qstr: constify instances in ext2

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/ext2/dir.c

@@ -358,8 +358,8 @@ ext2_readdir(struct file *file, struct dir_context *ctx)
  * and the entry itself. Page is returned mapped and unlocked.
  * Entry is guaranteed to be valid.
  */
-struct ext2_dir_entry_2 *ext2_find_entry (struct inode * dir,
-			struct qstr *child, struct page ** res_page)
+struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
+			const struct qstr *child, struct page **res_page)
 {
 	const char *name = child->name;
 	int namelen = child->len;
@@ -435,7 +435,7 @@ struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
 	return de;
 }
 
-ino_t ext2_inode_by_name(struct inode *dir, struct qstr *child)
+ino_t ext2_inode_by_name(struct inode *dir, const struct qstr *child)
 {
 	ino_t res = 0;
 	struct ext2_dir_entry_2 *de;

fs/ext2/ext2.h

@@ -754,9 +754,9 @@ extern void ext2_rsv_window_add(struct super_block *sb, struct ext2_reserve_wind
 
 /* dir.c */
 extern int ext2_add_link (struct dentry *, struct inode *);
-extern ino_t ext2_inode_by_name(struct inode *, struct qstr *);
+extern ino_t ext2_inode_by_name(struct inode *, const struct qstr *);
 extern int ext2_make_empty(struct inode *, struct inode *);
-extern struct ext2_dir_entry_2 * ext2_find_entry (struct inode *,struct qstr *, struct page **);
+extern struct ext2_dir_entry_2 * ext2_find_entry (struct inode *,const struct qstr *, struct page **);
 extern int ext2_delete_entry (struct ext2_dir_entry_2 *, struct page *);
 extern int ext2_empty_dir (struct inode *);
 extern struct ext2_dir_entry_2 * ext2_dotdot (struct inode *, struct page **);