Add the rt linux 4.1.3-rt3 as base
[kvmfornfv.git] / kernel / drivers / block / drbd / drbd_state.c
diff --git a/kernel/drivers/block/drbd/drbd_state.c b/kernel/drivers/block/drbd/drbd_state.c
new file mode 100644 (file)
index 0000000..2d7dd26
--- /dev/null
@@ -0,0 +1,1918 @@
+/*
+   drbd_state.c
+
+   This file is part of DRBD by Philipp Reisner and Lars Ellenberg.
+
+   Copyright (C) 2001-2008, LINBIT Information Technologies GmbH.
+   Copyright (C) 1999-2008, Philipp Reisner <philipp.reisner@linbit.com>.
+   Copyright (C) 2002-2008, Lars Ellenberg <lars.ellenberg@linbit.com>.
+
+   Thanks to Carter Burden, Bart Grantham and Gennadiy Nerubayev
+   from Logicworks, Inc. for making SDP replication support possible.
+
+   drbd is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   drbd is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with drbd; see the file COPYING.  If not, write to
+   the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/drbd_limits.h>
+#include "drbd_int.h"
+#include "drbd_protocol.h"
+#include "drbd_req.h"
+
+struct after_state_chg_work {
+       struct drbd_work w;
+       struct drbd_device *device;
+       union drbd_state os;
+       union drbd_state ns;
+       enum chg_state_flags flags;
+       struct completion *done;
+};
+
+enum sanitize_state_warnings {
+       NO_WARNING,
+       ABORTED_ONLINE_VERIFY,
+       ABORTED_RESYNC,
+       CONNECTION_LOST_NEGOTIATING,
+       IMPLICITLY_UPGRADED_DISK,
+       IMPLICITLY_UPGRADED_PDSK,
+};
+
+static int w_after_state_ch(struct drbd_work *w, int unused);
+static void after_state_ch(struct drbd_device *device, union drbd_state os,
+                          union drbd_state ns, enum chg_state_flags flags);
+static enum drbd_state_rv is_valid_state(struct drbd_device *, union drbd_state);
+static enum drbd_state_rv is_valid_soft_transition(union drbd_state, union drbd_state, struct drbd_connection *);
+static enum drbd_state_rv is_valid_transition(union drbd_state os, union drbd_state ns);
+static union drbd_state sanitize_state(struct drbd_device *device, union drbd_state os,
+                                      union drbd_state ns, enum sanitize_state_warnings *warn);
+
+static inline bool is_susp(union drbd_state s)
+{
+        return s.susp || s.susp_nod || s.susp_fen;
+}
+
+bool conn_all_vols_unconf(struct drbd_connection *connection)
+{
+       struct drbd_peer_device *peer_device;
+       bool rv = true;
+       int vnr;
+
+       rcu_read_lock();
+       idr_for_each_entry(&connection->peer_devices, peer_device, vnr) {
+               struct drbd_device *device = peer_device->device;
+               if (device->state.disk != D_DISKLESS ||
+                   device->state.conn != C_STANDALONE ||
+                   device->state.role != R_SECONDARY) {
+                       rv = false;
+                       break;
+               }
+       }
+       rcu_read_unlock();
+
+       return rv;
+}
+
+/* Unfortunately the states where not correctly ordered, when
+   they where defined. therefore can not use max_t() here. */
+static enum drbd_role max_role(enum drbd_role role1, enum drbd_role role2)
+{
+       if (role1 == R_PRIMARY || role2 == R_PRIMARY)
+               return R_PRIMARY;
+       if (role1 == R_SECONDARY || role2 == R_SECONDARY)
+               return R_SECONDARY;
+       return R_UNKNOWN;
+}
+static enum drbd_role min_role(enum drbd_role role1, enum drbd_role role2)
+{
+       if (role1 == R_UNKNOWN || role2 == R_UNKNOWN)
+               return R_UNKNOWN;
+       if (role1 == R_SECONDARY || role2 == R_SECONDARY)
+               return R_SECONDARY;
+       return R_PRIMARY;
+}
+
+enum drbd_role conn_highest_role(struct drbd_connection *connection)
+{
+       enum drbd_role role = R_UNKNOWN;
+       struct drbd_peer_device *peer_device;
+       int vnr;
+
+       rcu_read_lock();
+       idr_for_each_entry(&connection->peer_devices, peer_device, vnr) {
+               struct drbd_device *device = peer_device->device;
+               role = max_role(role, device->state.role);
+       }
+       rcu_read_unlock();
+
+       return role;
+}
+
+enum drbd_role conn_highest_peer(struct drbd_connection *connection)
+{
+       enum drbd_role peer = R_UNKNOWN;
+       struct drbd_peer_device *peer_device;
+       int vnr;
+
+       rcu_read_lock();
+       idr_for_each_entry(&connection->peer_devices, peer_device, vnr) {
+               struct drbd_device *device = peer_device->device;
+               peer = max_role(peer, device->state.peer);
+       }
+       rcu_read_unlock();
+
+       return peer;
+}
+
+enum drbd_disk_state conn_highest_disk(struct drbd_connection *connection)
+{
+       enum drbd_disk_state disk_state = D_DISKLESS;
+       struct drbd_peer_device *peer_device;
+       int vnr;
+
+       rcu_read_lock();
+       idr_for_each_entry(&connection->peer_devices, peer_device, vnr) {
+               struct drbd_device *device = peer_device->device;
+               disk_state = max_t(enum drbd_disk_state, disk_state, device->state.disk);
+       }
+       rcu_read_unlock();
+
+       return disk_state;
+}
+
+enum drbd_disk_state conn_lowest_disk(struct drbd_connection *connection)
+{
+       enum drbd_disk_state disk_state = D_MASK;
+       struct drbd_peer_device *peer_device;
+       int vnr;
+
+       rcu_read_lock();
+       idr_for_each_entry(&connection->peer_devices, peer_device, vnr) {
+               struct drbd_device *device = peer_device->device;
+               disk_state = min_t(enum drbd_disk_state, disk_state, device->state.disk);
+       }
+       rcu_read_unlock();
+
+       return disk_state;
+}
+
+enum drbd_disk_state conn_highest_pdsk(struct drbd_connection *connection)
+{
+       enum drbd_disk_state disk_state = D_DISKLESS;
+       struct drbd_peer_device *peer_device;
+       int vnr;
+
+       rcu_read_lock();
+       idr_for_each_entry(&connection->peer_devices, peer_device, vnr) {
+               struct drbd_device *device = peer_device->device;
+               disk_state = max_t(enum drbd_disk_state, disk_state, device->state.pdsk);
+       }
+       rcu_read_unlock();
+
+       return disk_state;
+}
+
+enum drbd_conns conn_lowest_conn(struct drbd_connection *connection)
+{
+       enum drbd_conns conn = C_MASK;
+       struct drbd_peer_device *peer_device;
+       int vnr;
+
+       rcu_read_lock();
+       idr_for_each_entry(&connection->peer_devices, peer_device, vnr) {
+               struct drbd_device *device = peer_device->device;
+               conn = min_t(enum drbd_conns, conn, device->state.conn);
+       }
+       rcu_read_unlock();
+
+       return conn;
+}
+
+static bool no_peer_wf_report_params(struct drbd_connection *connection)
+{
+       struct drbd_peer_device *peer_device;
+       int vnr;
+       bool rv = true;
+
+       rcu_read_lock();
+       idr_for_each_entry(&connection->peer_devices, peer_device, vnr)
+               if (peer_device->device->state.conn == C_WF_REPORT_PARAMS) {
+                       rv = false;
+                       break;
+               }
+       rcu_read_unlock();
+
+       return rv;
+}
+
+static void wake_up_all_devices(struct drbd_connection *connection)
+{
+       struct drbd_peer_device *peer_device;
+       int vnr;
+
+       rcu_read_lock();
+       idr_for_each_entry(&connection->peer_devices, peer_device, vnr)
+               wake_up(&peer_device->device->state_wait);
+       rcu_read_unlock();
+
+}
+
+
+/**
+ * cl_wide_st_chg() - true if the state change is a cluster wide one
+ * @device:    DRBD device.
+ * @os:                old (current) state.
+ * @ns:                new (wanted) state.
+ */
+static int cl_wide_st_chg(struct drbd_device *device,
+                         union drbd_state os, union drbd_state ns)
+{
+       return (os.conn >= C_CONNECTED && ns.conn >= C_CONNECTED &&
+                ((os.role != R_PRIMARY && ns.role == R_PRIMARY) ||
+                 (os.conn != C_STARTING_SYNC_T && ns.conn == C_STARTING_SYNC_T) ||
+                 (os.conn != C_STARTING_SYNC_S && ns.conn == C_STARTING_SYNC_S) ||
+                 (os.disk != D_FAILED && ns.disk == D_FAILED))) ||
+               (os.conn >= C_CONNECTED && ns.conn == C_DISCONNECTING) ||
+               (os.conn == C_CONNECTED && ns.conn == C_VERIFY_S) ||
+               (os.conn == C_CONNECTED && ns.conn == C_WF_REPORT_PARAMS);
+}
+
+static union drbd_state
+apply_mask_val(union drbd_state os, union drbd_state mask, union drbd_state val)
+{
+       union drbd_state ns;
+       ns.i = (os.i & ~mask.i) | val.i;
+       return ns;
+}
+
+enum drbd_state_rv
+drbd_change_state(struct drbd_device *device, enum chg_state_flags f,
+                 union drbd_state mask, union drbd_state val)
+{
+       unsigned long flags;
+       union drbd_state ns;
+       enum drbd_state_rv rv;
+
+       spin_lock_irqsave(&device->resource->req_lock, flags);
+       ns = apply_mask_val(drbd_read_state(device), mask, val);
+       rv = _drbd_set_state(device, ns, f, NULL);
+       spin_unlock_irqrestore(&device->resource->req_lock, flags);
+
+       return rv;
+}
+
+/**
+ * drbd_force_state() - Impose a change which happens outside our control on our state
+ * @device:    DRBD device.
