ext4: switch to using fscrypt_match_name()

Switch ext4 directory searches to use the fscrypt_match_name() helper
function.  There should be no functional change.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/namei.c

@@ -1245,29 +1245,17 @@ static void dx_insert_block(struct dx_frame *frame, u32 hash, ext4_lblk_t block)
 static inline int ext4_match(struct ext4_filename *fname,
 			     struct ext4_dir_entry_2 *de)
 {
-	const void *name = fname_name(fname);
-	u32 len = fname_len(fname);
+	struct fscrypt_name f;
 
 	if (!de->inode)
 		return 0;
 
+	f.usr_fname = fname->usr_fname;
+	f.disk_name = fname->disk_name;
 #ifdef CONFIG_EXT4_FS_ENCRYPTION
-	if (unlikely(!name)) {
-		if (fname->usr_fname->name[0] == '_') {
-			int ret;
-			if (de->name_len <= 32)
-				return 0;
-			ret = memcmp(de->name + ((de->name_len - 17) & ~15),
-				     fname->crypto_buf.name + 8, 16);
-			return (ret == 0) ? 1 : 0;
-		}
-		name = fname->crypto_buf.name;
-		len = fname->crypto_buf.len;
-	}
+	f.crypto_buf = fname->crypto_buf;
 #endif
-	if (de->name_len != len)
-		return 0;
-	return (memcmp(de->name, name, len) == 0) ? 1 : 0;
+	return fscrypt_match_name(&f, de->name, de->name_len);
 }
 
 /*