md/raid1: avoid reusing a resync bio after error handling.

NeilBrown · shligit · commit 0c9d5b127f69 · 2017-04-10T11:05:26.000-07:00
fix_sync_read_error() modifies a bio on a newly faulty device by setting bi_end_io to end_sync_write. This ensure that put_buf() will still call rdev_dec_pending() as required, but makes sure that subsequent code in fix_sync_read_error() doesn't try to read from the device. Unfortunately this interacts badly with sync_request_write() which assumes that any bio with bi_end_io set to non-NULL other than end_sync_read is safe to write to. As the device is now faulty it doesn't make sense to write. As the bio was recently used for a read, it is "dirty" and not suitable for immediate submission. In particular, ->bi_next might be non-NULL, which will cause generic_make_request() to complain. Break this interaction by refusing to write to devices which are marked as Faulty. Reported-and-tested-by: Michael Wang <yun.wang@profitbricks.com> Fixes: 2e52d44 ("md/raid1: add failfast handling for reads.") Cc: stable@vger.kernel.org (v4.10+) Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: Shaohua Li <shli@fb.com>
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
@@ -2218,6 +2218,8 @@ static void sync_request_write(struct mddev *mddev, struct r1bio *r1_bio)
 		     (i == r1_bio->read_disk ||
 		      !test_bit(MD_RECOVERY_SYNC, &mddev->recovery))))
 			continue;
+		if (test_bit(Faulty, &conf->mirrors[i].rdev->flags))
+			continue;
 
 		bio_set_op_attrs(wbio, REQ_OP_WRITE, 0);
 		if (test_bit(FailFast, &conf->mirrors[i].rdev->flags))
