ext4: explicit mount options parsing cleanup

Currently MOPT_EXPLICIT treated as EXPLICIT_DELALLOC which may be changed
in future. Let's fix it now.
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/super.c

@@ -1516,8 +1516,12 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
 		return -1;
 	if (args->from && (m->flags & MOPT_GTE0) && (arg < 0))
 		return -1;
-	if (m->flags & MOPT_EXPLICIT)
-		set_opt2(sb, EXPLICIT_DELALLOC);
+	if (m->flags & MOPT_EXPLICIT) {
+		if (m->mount_opt & EXT4_MOUNT_DELALLOC) {
+			set_opt2(sb, EXPLICIT_DELALLOC);
+		} else
+			return -1;
+	}
 	if (m->flags & MOPT_CLEAR_ERR)
 		clear_opt(sb, ERRORS_MASK);
 	if (token == Opt_noquota && sb_any_quota_loaded(sb)) {