Whamcloud - gitweb
LU-1252 recovery: reduce reconnect time for IR
[fs/lustre-release.git] / lustre / ptlrpc / import.c
index fe59707..7e68efb 100644 (file)
@@ -1,26 +1,41 @@
-/* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
- * vim:expandtab:shiftwidth=8:tabstop=8:
+/*
+ * GPL HEADER START
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 only,
+ * as published by the Free Software Foundation.
+ *
+ * This program 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 version 2 for more details (a copy is included
+ * in the LICENSE file that accompanied this code).
  *
- *  Copyright (c) 2002, 2003 Cluster File Systems, Inc.
- *   Author: Mike Shaver <shaver@clusterfs.com>
+ * You should have received a copy of the GNU General Public License
+ * version 2 along with this program; If not, see
+ * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  *
- *   This file is part of the Lustre file system, http://www.lustre.org
- *   Lustre is a trademark of Cluster File Systems, Inc.
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ * GPL HEADER END
+ */
+/*
+ * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Use is subject to license terms.
  *
- *   You may have signed or agreed to another license before downloading
- *   this software.  If so, you are bound by the terms and conditions
- *   of that agreement, and the following does not apply to you.  See the
- *   LICENSE file included with this distribution for more information.
+ * Copyright (c) 2011, Whamcloud, Inc.
+ */
+/*
+ * This file is part of Lustre, http://www.lustre.org/
+ * Lustre is a trademark of Sun Microsystems, Inc.
  *
- *   If you did not agree to a different license, then this copy of Lustre
- *   is open source software; you can redistribute it and/or modify it
- *   under the terms of version 2 of the GNU General Public License as
- *   published by the Free Software Foundation.
+ * lustre/ptlrpc/import.c
  *
- *   In either case, Lustre 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
- *   license text for more details.
+ * Author: Mike Shaver <shaver@clusterfs.com>
  */
 
 #define DEBUG_SUBSYSTEM S_RPC
@@ -34,6 +49,7 @@
 #include <lustre_import.h>
 #include <lustre_export.h>
 #include <obd.h>
+#include <obd_cksum.h>
 #include <obd_class.h>
 
 #include "ptlrpc_internal.h"
@@ -43,6 +59,21 @@ struct ptlrpc_connect_async_args {
         int pcaa_initial_connect;
 };
 
+/**
+ * Updates import \a imp current state to provided \a state value
+ * Helper function. Must be called under imp_lock.
+ */
+static void __import_set_state(struct obd_import *imp,
+                               enum lustre_imp_state state)
+{
+        imp->imp_state = state;
+        imp->imp_state_hist[imp->imp_state_hist_idx].ish_state = state;
+        imp->imp_state_hist[imp->imp_state_hist_idx].ish_time =
+                cfs_time_current_sec();
+        imp->imp_state_hist_idx = (imp->imp_state_hist_idx + 1) %
+                IMP_STATE_HIST_LEN;
+}
+
 /* A CLOSED import should remain so. */
 #define IMPORT_SET_STATE_NOLOCK(imp, state)                                    \
 do {                                                                           \
@@ -51,19 +82,20 @@ do {                                                                           \
                       imp, obd2cli_tgt(imp->imp_obd),                          \
                       ptlrpc_import_state_name(imp->imp_state),                \
                       ptlrpc_import_state_name(state));                        \
-               imp->imp_state = state;                                         \
+               __import_set_state(imp, state);                                 \
         }                                                                      \
 } while(0)
 
 #define IMPORT_SET_STATE(imp, state)            \
 do {                                            \
-        spin_lock(&imp->imp_lock);              \
+        cfs_spin_lock(&imp->imp_lock);          \
         IMPORT_SET_STATE_NOLOCK(imp, state);    \
-        spin_unlock(&imp->imp_lock);            \
+        cfs_spin_unlock(&imp->imp_lock);        \
 } while(0)
 
 
-static int ptlrpc_connect_interpret(struct ptlrpc_request *request,
+static int ptlrpc_connect_interpret(const struct lu_env *env,
+                                    struct ptlrpc_request *request,
                                     void * data, int rc);
 int ptlrpc_import_recovery_state_machine(struct obd_import *imp);
 
@@ -74,20 +106,19 @@ int ptlrpc_import_recovery_state_machine(struct obd_import *imp);
  * though. */
 int ptlrpc_init_import(struct obd_import *imp)
 {
-        spin_lock(&imp->imp_lock);
+        cfs_spin_lock(&imp->imp_lock);
 
         imp->imp_generation++;
         imp->imp_state =  LUSTRE_IMP_NEW;
 
-        spin_unlock(&imp->imp_lock);
+        cfs_spin_unlock(&imp->imp_lock);
 
         return 0;
 }
 EXPORT_SYMBOL(ptlrpc_init_import);
 
 #define UUID_STR "_UUID"
-static void deuuidify(char *uuid, const char *prefix, char **uuid_start,
-                      int *uuid_len)
+void deuuidify(char *uuid, const char *prefix, char **uuid_start, int *uuid_len)
 {
         *uuid_start = !prefix || strncmp(uuid, prefix, strlen(prefix))
                 ? uuid : uuid + strlen(prefix);
@@ -101,8 +132,10 @@ static void deuuidify(char *uuid, const char *prefix, char **uuid_start,
                     UUID_STR, strlen(UUID_STR)))
                 *uuid_len -= strlen(UUID_STR);
 }
+EXPORT_SYMBOL(deuuidify);
 
-/* Returns true if import was FULL, false if import was already not
+/**
+ * Returns true if import was FULL, false if import was already not
  * connected.
  * @imp - import to be disconnected
  * @conn_cnt - connection count (epoch) of the request that timed out
@@ -116,7 +149,7 @@ int ptlrpc_set_import_discon(struct obd_import *imp, __u32 conn_cnt)
 {
         int rc = 0;
 
-        spin_lock(&imp->imp_lock);
+        cfs_spin_lock(&imp->imp_lock);
 
         if (imp->imp_state == LUSTRE_IMP_FULL &&
             (conn_cnt == 0 || conn_cnt == imp->imp_conn_cnt)) {
@@ -125,29 +158,32 @@ int ptlrpc_set_import_discon(struct obd_import *imp, __u32 conn_cnt)
 
                 deuuidify(obd2cli_tgt(imp->imp_obd), NULL,
                           &target_start, &target_len);
+
                 if (imp->imp_replayable) {
-                        LCONSOLE_WARN("%s: Connection to service %.*s via nid "
-                               "%s was lost; in progress operations using this "
-                               "service will wait for recovery to complete.\n",
+                        LCONSOLE_WARN("%s: Connection to %.*s (at %s) was "
+                               "lost; in progress operations using this "
+                               "service will wait for recovery to complete\n",
                                imp->imp_obd->obd_name, target_len, target_start,
                                libcfs_nid2str(imp->imp_connection->c_peer.nid));
                 } else {
-                        LCONSOLE_ERROR("%s: Connection to service %.*s via nid "
-                               "%s was lost; in progress operations using this "
-                               "service will fail.\n",
-                               imp->imp_obd->obd_name, target_len, target_start,
+                        LCONSOLE_ERROR_MSG(0x166, "%s: Connection to "
+                               "%.*s (at %s) was lost; in progress "
+                               "operations using this service will fail\n",
+                               imp->imp_obd->obd_name,
+                               target_len, target_start,
                                libcfs_nid2str(imp->imp_connection->c_peer.nid));
                 }
+                ptlrpc_deactivate_timeouts(imp);
                 IMPORT_SET_STATE_NOLOCK(imp, LUSTRE_IMP_DISCON);
-                spin_unlock(&imp->imp_lock);
-    
+                cfs_spin_unlock(&imp->imp_lock);
+
                 if (obd_dump_on_timeout)
                         libcfs_debug_dumplog();
 
                 obd_import_event(imp->imp_obd, imp, IMP_EVENT_DISCON);
                 rc = 1;
         } else {
-                spin_unlock(&imp->imp_lock);
+                cfs_spin_unlock(&imp->imp_lock);
                 CDEBUG(D_HA, "%s: import %p already %s (conn %u, was %u): %s\n",
                        imp->imp_client->cli_name, imp,
                        (imp->imp_state == LUSTRE_IMP_FULL &&
@@ -159,25 +195,74 @@ int ptlrpc_set_import_discon(struct obd_import *imp, __u32 conn_cnt)
         return rc;
 }
 
-/*
- * This acts as a barrier; all existing requests are rejected, and
- * no new requests will be accepted until the import is valid again.
- */
-void ptlrpc_deactivate_import(struct obd_import *imp)
+/* Must be called with imp_lock held! */
+static void ptlrpc_deactivate_and_unlock_import(struct obd_import *imp)
 {
         ENTRY;
+        LASSERT_SPIN_LOCKED(&imp->imp_lock);
 
