drbd: disconnect, if the wrong UUIDs are attached on a connected peer

[ Upstream commit b17b59602b6dcf8f97a7dc7bc489a48388d7063a ]

With "on-no-data-accessible suspend-io", DRBD requires the next attach
or connect to be to the very same data generation uuid tag it lost last.

If we first lost connection to the peer,
then later lost connection to our own disk,
we would usually refuse to re-connect to the peer,
because it presents the wrong data set.

However, if the peer first connects without a disk,
and then attached its disk, we accepted that same wrong data set,
which would be "unexpected" by any user of that DRBD
and cause "undefined results" (read: very likely data corruption).

The fix is to forcefully disconnect as soon as we notice that the peer
attached to the "wrong" dataset.

Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 1b9822f264d24be7d268a814ee3d440b258bb4e3..e3da52b524d3b5b3aa54fd31dbe21c8462ffa4c1 100644 (file)
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -4143,7 +4143,7 @@ static int receive_uuids(struct drbd_connection *connection, struct packet_info
        kfree(device->p_uuid);
        device->p_uuid = p_uuid;
 
-       if (device->state.conn < C_CONNECTED &&
+       if ((device->state.conn < C_CONNECTED || device->state.pdsk == D_DISKLESS) &&
            device->state.disk < D_INCONSISTENT &&
            device->state.role == R_PRIMARY &&
            (device->ed_uuid & ~((u64)1)) != (p_uuid[UI_CURRENT] & ~((u64)1))) {