+ * @mask:      mask of state bits to change.
+ * @val:       value of new state bits.
+ */
+void drbd_force_state(struct drbd_device *device,
+       union drbd_state mask, union drbd_state val)
+{
+       drbd_change_state(device, CS_HARD, mask, val);
+}
+
+static enum drbd_state_rv
+_req_st_cond(struct drbd_device *device, union drbd_state mask,
+            union drbd_state val)
+{
+       union drbd_state os, ns;
+       unsigned long flags;
+       enum drbd_state_rv rv;
+
+       if (test_and_clear_bit(CL_ST_CHG_SUCCESS, &device->flags))
+               return SS_CW_SUCCESS;
+
+       if (test_and_clear_bit(CL_ST_CHG_FAIL, &device->flags))
+               return SS_CW_FAILED_BY_PEER;
+
+       spin_lock_irqsave(&device->resource->req_lock, flags);
+       os = drbd_read_state(device);
+       ns = sanitize_state(device, os, apply_mask_val(os, mask, val), NULL);
+       rv = is_valid_transition(os, ns);
+       if (rv >= SS_SUCCESS)
+               rv = SS_UNKNOWN_ERROR;  /* cont waiting, otherwise fail. */
+
+       if (!cl_wide_st_chg(device, os, ns))
+               rv = SS_CW_NO_NEED;
+       if (rv == SS_UNKNOWN_ERROR) {
+               rv = is_valid_state(device, ns);
+               if (rv >= SS_SUCCESS) {
+                       rv = is_valid_soft_transition(os, ns, first_peer_device(device)->connection);
+                       if (rv >= SS_SUCCESS)
+                               rv = SS_UNKNOWN_ERROR; /* cont waiting, otherwise fail. */
+               }
+       }
+       spin_unlock_irqrestore(&device->resource->req_lock, flags);
+
+       return rv;
+}
+
+/**
+ * drbd_req_state() - Perform an eventually cluster wide state change
+ * @device:    DRBD device.
+ * @mask:      mask of state bits to change.
+ * @val:       value of new state bits.
+ * @f:         flags
+ *
+ * Should not be called directly, use drbd_request_state() or
+ * _drbd_request_state().
+ */
+static enum drbd_state_rv
+drbd_req_state(struct drbd_device *device, union drbd_state mask,
+              union drbd_state val, enum chg_state_flags f)
+{
+       struct completion done;
+       unsigned long flags;
+       union drbd_state os, ns;
+       enum drbd_state_rv rv;
+
+       init_completion(&done);
+
+       if (f & CS_SERIALIZE)
+               mutex_lock(device->state_mutex);
+
+       spin_lock_irqsave(&device->resource->req_lock, flags);
+       os = drbd_read_state(device);
+       ns = sanitize_state(device, os, apply_mask_val(os, mask, val), NULL);
+       rv = is_valid_transition(os, ns);
+       if (rv < SS_SUCCESS) {
+               spin_unlock_irqrestore(&device->resource->req_lock, flags);
+               goto abort;
+       }
+
+       if (cl_wide_st_chg(device, os, ns)) {
+               rv = is_valid_state(device, ns);
+               if (rv == SS_SUCCESS)
+                       rv = is_valid_soft_transition(os, ns, first_peer_device(device)->connection);
+               spin_unlock_irqrestore(&device->resource->req_lock, flags);
+
+               if (rv < SS_SUCCESS) {
+                       if (f & CS_VERBOSE)
+                               print_st_err(device, os, ns, rv);
+                       goto abort;
+               }
+
+               if (drbd_send_state_req(first_peer_device(device), mask, val)) {
+                       rv = SS_CW_FAILED_BY_PEER;
+                       if (f & CS_VERBOSE)
+                               print_st_err(device, os, ns, rv);
+                       goto abort;
+               }
+
+               wait_event(device->state_wait,
+                       (rv = _req_st_cond(device, mask, val)));
+
+               if (rv < SS_SUCCESS) {
+                       if (f & CS_VERBOSE)
+                               print_st_err(device, os, ns, rv);
+                       goto abort;
+               }
+               spin_lock_irqsave(&device->resource->req_lock, flags);
+               ns = apply_mask_val(drbd_read_state(device), mask, val);
+               rv = _drbd_set_state(device, ns, f, &done);
+       } else {
+               rv = _drbd_set_state(device, ns, f, &done);
+       }
+
+       spin_unlock_irqrestore(&device->resource->req_lock, flags);
+
+       if (f & CS_WAIT_COMPLETE && rv == SS_SUCCESS) {
+               D_ASSERT(device, current != first_peer_device(device)->connection->worker.task);
+               wait_for_completion(&done);
+       }
+
+abort:
+       if (f & CS_SERIALIZE)
+               mutex_unlock(device->state_mutex);
+
+       return rv;
+}
+
+/**
+ * _drbd_request_state() - Request a state change (with flags)
+ * @device:    DRBD device.
+ * @mask:      mask of state bits to change.
+ * @val:       value of new state bits.
+ * @f:         flags
+ *
+ * Cousin of drbd_request_state(), useful with the CS_WAIT_COMPLETE
+ * flag, or when logging of failed state change requests is not desired.
+ */
+enum drbd_state_rv
+_drbd_request_state(struct drbd_device *device, union drbd_state mask,
+                   union drbd_state val, enum chg_state_flags f)
+{
+       enum drbd_state_rv rv;
+
+       wait_event(device->state_wait,
+                  (rv = drbd_req_state(device, mask, val, f)) != SS_IN_TRANSIENT_STATE);
+
+       return rv;
+}
+
+enum drbd_state_rv
+_drbd_request_state_holding_state_mutex(struct drbd_device *device, union drbd_state mask,
+                   union drbd_state val, enum chg_state_flags f)
+{
+       enum drbd_state_rv rv;
+
+       BUG_ON(f & CS_SERIALIZE);
+
+       wait_event_cmd(device->state_wait,
+                      (rv = drbd_req_state(device, mask, val, f)) != SS_IN_TRANSIENT_STATE,
+                      mutex_unlock(device->state_mutex),
+                      mutex_lock(device->state_mutex));
+
+       return rv;
+}
+
+static void print_st(struct drbd_device *device, const char *name, union drbd_state ns)
+{
+       drbd_err(device, " %s = { cs:%s ro:%s/%s ds:%s/%s %c%c%c%c%c%c }\n",
+           name,
+           drbd_conn_str(ns.conn),
+           drbd_role_str(ns.role),
+           drbd_role_str(ns.peer),
+           drbd_disk_str(ns.disk),
+           drbd_disk_str(ns.pdsk),
+           is_susp(ns) ? 's' : 'r',
+           ns.aftr_isp ? 'a' : '-',
+           ns.peer_isp ? 'p' : '-',
+           ns.user_isp ? 'u' : '-',
+           ns.susp_fen ? 'F' : '-',
+           ns.susp_nod ? 'N' : '-'
+           );
+}
+
+void print_st_err(struct drbd_device *device, union drbd_state os,
+                 union drbd_state ns, enum drbd_state_rv err)
+{
+       if (err == SS_IN_TRANSIENT_STATE)
+               return;
+       drbd_err(device, "State change failed: %s\n", drbd_set_st_err_str(err));
+       print_st(device, " state", os);
+       print_st(device, "wanted", ns);
+}
+
+static long print_state_change(char *pb, union drbd_state os, union drbd_state ns,
+                              enum chg_state_flags flags)
+{
+       char *pbp;
+       pbp = pb;
+       *pbp = 0;
+
+       if (ns.role != os.role && flags & CS_DC_ROLE)
+               pbp += sprintf(pbp, "role( %s -> %s ) ",
+                              drbd_role_str(os.role),
+                              drbd_role_str(ns.role));
+       if (ns.peer != os.peer && flags & CS_DC_PEER)
+               pbp += sprintf(pbp, "peer( %s -> %s ) ",
+                              drbd_role_str(os.peer),
+                              drbd_role_str(ns.peer));
+       if (ns.conn != os.conn && flags & CS_DC_CONN)
+               pbp += sprintf(pbp, "conn( %s -> %s ) ",
+                              drbd_conn_str(os.conn),
+                              drbd_conn_str(ns.conn));
+       if (ns.disk != os.disk && flags & CS_DC_DISK)
+               pbp += sprintf(pbp, "disk( %s -> %s ) ",
+                              drbd_disk_str(os.disk),
+                              drbd_disk_str(ns.disk));
+       if (ns.pdsk != os.pdsk && flags & CS_DC_PDSK)
+               pbp += sprintf(pbp, "pdsk( %s -> %s ) ",
+                              drbd_disk_str(os.pdsk),
+                              drbd_disk_str(ns.pdsk));
+
+       return pbp - pb;
+}
+
+static void drbd_pr_state_change(struct drbd_device *device, union drbd_state os, union drbd_state ns,
+                                enum chg_state_flags flags)
+{
+       char pb[300];
+       char *pbp = pb;
+
+       pbp += print_state_change(pbp, os, ns, flags ^ CS_DC_MASK);
+
+       if (ns.aftr_isp != os.aftr_isp)
+               pbp += sprintf(pbp, "aftr_isp( %d -> %d ) ",
+                              os.aftr_isp,
+                              ns.aftr_isp);
+       if (ns.peer_isp != os.peer_isp)
+               pbp += sprintf(pbp, "peer_isp( %d -> %d ) ",
+                              os.peer_isp,
+                              ns.peer_isp);
+       if (ns.user_isp != os.user_isp)
+               pbp += sprintf(pbp, "user_isp( %d -> %d ) ",
+                              os.user_isp,
+                              ns.user_isp);
+
+       if (pbp != pb)
+               drbd_info(device, "%s\n", pb);
+}
+
+static void conn_pr_state_change(struct drbd_connection *connection, union drbd_state os, union drbd_state ns,
+                                enum chg_state_flags flags)
+{
+       char pb[300];
+       char *pbp = pb;
+
+       pbp += print_state_change(pbp, os, ns, flags);
+
+       if (is_susp(ns) != is_susp(os) && flags & CS_DC_SUSP)
+               pbp += sprintf(pbp, "susp( %d -> %d ) ",
+                              is_susp(os),
+                              is_susp(ns));
+
+       if (pbp != pb)
+               drbd_info(connection, "%s\n", pb);
+}
+
+
+/**
+ * is_valid_state() - Returns an SS_ error code if ns is not valid
+ * @device:    DRBD device.