-        spin_lock(&imp->imp_lock);
         CDEBUG(D_HA, "setting import %s INVALID\n", obd2cli_tgt(imp->imp_obd));
         imp->imp_invalid = 1;
         imp->imp_generation++;
-        spin_unlock(&imp->imp_lock);
+        cfs_spin_unlock(&imp->imp_lock);
 
         ptlrpc_abort_inflight(imp);
         obd_import_event(imp->imp_obd, imp, IMP_EVENT_INACTIVE);
+
+        EXIT;
 }
 
 /*
+ * This acts as a barrier; all existing requests are rejected, and
+ * no new requests will be accepted until the import is valid again.
+ */
+void ptlrpc_deactivate_import(struct obd_import *imp)
+{
+        cfs_spin_lock(&imp->imp_lock);
+        ptlrpc_deactivate_and_unlock_import(imp);
+}
+
+static unsigned int
+ptlrpc_inflight_deadline(struct ptlrpc_request *req, time_t now)
+{
+        long dl;
+
+        if (!(((req->rq_phase == RQ_PHASE_RPC) && !req->rq_waiting) ||
+              (req->rq_phase == RQ_PHASE_BULK) ||
+              (req->rq_phase == RQ_PHASE_NEW)))
+                return 0;
+
+        if (req->rq_timedout)
+                return 0;
+
+        if (req->rq_phase == RQ_PHASE_NEW)
+                dl = req->rq_sent;
+        else
+                dl = req->rq_deadline;
+
+        if (dl <= now)
+                return 0;
+
+        return dl - now;
+}
+
+static unsigned int ptlrpc_inflight_timeout(struct obd_import *imp)
+{
+        time_t now = cfs_time_current_sec();
+        cfs_list_t *tmp, *n;
+        struct ptlrpc_request *req;
+        unsigned int timeout = 0;
+
+        cfs_spin_lock(&imp->imp_lock);
+        cfs_list_for_each_safe(tmp, n, &imp->imp_sending_list) {
+                req = cfs_list_entry(tmp, struct ptlrpc_request, rq_list);
+                timeout = max(ptlrpc_inflight_deadline(req, now), timeout);
+        }
+        cfs_spin_unlock(&imp->imp_lock);
+        return timeout;
+}
+
+/**
  * This function will invalidate the import, if necessary, then block
  * for all the RPC completions, and finally notify the obd to
  * invalidate its state (ie cancel locks, clear pending requests,
@@ -185,27 +270,114 @@ void ptlrpc_deactivate_import(struct obd_import *imp)
  */
 void ptlrpc_invalidate_import(struct obd_import *imp)
 {
+        cfs_list_t *tmp, *n;
+        struct ptlrpc_request *req;
         struct l_wait_info lwi;
+        unsigned int timeout;
         int rc;
 
-        if (!imp->imp_invalid)
+        cfs_atomic_inc(&imp->imp_inval_count);
+
+        if (!imp->imp_invalid || imp->imp_obd->obd_no_recov)
                 ptlrpc_deactivate_import(imp);
 
         LASSERT(imp->imp_invalid);
 
-        /* wait for all requests to error out and call completion callbacks */
-        lwi = LWI_TIMEOUT_INTERVAL(cfs_timeout_cap(cfs_time_seconds(obd_timeout)), 
-                                   HZ, NULL, NULL);
-        rc = l_wait_event(imp->imp_recovery_waitq,
-                          (atomic_read(&imp->imp_inflight) == 0),
-                          &lwi);
+        /* Wait forever until inflight == 0. We really can't do it another
+         * way because in some cases we need to wait for very long reply
+         * unlink. We can't do anything before that because there is really
+         * no guarantee that some rdma transfer is not in progress right now. */
+        do {
+                /* Calculate max timeout for waiting on rpcs to error
+                 * out. Use obd_timeout if calculated value is smaller
+                 * than it. */
+                if (!OBD_FAIL_CHECK(OBD_FAIL_PTLRPC_LONG_REPL_UNLINK)) {
+                        timeout = ptlrpc_inflight_timeout(imp);
+                        timeout += timeout / 3;
+
+                        if (timeout == 0)
+                                timeout = obd_timeout;
+                } else {
+                        /* decrease the interval to increase race condition */
+                        timeout = 1;
+                }
 
-        if (rc)
-                CDEBUG(D_HA, "%s: rc = %d waiting for callback (%d != 0)\n",
-                       obd2cli_tgt(imp->imp_obd), rc,
-                       atomic_read(&imp->imp_inflight));
+                CDEBUG(D_RPCTRACE,"Sleeping %d sec for inflight to error out\n",
+                       timeout);
 
+                /* Wait for all requests to error out and call completion
+                 * callbacks. Cap it at obd_timeout -- these should all
+                 * have been locally cancelled by ptlrpc_abort_inflight. */
+                lwi = LWI_TIMEOUT_INTERVAL(
+                        cfs_timeout_cap(cfs_time_seconds(timeout)),
+                        (timeout > 1)?cfs_time_seconds(1):cfs_time_seconds(1)/2,
+                        NULL, NULL);
+                rc = l_wait_event(imp->imp_recovery_waitq,
+                                  (cfs_atomic_read(&imp->imp_inflight) == 0),
+                                  &lwi);
+                if (rc) {
+                        const char *cli_tgt = obd2cli_tgt(imp->imp_obd);
+
+                        CERROR("%s: rc = %d waiting for callback (%d != 0)\n",
+                               cli_tgt, rc,
+                               cfs_atomic_read(&imp->imp_inflight));
+
+                        cfs_spin_lock(&imp->imp_lock);
+                        if (cfs_atomic_read(&imp->imp_inflight) == 0) {
+                                int count = cfs_atomic_read(&imp->imp_unregistering);
+
+                                /* We know that "unregistering" rpcs only can
+                                 * survive in sending or delaying lists (they
+                                 * maybe waiting for long reply unlink in
+                                 * sluggish nets). Let's check this. If there
+                                 * is no inflight and unregistering != 0, this
+                                 * is bug. */
+                                LASSERTF(count == 0, "Some RPCs are still "
+                                         "unregistering: %d\n", count);
+
+                                /* Let's save one loop as soon as inflight have
+                                 * dropped to zero. No new inflights possible at
+                                 * this point. */
+                                rc = 0;
+                        } else {
+                                cfs_list_for_each_safe(tmp, n,
+                                                       &imp->imp_sending_list) {
+                                        req = cfs_list_entry(tmp,
+                                                             struct ptlrpc_request,
+                                                             rq_list);
+                                        DEBUG_REQ(D_ERROR, req,
+                                                  "still on sending list");
+                                }
+                                cfs_list_for_each_safe(tmp, n,
+                                                       &imp->imp_delayed_list) {
+                                        req = cfs_list_entry(tmp,
+                                                             struct ptlrpc_request,
+                                                             rq_list);
+                                        DEBUG_REQ(D_ERROR, req,
+                                                  "still on delayed list");
+                                }
+
+                                CERROR("%s: RPCs in \"%s\" phase found (%d). "
+                                       "Network is sluggish? Waiting them "
+                                       "to error out.\n", cli_tgt,
+                                       ptlrpc_phase2str(RQ_PHASE_UNREGISTERING),
+                                       cfs_atomic_read(&imp->
+                                                       imp_unregistering));
+                        }
+                        cfs_spin_unlock(&imp->imp_lock);
+                  }
+        } while (rc != 0);
+
+        /*
+         * Let's additionally check that no new rpcs added to import in
+         * "invalidate" state.
+         */
+        LASSERT(cfs_atomic_read(&imp->imp_inflight) == 0);
         obd_import_event(imp->imp_obd, imp, IMP_EVENT_INVALIDATE);
+        sptlrpc_import_flush_all_ctx(imp);
+
+        cfs_atomic_dec(&imp->imp_inval_count);
+        cfs_waitq_broadcast(&imp->imp_recovery_waitq);
 }
 
 /* unset imp_invalid */
@@ -213,10 +385,10 @@ void ptlrpc_activate_import(struct obd_import *imp)
 {
         struct obd_device *obd = imp->imp_obd;
 
-        spin_lock(&imp->imp_lock);
+        cfs_spin_lock(&imp->imp_lock);
         imp->imp_invalid = 0;
-        spin_unlock(&imp->imp_lock);
-
+        ptlrpc_activate_timeouts(imp);
+        cfs_spin_unlock(&imp->imp_lock);
         obd_import_event(obd, imp, IMP_EVENT_ACTIVE);
 }
 
@@ -239,85 +411,143 @@ void ptlrpc_fail_import(struct obd_import *imp, __u32 conn_cnt)
                 CDEBUG(D_HA, "%s: waking up pinger\n",
                        obd2cli_tgt(imp->imp_obd));
 
