

@@ -92,6 +92,6 @@ extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
 extern void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list);
 extern void mark_mounts_for_expiry(struct list_head *mounts);
 
-extern dev_t name_to_dev_t(char *name);
+extern dev_t name_to_dev_t(const char *name);
 
 #endif /* _LINUX_MOUNT_H */

init/do_mounts.c

@@ -207,7 +207,7 @@ static dev_t devt_from_partuuid(const char *uuid_str)
  *	bangs.
  */
 
-dev_t name_to_dev_t(char *name)
+dev_t name_to_dev_t(const char *name)
 {
 	char s[32];
 	char *p;
@@ -286,6 +286,7 @@ dev_t name_to_dev_t(char *name)
 done:
 	return res;
 }
+EXPORT_SYMBOL_GPL(name_to_dev_t);
 
 static int __init root_dev_setup(char *line)
 {