ext4: enable block_validity by default

Enable by default the block_validity feature, which checks for
collisions between newly allocated blocks and critical system
metadata.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/super.c

@@ -3519,8 +3519,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 		set_opt(sb, ERRORS_CONT);
 	else
 		set_opt(sb, ERRORS_RO);
-	if (def_mount_opts & EXT4_DEFM_BLOCK_VALIDITY)
-		set_opt(sb, BLOCK_VALIDITY);
+	/* block_validity enabled by default; disable with noblock_validity */
+	set_opt(sb, BLOCK_VALIDITY);
 	if (def_mount_opts & EXT4_DEFM_DISCARD)
 		set_opt(sb, DISCARD);