drbd: Considering that the two_primaries config flag can change

Now since it is possible to change the two_primaries config
flag while the connection is up, make sure we treat a peer_req
in a consistent way if the config flag changes while the peer_req
is under IO.

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

2 files changed, 18 insertions, 5 deletions

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 83e6cadbe7aa..3833d56b8de8 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -661,6 +661,9 @@ enum {
 
         /* The peer wants a write ACK for this (wire proto C) */
         __EE_SEND_WRITE_ACK,
+
+        /* Is set when net_conf had two_primaries set while creating this peer_req */
+        __EE_IN_INTERVAL_TREE,
 };
 #define EE_CALL_AL_COMPLETE_IO (1<<__EE_CALL_AL_COMPLETE_IO)
 #define EE_MAY_SET_IN_SYNC     (1<<__EE_MAY_SET_IN_SYNC)
@@ -669,6 +672,7 @@ enum {
 #define EE_HAS_DIGEST          (1<<__EE_HAS_DIGEST)
 #define EE_RESTART_REQUESTS     (1<<__EE_RESTART_REQUESTS)
 #define EE_SEND_WRITE_ACK       (1<<__EE_SEND_WRITE_ACK)
+#define EE_IN_INTERVAL_TREE     (1<<__EE_IN_INTERVAL_TREE)
 
 /* flag bits per mdev */
 enum {
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 397f97701988..4665ad79b4ae 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -1752,7 +1752,7 @@ static int e_end_block(struct drbd_work *w, int cancel)
         }
         /* we delete from the conflict detection hash _after_ we sent out the
          * P_WRITE_ACK / P_NEG_ACK, to get the sequence number right.  */
-        if (mdev->tconn->net_conf->two_primaries) {
+        if (peer_req->flags & EE_IN_INTERVAL_TREE) {
                 spin_lock_irq(&mdev->tconn->req_lock);
                 D_ASSERT(!drbd_interval_empty(&peer_req->i));
                 drbd_remove_epoch_entry_interval(mdev, peer_req);
@@ -1811,14 +1811,19 @@ static u32 seq_max(u32 a, u32 b)
 static bool need_peer_seq(struct drbd_conf *mdev)
 {
         struct drbd_tconn *tconn = mdev->tconn;
+        int tp;
 
         /*
          * We only need to keep track of the last packet_seq number of our peer
          * if we are in dual-primary mode and we have the discard flag set; see
          * handle_write_conflicts().
          */
-        return tconn->net_conf->two_primaries &&
-               test_bit(DISCARD_CONCURRENT, &tconn->flags);
+
+        rcu_read_lock();
+        tp = rcu_dereference(mdev->tconn->net_conf)->two_primaries;
+        rcu_read_unlock();
+
+        return tp && test_bit(DISCARD_CONCURRENT, &tconn->flags);
 }
 
 static void update_peer_seq(struct drbd_conf *mdev, unsigned int peer_seq)
@@ -2049,7 +2054,7 @@ static int receive_Data(struct drbd_tconn *tconn, struct packet_info *pi)
         u32 peer_seq = be32_to_cpu(p->seq_num);
         int rw = WRITE;
         u32 dp_flags;
-        int err;
+        int err, tp;
 
         mdev = vnr_to_mdev(tconn, pi->vnr);
         if (!mdev)
@@ -2094,7 +2099,11 @@ static int receive_Data(struct drbd_tconn *tconn, struct packet_info *pi)
         atomic_inc(&peer_req->epoch->active);
         spin_unlock(&mdev->epoch_lock);
 
-        if (mdev->tconn->net_conf->two_primaries) {
+        rcu_read_lock();
+        tp = rcu_dereference(mdev->tconn->net_conf)->two_primaries;
+        rcu_read_unlock();
+        if (tp) {
+                peer_req->flags |= EE_IN_INTERVAL_TREE;
                 err = wait_for_and_update_peer_seq(mdev, peer_seq);
                 if (err)
                         goto out_interrupted;