[Drbd-dev] [PATCH] drbd: reply cancel to source when target of verify becomes inconsistent

[Zhang Duan]

Consider one situation below:
1. primary A disconnects with secondary B & C both of which are Uptodate
2. start a verify from B to C
3. during the verify above, A reconnects and starts a resync to C because of
primary-lost-quorum
4. C becomes resync target and Inconsistent, then ignore the verify requests
from B which are already in its receive buffer
5. verify from B to C stalls here

To resolve it, at step 4, C should reply a message of P_RS_CANCEL to B
Here is the result if do that:
Nov 6 16:25:46 node-2 kernel: drbd drbd1/0 drbd1 node-3: Skipped verify, 
too busy: start=170208, size=48 (sectors)
Nov 6 16:25:46 node-2 kernel: drbd drbd1/0 drbd1 node-3: Online verify 
done but 6 4k blocks skipped (total 314 sec; paused 0 sec; 3336 K/sec)
Nov 6 16:25:46 node-2 kernel: drbd drbd1/0 drbd1 node-3: repl( VerifyS 
-> Established )

Signed-off-by: ZhangDuan
---
drbd/drbd_receiver.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drbd/drbd_receiver.c b/drbd/drbd_receiver.c
index 268dbf4d..c6d4b7c9 100644
--- a/drbd/drbd_receiver.c
+++ b/drbd/drbd_receiver.c
@@ -3273,6 +3273,8 @@ static int receive_DataRequest(struct 
drbd_connection *connection, struct packet
break;
case P_OV_REQUEST:
verify_skipped_block(peer_device, sector, size);
+ drbd_send_ack_rp(peer_device, P_RS_CANCEL, p);
+ break;
/* Fall through */
case P_RS_THIN_REQ:
case P_RS_DATA_REQUEST:
-- 
2.24.0.windows.2

-- 
Sincerely Yours,
Zhang Duan

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