OSCL-LXR linux-6.0.1/​drivers/​block/​drbd/​drbd_state.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
    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.
 
  */
 
 #include <linux/drbd_limits.h>
 #include "drbd_int.h"
 #include "drbd_protocol.h"
 #include "drbd_req.h"
 #include "drbd_state_change.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;
     struct drbd_state_change *state_change;
 };
 
 enum sanitize_state_warnings {
     NO_WARNING,
     ABORTED_ONLINE_VERIFY,
     ABORTED_RESYNC,
     CONNECTION_LOST_NEGOTIATING,
     IMPLICITLY_UPGRADED_DISK,
     IMPLICITLY_UPGRADED_PDSK,
 };
 
 static void count_objects(struct drbd_resource *resource,
               unsigned int *n_devices,
               unsigned int *n_connections)
 {
     struct drbd_device *device;
     struct drbd_connection *connection;
     int vnr;
 
     *n_devices = 0;
     *n_connections = 0;
 
     idr_for_each_entry(&resource->devices, device, vnr)
         (*n_devices)++;
     for_each_connection(connection, resource)
         (*n_connections)++;
 }
 
 static struct drbd_state_change *alloc_state_change(unsigned int n_devices, unsigned int n_connections, gfp_t gfp)
 {
     struct drbd_state_change *state_change;
     unsigned int size, n;
 
     size = sizeof(struct drbd_state_change) +
            n_devices * sizeof(struct drbd_device_state_change) +
            n_connections * sizeof(struct drbd_connection_state_change) +
            n_devices * n_connections * sizeof(struct drbd_peer_device_state_change);
     state_change = kmalloc(size, gfp);
     if (!state_change)
         return NULL;
     state_change->n_devices = n_devices;
     state_change->n_connections = n_connections;
     state_change->devices = (void *)(state_change + 1);
     state_change->connections = (void *)&state_change->devices[n_devices];
     state_change->peer_devices = (void *)&state_change->connections[n_connections];
     state_change->resource->resource = NULL;
     for (n = 0; n < n_devices; n++)
         state_change->devices[n].device = NULL;
     for (n = 0; n < n_connections; n++)
         state_change->connections[n].connection = NULL;
     return state_change;
 }
 
 struct drbd_state_change *remember_old_state(struct drbd_resource *resource, gfp_t gfp)
 {
     struct drbd_state_change *state_change;
     struct drbd_device *device;
     unsigned int n_devices;
     struct drbd_connection *connection;
     unsigned int n_connections;
     int vnr;
 
     struct drbd_device_state_change *device_state_change;
     struct drbd_peer_device_state_change *peer_device_state_change;
     struct drbd_connection_state_change *connection_state_change;
 
     /* Caller holds req_lock spinlock.
      * No state, no device IDR, no connections lists can change. */
     count_objects(resource, &n_devices, &n_connections);
     state_change = alloc_state_change(n_devices, n_connections, gfp);
     if (!state_change)
         return NULL;
 
     kref_get(&resource->kref);
     state_change->resource->resource = resource;
     state_change->resource->role[OLD] =
         conn_highest_role(first_connection(resource));
     state_change->resource->susp[OLD] = resource->susp;
     state_change->resource->susp_nod[OLD] = resource->susp_nod;
     state_change->resource->susp_fen[OLD] = resource->susp_fen;
 
     connection_state_change = state_change->connections;
     for_each_connection(connection, resource) {
         kref_get(&connection->kref);
         connection_state_change->connection = connection;
         connection_state_change->cstate[OLD] =
             connection->cstate;
         connection_state_change->peer_role[OLD] =
             conn_highest_peer(connection);
         connection_state_change++;
     }
 
     device_state_change = state_change->devices;
     peer_device_state_change = state_change->peer_devices;
     idr_for_each_entry(&resource->devices, device, vnr) {
         kref_get(&device->kref);
         device_state_change->device = device;
         device_state_change->disk_state[OLD] = device->state.disk;
 