+ * @ns:                State to consider.
+ */
+static enum drbd_state_rv
+is_valid_state(struct drbd_device *device, union drbd_state ns)
+{
+       /* See drbd_state_sw_errors in drbd_strings.c */
+
+       enum drbd_fencing_p fp;
+       enum drbd_state_rv rv = SS_SUCCESS;
+       struct net_conf *nc;
+
+       rcu_read_lock();
+       fp = FP_DONT_CARE;
+       if (get_ldev(device)) {
+               fp = rcu_dereference(device->ldev->disk_conf)->fencing;
+               put_ldev(device);
+       }
+
+       nc = rcu_dereference(first_peer_device(device)->connection->net_conf);
+       if (nc) {
+               if (!nc->two_primaries && ns.role == R_PRIMARY) {
+                       if (ns.peer == R_PRIMARY)
+                               rv = SS_TWO_PRIMARIES;
+                       else if (conn_highest_peer(first_peer_device(device)->connection) == R_PRIMARY)
+                               rv = SS_O_VOL_PEER_PRI;
+               }
+       }
+
+       if (rv <= 0)
+               /* already found a reason to abort */;
+       else if (ns.role == R_SECONDARY && device->open_cnt)
+               rv = SS_DEVICE_IN_USE;
+
+       else if (ns.role == R_PRIMARY && ns.conn < C_CONNECTED && ns.disk < D_UP_TO_DATE)
+               rv = SS_NO_UP_TO_DATE_DISK;
+
+       else if (fp >= FP_RESOURCE &&
+                ns.role == R_PRIMARY && ns.conn < C_CONNECTED && ns.pdsk >= D_UNKNOWN)
+               rv = SS_PRIMARY_NOP;
+
+       else if (ns.role == R_PRIMARY && ns.disk <= D_INCONSISTENT && ns.pdsk <= D_INCONSISTENT)
+               rv = SS_NO_UP_TO_DATE_DISK;
+
+       else if (ns.conn > C_CONNECTED && ns.disk < D_INCONSISTENT)
+               rv = SS_NO_LOCAL_DISK;
+
+       else if (ns.conn > C_CONNECTED && ns.pdsk < D_INCONSISTENT)
+               rv = SS_NO_REMOTE_DISK;
+
+       else if (ns.conn > C_CONNECTED && ns.disk < D_UP_TO_DATE && ns.pdsk < D_UP_TO_DATE)
+               rv = SS_NO_UP_TO_DATE_DISK;
+
+       else if ((ns.conn == C_CONNECTED ||
+                 ns.conn == C_WF_BITMAP_S ||
+                 ns.conn == C_SYNC_SOURCE ||
+                 ns.conn == C_PAUSED_SYNC_S) &&
+                 ns.disk == D_OUTDATED)
+               rv = SS_CONNECTED_OUTDATES;
+
+       else if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) &&
+                (nc->verify_alg[0] == 0))
+               rv = SS_NO_VERIFY_ALG;
+
+       else if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) &&
+                 first_peer_device(device)->connection->agreed_pro_version < 88)
+               rv = SS_NOT_SUPPORTED;
+
+       else if (ns.role == R_PRIMARY && ns.disk < D_UP_TO_DATE && ns.pdsk < D_UP_TO_DATE)
+               rv = SS_NO_UP_TO_DATE_DISK;
+
+       else if ((ns.conn == C_STARTING_SYNC_S || ns.conn == C_STARTING_SYNC_T) &&
+                 ns.pdsk == D_UNKNOWN)
+               rv = SS_NEED_CONNECTION;
+
+       else if (ns.conn >= C_CONNECTED && ns.pdsk == D_UNKNOWN)
+               rv = SS_CONNECTED_OUTDATES;
+
+       rcu_read_unlock();
+
+       return rv;
+}
+
+/**
+ * is_valid_soft_transition() - Returns an SS_ error code if the state transition is not possible
+ * This function limits state transitions that may be declined by DRBD. I.e.
+ * user requests (aka soft transitions).
+ * @device:    DRBD device.
+ * @ns:                new state.
+ * @os:                old state.
+ */
+static enum drbd_state_rv
+is_valid_soft_transition(union drbd_state os, union drbd_state ns, struct drbd_connection *connection)
+{
+       enum drbd_state_rv rv = SS_SUCCESS;
+
+       if ((ns.conn == C_STARTING_SYNC_T || ns.conn == C_STARTING_SYNC_S) &&
+           os.conn > C_CONNECTED)
+               rv = SS_RESYNC_RUNNING;
+
+       if (ns.conn == C_DISCONNECTING && os.conn == C_STANDALONE)
+               rv = SS_ALREADY_STANDALONE;
+
+       if (ns.disk > D_ATTACHING && os.disk == D_DISKLESS)
+               rv = SS_IS_DISKLESS;
+
+       if (ns.conn == C_WF_CONNECTION && os.conn < C_UNCONNECTED)
+               rv = SS_NO_NET_CONFIG;
+
+       if (ns.disk == D_OUTDATED && os.disk < D_OUTDATED && os.disk != D_ATTACHING)
+               rv = SS_LOWER_THAN_OUTDATED;
+
+       if (ns.conn == C_DISCONNECTING && os.conn == C_UNCONNECTED)
+               rv = SS_IN_TRANSIENT_STATE;
+
+       /* While establishing a connection only allow cstate to change.
+          Delay/refuse role changes, detach attach etc... (they do not touch cstate) */
+       if (test_bit(STATE_SENT, &connection->flags) &&
+           !((ns.conn == C_WF_REPORT_PARAMS && os.conn == C_WF_CONNECTION) ||
+             (ns.conn >= C_CONNECTED && os.conn == C_WF_REPORT_PARAMS)))
+               rv = SS_IN_TRANSIENT_STATE;
+
+       if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) && os.conn < C_CONNECTED)
+               rv = SS_NEED_CONNECTION;
+
+       if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) &&
+           ns.conn != os.conn && os.conn > C_CONNECTED)
+               rv = SS_RESYNC_RUNNING;
+
+       if ((ns.conn == C_STARTING_SYNC_S || ns.conn == C_STARTING_SYNC_T) &&
+           os.conn < C_CONNECTED)
+               rv = SS_NEED_CONNECTION;
+
+       if ((ns.conn == C_SYNC_TARGET || ns.conn == C_SYNC_SOURCE)
+           && 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;
+}
+
+static enum drbd_state_rv
+is_valid_conn_transition(enum drbd_conns oc, enum drbd_conns nc)
+{
+       /* no change -> nothing to do, at least for the connection part */
+       if (oc == nc)
+               return SS_NOTHING_TO_DO;
+
+       /* disconnect of an unconfigured connection does not make sense */
+       if (oc == C_STANDALONE && nc == C_DISCONNECTING)
+               return SS_ALREADY_STANDALONE;
+
+       /* from C_STANDALONE, we start with C_UNCONNECTED */
+       if (oc == C_STANDALONE && nc != C_UNCONNECTED)
+               return SS_NEED_CONNECTION;
+
+       /* When establishing a connection we need to go through WF_REPORT_PARAMS!
+          Necessary to do the right thing upon invalidate-remote on a disconnected resource */
+       if (oc < C_WF_REPORT_PARAMS && nc >= C_CONNECTED)
+               return SS_NEED_CONNECTION;
+
+       /* After a network error only C_UNCONNECTED or C_DISCONNECTING may follow. */
+       if (oc >= C_TIMEOUT && oc <= C_TEAR_DOWN && nc != C_UNCONNECTED && nc != C_DISCONNECTING)
+               return SS_IN_TRANSIENT_STATE;
+
+       /* After C_DISCONNECTING only C_STANDALONE may follow */
+       if (oc == C_DISCONNECTING && nc != C_STANDALONE)
+               return SS_IN_TRANSIENT_STATE;
+
+       return SS_SUCCESS;
+}
+
+
+/**
+ * is_valid_transition() - Returns an SS_ error code if the state transition is not possible
+ * This limits hard state transitions. Hard state transitions are facts there are
+ * imposed on DRBD by the environment. E.g. disk broke or network broke down.
+ * But those hard state transitions are still not allowed to do everything.
+ * @ns:                new state.
+ * @os:                old state.
+ */
+static enum drbd_state_rv
+is_valid_transition(union drbd_state os, union drbd_state ns)
+{
+       enum drbd_state_rv rv;
+
+       rv = is_valid_conn_transition(os.conn, ns.conn);
+
+       /* we cannot fail (again) if we already detached */
+       if (ns.disk == D_FAILED && os.disk == D_DISKLESS)
+               rv = SS_IS_DISKLESS;
+
+       return rv;
+}
+
+static void print_sanitize_warnings(struct drbd_device *device, enum sanitize_state_warnings warn)
+{
+       static const char *msg_table[] = {
+               [NO_WARNING] = "",
+               [ABORTED_ONLINE_VERIFY] = "Online-verify aborted.",
+               [ABORTED_RESYNC] = "Resync aborted.",
+               [CONNECTION_LOST_NEGOTIATING] = "Connection lost while negotiating, no data!",
+               [IMPLICITLY_UPGRADED_DISK] = "Implicitly upgraded disk",
+               [IMPLICITLY_UPGRADED_PDSK] = "Implicitly upgraded pdsk",
+       };
+
+       if (warn != NO_WARNING)
+               drbd_warn(device, "%s\n", msg_table[warn]);
+}
+
+/**
+ * sanitize_state() - Resolves implicitly necessary additional changes to a state transition
+ * @device:    DRBD device.