-                spin_lock(&imp->imp_lock);
+                cfs_spin_lock(&imp->imp_lock);
                 imp->imp_force_verify = 1;
-                spin_unlock(&imp->imp_lock);
+                cfs_spin_unlock(&imp->imp_lock);
 
                 ptlrpc_pinger_wake_up();
         }
         EXIT;
 }
 
+int ptlrpc_reconnect_import(struct obd_import *imp)
+{
+        ptlrpc_set_import_discon(imp, 0);
+        /* Force a new connect attempt */
+        ptlrpc_invalidate_import(imp);
+        /* Do a fresh connect next time by zeroing the handle */
+        ptlrpc_disconnect_import(imp, 1);
+        /* Wait for all invalidate calls to finish */
+        if (cfs_atomic_read(&imp->imp_inval_count) > 0) {
+                int rc;
+                struct l_wait_info lwi = LWI_INTR(LWI_ON_SIGNAL_NOOP, NULL);
+                rc = l_wait_event(imp->imp_recovery_waitq,
+                                  (cfs_atomic_read(&imp->imp_inval_count) == 0),
+                                  &lwi);
+                if (rc)
+                        CERROR("Interrupted, inval=%d\n",
+                               cfs_atomic_read(&imp->imp_inval_count));
+        }
+
+        /* Allow reconnect attempts */
+        imp->imp_obd->obd_no_recov = 0;
+        /* Remove 'invalid' flag */
+        ptlrpc_activate_import(imp);
+        /* Attempt a new connect */
+        ptlrpc_recover_import(imp, NULL, 0);
+        return 0;
+}
+EXPORT_SYMBOL(ptlrpc_reconnect_import);
+
+/**
+ * Connection on import \a imp is changed to another one (if more than one is
+ * present). We typically chose connection that we have not tried to connect to
+ * the longest
+ */
 static int import_select_connection(struct obd_import *imp)
 {
         struct obd_import_conn *imp_conn = NULL, *conn;
         struct obd_export *dlmexp;
+        char *target_start;
+        int target_len, tried_all = 1;
         ENTRY;
 
-        spin_lock(&imp->imp_lock);
+        cfs_spin_lock(&imp->imp_lock);
 
-        if (list_empty(&imp->imp_conn_list)) {
+        if (cfs_list_empty(&imp->imp_conn_list)) {
                 CERROR("%s: no connections available\n",
                         imp->imp_obd->obd_name);
-                spin_unlock(&imp->imp_lock);
+                cfs_spin_unlock(&imp->imp_lock);
                 RETURN(-EINVAL);
         }
 
-        list_for_each_entry(conn, &imp->imp_conn_list, oic_item) {
+        cfs_list_for_each_entry(conn, &imp->imp_conn_list, oic_item) {
                 CDEBUG(D_HA, "%s: connect to NID %s last attempt "LPU64"\n",
                        imp->imp_obd->obd_name,
                        libcfs_nid2str(conn->oic_conn->c_peer.nid),
                        conn->oic_last_attempt);
-                /* Throttle the reconnect rate to once per RECONNECT_INTERVAL */
-                if (cfs_time_before_64(conn->oic_last_attempt + 
-                                       RECONNECT_INTERVAL * HZ,
-                                       cfs_time_current_64())) {
-                        /* If we have never tried this connection since the
-                           the last successful attempt, go with this one */
-                        if (cfs_time_before_64(conn->oic_last_attempt,
-                                               imp->imp_last_success_conn)) {
-                                imp_conn = conn;
-                                break;
-                        }
 
-                        /* Both of these connections have already been tried
-                           since the last successful connection; just choose the
-                           least recently used */
-                        if (!imp_conn)
-                                imp_conn = conn;
-                        else if (cfs_time_before_64(conn->oic_last_attempt,
-                                                    imp_conn->oic_last_attempt))
-                                imp_conn = conn;
+                /* If we have not tried this connection since
+                   the last successful attempt, go with this one */
+                if ((conn->oic_last_attempt == 0) ||
+                    cfs_time_beforeq_64(conn->oic_last_attempt,
+                                       imp->imp_last_success_conn)) {
+                        imp_conn = conn;
+                        tried_all = 0;
+                        break;
                 }
+
+                /* If all of the connections have already been tried
+                   since the last successful connection; just choose the
+                   least recently used */
+                if (!imp_conn)
+                        imp_conn = conn;
+                else if (cfs_time_before_64(conn->oic_last_attempt,
+                                            imp_conn->oic_last_attempt))
+                        imp_conn = conn;
         }
 
         /* if not found, simply choose the current one */
-        if (!imp_conn) {
+        if (!imp_conn || imp->imp_force_reconnect) {
                 LASSERT(imp->imp_conn_current);
                 imp_conn = imp->imp_conn_current;
+                tried_all = 0;
         }
         LASSERT(imp_conn->oic_conn);
 
+        /* If we've tried everything, and we're back to the beginning of the
+           list, increase our timeout and try again. It will be reset when
+           we do finally connect. (FIXME: really we should wait for all network
+           state associated with the last connection attempt to drain before
+           trying to reconnect on it.) */
+        if (tried_all && (imp->imp_conn_list.next == &imp_conn->oic_item)) {
+               struct adaptive_timeout *at = &imp->imp_at.iat_net_latency;
+               if (at_get(at) < CONNECTION_SWITCH_MAX) {
+                       at_measured(at, at_get(at) + CONNECTION_SWITCH_INC);
+                       if (at_get(at) > CONNECTION_SWITCH_MAX)
+                               at_reset(at, CONNECTION_SWITCH_MAX);
+               }
+               LASSERT(imp_conn->oic_last_attempt);
+               CDEBUG(D_HA, "%s: tried all connections, increasing latency "
+                       "to %ds\n", imp->imp_obd->obd_name, at_get(at));
+       }
+
         imp_conn->oic_last_attempt = cfs_time_current_64();
 
         /* switch connection, don't mind if it's same as the current one */
         if (imp->imp_connection)
-                ptlrpc_put_connection(imp->imp_connection);
+                ptlrpc_connection_put(imp->imp_connection);
         imp->imp_connection = ptlrpc_connection_addref(imp_conn->oic_conn);
 
         dlmexp =  class_conn2export(&imp->imp_dlm_handle);
         LASSERT(dlmexp != NULL);
         if (dlmexp->exp_connection)
-                ptlrpc_put_connection(dlmexp->exp_connection);
+                ptlrpc_connection_put(dlmexp->exp_connection);
         dlmexp->exp_connection = ptlrpc_connection_addref(imp_conn->oic_conn);
         class_export_put(dlmexp);
 
         if (imp->imp_conn_current != imp_conn) {
-                if (imp->imp_conn_current)
-                        LCONSOLE_INFO("Changing connection for %s to %s/%s\n",
-                                      imp->imp_obd->obd_name,
-                                      imp_conn->oic_uuid.uuid,
-                                      libcfs_nid2str(imp_conn->oic_conn->c_peer.nid));
+                if (imp->imp_conn_current) {
+                        deuuidify(obd2cli_tgt(imp->imp_obd), NULL,
+                                  &target_start, &target_len);
+
+                        CDEBUG(D_HA, "%s: Connection changing to"
+                               " %.*s (at %s)\n",
+                               imp->imp_obd->obd_name,
+                               target_len, target_start,
+                               libcfs_nid2str(imp_conn->oic_conn->c_peer.nid));
+                }
+
                 imp->imp_conn_current = imp_conn;
         }
 
@@ -325,42 +555,65 @@ static int import_select_connection(struct obd_import *imp)
                imp->imp_obd->obd_name, imp, imp_conn->oic_uuid.uuid,
                libcfs_nid2str(imp_conn->oic_conn->c_peer.nid));
 
-        spin_unlock(&imp->imp_lock);
+        cfs_spin_unlock(&imp->imp_lock);
 
         RETURN(0);
 }
 
-int ptlrpc_connect_import(struct obd_import *imp, char *new_uuid)
+/*
+ * must be called under imp_lock
+ */
+static int ptlrpc_first_transno(struct obd_import *imp, __u64 *transno)
+{
+        struct ptlrpc_request *req;
+        cfs_list_t *tmp;
+
+        if (cfs_list_empty(&imp->imp_replay_list))
+                return 0;
+        tmp = imp->imp_replay_list.next;
+        req = cfs_list_entry(tmp, struct ptlrpc_request, rq_replay_list);
+        *transno = req->rq_transno;
+        if (req->rq_transno == 0) {
+                DEBUG_REQ(D_ERROR, req, "zero transno in replay");
+                LBUG();
+        }
+
+        return 1;
+}
+
+/**
+ * Attempt to (re)connect import \a imp. This includes all preparations,
+ * initializing CONNECT RPC request and passing it to ptlrpcd for
+ * actual sending.
+ * Returns 0 on success or error code.
+ */
+int ptlrpc_connect_import(struct obd_import *imp)
 {
         struct obd_device *obd = imp->imp_obd;
         int initial_connect = 0;
-        int rc;
+        int set_transno = 0;
         __u64 committed_before_reconnect = 0;
         struct ptlrpc_request *request;
-        int size[] = { sizeof(struct ptlrpc_body),
-                       sizeof(imp->imp_obd->u.cli.cl_target_uuid),
-                       sizeof(obd->obd_uuid),
-                       sizeof(imp->imp_dlm_handle),
-                       sizeof(imp->imp_connect_data) };
-        char *tmp[] = { NULL,
-                        obd2cli_tgt(imp->imp_obd),
-                        obd->obd_uuid.uuid,
-                        (char *)&imp->imp_dlm_handle,
-                        (char *)&imp->imp_connect_data };
+        char *bufs[] = { NULL,
+                         obd2cli_tgt(imp->imp_obd),
+                         obd->obd_uuid.uuid,
+                         (char *)&imp->imp_dlm_handle,
+                         (char *)&imp->imp_connect_data };
         struct ptlrpc_connect_async_args *aa;
-
+        int rc;
         ENTRY;
-        spin_lock(&imp->imp_lock);
+
+        cfs_spin_lock(&imp->imp_lock);
         if (imp->imp_state == LUSTRE_IMP_CLOSED) {
-                spin_unlock(&imp->imp_lock);
+                cfs_spin_unlock(&imp->imp_lock);
                 CERROR("can't connect to a closed import\n");
                 RETURN(-EINVAL);
         } else if (imp->imp_state == LUSTRE_IMP_FULL) {
-                spin_unlock(&imp->imp_lock);
+                cfs_spin_unlock(&imp->imp_lock);
                 CERROR("already connected\n");
                 RETURN(0);
         } else if (imp->imp_state == LUSTRE_IMP_CONNECTING) {
-                spin_unlock(&imp->imp_lock);
+                cfs_spin_unlock(&imp->imp_lock);
                 CERROR("already connecting\n");
                 RETURN(-EALREADY);
         }
@@ -375,89 +628,88 @@ int ptlrpc_connect_import(struct obd_import *imp, char *new_uuid)
         else
                 committed_before_reconnect = imp->imp_peer_committed_transno;
 