         /* The peer_devices for each device have to be enumerated in
            the order of the connections. We may not use for_each_peer_device() here. */
         for_each_connection(connection, resource) {
             struct drbd_peer_device *peer_device;
 
             peer_device = conn_peer_device(connection, device->vnr);
             peer_device_state_change->peer_device = peer_device;
             peer_device_state_change->disk_state[OLD] =
                 device->state.pdsk;
             peer_device_state_change->repl_state[OLD] =
                 max_t(enum drbd_conns,
                       C_WF_REPORT_PARAMS, device->state.conn);
             peer_device_state_change->resync_susp_user[OLD] =
                 device->state.user_isp;
             peer_device_state_change->resync_susp_peer[OLD] =
                 device->state.peer_isp;
             peer_device_state_change->resync_susp_dependency[OLD] =
                 device->state.aftr_isp;
             peer_device_state_change++;
         }
         device_state_change++;
     }
 
     return state_change;
 }
 
 static void remember_new_state(struct drbd_state_change *state_change)
 {
     struct drbd_resource_state_change *resource_state_change;
     struct drbd_resource *resource;
     unsigned int n;
 
     if (!state_change)
         return;
 
     resource_state_change = &state_change->resource[0];
     resource = resource_state_change->resource;
 
     resource_state_change->role[NEW] =
         conn_highest_role(first_connection(resource));
     resource_state_change->susp[NEW] = resource->susp;
     resource_state_change->susp_nod[NEW] = resource->susp_nod;
     resource_state_change->susp_fen[NEW] = resource->susp_fen;
 
     for (n = 0; n < state_change->n_devices; n++) {
         struct drbd_device_state_change *device_state_change =
             &state_change->devices[n];
         struct drbd_device *device = device_state_change->device;
 
         device_state_change->disk_state[NEW] = device->state.disk;
     }
 
     for (n = 0; n < state_change->n_connections; n++) {
         struct drbd_connection_state_change *connection_state_change =
             &state_change->connections[n];
         struct drbd_connection *connection =
             connection_state_change->connection;
 
         connection_state_change->cstate[NEW] = connection->cstate;
         connection_state_change->peer_role[NEW] =
             conn_highest_peer(connection);
     }
 
     for (n = 0; n < state_change->n_devices * state_change->n_connections; n++) {
         struct drbd_peer_device_state_change *peer_device_state_change =
             &state_change->peer_devices[n];
         struct drbd_device *device =
             peer_device_state_change->peer_device->device;
         union drbd_dev_state state = device->state;
 
         peer_device_state_change->disk_state[NEW] = state.pdsk;
         peer_device_state_change->repl_state[NEW] =
             max_t(enum drbd_conns, C_WF_REPORT_PARAMS, state.conn);
         peer_device_state_change->resync_susp_user[NEW] =
             state.user_isp;
         peer_device_state_change->resync_susp_peer[NEW] =
             state.peer_isp;
         peer_device_state_change->resync_susp_dependency[NEW] =
             state.aftr_isp;
     }
 }
 
 void copy_old_to_new_state_change(struct drbd_state_change *state_change)
 {
     struct drbd_resource_state_change *resource_state_change = &state_change->resource[0];
     unsigned int n_device, n_connection, n_peer_device, n_peer_devices;
 
 #define OLD_TO_NEW(x) \
     (x[NEW] = x[OLD])
 
     OLD_TO_NEW(resource_state_change->role);
     OLD_TO_NEW(resource_state_change->susp);
     OLD_TO_NEW(resource_state_change->susp_nod);
     OLD_TO_NEW(resource_state_change->susp_fen);
 
     for (n_connection = 0; n_connection < state_change->n_connections; n_connection++) {
         struct drbd_connection_state_change *connection_state_change =
                 &state_change->connections[n_connection];
 
         OLD_TO_NEW(connection_state_change->peer_role);
         OLD_TO_NEW(connection_state_change->cstate);
     }
 
     for (n_device = 0; n_device < state_change->n_devices; n_device++) {
         struct drbd_device_state_change *device_state_change =
             &state_change->devices[n_device];
 
         OLD_TO_NEW(device_state_change->disk_state);
     }
 
     n_peer_devices = state_change->n_devices * state_change->n_connections;
     for (n_peer_device = 0; n_peer_device < n_peer_devices; n_peer_device++) {
         struct drbd_peer_device_state_change *p =
             &state_change->peer_devices[n_peer_device];
 
         OLD_TO_NEW(p->disk_state);
         OLD_TO_NEW(p->repl_state);
         OLD_TO_NEW(p->resync_susp_user);
         OLD_TO_NEW(p->resync_susp_peer);
         OLD_TO_NEW(p->resync_susp_dependency);
     }
 