+ * @os:                old state.
+ * @ns:                new state.
+ * @warn_sync_abort:
+ *
+ * When we loose connection, we have to set the state of the peers disk (pdsk)
+ * to D_UNKNOWN. This rule and many more along those lines are in this function.
+ */
+static union drbd_state sanitize_state(struct drbd_device *device, union drbd_state os,
+                                      union drbd_state ns, enum sanitize_state_warnings *warn)
+{
+       enum drbd_fencing_p fp;
+       enum drbd_disk_state disk_min, disk_max, pdsk_min, pdsk_max;
+
+       if (warn)
+               *warn = NO_WARNING;
+
+       fp = FP_DONT_CARE;
+       if (get_ldev(device)) {
+               rcu_read_lock();
+               fp = rcu_dereference(device->ldev->disk_conf)->fencing;
+               rcu_read_unlock();
+               put_ldev(device);
+       }
+
+       /* Implications from connection to peer and peer_isp */
+       if (ns.conn < C_CONNECTED) {
+               ns.peer_isp = 0;
+               ns.peer = R_UNKNOWN;
+               if (ns.pdsk > D_UNKNOWN || ns.pdsk < D_INCONSISTENT)
+                       ns.pdsk = D_UNKNOWN;
+       }
+
+       /* Clear the aftr_isp when becoming unconfigured */
+       if (ns.conn == C_STANDALONE && ns.disk == D_DISKLESS && ns.role == R_SECONDARY)
+               ns.aftr_isp = 0;
+
+       /* An implication of the disk states onto the connection state */
+       /* Abort resync if a disk fails/detaches */
+       if (ns.conn > C_CONNECTED && (ns.disk <= D_FAILED || ns.pdsk <= D_FAILED)) {
+               if (warn)
+                       *warn = ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T ?
+                               ABORTED_ONLINE_VERIFY : ABORTED_RESYNC;
+               ns.conn = C_CONNECTED;
+       }
+
+       /* Connection breaks down before we finished "Negotiating" */
+       if (ns.conn < C_CONNECTED && ns.disk == D_NEGOTIATING &&
+           get_ldev_if_state(device, D_NEGOTIATING)) {
+               if (device->ed_uuid == device->ldev->md.uuid[UI_CURRENT]) {
+                       ns.disk = device->new_state_tmp.disk;
+                       ns.pdsk = device->new_state_tmp.pdsk;
+               } else {
+                       if (warn)
+                               *warn = CONNECTION_LOST_NEGOTIATING;
+                       ns.disk = D_DISKLESS;
+                       ns.pdsk = D_UNKNOWN;
+               }
+               put_ldev(device);
+       }
+
+       /* D_CONSISTENT and D_OUTDATED vanish when we get connected */
+       if (ns.conn >= C_CONNECTED && ns.conn < C_AHEAD) {
+               if (ns.disk == D_CONSISTENT || ns.disk == D_OUTDATED)
+                       ns.disk = D_UP_TO_DATE;
+               if (ns.pdsk == D_CONSISTENT || ns.pdsk == D_OUTDATED)
+                       ns.pdsk = D_UP_TO_DATE;
+       }
+
+       /* Implications of the connection stat on the disk states */
+       disk_min = D_DISKLESS;
+       disk_max = D_UP_TO_DATE;
+       pdsk_min = D_INCONSISTENT;
+       pdsk_max = D_UNKNOWN;
+       switch ((enum drbd_conns)ns.conn) {
+       case C_WF_BITMAP_T:
+       case C_PAUSED_SYNC_T:
+       case C_STARTING_SYNC_T:
+       case C_WF_SYNC_UUID:
+       case C_BEHIND:
+               disk_min = D_INCONSISTENT;
+               disk_max = D_OUTDATED;
+               pdsk_min = D_UP_TO_DATE;
+               pdsk_max = D_UP_TO_DATE;
+               break;
+       case C_VERIFY_S:
+       case C_VERIFY_T:
+               disk_min = D_UP_TO_DATE;
+               disk_max = D_UP_TO_DATE;
+               pdsk_min = D_UP_TO_DATE;
+               pdsk_max = D_UP_TO_DATE;
+               break;
+       case C_CONNECTED:
+               disk_min = D_DISKLESS;
+               disk_max = D_UP_TO_DATE;
+               pdsk_min = D_DISKLESS;
+               pdsk_max = D_UP_TO_DATE;
+               break;
+       case C_WF_BITMAP_S:
+       case C_PAUSED_SYNC_S:
+       case C_STARTING_SYNC_S:
+       case C_AHEAD:
+               disk_min = D_UP_TO_DATE;
+               disk_max = D_UP_TO_DATE;
+               pdsk_min = D_INCONSISTENT;
+               pdsk_max = D_CONSISTENT; /* D_OUTDATED would be nice. But explicit outdate necessary*/
+               break;
+       case C_SYNC_TARGET:
+               disk_min = D_INCONSISTENT;
+               disk_max = D_INCONSISTENT;
+               pdsk_min = D_UP_TO_DATE;
+               pdsk_max = D_UP_TO_DATE;
+               break;
+       case C_SYNC_SOURCE:
+               disk_min = D_UP_TO_DATE;
+               disk_max = D_UP_TO_DATE;
+               pdsk_min = D_INCONSISTENT;
+               pdsk_max = D_INCONSISTENT;
+               break;
+       case C_STANDALONE:
+       case C_DISCONNECTING:
+       case C_UNCONNECTED:
+       case C_TIMEOUT:
+       case C_BROKEN_PIPE:
+       case C_NETWORK_FAILURE:
+       case C_PROTOCOL_ERROR:
+       case C_TEAR_DOWN:
+       case C_WF_CONNECTION:
+       case C_WF_REPORT_PARAMS:
+       case C_MASK:
+               break;
+       }
+       if (ns.disk > disk_max)
+               ns.disk = disk_max;
+
+       if (ns.disk < disk_min) {
+               if (warn)
+                       *warn = IMPLICITLY_UPGRADED_DISK;
+               ns.disk = disk_min;
+       }
+       if (ns.pdsk > pdsk_max)
+               ns.pdsk = pdsk_max;
+
+       if (ns.pdsk < pdsk_min) {
+               if (warn)
+                       *warn = IMPLICITLY_UPGRADED_PDSK;
+               ns.pdsk = pdsk_min;
+       }
+
+       if (fp == FP_STONITH &&
+           (ns.role == R_PRIMARY && ns.conn < C_CONNECTED && ns.pdsk > D_OUTDATED) &&
+           !(os.role == R_PRIMARY && os.conn < C_CONNECTED && os.pdsk > D_OUTDATED))
+               ns.susp_fen = 1; /* Suspend IO while fence-peer handler runs (peer lost) */
+
+       if (device->resource->res_opts.on_no_data == OND_SUSPEND_IO &&
+           (ns.role == R_PRIMARY && ns.disk < D_UP_TO_DATE && ns.pdsk < D_UP_TO_DATE) &&
+           !(os.role == R_PRIMARY && os.disk < D_UP_TO_DATE && os.pdsk < D_UP_TO_DATE))
+               ns.susp_nod = 1; /* Suspend IO while no data available (no accessible data available) */
+
+       if (ns.aftr_isp || ns.peer_isp || ns.user_isp) {
+               if (ns.conn == C_SYNC_SOURCE)
+                       ns.conn = C_PAUSED_SYNC_S;
+               if (ns.conn == C_SYNC_TARGET)
+                       ns.conn = C_PAUSED_SYNC_T;
+       } else {
+               if (ns.conn == C_PAUSED_SYNC_S)
+                       ns.conn = C_SYNC_SOURCE;
+               if (ns.conn == C_PAUSED_SYNC_T)
+                       ns.conn = C_SYNC_TARGET;
+       }
+
+       return ns;
+}
+
+void drbd_resume_al(struct drbd_device *device)
+{
+       if (test_and_clear_bit(AL_SUSPENDED, &device->flags))
+               drbd_info(device, "Resumed AL updates\n");
+}
+
+/* helper for __drbd_set_state */
+static void set_ov_position(struct drbd_device *device, enum drbd_conns cs)
+{
+       if (first_peer_device(device)->connection->agreed_pro_version < 90)
+               device->ov_start_sector = 0;
+       device->rs_total = drbd_bm_bits(device);
+       device->ov_position = 0;
+       if (cs == C_VERIFY_T) {
+               /* starting online verify from an arbitrary position
+                * does not fit well into the existing protocol.
+                * on C_VERIFY_T, we initialize ov_left and friends
+                * implicitly in receive_DataRequest once the
+                * first P_OV_REQUEST is received */
+               device->ov_start_sector = ~(sector_t)0;
+       } else {
+               unsigned long bit = BM_SECT_TO_BIT(device->ov_start_sector);
+               if (bit >= device->rs_total) {
+                       device->ov_start_sector =
+                               BM_BIT_TO_SECT(device->rs_total - 1);
+                       device->rs_total = 1;
+               } else
+                       device->rs_total -= bit;
+               device->ov_position = device->ov_start_sector;
+       }
+       device->ov_left = device->rs_total;
+}
+
+/**
+ * __drbd_set_state() - Set a new DRBD state
+ * @device:    DRBD device.
+ * @ns:                new state.
+ * @flags:     Flags
+ * @done:      Optional completion, that will get completed after the after_state_ch() finished
+ *
+ * Caller needs to hold req_lock, and global_state_lock. Do not call directly.