-        spin_unlock(&imp->imp_lock);
-
-        if (new_uuid) {
-                struct obd_uuid uuid;
-
-                obd_str2uuid(&uuid, new_uuid);
-                rc = import_set_conn_priority(imp, &uuid);
-                if (rc)
-                        GOTO(out, rc);
-        }
+        set_transno = ptlrpc_first_transno(imp,
+                                           &imp->imp_connect_data.ocd_transno);
+        cfs_spin_unlock(&imp->imp_lock);
 
         rc = import_select_connection(imp);
         if (rc)
                 GOTO(out, rc);
 
-        /* last in connection list */
-        if (imp->imp_conn_current->oic_item.next == &imp->imp_conn_list) {
-                if (imp->imp_initial_recov_bk && initial_connect) {
-                        CDEBUG(D_HA, "Last connection attempt (%d) for %s\n",
-                               imp->imp_conn_cnt, obd2cli_tgt(imp->imp_obd));
-                        /* Don't retry if connect fails */
-                        rc = 0;
-                        obd_set_info_async(obd->obd_self_export,
-                                           strlen(KEY_INIT_RECOV),
-                                           KEY_INIT_RECOV,
-                                           sizeof(rc), &rc, NULL);
-                }
-                if (imp->imp_recon_bk) {
-                        CDEBUG(D_HA, "Last reconnection attempt (%d) for %s\n",
-                               imp->imp_conn_cnt, obd2cli_tgt(imp->imp_obd));
-                        spin_lock(&imp->imp_lock);
-                        imp->imp_last_recon = 1;
-                        spin_unlock(&imp->imp_lock);
-                }
-        }
+        rc = sptlrpc_import_sec_adapt(imp, NULL, 0);
+        if (rc)
+                GOTO(out, rc);
 
         /* Reset connect flags to the originally requested flags, in case
          * the server is updated on-the-fly we will get the new features. */
         imp->imp_connect_data.ocd_connect_flags = imp->imp_connect_flags_orig;
-        rc = obd_reconnect(imp->imp_obd->obd_self_export, obd,
-                           &obd->obd_uuid, &imp->imp_connect_data);
+        imp->imp_msghdr_flags &= ~MSGHDR_AT_SUPPORT;
+        imp->imp_msghdr_flags &= ~MSGHDR_CKSUM_INCOMPAT18;
+
+        rc = obd_reconnect(NULL, imp->imp_obd->obd_self_export, obd,
+                           &obd->obd_uuid, &imp->imp_connect_data, NULL);
         if (rc)
                 GOTO(out, rc);
 
-        request = ptlrpc_prep_req(imp, LUSTRE_OBD_VERSION, imp->imp_connect_op,
-                                  5, size, tmp);
-        if (!request)
+        request = ptlrpc_request_alloc(imp, &RQF_MDS_CONNECT);
+        if (request == NULL)
                 GOTO(out, rc = -ENOMEM);
 
+        rc = ptlrpc_request_bufs_pack(request, LUSTRE_OBD_VERSION,
+                                      imp->imp_connect_op, bufs, NULL);
+        if (rc) {
+                ptlrpc_request_free(request);
+                GOTO(out, rc);
+        }
+
+        /* Report the rpc service time to the server so that it knows how long
+         * to wait for clients to join recovery */
+        lustre_msg_set_service_time(request->rq_reqmsg,
+                                    at_timeout2est(request->rq_timeout));
+
+        /* The amount of time we give the server to process the connect req.
+         * import_select_connection will increase the net latency on
+         * repeated reconnect attempts to cover slow networks.
+         * We override/ignore the server rpc completion estimate here,
+         * which may be large if this is a reconnect attempt */
+        request->rq_timeout = INITIAL_CONNECT_TIMEOUT;
+        lustre_msg_set_timeout(request->rq_reqmsg, request->rq_timeout);
+
 #ifndef __KERNEL__
         lustre_msg_add_op_flags(request->rq_reqmsg, MSG_CONNECT_LIBCLIENT);
 #endif
         lustre_msg_add_op_flags(request->rq_reqmsg, MSG_CONNECT_NEXT_VER);
 
+        request->rq_no_resend = request->rq_no_delay = 1;
         request->rq_send_state = LUSTRE_IMP_CONNECTING;
         /* Allow a slightly larger reply for future growth compatibility */
-        size[REPLY_REC_OFF] = sizeof(struct obd_connect_data) +
-                              16 * sizeof(__u64);
-        ptlrpc_req_set_repsize(request, 2, size);
+        req_capsule_set_size(&request->rq_pill, &RMF_CONNECT_DATA, RCL_SERVER,
+                             sizeof(struct obd_connect_data)+16*sizeof(__u64));
+        ptlrpc_request_set_replen(request);
         request->rq_interpret_reply = ptlrpc_connect_interpret;
 
         CLASSERT(sizeof (*aa) <= sizeof (request->rq_async_args));
-        aa = (struct ptlrpc_connect_async_args *)&request->rq_async_args;
+        aa = ptlrpc_req_async_args(request);
         memset(aa, 0, sizeof *aa);
 
         aa->pcaa_peer_committed = committed_before_reconnect;
         aa->pcaa_initial_connect = initial_connect;
 
         if (aa->pcaa_initial_connect) {
-                spin_lock(&imp->imp_lock);
+                cfs_spin_lock(&imp->imp_lock);
                 imp->imp_replayable = 1;
-                spin_unlock(&imp->imp_lock);
-                /* On an initial connect, we don't know which one of a
-                   failover server pair is up.  Don't wait long. */
-#ifdef CRAY_XT3
-                request->rq_timeout = max((int)(obd_timeout / 2), 5);
-#else
-                request->rq_timeout = max((int)(obd_timeout / 20), 5);
-#endif
+                cfs_spin_unlock(&imp->imp_lock);
+                lustre_msg_add_op_flags(request->rq_reqmsg,
+                                        MSG_CONNECT_INITIAL);
         }
 
-        DEBUG_REQ(D_RPCTRACE, request, "(re)connect request");
-        ptlrpcd_add_req(request);
+        if (set_transno)
+                lustre_msg_add_op_flags(request->rq_reqmsg,
+                                        MSG_CONNECT_TRANSNO);
+
+        DEBUG_REQ(D_RPCTRACE, request, "(re)connect request (timeout %d)",
+                  request->rq_timeout);
+        ptlrpcd_add_req(request, PDL_POLICY_ROUND, -1);
         rc = 0;
 out:
         if (rc != 0) {
@@ -471,57 +723,57 @@ EXPORT_SYMBOL(ptlrpc_connect_import);
 static void ptlrpc_maybe_ping_import_soon(struct obd_import *imp)
 {
 #ifdef __KERNEL__
-        struct obd_import_conn *imp_conn;
-#endif
-        int wake_pinger = 0;
-
-        ENTRY;
-
-        spin_lock(&imp->imp_lock);
-        if (list_empty(&imp->imp_conn_list))
-                GOTO(unlock, 0);
-
-#ifdef __KERNEL__
-        imp_conn = list_entry(imp->imp_conn_list.prev,
-                              struct obd_import_conn,
-                              oic_item);
+        int force_verify;
 
-        if (imp->imp_conn_current != imp_conn) {
-                ptlrpc_ping_import_soon(imp);
-                wake_pinger = 1;
-        }
-
-#else
-        /* liblustre has no pinger thead, so we wakup pinger anyway */
-        wake_pinger = 1;
-#endif 
- unlock:
-        spin_unlock(&imp->imp_lock);
+        cfs_spin_lock(&imp->imp_lock);
+        force_verify = imp->imp_force_verify != 0;
+        cfs_spin_unlock(&imp->imp_lock);
 
