drbd: Delay/reject other state changes while establishing a connection

Changes to the role and disk state should be delayed or rejected
while we establish a connection.

This is necessary, since the peer will base its resync decision
on the UUIDs and the state we sent in the drbd_connect() function.

The most prominent example for this race is becoming primary after
sending state and UUIDs and before the state changes to C_WF_CONNECTION.

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

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 8576908..4fad3f5 100644 (file)
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -808,6 +808,7 @@ enum {
        CONN_WD_ST_CHG_FAIL,
        CONN_DRY_RUN,           /* Expect disconnect after resync handshake. */
        CREATE_BARRIER,         /* next P_DATA is preceded by a P_BARRIER */
+       STATE_SENT,             /* Do not change state/UUIDs while this is set */
 };
 
 struct drbd_tconn {                    /* is a resource from the config file */

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index ce9f4ca..3a8fa89 100644 (file)
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -502,7 +502,7 @@ bool conn_try_outdate_peer(struct drbd_tconn *tconn)
           here, because we might were able to re-establish the connection in the
           meantime. */
        spin_lock_irq(&tconn->req_lock);
-       if (tconn->cstate < C_WF_REPORT_PARAMS)
+       if (tconn->cstate < C_WF_REPORT_PARAMS && !test_bit(STATE_SENT, &tconn->flags))
                _conn_request_state(tconn, mask, val, CS_VERBOSE);
        spin_unlock_irq(&tconn->req_lock);
 

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index e8cd4c4..7b69034 100644 (file)
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -848,6 +848,7 @@ static int conn_connect(struct drbd_tconn *tconn)
        struct net_conf *nc;
        int vnr, timeout, try, h, ok;
        bool discard_my_data;
+       enum drbd_state_rv rv;
 
        if (conn_request_state(tconn, NS(conn, C_WF_CONNECTION), CS_VERBOSE) < SS_SUCCESS)
                return -2;
@@ -1008,6 +1009,8 @@ retry:
        if (drbd_send_protocol(tconn) == -EOPNOTSUPP)
                return -1;
 
+       set_bit(STATE_SENT, &tconn->flags);
+
        rcu_read_lock();
        idr_for_each_entry(&tconn->volumes, mdev, vnr) {
                kref_get(&mdev->kref);
@@ -1024,8 +1027,11 @@ retry:
        }
        rcu_read_unlock();
 
-       if (conn_request_state(tconn, NS(conn, C_WF_REPORT_PARAMS), CS_VERBOSE) < SS_SUCCESS)
+       rv = conn_request_state(tconn, NS(conn, C_WF_REPORT_PARAMS), CS_VERBOSE);
+       if (rv < SS_SUCCESS) {
+               clear_bit(STATE_SENT, &tconn->flags);
                return 0;
+       }
 
        drbd_thread_start(&tconn->asender);
 

diff --git a/drivers/block/drbd/drbd_state.c b/drivers/block/drbd/drbd_state.c
index 8c5cedf..c4554b1 100644 (file)
--- a/drivers/block/drbd/drbd_state.c
+++ b/drivers/block/drbd/drbd_state.c
@@ -53,7 +53,7 @@ static int w_after_state_ch(struct drbd_work *w, int unused);
 static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
                           union drbd_state ns, enum chg_state_flags flags);
 static enum drbd_state_rv is_valid_state(struct drbd_conf *, union drbd_state);
-static enum drbd_state_rv is_valid_soft_transition(union drbd_state, union drbd_state);
+static enum drbd_state_rv is_valid_soft_transition(union drbd_state, union drbd_state, struct drbd_tconn *);
 static enum drbd_state_rv is_valid_transition(union drbd_state os, union drbd_state ns);
 static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state ns,
                                       enum sanitize_state_warnings *warn);
@@ -267,7 +267,7 @@ _req_st_cond(struct drbd_conf *mdev, union drbd_state mask,
        if (rv == SS_UNKNOWN_ERROR) {
                rv = is_valid_state(mdev, ns);
                if (rv == SS_SUCCESS) {
-                       rv = is_valid_soft_transition(os, ns);
+                       rv = is_valid_soft_transition(os, ns, mdev->tconn);
                        if (rv == SS_SUCCESS)
                                rv = SS_UNKNOWN_ERROR; /* cont waiting, otherwise fail. */
                }
@@ -313,7 +313,7 @@ drbd_req_state(struct drbd_conf *mdev, union drbd_state mask,
        if (cl_wide_st_chg(mdev, os, ns)) {
                rv = is_valid_state(mdev, ns);
                if (rv == SS_SUCCESS)
-                       rv = is_valid_soft_transition(os, ns);
+                       rv = is_valid_soft_transition(os, ns, mdev->tconn);
                spin_unlock_irqrestore(&mdev->tconn->req_lock, flags);
 