+ */
+enum drbd_state_rv
+__drbd_set_state(struct drbd_device *device, union drbd_state ns,
+                enum chg_state_flags flags, struct completion *done)
+{
+       struct drbd_peer_device *peer_device = first_peer_device(device);
+       struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
+       union drbd_state os;
+       enum drbd_state_rv rv = SS_SUCCESS;
+       enum sanitize_state_warnings ssw;
+       struct after_state_chg_work *ascw;
+
+       os = drbd_read_state(device);
+
+       ns = sanitize_state(device, os, ns, &ssw);
+       if (ns.i == os.i)
+               return SS_NOTHING_TO_DO;
+
+       rv = is_valid_transition(os, ns);
+       if (rv < SS_SUCCESS)
+               return rv;
+
+       if (!(flags & CS_HARD)) {
+               /*  pre-state-change checks ; only look at ns  */
+               /* See drbd_state_sw_errors in drbd_strings.c */
+
+               rv = is_valid_state(device, ns);
+               if (rv < SS_SUCCESS) {
+                       /* If the old state was illegal as well, then let
+                          this happen...*/
+
+                       if (is_valid_state(device, os) == rv)
+                               rv = is_valid_soft_transition(os, ns, connection);
+               } else
+                       rv = is_valid_soft_transition(os, ns, connection);
+       }
+
+       if (rv < SS_SUCCESS) {
+               if (flags & CS_VERBOSE)
+                       print_st_err(device, os, ns, rv);
+               return rv;
+       }
+
+       print_sanitize_warnings(device, ssw);
+
+       drbd_pr_state_change(device, os, ns, flags);
+
+       /* Display changes to the susp* flags that where caused by the call to
+          sanitize_state(). Only display it here if we where not called from
+          _conn_request_state() */
+       if (!(flags & CS_DC_SUSP))
+               conn_pr_state_change(connection, os, ns,
+                                    (flags & ~CS_DC_MASK) | CS_DC_SUSP);
+
+       /* if we are going -> D_FAILED or D_DISKLESS, grab one extra reference
+        * on the ldev here, to be sure the transition -> D_DISKLESS resp.
+        * drbd_ldev_destroy() won't happen before our corresponding
+        * after_state_ch works run, where we put_ldev again. */
+       if ((os.disk != D_FAILED && ns.disk == D_FAILED) ||
+           (os.disk != D_DISKLESS && ns.disk == D_DISKLESS))
+               atomic_inc(&device->local_cnt);
+
+       if (!is_sync_state(os.conn) && is_sync_state(ns.conn))
+               clear_bit(RS_DONE, &device->flags);
+
+       /* changes to local_cnt and device flags should be visible before
+        * changes to state, which again should be visible before anything else
+        * depending on that change happens. */
+       smp_wmb();
+       device->state.i = ns.i;
+       device->resource->susp = ns.susp;
+       device->resource->susp_nod = ns.susp_nod;
+       device->resource->susp_fen = ns.susp_fen;
+       smp_wmb();
+
+       /* put replicated vs not-replicated requests in seperate epochs */
+       if (drbd_should_do_remote((union drbd_dev_state)os.i) !=
+           drbd_should_do_remote((union drbd_dev_state)ns.i))
+               start_new_tl_epoch(connection);
+
+       if (os.disk == D_ATTACHING && ns.disk >= D_NEGOTIATING)
+               drbd_print_uuids(device, "attached to UUIDs");
+
+       /* Wake up role changes, that were delayed because of connection establishing */
+       if (os.conn == C_WF_REPORT_PARAMS && ns.conn != C_WF_REPORT_PARAMS &&
+           no_peer_wf_report_params(connection)) {
+               clear_bit(STATE_SENT, &connection->flags);
+               wake_up_all_devices(connection);
+       }
+
+       wake_up(&device->misc_wait);
+       wake_up(&device->state_wait);
+       wake_up(&connection->ping_wait);
+
+       /* Aborted verify run, or we reached the stop sector.
+        * Log the last position, unless end-of-device. */
+       if ((os.conn == C_VERIFY_S || os.conn == C_VERIFY_T) &&
+           ns.conn <= C_CONNECTED) {
+               device->ov_start_sector =
+                       BM_BIT_TO_SECT(drbd_bm_bits(device) - device->ov_left);
+               if (device->ov_left)
+                       drbd_info(device, "Online Verify reached sector %llu\n",
+                               (unsigned long long)device->ov_start_sector);
+       }
+
+       if ((os.conn == C_PAUSED_SYNC_T || os.conn == C_PAUSED_SYNC_S) &&
+           (ns.conn == C_SYNC_TARGET  || ns.conn == C_SYNC_SOURCE)) {
+               drbd_info(device, "Syncer continues.\n");
+               device->rs_paused += (long)jiffies
+                                 -(long)device->rs_mark_time[device->rs_last_mark];
+               if (ns.conn == C_SYNC_TARGET)
+                       mod_timer(&device->resync_timer, jiffies);
+       }
+
+       if ((os.conn == C_SYNC_TARGET  || os.conn == C_SYNC_SOURCE) &&
+           (ns.conn == C_PAUSED_SYNC_T || ns.conn == C_PAUSED_SYNC_S)) {
+               drbd_info(device, "Resync suspended\n");
+               device->rs_mark_time[device->rs_last_mark] = jiffies;
+       }
+
+       if (os.conn == C_CONNECTED &&
+           (ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T)) {
+               unsigned long now = jiffies;
+               int i;
+
+               set_ov_position(device, ns.conn);
+               device->rs_start = now;
+               device->rs_last_sect_ev = 0;
+               device->ov_last_oos_size = 0;
+               device->ov_last_oos_start = 0;
+
+               for (i = 0; i < DRBD_SYNC_MARKS; i++) {
+                       device->rs_mark_left[i] = device->ov_left;
+                       device->rs_mark_time[i] = now;
+               }
+
+               drbd_rs_controller_reset(device);
+
+               if (ns.conn == C_VERIFY_S) {
+                       drbd_info(device, "Starting Online Verify from sector %llu\n",
+                                       (unsigned long long)device->ov_position);
+                       mod_timer(&device->resync_timer, jiffies);
+               }
+       }
+
+       if (get_ldev(device)) {
+               u32 mdf = device->ldev->md.flags & ~(MDF_CONSISTENT|MDF_PRIMARY_IND|
+                                                MDF_CONNECTED_IND|MDF_WAS_UP_TO_DATE|
+                                                MDF_PEER_OUT_DATED|MDF_CRASHED_PRIMARY);
+
+               mdf &= ~MDF_AL_CLEAN;
+               if (test_bit(CRASHED_PRIMARY, &device->flags))
+                       mdf |= MDF_CRASHED_PRIMARY;
+               if (device->state.role == R_PRIMARY ||
+                   (device->state.pdsk < D_INCONSISTENT && device->state.peer == R_PRIMARY))
+                       mdf |= MDF_PRIMARY_IND;
+               if (device->state.conn > C_WF_REPORT_PARAMS)
+                       mdf |= MDF_CONNECTED_IND;
+               if (device->state.disk > D_INCONSISTENT)
+                       mdf |= MDF_CONSISTENT;
+               if (device->state.disk > D_OUTDATED)
+                       mdf |= MDF_WAS_UP_TO_DATE;
+               if (device->state.pdsk <= D_OUTDATED && device->state.pdsk >= D_INCONSISTENT)
+                       mdf |= MDF_PEER_OUT_DATED;
+               if (mdf != device->ldev->md.flags) {
+                       device->ldev->md.flags = mdf;
+                       drbd_md_mark_dirty(device);
+               }
+               if (os.disk < D_CONSISTENT && ns.disk >= D_CONSISTENT)
+                       drbd_set_ed_uuid(device, device->ldev->md.uuid[UI_CURRENT]);
+               put_ldev(device);
+       }
+
+       /* Peer was forced D_UP_TO_DATE & R_PRIMARY, consider to resync */
+       if (os.disk == D_INCONSISTENT && os.pdsk == D_INCONSISTENT &&
+           os.peer == R_SECONDARY && ns.peer == R_PRIMARY)
+               set_bit(CONSIDER_RESYNC, &device->flags);
+
+       /* Receiver should clean up itself */
+       if (os.conn != C_DISCONNECTING && ns.conn == C_DISCONNECTING)
+               drbd_thread_stop_nowait(&connection->receiver);
+
+       /* Now the receiver finished cleaning up itself, it should die */
+       if (os.conn != C_STANDALONE && ns.conn == C_STANDALONE)
+               drbd_thread_stop_nowait(&connection->receiver);
+
+       /* Upon network failure, we need to restart the receiver. */
+       if (os.conn > C_WF_CONNECTION &&
+           ns.conn <= C_TEAR_DOWN && ns.conn >= C_TIMEOUT)
+               drbd_thread_restart_nowait(&connection->receiver);
+
+       /* Resume AL writing if we get a connection */
+       if (os.conn < C_CONNECTED && ns.conn >= C_CONNECTED) {
+               drbd_resume_al(device);
+               connection->connect_cnt++;
+       }
+
+       /* remember last attach time so request_timer_fn() won't
+        * kill newly established sessions while we are still trying to thaw
+        * previously frozen IO */
+       if ((os.disk == D_ATTACHING || os.disk == D_NEGOTIATING) &&
+           ns.disk > D_NEGOTIATING)
+               device->last_reattach_jif = jiffies;
+
+       ascw = kmalloc(sizeof(*ascw), GFP_ATOMIC);
+       if (ascw) {
+               ascw->os = os;
+               ascw->ns = ns;
+               ascw->flags = flags;
+               ascw->w.cb = w_after_state_ch;
+               ascw->device = device;
+               ascw->done = done;
+               drbd_queue_work(&connection->sender_work,
+                               &ascw->w);
+       } else {
+               drbd_err(device, "Could not kmalloc an ascw\n");
+       }
+
+       return rv;
+}
+
+static int w_after_state_ch(struct drbd_work *w, int unused)
+{
+       struct after_state_chg_work *ascw =
+               container_of(w, struct after_state_chg_work, w);
+       struct drbd_device *device = ascw->device;
+
+       after_state_ch(device, ascw->os, ascw->ns, ascw->flags);
+       if (ascw->flags & CS_WAIT_COMPLETE)
+               complete(ascw->done);
+       kfree(ascw);
+
+       return 0;
+}
+
+static void abw_start_sync(struct drbd_device *device, int rv)
+{
+       if (rv) {
+               drbd_err(device, "Writing the bitmap failed not starting resync.\n");
+               _drbd_request_state(device, NS(conn, C_CONNECTED), CS_VERBOSE);
+               return;
+       }
+
+       switch (device->state.conn) {
+       case C_STARTING_SYNC_T:
+               _drbd_request_state(device, NS(conn, C_WF_SYNC_UUID), CS_VERBOSE);
+               break;
+       case C_STARTING_SYNC_S:
+               drbd_start_resync(device, C_SYNC_SOURCE);
+               break;
+       }
+}
+
+int drbd_bitmap_io_from_worker(struct drbd_device *device,
+               int (*io_fn)(struct drbd_device *),
+               char *why, enum bm_flag flags)
+{
+       int rv;
+
+       D_ASSERT(device, current == first_peer_device(device)->connection->worker.task);
+
+       /* open coded non-blocking drbd_suspend_io(device); */
+       set_bit(SUSPEND_IO, &device->flags);
+
+       drbd_bm_lock(device, why, flags);
+       rv = io_fn(device);
+       drbd_bm_unlock(device);
+
+       drbd_resume_io(device);
+
+       return rv;
+}
+
+/**
+ * after_state_ch() - Perform after state change actions that may sleep
+ * @device:    DRBD device.