-        if (wake_pinger)
+        if (force_verify)
                 ptlrpc_pinger_wake_up();
+#else
+        /* liblustre has no pinger thread, so we wakeup pinger anyway */
+        ptlrpc_pinger_wake_up();
+#endif
+}
 
-        EXIT;
+static int ptlrpc_busy_reconnect(int rc)
+{
+        return (rc == -EBUSY) || (rc == -EAGAIN);
 }
 
-static int ptlrpc_connect_interpret(struct ptlrpc_request *request,
-                                    void * data, int rc)
+/**
+ * interpret_reply callback for connect RPCs.
+ * Looks into returned status of connect operation and decides
+ * what to do with the import - i.e enter recovery, promote it to
+ * full state for normal operations of disconnect it due to an error.
+ */
+static int ptlrpc_connect_interpret(const struct lu_env *env,
+                                    struct ptlrpc_request *request,
+                                    void *data, int rc)
 {
         struct ptlrpc_connect_async_args *aa = data;
         struct obd_import *imp = request->rq_import;
         struct client_obd *cli = &imp->imp_obd->u.cli;
         struct lustre_handle old_hdl;
+        __u64 old_connect_flags;
         int msg_flags;
         ENTRY;
 
-        spin_lock(&imp->imp_lock);
+        cfs_spin_lock(&imp->imp_lock);
         if (imp->imp_state == LUSTRE_IMP_CLOSED) {
-                spin_unlock(&imp->imp_lock);
+                cfs_spin_unlock(&imp->imp_lock);
                 RETURN(0);
         }
 
-        if (rc)
+        if (rc) {
+                /* if this reconnect to busy export - not need select new target
+                 * for connecting*/
+                imp->imp_force_reconnect = ptlrpc_busy_reconnect(rc);
+                cfs_spin_unlock(&imp->imp_lock);
+                ptlrpc_maybe_ping_import_soon(imp);
                 GOTO(out, rc);
+        }
 
         LASSERT(imp->imp_conn_current);
 
@@ -529,34 +781,41 @@ static int ptlrpc_connect_interpret(struct ptlrpc_request *request,
 
         /* All imports are pingable */
         imp->imp_pingable = 1;
+        imp->imp_force_reconnect = 0;
+        imp->imp_force_verify = 0;
 
         if (aa->pcaa_initial_connect) {
                 if (msg_flags & MSG_CONNECT_REPLAYABLE) {
                         imp->imp_replayable = 1;
-                        spin_unlock(&imp->imp_lock);
+                        cfs_spin_unlock(&imp->imp_lock);
                         CDEBUG(D_HA, "connected to replayable target: %s\n",
                                obd2cli_tgt(imp->imp_obd));
                 } else {
                         imp->imp_replayable = 0;
-                        spin_unlock(&imp->imp_lock);
+                        cfs_spin_unlock(&imp->imp_lock);
                 }
 
-                if (msg_flags & MSG_CONNECT_NEXT_VER) {
-                        imp->imp_msg_magic = LUSTRE_MSG_MAGIC_V2;
-                        CDEBUG(D_RPCTRACE, "connect to %s with lustre_msg_v2\n",
-                               obd2cli_tgt(imp->imp_obd));
-                } else {
-                        CDEBUG(D_RPCTRACE, "connect to %s with lustre_msg_v1\n",
-                               obd2cli_tgt(imp->imp_obd));
-                }
+                /* if applies, adjust the imp->imp_msg_magic here
+                 * according to reply flags */
 
                 imp->imp_remote_handle =
                                 *lustre_msg_get_handle(request->rq_repmsg);
 
-                IMPORT_SET_STATE(imp, LUSTRE_IMP_FULL);
+                /* Initial connects are allowed for clients with non-random
+                 * uuids when servers are in recovery.  Simply signal the
+                 * servers replay is complete and wait in REPLAY_WAIT. */
+                if (msg_flags & MSG_CONNECT_RECOVERING) {
+                        CDEBUG(D_HA, "connect to %s during recovery\n",
+                               obd2cli_tgt(imp->imp_obd));
+                        IMPORT_SET_STATE(imp, LUSTRE_IMP_REPLAY_LOCKS);
+                } else {
+                        IMPORT_SET_STATE(imp, LUSTRE_IMP_FULL);
+                        ptlrpc_activate_import(imp);
+                }
+
                 GOTO(finish, rc = 0);
         } else {
-                spin_unlock(&imp->imp_lock);
+                cfs_spin_unlock(&imp->imp_lock);
         }
 
         /* Determine what recovery state to move the import to. */
@@ -564,32 +823,57 @@ static int ptlrpc_connect_interpret(struct ptlrpc_request *request,
                 memset(&old_hdl, 0, sizeof(old_hdl));
                 if (!memcmp(&old_hdl, lustre_msg_get_handle(request->rq_repmsg),
                             sizeof (old_hdl))) {
-                        CERROR("%s@%s didn't like our handle "LPX64
-                               ", failed\n", obd2cli_tgt(imp->imp_obd),
-                               imp->imp_connection->c_remote_uuid.uuid,
-                               imp->imp_dlm_handle.cookie);
+                        LCONSOLE_WARN("Reconnect to %s (at @%s) failed due "
+                                      "bad handle "LPX64"\n",
+                                      obd2cli_tgt(imp->imp_obd),
+                                      imp->imp_connection->c_remote_uuid.uuid,
+                                      imp->imp_dlm_handle.cookie);
                         GOTO(out, rc = -ENOTCONN);
                 }
 
                 if (memcmp(&imp->imp_remote_handle,
                            lustre_msg_get_handle(request->rq_repmsg),
                            sizeof(imp->imp_remote_handle))) {
-                        int level = D_ERROR;
-                        /* Old MGC can reconnect to a restarted MGS */
-                        if (strcmp(imp->imp_obd->obd_type->typ_name,
-                                   LUSTRE_MGC_NAME) == 0) {
-                                level = D_CONFIG;
+                        int level = msg_flags & MSG_CONNECT_RECOVERING ?
+                                D_HA : D_WARNING;
+
+                        /* Bug 16611/14775: if server handle have changed,
+                         * that means some sort of disconnection happened.
+                         * If the server is not in recovery, that also means it
+                         * already erased all of our state because of previous
+                         * eviction. If it is in recovery - we are safe to
+                         * participate since we can reestablish all of our state
+                         * with server again */
+                        if ((MSG_CONNECT_RECOVERING & msg_flags)) {
+                                CDEBUG(level,"%s@%s changed server handle from "
+                                       LPX64" to "LPX64
+                                       " but is still in recovery\n",
+                                       obd2cli_tgt(imp->imp_obd),
+                                       imp->imp_connection->c_remote_uuid.uuid,
+                                       imp->imp_remote_handle.cookie,
+                                       lustre_msg_get_handle(
+                                       request->rq_repmsg)->cookie);
+                        } else {
+                                LCONSOLE_WARN("Evicted from %s (at %s) "
+                                              "after server handle changed from "
+                                              LPX64" to "LPX64"\n",
+                                              obd2cli_tgt(imp->imp_obd),
+                                              imp->imp_connection-> \
+                                              c_remote_uuid.uuid,
+                                              imp->imp_remote_handle.cookie,
+                                              lustre_msg_get_handle(
+                                              request->rq_repmsg)->cookie);
                         }
-                        CDEBUG(level, 
-                               "%s@%s changed handle from "LPX64" to "LPX64
-                               "; copying, but this may foreshadow disaster\n",
-                               obd2cli_tgt(imp->imp_obd),
-                               imp->imp_connection->c_remote_uuid.uuid,
-                               imp->imp_remote_handle.cookie,
-                               lustre_msg_get_handle(request->rq_repmsg)->
-                                        cookie);
+
+
                         imp->imp_remote_handle =
                                      *lustre_msg_get_handle(request->rq_repmsg);
+
+                        if (!(MSG_CONNECT_RECOVERING & msg_flags)) {
+                                IMPORT_SET_STATE(imp, LUSTRE_IMP_EVICTED);
+                                GOTO(finish, rc = 0);
+                        }
+
                 } else {
                         CDEBUG(D_HA, "reconnected to %s@%s after partition\n",
                                obd2cli_tgt(imp->imp_obd),
@@ -597,15 +881,17 @@ static int ptlrpc_connect_interpret(struct ptlrpc_request *request,
                 }
 
                 if (imp->imp_invalid) {
+                        CDEBUG(D_HA, "%s: reconnected but import is invalid; "
+                               "marking evicted\n", imp->imp_obd->obd_name);
                         IMPORT_SET_STATE(imp, LUSTRE_IMP_EVICTED);
                 } else if (MSG_CONNECT_RECOVERING & msg_flags) {
                         CDEBUG(D_HA, "%s: reconnected to %s during replay\n",
                                imp->imp_obd->obd_name,
                                obd2cli_tgt(imp->imp_obd));
 
-                        spin_lock(&imp->imp_lock);
+                        cfs_spin_lock(&imp->imp_lock);
                         imp->imp_resend_replay = 1;
-                        spin_unlock(&imp->imp_lock);
+                        cfs_spin_unlock(&imp->imp_lock);
 
