drbd: only fail empty flushes if no good data is reachable
We completed empty flushes (blkdev_issue_flush()) with IO error
if we lost the local disk, even if we still have an established
replication link to a healthy remote disk.
Fix this to only report errors to upper layers,
if neither local nor remote data is reachable.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 9f7ff1c..beefe65 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -263,8 +263,7 @@
else
root = &mdev->read_requests;
drbd_remove_request_interval(root, req);
- } else if (!(s & RQ_POSTPONED))
- D_ASSERT((s & (RQ_NET_MASK & ~RQ_NET_DONE)) == 0);
+ }
/* Before we can signal completion to the upper layers,
* we may need to close the current transfer log epoch.
@@ -755,6 +754,11 @@
D_ASSERT(req->rq_state & RQ_NET_PENDING);
mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_OK|RQ_NET_DONE);
break;
+
+ case QUEUE_AS_DRBD_BARRIER:
+ start_new_tl_epoch(mdev->tconn);
+ mod_rq_state(req, m, 0, RQ_NET_OK|RQ_NET_DONE);
+ break;
};
return rv;
@@ -975,8 +979,8 @@
/* The only size==0 bios we expect are empty flushes. */
D_ASSERT(req->master_bio->bi_rw & REQ_FLUSH);
if (remote)
- start_new_tl_epoch(mdev->tconn);
- return 0;
+ _req_mod(req, QUEUE_AS_DRBD_BARRIER);
+ return remote;
}
if (!remote && !send_oos)
diff --git a/drivers/block/drbd/drbd_req.h b/drivers/block/drbd/drbd_req.h
index c08d229..978cb1a 100644
--- a/drivers/block/drbd/drbd_req.h
+++ b/drivers/block/drbd/drbd_req.h
@@ -88,6 +88,14 @@
QUEUE_FOR_NET_READ,
QUEUE_FOR_SEND_OOS,
+ /* An empty flush is queued as P_BARRIER,
+ * which will cause it to complete "successfully",
+ * even if the local disk flush failed.
+ *
+ * Just like "real" requests, empty flushes (blkdev_issue_flush()) will
+ * only see an error if neither local nor remote data is reachable. */
+ QUEUE_AS_DRBD_BARRIER,
+
SEND_CANCELED,
SEND_FAILED,
HANDED_OVER_TO_NETWORK,