+ * @os:                old state.
+ * @ns:                new state.
+ * @flags:     Flags
+ */
+static void after_state_ch(struct drbd_device *device, union drbd_state os,
+                          union drbd_state ns, enum chg_state_flags flags)
+{
+       struct drbd_resource *resource = device->resource;
+       struct drbd_peer_device *peer_device = first_peer_device(device);
+       struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
+       struct sib_info sib;
+
+       sib.sib_reason = SIB_STATE_CHANGE;
+       sib.os = os;
+       sib.ns = ns;
+
+       if ((os.disk != D_UP_TO_DATE || os.pdsk != D_UP_TO_DATE)
+       &&  (ns.disk == D_UP_TO_DATE && ns.pdsk == D_UP_TO_DATE)) {
+               clear_bit(CRASHED_PRIMARY, &device->flags);
+               if (device->p_uuid)
+                       device->p_uuid[UI_FLAGS] &= ~((u64)2);
+       }
+
+       /* Inform userspace about the change... */
+       drbd_bcast_event(device, &sib);
+
+       if (!(os.role == R_PRIMARY && os.disk < D_UP_TO_DATE && os.pdsk < D_UP_TO_DATE) &&
+           (ns.role == R_PRIMARY && ns.disk < D_UP_TO_DATE && ns.pdsk < D_UP_TO_DATE))
+               drbd_khelper(device, "pri-on-incon-degr");
+
+       /* Here we have the actions that are performed after a
+          state change. This function might sleep */
+
+       if (ns.susp_nod) {
+               enum drbd_req_event what = NOTHING;
+
+               spin_lock_irq(&device->resource->req_lock);
+               if (os.conn < C_CONNECTED && conn_lowest_conn(connection) >= C_CONNECTED)
+                       what = RESEND;
+
+               if ((os.disk == D_ATTACHING || os.disk == D_NEGOTIATING) &&
+                   conn_lowest_disk(connection) > D_NEGOTIATING)
+                       what = RESTART_FROZEN_DISK_IO;
+
+               if (resource->susp_nod && what != NOTHING) {
+                       _tl_restart(connection, what);
+                       _conn_request_state(connection,
+                                           (union drbd_state) { { .susp_nod = 1 } },
+                                           (union drbd_state) { { .susp_nod = 0 } },
+                                           CS_VERBOSE);
+               }
+               spin_unlock_irq(&device->resource->req_lock);
+       }
+
+       if (ns.susp_fen) {
+               spin_lock_irq(&device->resource->req_lock);
+               if (resource->susp_fen && conn_lowest_conn(connection) >= C_CONNECTED) {
+                       /* case2: The connection was established again: */
+                       struct drbd_peer_device *peer_device;
+                       int vnr;
+
+                       rcu_read_lock();
+                       idr_for_each_entry(&connection->peer_devices, peer_device, vnr)
+                               clear_bit(NEW_CUR_UUID, &peer_device->device->flags);
+                       rcu_read_unlock();
+                       _tl_restart(connection, RESEND);
+                       _conn_request_state(connection,
+                                           (union drbd_state) { { .susp_fen = 1 } },
+                                           (union drbd_state) { { .susp_fen = 0 } },
+                                           CS_VERBOSE);
+               }
+               spin_unlock_irq(&device->resource->req_lock);
+       }
+
+       /* Became sync source.  With protocol >= 96, we still need to send out
+        * the sync uuid now. Need to do that before any drbd_send_state, or
+        * the other side may go "paused sync" before receiving the sync uuids,
+        * which is unexpected. */
+       if ((os.conn != C_SYNC_SOURCE && os.conn != C_PAUSED_SYNC_S) &&
+           (ns.conn == C_SYNC_SOURCE || ns.conn == C_PAUSED_SYNC_S) &&
+           connection->agreed_pro_version >= 96 && get_ldev(device)) {
+               drbd_gen_and_send_sync_uuid(peer_device);
+               put_ldev(device);
+       }
+
+       /* Do not change the order of the if above and the two below... */
+       if (os.pdsk == D_DISKLESS &&
+           ns.pdsk > D_DISKLESS && ns.pdsk != D_UNKNOWN) {      /* attach on the peer */
+               /* we probably will start a resync soon.
+                * make sure those things are properly reset. */
+               device->rs_total = 0;
+               device->rs_failed = 0;
+               atomic_set(&device->rs_pending_cnt, 0);
+               drbd_rs_cancel_all(device);
+
+               drbd_send_uuids(peer_device);
+               drbd_send_state(peer_device, ns);
+       }
+       /* No point in queuing send_bitmap if we don't have a connection
+        * anymore, so check also the _current_ state, not only the new state
+        * at the time this work was queued. */
+       if (os.conn != C_WF_BITMAP_S && ns.conn == C_WF_BITMAP_S &&
+           device->state.conn == C_WF_BITMAP_S)
+               drbd_queue_bitmap_io(device, &drbd_send_bitmap, NULL,
+                               "send_bitmap (WFBitMapS)",
+                               BM_LOCKED_TEST_ALLOWED);
+
+       /* Lost contact to peer's copy of the data */
+       if ((os.pdsk >= D_INCONSISTENT &&
+            os.pdsk != D_UNKNOWN &&
+            os.pdsk != D_OUTDATED)
+       &&  (ns.pdsk < D_INCONSISTENT ||
+            ns.pdsk == D_UNKNOWN ||
+            ns.pdsk == D_OUTDATED)) {
+               if (get_ldev(device)) {
+                       if ((ns.role == R_PRIMARY || ns.peer == R_PRIMARY) &&
+                           device->ldev->md.uuid[UI_BITMAP] == 0 && ns.disk >= D_UP_TO_DATE) {
+                               if (drbd_suspended(device)) {
+                                       set_bit(NEW_CUR_UUID, &device->flags);
+                               } else {
+                                       drbd_uuid_new_current(device);
+                                       drbd_send_uuids(peer_device);
+                               }
+                       }
+                       put_ldev(device);
+               }
+       }
+
+       if (ns.pdsk < D_INCONSISTENT && get_ldev(device)) {
+               if (os.peer == R_SECONDARY && ns.peer == R_PRIMARY &&
+                   device->ldev->md.uuid[UI_BITMAP] == 0 && ns.disk >= D_UP_TO_DATE) {
+                       drbd_uuid_new_current(device);
+                       drbd_send_uuids(peer_device);
+               }
+               /* D_DISKLESS Peer becomes secondary */
+               if (os.peer == R_PRIMARY && ns.peer == R_SECONDARY)
+                       /* We may still be Primary ourselves.
+                        * No harm done if the bitmap still changes,
+                        * redirtied pages will follow later. */
+                       drbd_bitmap_io_from_worker(device, &drbd_bm_write,
+                               "demote diskless peer", BM_LOCKED_SET_ALLOWED);
+               put_ldev(device);
+       }
+
+       /* Write out all changed bits on demote.
+        * Though, no need to da that just yet
+        * if there is a resync going on still */
+       if (os.role == R_PRIMARY && ns.role == R_SECONDARY &&
+               device->state.conn <= C_CONNECTED && get_ldev(device)) {
+               /* No changes to the bitmap expected this time, so assert that,
+                * even though no harm was done if it did change. */
+               drbd_bitmap_io_from_worker(device, &drbd_bm_write,
+                               "demote", BM_LOCKED_TEST_ALLOWED);
+               put_ldev(device);
+       }
+
+       /* Last part of the attaching process ... */
+       if (ns.conn >= C_CONNECTED &&
+           os.disk == D_ATTACHING && ns.disk == D_NEGOTIATING) {
+               drbd_send_sizes(peer_device, 0, 0);  /* to start sync... */
+               drbd_send_uuids(peer_device);
+               drbd_send_state(peer_device, ns);
+       }
+
+       /* We want to pause/continue resync, tell peer. */
+       if (ns.conn >= C_CONNECTED &&
+            ((os.aftr_isp != ns.aftr_isp) ||
+             (os.user_isp != ns.user_isp)))
+               drbd_send_state(peer_device, ns);
+
+       /* In case one of the isp bits got set, suspend other devices. */
+       if ((!os.aftr_isp && !os.peer_isp && !os.user_isp) &&
+           (ns.aftr_isp || ns.peer_isp || ns.user_isp))
+               suspend_other_sg(device);
+
+       /* Make sure the peer gets informed about eventual state
+          changes (ISP bits) while we were in WFReportParams. */
+       if (os.conn == C_WF_REPORT_PARAMS && ns.conn >= C_CONNECTED)
+               drbd_send_state(peer_device, ns);
+
+       if (os.conn != C_AHEAD && ns.conn == C_AHEAD)
+               drbd_send_state(peer_device, ns);
+
+       /* 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))
+               /* no other bitmap changes expected during this phase */
+               drbd_queue_bitmap_io(device,
+                       &drbd_bmio_set_n_write, &abw_start_sync,
+                       "set_n_write from StartingSync", BM_LOCKED_TEST_ALLOWED);
+
+       /* first half of local IO error, failure to attach,
+        * or administrative detach */
+       if (os.disk != D_FAILED && ns.disk == D_FAILED) {
+               enum drbd_io_error_p eh = EP_PASS_ON;
+               int was_io_error = 0;
+               /* corresponding get_ldev was in __drbd_set_state, to serialize
+                * our cleanup here with the transition to D_DISKLESS.