                         IMPORT_SET_STATE(imp, LUSTRE_IMP_REPLAY);
                 } else {
@@ -618,6 +904,8 @@ static int ptlrpc_connect_interpret(struct ptlrpc_request *request,
                 imp->imp_last_replay_transno = 0;
                 IMPORT_SET_STATE(imp, LUSTRE_IMP_REPLAY);
         } else {
+                DEBUG_REQ(D_HA, request, "%s: evicting (reconnect/recover flags"
+                          " not set: %x)", imp->imp_obd->obd_name, msg_flags);
                 imp->imp_remote_handle =
                                 *lustre_msg_get_handle(request->rq_repmsg);
                 IMPORT_SET_STATE(imp, LUSTRE_IMP_EVICTED);
@@ -629,12 +917,13 @@ static int ptlrpc_connect_interpret(struct ptlrpc_request *request,
                        "after reconnect. We should LBUG right here.\n");
         }
 
-        if (lustre_msg_get_last_committed(request->rq_repmsg) <
+        if (lustre_msg_get_last_committed(request->rq_repmsg) > 0 &&
+            lustre_msg_get_last_committed(request->rq_repmsg) <
             aa->pcaa_peer_committed) {
                 CERROR("%s went back in time (transno "LPD64
                        " was previously committed, server now claims "LPD64
-                       ")!  See https://bugzilla.clusterfs.com/"
-                       "long_list.cgi?buglist=9646\n",
+                       ")!  See https://bugzilla.lustre.org/show_bug.cgi?"
+                       "id=9646\n",
                        obd2cli_tgt(imp->imp_obd), aa->pcaa_peer_committed,
                        lustre_msg_get_last_committed(request->rq_repmsg));
         }
@@ -647,33 +936,39 @@ finish:
                                "invalidating and reconnecting\n",
                                obd2cli_tgt(imp->imp_obd),
                                imp->imp_connection->c_remote_uuid.uuid);
-                        ptlrpc_connect_import(imp, NULL);
+                        ptlrpc_connect_import(imp);
                         RETURN(0);
                 }
         } else {
                 struct obd_connect_data *ocd;
                 struct obd_export *exp;
-
-                ocd = lustre_swab_repbuf(request, REPLY_REC_OFF, sizeof(*ocd),
-                                         lustre_swab_connect);
-
-                spin_lock(&imp->imp_lock);
-                list_del(&imp->imp_conn_current->oic_item);
-                list_add(&imp->imp_conn_current->oic_item, &imp->imp_conn_list);
+                int ret;
+                ret = req_capsule_get_size(&request->rq_pill, &RMF_CONNECT_DATA,
+                                           RCL_SERVER);
+                /* server replied obd_connect_data is always bigger */
+                ocd = req_capsule_server_sized_get(&request->rq_pill,
+                                                   &RMF_CONNECT_DATA, ret);
+
+                cfs_spin_lock(&imp->imp_lock);
+                cfs_list_del(&imp->imp_conn_current->oic_item);
+                cfs_list_add(&imp->imp_conn_current->oic_item,
+                             &imp->imp_conn_list);
                 imp->imp_last_success_conn =
                         imp->imp_conn_current->oic_last_attempt;
 
                 if (ocd == NULL) {
-                        spin_unlock(&imp->imp_lock);
+                        cfs_spin_unlock(&imp->imp_lock);
                         CERROR("Wrong connect data from server\n");
                         rc = -EPROTO;
                         GOTO(out, rc);
                 }
 
                 imp->imp_connect_data = *ocd;
+                CDEBUG(D_HA, "obd %s to target with inst %u\n",
+                       imp->imp_obd->obd_name, ocd->ocd_instance);
 
                 exp = class_conn2export(&imp->imp_dlm_handle);
-                spin_unlock(&imp->imp_lock);
+                cfs_spin_unlock(&imp->imp_lock);
 
                 /* check that server granted subset of flags we asked for. */
                 LASSERTF((ocd->ocd_connect_flags &
@@ -682,14 +977,16 @@ finish:
                          imp->imp_connect_flags_orig, ocd->ocd_connect_flags);
 
                 if (!exp) {
-                        /* This could happen if export is cleaned during the 
+                        /* This could happen if export is cleaned during the
                            connect attempt */
-                        spin_unlock(&imp->imp_lock);
-                        CERROR("Missing export for %s\n", 
+                        CERROR("Missing export for %s\n",
                                imp->imp_obd->obd_name);
                         GOTO(out, rc = -ENODEV);
                 }
+                old_connect_flags = exp->exp_connect_flags;
                 exp->exp_connect_flags = ocd->ocd_connect_flags;
+                imp->imp_obd->obd_self_export->exp_connect_flags =
+                                                        ocd->ocd_connect_flags;
                 class_export_put(exp);
 
                 obd_import_event(imp->imp_obd, imp, IMP_EVENT_OCD);
@@ -707,13 +1004,14 @@ finish:
                         /* Sigh, some compilers do not like #ifdef in the middle
                            of macro arguments */
 #ifdef __KERNEL__
-                        const char *older =
-                                "older.  Consider upgrading this client";
+                        const char *older = "older. Consider upgrading server "
+                                            "or downgrading client";
 #else
-                        const char *older =
-                                "older.  Consider recompiling this application";
+                        const char *older = "older. Consider recompiling this "
+                                            "application";
 #endif
-                        const char *newer = "newer than client version";
+                        const char *newer = "newer than client version. "
+                                            "Consider upgrading client";
 
                         LCONSOLE_WARN("Server %s version (%d.%d.%d.%d) "
                                       "is much %s (%s)\n",
@@ -726,39 +1024,105 @@ finish:
                                       newer : older, LUSTRE_VERSION_STRING);
                 }
 
-                if (ocd->ocd_connect_flags & OBD_CONNECT_BRW_SIZE) {
-                        cli->cl_max_pages_per_rpc = 
+                if (ocd->ocd_connect_flags & OBD_CONNECT_CKSUM) {
+                        /* We sent to the server ocd_cksum_types with bits set
+                         * for algorithms we understand. The server masked off
+                         * the checksum types it doesn't support */
+                        if ((ocd->ocd_cksum_types & cksum_types_supported()) == 0) {
+                                LCONSOLE_WARN("The negotiation of the checksum "
+                                              "alogrithm to use with server %s "
+                                              "failed (%x/%x), disabling "
+                                              "checksums\n",
+                                              obd2cli_tgt(imp->imp_obd),
+                                              ocd->ocd_cksum_types,
+                                              cksum_types_supported());
+                                cli->cl_checksum = 0;
+                                cli->cl_supp_cksum_types = OBD_CKSUM_CRC32;
+                        } else {
+                                cli->cl_supp_cksum_types = ocd->ocd_cksum_types;
+                        }
+                } else {
+                        /* The server does not support OBD_CONNECT_CKSUM.
+                         * Enforce CRC32 for backward compatibility*/
+                        cli->cl_supp_cksum_types = OBD_CKSUM_CRC32;
+                }
+                cli->cl_cksum_type =cksum_type_select(cli->cl_supp_cksum_types);
+
+                if (ocd->ocd_connect_flags & OBD_CONNECT_BRW_SIZE)
+                        cli->cl_max_pages_per_rpc =
                                 ocd->ocd_brw_size >> CFS_PAGE_SHIFT;
+                else if (imp->imp_connect_op == MDS_CONNECT ||
+                         imp->imp_connect_op == MGS_CONNECT)
+                        cli->cl_max_pages_per_rpc = 1;
+
+                /* Reset ns_connect_flags only for initial connect. It might be
+                 * changed in while using FS and if we reset it in reconnect
+                 * this leads to losing user settings done before such as
+                 * disable lru_resize, etc. */
+                if (old_connect_flags != exp->exp_connect_flags ||
+                    aa->pcaa_initial_connect) {
+                        CDEBUG(D_HA, "%s: Resetting ns_connect_flags to server "
+                               "flags: "LPX64"\n", imp->imp_obd->obd_name,
+                              ocd->ocd_connect_flags);
+                        imp->imp_obd->obd_namespace->ns_connect_flags =
+                                ocd->ocd_connect_flags;
+                        imp->imp_obd->obd_namespace->ns_orig_connect_flags =
+                                ocd->ocd_connect_flags;
                 }
 
+                if ((ocd->ocd_connect_flags & OBD_CONNECT_AT) &&
+                    (imp->imp_msg_magic == LUSTRE_MSG_MAGIC_V2))
+                        /* We need a per-message support flag, because
+                           a. we don't know if the incoming connect reply
+                              supports AT or not (in reply_in_callback)
+                              until we unpack it.
+                           b. failovered server means export and flags are gone
+                              (in ptlrpc_send_reply).
+                           Can only be set when we know AT is supported at
+                           both ends */
+                        imp->imp_msghdr_flags |= MSGHDR_AT_SUPPORT;
+                else
+                        imp->imp_msghdr_flags &= ~MSGHDR_AT_SUPPORT;
+
+                if ((ocd->ocd_connect_flags & OBD_CONNECT_FULL20) &&
+                    (imp->imp_msg_magic == LUSTRE_MSG_MAGIC_V2))
+                        imp->imp_msghdr_flags |= MSGHDR_CKSUM_INCOMPAT18;
+                else
+                        imp->imp_msghdr_flags &= ~MSGHDR_CKSUM_INCOMPAT18;
+
                 LASSERT((cli->cl_max_pages_per_rpc <= PTLRPC_MAX_BRW_PAGES) &&
                         (cli->cl_max_pages_per_rpc > 0));
         }
 
