drbd: Fix disconnect to keep the peer disk state if connection breaks during operation

The issue was that if the connection broke while we did the
gracefull state change to C_DISCONNECTING (C_TEARDOWN), then
we returned a success code from the state engine. (SS_CW_NO_NEED)

The result of that is that we missed to call the fence-peer
script in such a case.

Fixed that by introducing a new error code (SS_OUTDATE_WO_CONN).
This one should never reach back into user space.

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>

3 files changed, 13 insertions, 9 deletions

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 56bafdcd943e..39e9a91a8f31 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -2198,8 +2198,11 @@ static enum drbd_state_rv conn_try_disconnect(struct drbd_tconn *tconn, bool for
                 return SS_SUCCESS;
         case SS_PRIMARY_NOP:
                 /* Our state checking code wants to see the peer outdated. */
-                rv = conn_request_state(tconn, NS2(conn, C_DISCONNECTING,
-                                                pdsk, D_OUTDATED), CS_VERBOSE);
+                rv = conn_request_state(tconn, NS2(conn, C_DISCONNECTING, pdsk, D_OUTDATED), 0);
+
+                if (rv == SS_OUTDATE_WO_CONN) /* lost connection before graceful disconnect succeeded */
+                        rv = conn_request_state(tconn, NS(conn, C_DISCONNECTING), CS_VERBOSE);
+
                 break;
         case SS_CW_FAILED_BY_PEER:
                 /* The peer probably wants to see us outdated. */
diff --git a/drivers/block/drbd/drbd_state.c b/drivers/block/drbd/drbd_state.c
index 22e259f34370..90c5be2b1d30 100644
--- a/drivers/block/drbd/drbd_state.c
+++ b/drivers/block/drbd/drbd_state.c
@@ -642,6 +642,10 @@ is_valid_soft_transition(union drbd_state os, union drbd_state ns, struct drbd_t
             && os.conn < C_WF_REPORT_PARAMS)
                 rv = SS_NEED_CONNECTION; /* No NetworkFailure -> SyncTarget etc... */
 
+        if (ns.conn == C_DISCONNECTING && ns.pdsk == D_OUTDATED &&
+            os.conn < C_CONNECTED && os.pdsk > D_OUTDATED)
+                rv = SS_OUTDATE_WO_CONN;
+
         return rv;
 }
 
@@ -1748,13 +1752,9 @@ _conn_rq_cond(struct drbd_tconn *tconn, union drbd_state mask, union drbd_state
         if (test_and_clear_bit(CONN_WD_ST_CHG_FAIL, &tconn->flags))
                 return SS_CW_FAILED_BY_PEER;
 
-        rv = tconn->cstate != C_WF_REPORT_PARAMS ? SS_CW_NO_NEED : SS_UNKNOWN_ERROR;
-
-        if (rv == SS_UNKNOWN_ERROR)
-                rv = conn_is_valid_transition(tconn, mask, val, 0);
-
-        if (rv == SS_SUCCESS)
-                rv = SS_UNKNOWN_ERROR; /* cont waiting, otherwise fail. */
+        rv = conn_is_valid_transition(tconn, mask, val, 0);
+        if (rv == SS_SUCCESS && tconn->cstate == C_WF_REPORT_PARAMS)
+                rv = SS_UNKNOWN_ERROR; /* continue waiting */
 
         return rv;
 }
diff --git a/drivers/block/drbd/drbd_strings.c b/drivers/block/drbd/drbd_strings.c
index 9a664bd27404..58e08ff2b2ce 100644
--- a/drivers/block/drbd/drbd_strings.c
+++ b/drivers/block/drbd/drbd_strings.c
@@ -89,6 +89,7 @@ static const char *drbd_state_sw_errors[] = {
         [-SS_LOWER_THAN_OUTDATED] = "Disk state is lower than outdated",
         [-SS_IN_TRANSIENT_STATE] = "In transient state, retry after next state change",
         [-SS_CONCURRENT_ST_CHG] = "Concurrent state changes detected and aborted",
+        [-SS_OUTDATE_WO_CONN] = "Need a connection for a graceful disconnect/outdate peer",
         [-SS_O_VOL_PEER_PRI] = "Other vol primary on peer not allowed by config",
 };