+                * But is is still not save to dreference ldev here, since
+                * we might come from an failed Attach before ldev was set. */
+               if (device->ldev) {
+                       rcu_read_lock();
+                       eh = rcu_dereference(device->ldev->disk_conf)->on_io_error;
+                       rcu_read_unlock();
+
+                       was_io_error = test_and_clear_bit(WAS_IO_ERROR, &device->flags);
+
+                       if (was_io_error && eh == EP_CALL_HELPER)
+                               drbd_khelper(device, "local-io-error");
+
+                       /* Immediately allow completion of all application IO,
+                        * that waits for completion from the local disk,
+                        * if this was a force-detach due to disk_timeout
+                        * or administrator request (drbdsetup detach --force).
+                        * Do NOT abort otherwise.
+                        * Aborting local requests may cause serious problems,
+                        * if requests are completed to upper layers already,
+                        * and then later the already submitted local bio completes.
+                        * This can cause DMA into former bio pages that meanwhile
+                        * have been re-used for other things.
+                        * So aborting local requests may cause crashes,
+                        * or even worse, silent data corruption.
+                        */
+                       if (test_and_clear_bit(FORCE_DETACH, &device->flags))
+                               tl_abort_disk_io(device);
+
+                       /* current state still has to be D_FAILED,
+                        * there is only one way out: to D_DISKLESS,
+                        * and that may only happen after our put_ldev below. */
+                       if (device->state.disk != D_FAILED)
+                               drbd_err(device,
+                                       "ASSERT FAILED: disk is %s during detach\n",
+                                       drbd_disk_str(device->state.disk));
+
+                       if (ns.conn >= C_CONNECTED)
+                               drbd_send_state(peer_device, ns);
+
+                       drbd_rs_cancel_all(device);
+
+                       /* In case we want to get something to stable storage still,
+                        * this may be the last chance.
+                        * Following put_ldev may transition to D_DISKLESS. */
+                       drbd_md_sync(device);
+               }
+               put_ldev(device);
+       }
+
+       /* second half of local IO error, failure to attach,
+        * or administrative detach,
+        * after local_cnt references have reached zero again */
+       if (os.disk != D_DISKLESS && ns.disk == D_DISKLESS) {
+               /* We must still be diskless,
+                * re-attach has to be serialized with this! */
+               if (device->state.disk != D_DISKLESS)
+                       drbd_err(device,
+                                "ASSERT FAILED: disk is %s while going diskless\n",
+                                drbd_disk_str(device->state.disk));
+
+               if (ns.conn >= C_CONNECTED)
+                       drbd_send_state(peer_device, ns);
+               /* corresponding get_ldev in __drbd_set_state
+                * this may finally trigger drbd_ldev_destroy. */
+               put_ldev(device);
+       }
+
+       /* Notify peer that I had a local IO error, and did not detached.. */
+       if (os.disk == D_UP_TO_DATE && ns.disk == D_INCONSISTENT && ns.conn >= C_CONNECTED)
+               drbd_send_state(peer_device, ns);
+
+       /* Disks got bigger while they were detached */
+       if (ns.disk > D_NEGOTIATING && ns.pdsk > D_NEGOTIATING &&
+           test_and_clear_bit(RESYNC_AFTER_NEG, &device->flags)) {
+               if (ns.conn == C_CONNECTED)
+                       resync_after_online_grow(device);
+       }
+
+       /* A resync finished or aborted, wake paused devices... */
+       if ((os.conn > C_CONNECTED && ns.conn <= C_CONNECTED) ||
+           (os.peer_isp && !ns.peer_isp) ||
+           (os.user_isp && !ns.user_isp))
+               resume_next_sg(device);
+
+       /* sync target done with resync.  Explicitly notify peer, even though
+        * it should (at least for non-empty resyncs) already know itself. */
+       if (os.disk < D_UP_TO_DATE && os.conn >= C_SYNC_SOURCE && ns.conn == C_CONNECTED)
+               drbd_send_state(peer_device, ns);
+
+       /* Verify finished, or reached stop sector.  Peer did not know about
+        * the stop sector, and we may even have changed the stop sector during
+        * verify to interrupt/stop early.  Send the new state. */
+       if (os.conn == C_VERIFY_S && ns.conn == C_CONNECTED
+       && verify_can_do_stop_sector(device))
+               drbd_send_state(peer_device, ns);
+
+       /* 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.
+        * For resync aborted because of local disk failure, we cannot do
+        * any bitmap writeout anymore.
+        * No harm done if some bits change during this phase.
+        */
+       if (os.conn > C_CONNECTED && ns.conn <= C_CONNECTED && get_ldev(device)) {
+               drbd_queue_bitmap_io(device, &drbd_bm_write_copy_pages, NULL,
+                       "write from resync_finished", BM_LOCKED_CHANGE_ALLOWED);
+               put_ldev(device);
+       }
+
+       if (ns.disk == D_DISKLESS &&
+           ns.conn == C_STANDALONE &&
+           ns.role == R_SECONDARY) {
+               if (os.aftr_isp != ns.aftr_isp)
+                       resume_next_sg(device);
+       }
+
+       drbd_md_sync(device);
+}
+
+struct after_conn_state_chg_work {
+       struct drbd_work w;
+       enum drbd_conns oc;
+       union drbd_state ns_min;
+       union drbd_state ns_max; /* new, max state, over all devices */
+       enum chg_state_flags flags;
+       struct drbd_connection *connection;
+};
+
+static int w_after_conn_state_ch(struct drbd_work *w, int unused)
+{
+       struct after_conn_state_chg_work *acscw =
+               container_of(w, struct after_conn_state_chg_work, w);
+       struct drbd_connection *connection = acscw->connection;
+       enum drbd_conns oc = acscw->oc;
+       union drbd_state ns_max = acscw->ns_max;
+       struct drbd_peer_device *peer_device;
+       int vnr;
+
+       kfree(acscw);
+
+       /* Upon network configuration, we need to start the receiver */
+       if (oc == C_STANDALONE && ns_max.conn == C_UNCONNECTED)
+               drbd_thread_start(&connection->receiver);
+
+       if (oc == C_DISCONNECTING && ns_max.conn == C_STANDALONE) {
+               struct net_conf *old_conf;
+
+               mutex_lock(&connection->resource->conf_update);
+               old_conf = connection->net_conf;
+               connection->my_addr_len = 0;
+               connection->peer_addr_len = 0;
+               RCU_INIT_POINTER(connection->net_conf, NULL);
+               conn_free_crypto(connection);
+               mutex_unlock(&connection->resource->conf_update);
+
+               synchronize_rcu();
+               kfree(old_conf);
+       }
+
+       if (ns_max.susp_fen) {
+               /* case1: The outdate peer handler is successful: */
+               if (ns_max.pdsk <= D_OUTDATED) {
+                       rcu_read_lock();
+                       idr_for_each_entry(&connection->peer_devices, peer_device, vnr) {
+                               struct drbd_device *device = peer_device->device;
+                               if (test_bit(NEW_CUR_UUID, &device->flags)) {
+                                       drbd_uuid_new_current(device);
+                                       clear_bit(NEW_CUR_UUID, &device->flags);
+                               }
+                       }
+                       rcu_read_unlock();
+                       spin_lock_irq(&connection->resource->req_lock);
+                       _tl_restart(connection, CONNECTION_LOST_WHILE_PENDING);
+                       _conn_request_state(connection,
+                                           (union drbd_state) { { .susp_fen = 1 } },
+                                           (union drbd_state) { { .susp_fen = 0 } },
+                                           CS_VERBOSE);
+                       spin_unlock_irq(&connection->resource->req_lock);
+               }
+       }
+       kref_put(&connection->kref, drbd_destroy_connection);
+
+       conn_md_sync(connection);
+
+       return 0;
+}
+
+static void conn_old_common_state(struct drbd_connection *connection, union drbd_state *pcs, enum chg_state_flags *pf)
+{
+       enum chg_state_flags flags = ~0;
+       struct drbd_peer_device *peer_device;
+       int vnr, first_vol = 1;
+       union drbd_dev_state os, cs = {
+               { .role = R_SECONDARY,
+                 .peer = R_UNKNOWN,
+                 .conn = connection->cstate,
+                 .disk = D_DISKLESS,
+                 .pdsk = D_UNKNOWN,
+               } };
+
+       rcu_read_lock();
+       idr_for_each_entry(&connection->peer_devices, peer_device, vnr) {
+               struct drbd_device *device = peer_device->device;
+               os = device->state;
+
+               if (first_vol) {
+                       cs = os;
+                       first_vol = 0;
+                       continue;
+               }
+
+               if (cs.role != os.role)
+                       flags &= ~CS_DC_ROLE;
+
+               if (cs.peer != os.peer)
+                       flags &= ~CS_DC_PEER;
+
+               if (cs.conn != os.conn)
+                       flags &= ~CS_DC_CONN;
+
+               if (cs.disk != os.disk)
+                       flags &= ~CS_DC_DISK;
+
+               if (cs.pdsk != os.pdsk)
