drbd: Implemented two new connection states Ahead/Behind

In this connection mode, the ahead node no longer replicates
application IO. The behind's disk becomes out dated.

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 c804e44..21b7439 100644 (file)
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -2217,6 +2217,8 @@ static inline int drbd_state_is_stable(union drbd_state s)
        case C_VERIFY_T:
        case C_PAUSED_SYNC_S:
        case C_PAUSED_SYNC_T:
+       case C_AHEAD:
+       case C_BEHIND:
                /* maybe stable, look at the disk state */
                break;
 

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index e81d009..46f27d6 100644 (file)
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -871,16 +871,19 @@ static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state
 
        if (ns.conn >= C_CONNECTED &&
            ((ns.disk == D_CONSISTENT || ns.disk == D_OUTDATED) ||
-            (ns.disk == D_NEGOTIATING && ns.conn == C_WF_BITMAP_T))) {
+            (ns.disk == D_NEGOTIATING && ns.conn == C_WF_BITMAP_T) ||
+            ns.conn >= C_AHEAD)) {
                switch (ns.conn) {
                case C_WF_BITMAP_T:
                case C_PAUSED_SYNC_T:
+               case C_BEHIND:
                        ns.disk = D_OUTDATED;
                        break;
                case C_CONNECTED:
                case C_WF_BITMAP_S:
                case C_SYNC_SOURCE:
                case C_PAUSED_SYNC_S:
+               case C_AHEAD:
                        ns.disk = D_UP_TO_DATE;
                        break;
                case C_SYNC_TARGET:
@@ -893,16 +896,18 @@ static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state
        }
 
        if (ns.conn >= C_CONNECTED &&
-           (ns.pdsk == D_CONSISTENT || ns.pdsk == D_OUTDATED)) {
+           (ns.pdsk == D_CONSISTENT || ns.pdsk == D_OUTDATED || ns.conn >= C_AHEAD)) {
                switch (ns.conn) {
                case C_CONNECTED:
                case C_WF_BITMAP_T:
                case C_PAUSED_SYNC_T:
                case C_SYNC_TARGET:
+               case C_BEHIND:
                        ns.pdsk = D_UP_TO_DATE;
                        break;
                case C_WF_BITMAP_S:
                case C_PAUSED_SYNC_S:
+               case C_AHEAD:
                        /* remap any consistent state to D_OUTDATED,
                         * but disallow "upgrade" of not even consistent states.
                         */
@@ -1374,6 +1379,9 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
        if (os.conn == C_WF_REPORT_PARAMS && ns.conn >= C_CONNECTED)
                drbd_send_state(mdev);
 
+       if (os.conn != C_AHEAD && ns.conn == C_AHEAD)
+               drbd_send_state(mdev);
+
        /* We are in the progress to start a full sync... */
        if ((os.conn != C_STARTING_SYNC_T && ns.conn == C_STARTING_SYNC_T) ||
            (os.conn != C_STARTING_SYNC_S && ns.conn == C_STARTING_SYNC_S))

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index f3052d8..b19e8b2 100644 (file)
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -3179,6 +3179,9 @@ static int receive_state(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
        if (ns.conn == C_WF_REPORT_PARAMS)
                ns.conn = C_CONNECTED;
 
+       if (peer_state.conn == C_AHEAD)
+               ns.conn = C_BEHIND;
+
        if (mdev->p_uuid && peer_state.disk >= D_NEGOTIATING &&
            get_ldev_if_state(mdev, D_NEGOTIATING)) {
                int cr; /* consider resync */

diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 5c60d77..60288fb 100644 (file)
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -948,6 +948,29 @@ allocate_barrier:
                                ? queue_for_net_write
                                : queue_for_net_read);
        }
+
+       if (remote && mdev->net_conf->on_congestion != OC_BLOCK) {
+               int congested = 0;
+
+               if (mdev->net_conf->cong_fill &&
+                   atomic_read(&mdev->ap_in_flight) >= mdev->net_conf->cong_fill) {
+                       dev_info(DEV, "Congestion-fill threshold reached\n");
+                       congested = 1;
+               }
+
+               if (mdev->act_log->used >= mdev->net_conf->cong_extents) {
+                       dev_info(DEV, "Congestion-extents threshold reached\n");
+                       congested = 1;
+               }
+
+               if (congested) {
+                       if (mdev->net_conf->on_congestion == OC_PULL_AHEAD)
+                               _drbd_set_state(_NS(mdev, conn, C_AHEAD), 0, NULL);
+                       else  /*mdev->net_conf->on_congestion == OC_DISCONNECT */
+                               _drbd_set_state(_NS(mdev, conn, C_DISCONNECTING), 0, NULL);
+               }
+       }
+
        spin_unlock_irq(&mdev->req_lock);
        kfree(b); /* if someone else has beaten us to it... */
 

diff --git a/drivers/block/drbd/drbd_strings.c b/drivers/block/drbd/drbd_strings.c
index 85179e1..5b970ad 100644 (file)
--- a/drivers/block/drbd/drbd_strings.c
+++ b/drivers/block/drbd/drbd_strings.c
@@ -48,6 +48,8 @@ static const char *drbd_conn_s_names[] = {
        [C_PAUSED_SYNC_T]    = "PausedSyncT",
        [C_VERIFY_S]         = "VerifyS",
        [C_VERIFY_T]         = "VerifyT",
+       [C_AHEAD]            = "Ahead",
+       [C_BEHIND]           = "Behind",
 };
 
 static const char *drbd_role_s_names[] = {
@@ -92,7 +94,7 @@ static const char *drbd_state_sw_errors[] = {
 const char *drbd_conn_str(enum drbd_conns s)
 {
        /* enums are unsigned... */
-       return s > C_PAUSED_SYNC_T ? "TOO_LARGE" : drbd_conn_s_names[s];
+       return s > C_BEHIND ? "TOO_LARGE" : drbd_conn_s_names[s];
 }
 
 const char *drbd_role_str(enum drbd_role s)

diff --git a/include/linux/drbd.h b/include/linux/drbd.h
index 03a08ba..23f31be 100644 (file)
--- a/include/linux/drbd.h
+++ b/include/linux/drbd.h
@@ -206,6 +206,10 @@ enum drbd_conns {
        C_VERIFY_T,
        C_PAUSED_SYNC_S,
        C_PAUSED_SYNC_T,
+
+       C_AHEAD,
+       C_BEHIND,
+
        C_MASK = 31
 };