drbd: Refuse to change network options online when...

* the peer does not speak protocol_version 100 and the
  user wants to change one of:
    - wire_protocol
    - two_primaries
    - integrity_alg

* the user wants to remove the allow_two_primaries flag
  when there are two primaries

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

2 files changed, 19 insertions, 4 deletions

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 74c27f1507f3..133a6724657d 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -1722,10 +1722,24 @@ _check_net_options(struct drbd_tconn *tconn, struct net_conf *old_conf, struct n
         struct drbd_conf *mdev;
         int i;
 
-        if (old_conf && tconn->agreed_pro_version < 100 &&
-            tconn->cstate == C_WF_REPORT_PARAMS &&
-            new_conf->wire_protocol != old_conf->wire_protocol)
-                return ERR_NEED_APV_100;
+        if (old_conf && tconn->cstate == C_WF_REPORT_PARAMS && tconn->agreed_pro_version < 100) {
+                if (new_conf->wire_protocol != old_conf->wire_protocol)
+                        return ERR_NEED_APV_100;
+
+                if (new_conf->two_primaries != old_conf->two_primaries)
+                        return ERR_NEED_APV_100;
+
+                if (!new_conf->integrity_alg != !old_conf->integrity_alg)
+                        return ERR_NEED_APV_100;
+
+                if (strcmp(new_conf->integrity_alg, old_conf->integrity_alg))
+                        return ERR_NEED_APV_100;
+        }
+
+        if (!new_conf->two_primaries &&
+            conn_highest_role(tconn) == R_PRIMARY &&
+            conn_highest_peer(tconn) == R_PRIMARY)
+                return ERR_NEED_ALLOW_TWO_PRI;
 
         if (new_conf->two_primaries &&
             (new_conf->wire_protocol != DRBD_PROT_C))
diff --git a/include/linux/drbd.h b/include/linux/drbd.h
index 05063e6db81f..679e81123229 100644
--- a/include/linux/drbd.h
+++ b/include/linux/drbd.h
@@ -161,6 +161,7 @@ enum drbd_ret_code {
         ERR_MINOR_EXISTS        = 161,
         ERR_INVALID_REQUEST     = 162,
         ERR_NEED_APV_100        = 163,
+        ERR_NEED_ALLOW_TWO_PRI  = 164,
 
         /* insert new ones above this line */
         AFTER_LAST_ERR_CODE