- out:
+out:
         if (rc != 0) {
                 IMPORT_SET_STATE(imp, LUSTRE_IMP_DISCON);
-                if (aa->pcaa_initial_connect && !imp->imp_initial_recov)
-                        ptlrpc_deactivate_import(imp);
-
-                if (imp->imp_recon_bk && imp->imp_last_recon) {
-                        /* Give up trying to reconnect */
+                if (rc == -EACCES) {
+                        /*
+                         * Give up trying to reconnect
+                         * EACCES means client has no permission for connection
+                         */
                         imp->imp_obd->obd_no_recov = 1;
                         ptlrpc_deactivate_import(imp);
                 }
 
                 if (rc == -EPROTO) {
                         struct obd_connect_data *ocd;
-                        ocd = lustre_swab_repbuf(request, REPLY_REC_OFF,
-                                                 sizeof *ocd,
-                                                 lustre_swab_connect);
+
+                        /* reply message might not be ready */
+                        if (request->rq_repmsg == NULL)
+                                RETURN(-EPROTO);
+
+                        ocd = req_capsule_server_get(&request->rq_pill,
+                                                     &RMF_CONNECT_DATA);
                         if (ocd &&
                             (ocd->ocd_connect_flags & OBD_CONNECT_VERSION) &&
                             (ocd->ocd_version != LUSTRE_VERSION_CODE)) {
                            /* Actually servers are only supposed to refuse
                               connection from liblustre clients, so we should
                               never see this from VFS context */
-                                LCONSOLE_ERROR("Server %s version (%d.%d.%d.%d)"
+                                LCONSOLE_ERROR_MSG(0x16a, "Server %s version "
+                                        "(%d.%d.%d.%d)"
                                         " refused connection from this client "
                                         "with an incompatible version (%s).  "
                                         "Client must be recompiled\n",
@@ -780,65 +1144,89 @@ finish:
                        obd2cli_tgt(imp->imp_obd),
                        (char *)imp->imp_connection->c_remote_uuid.uuid, rc);
         }
-        
-        spin_lock(&imp->imp_lock);
-        imp->imp_last_recon = 0;
-        spin_unlock(&imp->imp_lock);
 
-        cfs_waitq_signal(&imp->imp_recovery_waitq);
+        cfs_waitq_broadcast(&imp->imp_recovery_waitq);
         RETURN(rc);
 }
 
-static int completed_replay_interpret(struct ptlrpc_request *req,
-                                    void * data, int rc)
+/**
+ * interpret callback for "completed replay" RPCs.
+ * \see signal_completed_replay
+ */
+static int completed_replay_interpret(const struct lu_env *env,
+                                      struct ptlrpc_request *req,
+                                      void * data, int rc)
 {
         ENTRY;
-        atomic_dec(&req->rq_import->imp_replay_inflight);
-        if (req->rq_status == 0) {
+        cfs_atomic_dec(&req->rq_import->imp_replay_inflight);
+        if (req->rq_status == 0 &&
+            !req->rq_import->imp_vbr_failed) {
                 ptlrpc_import_recovery_state_machine(req->rq_import);
         } else {
-                CDEBUG(D_HA, "%s: LAST_REPLAY message error: %d, "
-                       "reconnecting\n",
-                       req->rq_import->imp_obd->obd_name, req->rq_status);
-                ptlrpc_connect_import(req->rq_import, NULL);
+                if (req->rq_import->imp_vbr_failed) {
+                        CDEBUG(D_WARNING,
+                               "%s: version recovery fails, reconnecting\n",
+                               req->rq_import->imp_obd->obd_name);
+                } else {
+                        CDEBUG(D_HA, "%s: LAST_REPLAY message error: %d, "
+                                     "reconnecting\n",
+                               req->rq_import->imp_obd->obd_name,
+                               req->rq_status);
+                }
+                ptlrpc_connect_import(req->rq_import);
         }
 
         RETURN(0);
 }
 
+/**
+ * Let server know that we have no requests to replay anymore.
+ * Achieved by just sending a PING request
+ */
 static int signal_completed_replay(struct obd_import *imp)
 {
         struct ptlrpc_request *req;
         ENTRY;
 
-        LASSERT(atomic_read(&imp->imp_replay_inflight) == 0);
-        atomic_inc(&imp->imp_replay_inflight);
+        if (unlikely(OBD_FAIL_CHECK(OBD_FAIL_PTLRPC_FINISH_REPLAY)))
+                RETURN(0);
 
-        req = ptlrpc_prep_req(imp, LUSTRE_OBD_VERSION, OBD_PING, 1, NULL, NULL);
-        if (!req) {
-                atomic_dec(&imp->imp_replay_inflight);
+        LASSERT(cfs_atomic_read(&imp->imp_replay_inflight) == 0);
+        cfs_atomic_inc(&imp->imp_replay_inflight);
+
+        req = ptlrpc_request_alloc_pack(imp, &RQF_OBD_PING, LUSTRE_OBD_VERSION,
+                                        OBD_PING);
+        if (req == NULL) {
+                cfs_atomic_dec(&imp->imp_replay_inflight);
                 RETURN(-ENOMEM);
         }
 
-        ptlrpc_req_set_repsize(req, 1, NULL);
+        ptlrpc_request_set_replen(req);
         req->rq_send_state = LUSTRE_IMP_REPLAY_WAIT;
-        lustre_msg_add_flags(req->rq_reqmsg, MSG_LAST_REPLAY);
-        req->rq_timeout *= 3;
+        lustre_msg_add_flags(req->rq_reqmsg,
+                             MSG_LOCK_REPLAY_DONE | MSG_REQ_REPLAY_DONE);
+        if (AT_OFF)
+                req->rq_timeout *= 3;
         req->rq_interpret_reply = completed_replay_interpret;
 
-        ptlrpcd_add_req(req);
+        ptlrpcd_add_req(req, PDL_POLICY_ROUND, -1);
         RETURN(0);
 }
 
 #ifdef __KERNEL__
+/**
+ * In kernel code all import invalidation happens in its own
+ * separate thread, so that whatever application happened to encounter
+ * a problem could still be killed or otherwise continue
+ */
 static int ptlrpc_invalidate_import_thread(void *data)
 {
         struct obd_import *imp = data;
 
         ENTRY;
 
-        ptlrpc_daemonize("ll_imp_inval");
-        
+        cfs_daemonize_ctxt("ll_imp_inval");
+
         CDEBUG(D_HA, "thread invalidate import %s to %s@%s\n",
                imp->imp_obd->obd_name, obd2cli_tgt(imp->imp_obd),
                imp->imp_connection->c_remote_uuid.uuid);
@@ -853,10 +1241,31 @@ static int ptlrpc_invalidate_import_thread(void *data)
         IMPORT_SET_STATE(imp, LUSTRE_IMP_RECOVER);
         ptlrpc_import_recovery_state_machine(imp);
 
+        class_import_put(imp);
         RETURN(0);
 }
 #endif
 
+/**
+ * This is the state machine for client-side recovery on import.
+ *
+ * Typicaly we have two possibly paths. If we came to server and it is not
+ * in recovery, we just enter IMP_EVICTED state, invalidate our import
+ * state and reconnect from scratch.
+ * If we came to server that is in recovery, we enter IMP_REPLAY import state.
+ * We go through our list of requests to replay and send them to server one by
+ * one.
+ * After sending all request from the list we change import state to
+ * IMP_REPLAY_LOCKS and re-request all the locks we believe we have from server
+ * and also all the locks we don't yet have and wait for server to grant us.
+ * After that we send a special "replay completed" request and change import
+ * state to IMP_REPLAY_WAIT.
+ * Upon receiving reply to that "replay completed" RPC we enter IMP_RECOVER
+ * state and resend all requests from sending list.
+ * After that we promote import to FULL state and send all delayed requests
+ * and import is fully operational after that.
+ *
+ */
 int ptlrpc_import_recovery_state_machine(struct obd_import *imp)
 {
         int rc = 0;
@@ -871,22 +1280,33 @@ int ptlrpc_import_recovery_state_machine(struct obd_import *imp)
                 /* Don't care about MGC eviction */
                 if (strcmp(imp->imp_obd->obd_type->typ_name,
                            LUSTRE_MGC_NAME) != 0) {
-                        LCONSOLE_ERROR("This client was evicted by %.*s; "
-                                       "in progress operations using this "
-                                       "service will fail.\n",
-                                       target_len, target_start);
+                        LCONSOLE_ERROR_MSG(0x167, "This client was evicted by "
+                                           "%.*s; in progress operations using "
+                                           "this service will fail.\n",
+                                           target_len, target_start);
                 }
                 CDEBUG(D_HA, "evicted from %s@%s; invalidating\n",
                        obd2cli_tgt(imp->imp_obd),
                        imp->imp_connection->c_remote_uuid.uuid);
+                /* reset vbr_failed flag upon eviction */
+                cfs_spin_lock(&imp->imp_lock);
+                imp->imp_vbr_failed = 0;
+                cfs_spin_unlock(&imp->imp_lock);
 