 #undef OLD_TO_NEW
 }
 
 void forget_state_change(struct drbd_state_change *state_change)
 {
     unsigned int n;
 
     if (!state_change)
         return;
 
     if (state_change->resource->resource)
         kref_put(&state_change->resource->resource->kref, drbd_destroy_resource);
     for (n = 0; n < state_change->n_devices; n++) {
         struct drbd_device *device = state_change->devices[n].device;
 
         if (device)
             kref_put(&device->kref, drbd_destroy_device);
     }
     for (n = 0; n < state_change->n_connections; n++) {
         struct drbd_connection *connection =
             state_change->connections[n].connection;
 
         if (connection)
             kref_put(&connection->kref, drbd_destroy_connection);
     }
     kfree(state_change);
 }
 
 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,
                struct drbd_state_change *);
 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_SECONDARY;
     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;
     void *buffer = NULL;
 
     init_completion(&done);
 
     if (f & CS_SERIALIZE)
         mutex_lock(device->state_mutex);
     if (f & CS_INHIBIT_MD_IO)
         buffer = drbd_md_get_buffer(device, __func__);
 
     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 (buffer)
         drbd_md_put_buffer(device);
     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;
 }
 
 /*
  * We grab drbd_md_get_buffer(), because we don't want to "fail" the disk while
  * there is IO in-flight: the transition into D_FAILED for detach purposes
  * may get misinterpreted as actual IO error in a confused endio function.
  *
  * We wrap it all into wait_event(), to retry in case the drbd_req_state()
  * returns SS_IN_TRANSIENT_STATE.
  *
  * To avoid potential deadlock with e.g. the receiver thread trying to grab
  * drbd_md_get_buffer() while trying to get out of the "transient state", we
  * need to grab and release the meta data buffer inside of that wait_event loop.
  */
 static enum drbd_state_rv
 request_detach(struct drbd_device *device)
 {
     return drbd_req_state(device, NS(disk, D_FAILED),
             CS_VERBOSE | CS_ORDERED | CS_INHIBIT_MD_IO);
 }
 
 int drbd_request_detach_interruptible(struct drbd_device *device)
 {
     int ret, rv;
 
     drbd_suspend_io(device); /* so no-one is stuck in drbd_al_begin_io */
     wait_event_interruptible(device->state_wait,
         (rv = request_detach(device)) != SS_IN_TRANSIENT_STATE);
     drbd_resume_io(device);
 
     ret = wait_event_interruptible(device->misc_wait,
             device->state.disk != D_FAILED);
 
     if (rv == SS_IS_DISKLESS)
         rv = SS_NOTHING_TO_DO;
     if (ret)
         rv = ERR_INTR;
 
     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)
         goto out; /* 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;
 
 out:
     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).
  * @os:     old state.
  * @ns:     new state.
  * @connection:  DRBD connection.
  */
 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;
 
     /* Do not promote during resync handshake triggered by "force primary".
      * This is a hack. It should really be rejected by the peer during the
      * cluster wide state change request. */
     if (os.role != R_PRIMARY && ns.role == R_PRIMARY
         && ns.pdsk == D_UP_TO_DATE
         && ns.disk != D_UP_TO_DATE && ns.disk != D_DISKLESS
         && (ns.conn <= C_WF_SYNC_UUID || ns.conn != os.conn))
             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:   placeholder for returned state warning.
  *
  * 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 state 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. 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;
     struct drbd_state_change *state_change;
 
     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);
 
     /* FIXME: Have any flags been set earlier in this function already? */
     state_change = remember_old_state(device->resource, GFP_ATOMIC);
 
     /* 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();
 
     remember_new_state(state_change);
 
