qstr: constify instances in f2fs

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index f9313f6..3b095a3 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -214,7 +214,7 @@
  * Entry is guaranteed to be valid.
  */
 struct f2fs_dir_entry *f2fs_find_entry(struct inode *dir,
-			struct qstr *child, struct page **res_page)
+			const struct qstr *child, struct page **res_page)
 {
 	unsigned long npages = dir_blocks(dir);
 	struct f2fs_dir_entry *de = NULL;
@@ -277,7 +277,7 @@
 	return de;
 }
 
-ino_t f2fs_inode_by_name(struct inode *dir, struct qstr *qstr)
+ino_t f2fs_inode_by_name(struct inode *dir, const struct qstr *qstr)
 {
 	ino_t res = 0;
 	struct f2fs_dir_entry *de;