md/raid1: add error handling of read error from FailFast device

Current handle_read_error() function calls fix_read_error()
only if md device is RW and rdev does not include FailFast flag.
It does not handle a read error from a RW device including
FailFast flag.

I am not sure it is intended. But I found that write IO error
sets rdev faulty. The md module should handle the read IO error and
write IO error equally. So I think read IO error should set rdev faulty.
Signed-off-by: Gioh Kim <gi-oh.kim@profitbricks.com>
Reviewed-by: Jack Wang <jinpu.wang@profitbricks.com>
Signed-off-by: Shaohua Li <shli@fb.com>

drivers/md/raid1.c

@@ -2472,6 +2472,8 @@ static void handle_read_error(struct r1conf *conf, struct r1bio *r1_bio)
 		fix_read_error(conf, r1_bio->read_disk,
 			       r1_bio->sector, r1_bio->sectors);
 		unfreeze_array(conf);
+	} else if (mddev->ro == 0 && test_bit(FailFast, &rdev->flags)) {
+		md_error(mddev, rdev);
 	} else {
 		r1_bio->bios[r1_bio->read_disk] = IO_BLOCKED;
 	}