+                       flags &= ~CS_DC_PDSK;
+       }
+       rcu_read_unlock();
+
+       *pf |= CS_DC_MASK;
+       *pf &= flags;
+       (*pcs).i = cs.i;
+}
+
+static enum drbd_state_rv
+conn_is_valid_transition(struct drbd_connection *connection, union drbd_state mask, union drbd_state val,
+                        enum chg_state_flags flags)
+{
+       enum drbd_state_rv rv = SS_SUCCESS;
+       union drbd_state ns, os;
+       struct drbd_peer_device *peer_device;
+       int vnr;
+
+       rcu_read_lock();
+       idr_for_each_entry(&connection->peer_devices, peer_device, vnr) {
+               struct drbd_device *device = peer_device->device;
+               os = drbd_read_state(device);
+               ns = sanitize_state(device, os, apply_mask_val(os, mask, val), NULL);
+
+               if (flags & CS_IGN_OUTD_FAIL && ns.disk == D_OUTDATED && os.disk < D_OUTDATED)
+                       ns.disk = os.disk;
+
+               if (ns.i == os.i)
+                       continue;
+
+               rv = is_valid_transition(os, ns);
+
+               if (rv >= SS_SUCCESS && !(flags & CS_HARD)) {
+                       rv = is_valid_state(device, ns);
+                       if (rv < SS_SUCCESS) {
+                               if (is_valid_state(device, os) == rv)
+                                       rv = is_valid_soft_transition(os, ns, connection);
+                       } else
+                               rv = is_valid_soft_transition(os, ns, connection);
+               }
+
+               if (rv < SS_SUCCESS) {
+                       if (flags & CS_VERBOSE)
+                               print_st_err(device, os, ns, rv);
+                       break;
+               }
+       }
+       rcu_read_unlock();
+
+       return rv;
+}
+
+static void
+conn_set_state(struct drbd_connection *connection, union drbd_state mask, union drbd_state val,
+              union drbd_state *pns_min, union drbd_state *pns_max, enum chg_state_flags flags)
+{
+       union drbd_state ns, os, ns_max = { };
+       union drbd_state ns_min = {
+               { .role = R_MASK,
+                 .peer = R_MASK,
+                 .conn = val.conn,
+                 .disk = D_MASK,
+                 .pdsk = D_MASK
+               } };
+       struct drbd_peer_device *peer_device;
+       enum drbd_state_rv rv;
+       int vnr, number_of_volumes = 0;
+
+       if (mask.conn == C_MASK) {
+               /* remember last connect time so request_timer_fn() won't
+                * kill newly established sessions while we are still trying to thaw
+                * previously frozen IO */
+               if (connection->cstate != C_WF_REPORT_PARAMS && val.conn == C_WF_REPORT_PARAMS)
+                       connection->last_reconnect_jif = jiffies;
+
+               connection->cstate = val.conn;
+       }
+
+       rcu_read_lock();
+       idr_for_each_entry(&connection->peer_devices, peer_device, vnr) {
+               struct drbd_device *device = peer_device->device;
+               number_of_volumes++;
+               os = drbd_read_state(device);
+               ns = apply_mask_val(os, mask, val);
+               ns = sanitize_state(device, os, ns, NULL);
+
+               if (flags & CS_IGN_OUTD_FAIL && ns.disk == D_OUTDATED && os.disk < D_OUTDATED)
+                       ns.disk = os.disk;
+
+               rv = __drbd_set_state(device, ns, flags, NULL);
+               if (rv < SS_SUCCESS)
+                       BUG();
+
+               ns.i = device->state.i;
+               ns_max.role = max_role(ns.role, ns_max.role);
+               ns_max.peer = max_role(ns.peer, ns_max.peer);
+               ns_max.conn = max_t(enum drbd_conns, ns.conn, ns_max.conn);
+               ns_max.disk = max_t(enum drbd_disk_state, ns.disk, ns_max.disk);
+               ns_max.pdsk = max_t(enum drbd_disk_state, ns.pdsk, ns_max.pdsk);
+
+               ns_min.role = min_role(ns.role, ns_min.role);
+               ns_min.peer = min_role(ns.peer, ns_min.peer);
+               ns_min.conn = min_t(enum drbd_conns, ns.conn, ns_min.conn);
+               ns_min.disk = min_t(enum drbd_disk_state, ns.disk, ns_min.disk);
+               ns_min.pdsk = min_t(enum drbd_disk_state, ns.pdsk, ns_min.pdsk);
+       }
+       rcu_read_unlock();
+
+       if (number_of_volumes == 0) {
+               ns_min = ns_max = (union drbd_state) { {
+                               .role = R_SECONDARY,
+                               .peer = R_UNKNOWN,
+                               .conn = val.conn,
+                               .disk = D_DISKLESS,
+                               .pdsk = D_UNKNOWN
+                       } };
+       }
+
+       ns_min.susp = ns_max.susp = connection->resource->susp;
+       ns_min.susp_nod = ns_max.susp_nod = connection->resource->susp_nod;
+       ns_min.susp_fen = ns_max.susp_fen = connection->resource->susp_fen;
+
+       *pns_min = ns_min;
+       *pns_max = ns_max;
+}
+
+static enum drbd_state_rv
+_conn_rq_cond(struct drbd_connection *connection, union drbd_state mask, union drbd_state val)
+{
+       enum drbd_state_rv err, rv = SS_UNKNOWN_ERROR; /* continue waiting */;
+
+       if (test_and_clear_bit(CONN_WD_ST_CHG_OKAY, &connection->flags))
+               rv = SS_CW_SUCCESS;
+
+       if (test_and_clear_bit(CONN_WD_ST_CHG_FAIL, &connection->flags))
+               rv = SS_CW_FAILED_BY_PEER;
+
+       err = conn_is_valid_transition(connection, mask, val, 0);
+       if (err == SS_SUCCESS && connection->cstate == C_WF_REPORT_PARAMS)
+               return rv;
+
+       return err;
+}
+
+enum drbd_state_rv
+_conn_request_state(struct drbd_connection *connection, union drbd_state mask, union drbd_state val,
+                   enum chg_state_flags flags)
+{
+       enum drbd_state_rv rv = SS_SUCCESS;
+       struct after_conn_state_chg_work *acscw;
+       enum drbd_conns oc = connection->cstate;
+       union drbd_state ns_max, ns_min, os;
+       bool have_mutex = false;
+
+       if (mask.conn) {
+               rv = is_valid_conn_transition(oc, val.conn);
+               if (rv < SS_SUCCESS)
+                       goto abort;
+       }
+
+       rv = conn_is_valid_transition(connection, mask, val, flags);
+       if (rv < SS_SUCCESS)
+               goto abort;
+
+       if (oc == C_WF_REPORT_PARAMS && val.conn == C_DISCONNECTING &&
+           !(flags & (CS_LOCAL_ONLY | CS_HARD))) {
+
+               /* This will be a cluster-wide state change.
+                * Need to give up the spinlock, grab the mutex,
+                * then send the state change request, ... */
+               spin_unlock_irq(&connection->resource->req_lock);
+               mutex_lock(&connection->cstate_mutex);
+               have_mutex = true;
+
+               set_bit(CONN_WD_ST_CHG_REQ, &connection->flags);
+               if (conn_send_state_req(connection, mask, val)) {
+                       /* sending failed. */
+                       clear_bit(CONN_WD_ST_CHG_REQ, &connection->flags);
+                       rv = SS_CW_FAILED_BY_PEER;
+                       /* need to re-aquire the spin lock, though */
+                       goto abort_unlocked;
+               }
+
+               if (val.conn == C_DISCONNECTING)
+                       set_bit(DISCONNECT_SENT, &connection->flags);
+
+               /* ... and re-aquire the spinlock.
+                * If _conn_rq_cond() returned >= SS_SUCCESS, we must call
+                * conn_set_state() within the same spinlock. */
+               spin_lock_irq(&connection->resource->req_lock);
+               wait_event_lock_irq(connection->ping_wait,
+                               (rv = _conn_rq_cond(connection, mask, val)),
+                               connection->resource->req_lock);
+               clear_bit(CONN_WD_ST_CHG_REQ, &connection->flags);
+               if (rv < SS_SUCCESS)
+                       goto abort;
+       }
+
+       conn_old_common_state(connection, &os, &flags);
+       flags |= CS_DC_SUSP;
+       conn_set_state(connection, mask, val, &ns_min, &ns_max, flags);
+       conn_pr_state_change(connection, os, ns_max, flags);
+
+       acscw = kmalloc(sizeof(*acscw), GFP_ATOMIC);
+       if (acscw) {
+               acscw->oc = os.conn;
+               acscw->ns_min = ns_min;
+               acscw->ns_max = ns_max;
+               acscw->flags = flags;
+               acscw->w.cb = w_after_conn_state_ch;
+               kref_get(&connection->kref);
+               acscw->connection = connection;
+               drbd_queue_work(&connection->sender_work, &acscw->w);
+       } else {
+               drbd_err(connection, "Could not kmalloc an acscw\n");
+       }
+
+ abort:
+       if (have_mutex) {
+               /* mutex_unlock() "... must not be used in interrupt context.",
+                * so give up the spinlock, then re-aquire it */
+               spin_unlock_irq(&connection->resource->req_lock);
+ abort_unlocked:
+               mutex_unlock(&connection->cstate_mutex);
+               spin_lock_irq(&connection->resource->req_lock);
+       }
+       if (rv < SS_SUCCESS && flags & CS_VERBOSE) {
+               drbd_err(connection, "State change failed: %s\n", drbd_set_st_err_str(rv));
+               drbd_err(connection, " mask = 0x%x val = 0x%x\n", mask.i, val.i);
+               drbd_err(connection, " old_conn:%s wanted_conn:%s\n", drbd_conn_str(oc), drbd_conn_str(val.conn));
+       }
+       return rv;
+}
+
+enum drbd_state_rv
+conn_request_state(struct drbd_connection *connection, union drbd_state mask, union drbd_state val,
+                  enum chg_state_flags flags)
+{
+       enum drbd_state_rv rv;
+
+       spin_lock_irq(&connection->resource->req_lock);
+       rv = _conn_request_state(connection, mask, val, flags);
+       spin_unlock_irq(&connection->resource->req_lock);
+
+       return rv;
+}