     /* 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;
         ascw->state_change = state_change;
         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, ascw->state_change);
     forget_state_change(ascw->state_change);
     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); */
     atomic_inc(&device->suspend_cnt);
 
     drbd_bm_lock(device, why, flags);
     rv = io_fn(device);
     drbd_bm_unlock(device);
 
     drbd_resume_io(device);
 
     return rv;
 }
 
 int notify_resource_state_change(struct sk_buff *skb,
                   unsigned int seq,
                   struct drbd_resource_state_change *resource_state_change,
                   enum drbd_notification_type type)
 {
     struct drbd_resource *resource = resource_state_change->resource;
     struct resource_info resource_info = {
         .res_role = resource_state_change->role[NEW],
         .res_susp = resource_state_change->susp[NEW],
         .res_susp_nod = resource_state_change->susp_nod[NEW],
         .res_susp_fen = resource_state_change->susp_fen[NEW],
     };
 
     return notify_resource_state(skb, seq, resource, &resource_info, type);
 }
 
 int notify_connection_state_change(struct sk_buff *skb,
                     unsigned int seq,
                     struct drbd_connection_state_change *connection_state_change,
                     enum drbd_notification_type type)
 {
     struct drbd_connection *connection = connection_state_change->connection;
     struct connection_info connection_info = {
         .conn_connection_state = connection_state_change->cstate[NEW],
         .conn_role = connection_state_change->peer_role[NEW],
     };
 
     return notify_connection_state(skb, seq, connection, &connection_info, type);
 }
 
 int notify_device_state_change(struct sk_buff *skb,
                 unsigned int seq,
                 struct drbd_device_state_change *device_state_change,
                 enum drbd_notification_type type)
 {
     struct drbd_device *device = device_state_change->device;
     struct device_info device_info = {
         .dev_disk_state = device_state_change->disk_state[NEW],
     };
 
     return notify_device_state(skb, seq, device, &device_info, type);
 }
 
 int notify_peer_device_state_change(struct sk_buff *skb,
                      unsigned int seq,
                      struct drbd_peer_device_state_change *p,
                      enum drbd_notification_type type)
 {
     struct drbd_peer_device *peer_device = p->peer_device;
     struct peer_device_info peer_device_info = {
         .peer_repl_state = p->repl_state[NEW],
         .peer_disk_state = p->disk_state[NEW],
         .peer_resync_susp_user = p->resync_susp_user[NEW],
         .peer_resync_susp_peer = p->resync_susp_peer[NEW],
         .peer_resync_susp_dependency = p->resync_susp_dependency[NEW],
     };
 
     return notify_peer_device_state(skb, seq, peer_device, &peer_device_info, type);
 }
 
 static void broadcast_state_change(struct drbd_state_change *state_change)
 {
     struct drbd_resource_state_change *resource_state_change = &state_change->resource[0];
     bool resource_state_has_changed;
     unsigned int n_device, n_connection, n_peer_device, n_peer_devices;
     int (*last_func)(struct sk_buff *, unsigned int, void *,
               enum drbd_notification_type) = NULL;
     void *last_arg = NULL;
 
 #define HAS_CHANGED(state) ((state)[OLD] != (state)[NEW])
 #define FINAL_STATE_CHANGE(type) \
     ({ if (last_func) \
         last_func(NULL, 0, last_arg, type); \
     })
 #define REMEMBER_STATE_CHANGE(func, arg, type) \
     ({ FINAL_STATE_CHANGE(type | NOTIFY_CONTINUES); \
        last_func = (typeof(last_func))func; \
        last_arg = arg; \
      })
 
     mutex_lock(&notification_mutex);
 
     resource_state_has_changed =
         HAS_CHANGED(resource_state_change->role) ||
         HAS_CHANGED(resource_state_change->susp) ||
         HAS_CHANGED(resource_state_change->susp_nod) ||
         HAS_CHANGED(resource_state_change->susp_fen);
 
     if (resource_state_has_changed)
         REMEMBER_STATE_CHANGE(notify_resource_state_change,
                       resource_state_change, NOTIFY_CHANGE);
 
     for (n_connection = 0; n_connection < state_change->n_connections; n_connection++) {
         struct drbd_connection_state_change *connection_state_change =
                 &state_change->connections[n_connection];
 
         if (HAS_CHANGED(connection_state_change->peer_role) ||
             HAS_CHANGED(connection_state_change->cstate))
             REMEMBER_STATE_CHANGE(notify_connection_state_change,
                           connection_state_change, NOTIFY_CHANGE);
     }
 
     for (n_device = 0; n_device < state_change->n_devices; n_device++) {
         struct drbd_device_state_change *device_state_change =
             &state_change->devices[n_device];
 
         if (HAS_CHANGED(device_state_change->disk_state))
             REMEMBER_STATE_CHANGE(notify_device_state_change,
                           device_state_change, NOTIFY_CHANGE);
     }
 