                if (rv < SS_SUCCESS) {
@@ -569,7 +569,7 @@ is_valid_state(struct drbd_conf *mdev, union drbd_state ns)
  * @os:                old state.
  */
 static enum drbd_state_rv
-is_valid_soft_transition(union drbd_state os, union drbd_state ns)
+is_valid_soft_transition(union drbd_state os, union drbd_state ns, struct drbd_tconn *tconn)
 {
        enum drbd_state_rv rv = SS_SUCCESS;
 
@@ -595,6 +595,13 @@ is_valid_soft_transition(union drbd_state os, union drbd_state ns)
        /* if (ns.conn == os.conn && ns.conn == C_WF_REPORT_PARAMS)
           rv = SS_IN_TRANSIENT_STATE; */
 
+       /* While establishing a connection only allow cstate to change.
+          Delay/refuse role changes, detach attach etc... */
+       if (test_bit(STATE_SENT, &tconn->flags) &&
+           !(os.conn == C_WF_REPORT_PARAMS ||
+             (ns.conn == C_WF_REPORT_PARAMS && os.conn == C_WF_CONNECTION)))
+               rv = SS_IN_TRANSIENT_STATE;
+
        if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) && os.conn < C_CONNECTED)
                rv = SS_NEED_CONNECTION;
 
@@ -927,9 +934,9 @@ __drbd_set_state(struct drbd_conf *mdev, union drbd_state ns,
                           this happen...*/
 
                        if (is_valid_state(mdev, os) == rv)
-                               rv = is_valid_soft_transition(os, ns);
+                               rv = is_valid_soft_transition(os, ns, mdev->tconn);
                } else
-                       rv = is_valid_soft_transition(os, ns);
+                       rv = is_valid_soft_transition(os, ns, mdev->tconn);
        }
 
        if (rv < SS_SUCCESS) {
@@ -1393,6 +1400,12 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
        if (os.disk < D_UP_TO_DATE && os.conn >= C_SYNC_SOURCE && ns.conn == C_CONNECTED)
                drbd_send_state(mdev, ns);
 
+       /* Wake up role changes, that were delayed because of connection establishing */
+       if (os.conn == C_WF_REPORT_PARAMS && ns.conn != C_WF_REPORT_PARAMS) {
+               if (test_and_clear_bit(STATE_SENT, &mdev->tconn->flags))
+                       wake_up(&mdev->state_wait);
+       }
+
        /* This triggers bitmap writeout of potentially still unwritten pages
         * if the resync finished cleanly, or aborted because of peer disk
         * failure, or because of connection loss.
@@ -1565,9 +1578,9 @@ conn_is_valid_transition(struct drbd_tconn *tconn, union drbd_state mask, union
                        rv = is_valid_state(mdev, ns);
                        if (rv < SS_SUCCESS) {
                                if (is_valid_state(mdev, os) == rv)
-                                       rv = is_valid_soft_transition(os, ns);
+                                       rv = is_valid_soft_transition(os, ns, tconn);
                        } else
-                               rv = is_valid_soft_transition(os, ns);
+                               rv = is_valid_soft_transition(os, ns, tconn);
                }
                if (rv < SS_SUCCESS)
                        break;