     n_peer_devices = state_change->n_devices * state_change->n_connections;
     for (n_peer_device = 0; n_peer_device < n_peer_devices; n_peer_device++) {
         struct drbd_peer_device_state_change *p =
             &state_change->peer_devices[n_peer_device];
 
         if (HAS_CHANGED(p->disk_state) ||
             HAS_CHANGED(p->repl_state) ||
             HAS_CHANGED(p->resync_susp_user) ||
             HAS_CHANGED(p->resync_susp_peer) ||
             HAS_CHANGED(p->resync_susp_dependency))
             REMEMBER_STATE_CHANGE(notify_peer_device_state_change,
                           p, NOTIFY_CHANGE);
     }
 
     FINAL_STATE_CHANGE(NOTIFY_CHANGE);
     mutex_unlock(&notification_mutex);
 
 #undef HAS_CHANGED
 #undef FINAL_STATE_CHANGE
 #undef REMEMBER_STATE_CHANGE
 }
 
 /* takes old and new peer disk state */
 static bool lost_contact_to_peer_data(enum drbd_disk_state os, enum drbd_disk_state ns)
 {
     if ((os >= D_INCONSISTENT && os != D_UNKNOWN && os != D_OUTDATED)
     &&  (ns < D_INCONSISTENT || ns == D_UNKNOWN || ns == D_OUTDATED))
         return true;
 
     /* Scenario, starting with normal operation
      * Connected Primary/Secondary UpToDate/UpToDate
      * NetworkFailure Primary/Unknown UpToDate/DUnknown (frozen)
      * ...
      * Connected Primary/Secondary UpToDate/Diskless (resumed; needs to bump uuid!)
      */
     if (os == D_UNKNOWN
     &&  (ns == D_DISKLESS || ns == D_FAILED || ns == D_OUTDATED))
         return true;
 
     return false;
 }
 
 /**
  * after_state_ch() - Perform after state change actions that may sleep
  * @device: DRBD device.
  * @os:     old state.
  * @ns:     new state.
  * @flags:  Flags
  * @state_change: state change to broadcast
  */
 static void after_state_ch(struct drbd_device *device, union drbd_state os,
                union drbd_state ns, enum chg_state_flags flags,
                struct drbd_state_change *state_change)
 {
     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;
 
     broadcast_state_change(state_change);
 
     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_UP_TO_DATE)
             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();
 
             /* We should actively create a new uuid, _before_
              * we resume/resent, if the peer is diskless
              * (recovery from a multiple error scenario).
              * Currently, this happens with a slight delay
              * below when checking lost_contact_to_peer_data() ...
              */
             _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 (lost_contact_to_peer_data(os.pdsk, ns.pdsk)) {
         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_PRIMARY && 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);
 
             /* Intentionally call this handler first, before drbd_send_state().
              * See: 2932204 drbd: call local-io-error handler early
              * People may chose to hard-reset the box from this handler.
              * It is useful if this looks like a "regular node crash". */
             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 on transition from resync back to AHEAD/BEHIND.
      *
      * Connection loss is handled in drbd_disconnected() by the receiver.
      *
      * 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 && os.conn < C_AHEAD) &&
         (ns.conn == C_CONNECTED || ns.conn >= C_AHEAD) && 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;
     struct drbd_state_change *state_change;
 };
 
 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;
 
     broadcast_state_change(acscw->state_change);
     forget_state_change(acscw->state_change);
     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(&notification_mutex);
         idr_for_each_entry(&connection->peer_devices, peer_device, vnr)
             notify_peer_device_state(NULL, 0, peer_device, NULL,
                          NOTIFY_DESTROY | NOTIFY_CONTINUES);
         notify_connection_state(NULL, 0, connection, NULL, NOTIFY_DESTROY);
         mutex_unlock(&notification_mutex);
 
         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);
 
         kvfree_rcu(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);
         }
     }
     conn_md_sync(connection);
     kref_put(&connection->kref, drbd_destroy_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);
         BUG_ON(rv < SS_SUCCESS);
         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;
     struct drbd_state_change *state_change;
 
     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;
     }
 
     state_change = remember_old_state(connection->resource, GFP_ATOMIC);
     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);
     remember_new_state(state_change);
 
     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;
         acscw->state_change = state_change;
         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;
 }