 #ifdef __KERNEL__
-                rc = cfs_kernel_thread(ptlrpc_invalidate_import_thread, imp,
-                                   CLONE_VM | CLONE_FILES);
-                if (rc < 0)
+                /* bug 17802:  XXX client_disconnect_export vs connect request
+                 * race. if client will evicted at this time, we start
+                 * invalidate thread without reference to import and import can
+                 * be freed at same time. */
+                class_import_get(imp);
+                rc = cfs_create_thread(ptlrpc_invalidate_import_thread, imp,
+                                       CFS_DAEMON_FLAGS);
+                if (rc < 0) {
+                        class_import_put(imp);
                         CERROR("error starting invalidate thread: %d\n", rc);
-                else
+                } else {
                         rc = 0;
+                }
                 RETURN(rc);
 #else
                 ptlrpc_invalidate_import(imp);
@@ -900,7 +1320,7 @@ int ptlrpc_import_recovery_state_machine(struct obd_import *imp)
                        obd2cli_tgt(imp->imp_obd));
                 rc = ptlrpc_replay_next(imp, &inflight);
                 if (inflight == 0 &&
-                    atomic_read(&imp->imp_replay_inflight) == 0) {
+                    cfs_atomic_read(&imp->imp_replay_inflight) == 0) {
                         IMPORT_SET_STATE(imp, LUSTRE_IMP_REPLAY_LOCKS);
                         rc = ldlm_replay_locks(imp);
                         if (rc)
@@ -910,7 +1330,7 @@ int ptlrpc_import_recovery_state_machine(struct obd_import *imp)
         }
 
         if (imp->imp_state == LUSTRE_IMP_REPLAY_LOCKS) {
-                if (atomic_read(&imp->imp_replay_inflight) == 0) {
+                if (cfs_atomic_read(&imp->imp_replay_inflight) == 0) {
                         IMPORT_SET_STATE(imp, LUSTRE_IMP_REPLAY_WAIT);
                         rc = signal_completed_replay(imp);
                         if (rc)
@@ -920,7 +1340,7 @@ int ptlrpc_import_recovery_state_machine(struct obd_import *imp)
         }
 
         if (imp->imp_state == LUSTRE_IMP_REPLAY_WAIT) {
-                if (atomic_read(&imp->imp_replay_inflight) == 0) {
+                if (cfs_atomic_read(&imp->imp_replay_inflight) == 0) {
                         IMPORT_SET_STATE(imp, LUSTRE_IMP_RECOVER);
                 }
         }
@@ -938,32 +1358,31 @@ int ptlrpc_import_recovery_state_machine(struct obd_import *imp)
 
                 deuuidify(obd2cli_tgt(imp->imp_obd), NULL,
                           &target_start, &target_len);
-                LCONSOLE_INFO("%s: Connection restored to service %.*s "
-                              "using nid %s.\n", imp->imp_obd->obd_name,
+                LCONSOLE_INFO("%s: Connection restored to %.*s (at %s)\n",
+                              imp->imp_obd->obd_name,
                               target_len, target_start,
                               libcfs_nid2str(imp->imp_connection->c_peer.nid));
         }
 
         if (imp->imp_state == LUSTRE_IMP_FULL) {
-                cfs_waitq_signal(&imp->imp_recovery_waitq);
+                cfs_waitq_broadcast(&imp->imp_recovery_waitq);
                 ptlrpc_wake_delayed(imp);
         }
 
- out:
+out:
         RETURN(rc);
 }
 
-static int back_to_sleep(void *unused)
-{
-        return 0;
-}
-
 int ptlrpc_disconnect_import(struct obd_import *imp, int noclose)
 {
         struct ptlrpc_request *req;
         int rq_opc, rc = 0;
+        int nowait = imp->imp_obd->obd_force;
         ENTRY;
 
+        if (nowait)
+                GOTO(set_state, rc);
+
         switch (imp->imp_connect_op) {
         case OST_CONNECT: rq_opc = OST_DISCONNECT; break;
         case MDS_CONNECT: rq_opc = MDS_DISCONNECT; break;
@@ -976,48 +1395,201 @@ int ptlrpc_disconnect_import(struct obd_import *imp, int noclose)
 
         if (ptlrpc_import_in_recovery(imp)) {
                 struct l_wait_info lwi;
-                cfs_duration_t timeout = cfs_time_seconds(obd_timeout);
+                cfs_duration_t timeout;
+
 
-                lwi = LWI_TIMEOUT_INTR(cfs_timeout_cap(timeout), 
+                if (AT_OFF) {
+                        if (imp->imp_server_timeout)
+                                timeout = cfs_time_seconds(obd_timeout / 2);
+                        else
+                                timeout = cfs_time_seconds(obd_timeout);
+                } else {
+                        int idx = import_at_get_index(imp,
+                                imp->imp_client->cli_request_portal);
+                        timeout = cfs_time_seconds(
+                                at_get(&imp->imp_at.iat_service_estimate[idx]));
+                }
+
+                lwi = LWI_TIMEOUT_INTR(cfs_timeout_cap(timeout),
                                        back_to_sleep, LWI_ON_SIGNAL_NOOP, NULL);
                 rc = l_wait_event(imp->imp_recovery_waitq,
                                   !ptlrpc_import_in_recovery(imp), &lwi);
 
         }
 
-        spin_lock(&imp->imp_lock);
+        cfs_spin_lock(&imp->imp_lock);
         if (imp->imp_state != LUSTRE_IMP_FULL)
                 GOTO(out, 0);
 
-        spin_unlock(&imp->imp_lock);
+        cfs_spin_unlock(&imp->imp_lock);
 
-        req = ptlrpc_prep_req(imp, LUSTRE_OBD_VERSION, rq_opc, 1, NULL, NULL);
+        req = ptlrpc_request_alloc_pack(imp, &RQF_MDS_DISCONNECT,
+                                        LUSTRE_OBD_VERSION, rq_opc);
         if (req) {
                 /* We are disconnecting, do not retry a failed DISCONNECT rpc if
                  * it fails.  We can get through the above with a down server
                  * if the client doesn't know the server is gone yet. */
                 req->rq_no_resend = 1;
-#ifdef CRAY_XT3
-                req->rq_timeout = obd_timeout / 3;
+
+#ifndef CRAY_XT3
+                /* We want client umounts to happen quickly, no matter the
+                   server state... */
+                req->rq_timeout = min_t(int, req->rq_timeout,
+                                        INITIAL_CONNECT_TIMEOUT);
 #else
-                req->rq_timeout = 5;
+                /* ... but we always want liblustre clients to nicely
+                   disconnect, so only use the adaptive value. */
+                if (AT_OFF)
+                        req->rq_timeout = obd_timeout / 3;
 #endif
+
                 IMPORT_SET_STATE(imp, LUSTRE_IMP_CONNECTING);
                 req->rq_send_state =  LUSTRE_IMP_CONNECTING;
-                ptlrpc_req_set_repsize(req, 1, NULL);
+                ptlrpc_request_set_replen(req);
                 rc = ptlrpc_queue_wait(req);
                 ptlrpc_req_finished(req);
         }
 
-        spin_lock(&imp->imp_lock);
+set_state:
+        cfs_spin_lock(&imp->imp_lock);
 out:
-        if (noclose) 
+        if (noclose)
                 IMPORT_SET_STATE_NOLOCK(imp, LUSTRE_IMP_DISCON);
         else
                 IMPORT_SET_STATE_NOLOCK(imp, LUSTRE_IMP_CLOSED);
         memset(&imp->imp_remote_handle, 0, sizeof(imp->imp_remote_handle));
-        spin_unlock(&imp->imp_lock);
+        cfs_spin_unlock(&imp->imp_lock);
 
         RETURN(rc);
 }
 
+void ptlrpc_cleanup_imp(struct obd_import *imp)
+{
+        ENTRY;
+
+        cfs_spin_lock(&imp->imp_lock);
+        IMPORT_SET_STATE_NOLOCK(imp, LUSTRE_IMP_CLOSED);
+        imp->imp_generation++;
+        cfs_spin_unlock(&imp->imp_lock);
+        ptlrpc_abort_inflight(imp);
+
+        EXIT;
+}
+
+/* Adaptive Timeout utils */
+extern unsigned int at_min, at_max, at_history;
+
+/* Bin into timeslices using AT_BINS bins.
+   This gives us a max of the last binlimit*AT_BINS secs without the storage,
+   but still smoothing out a return to normalcy from a slow response.
+   (E.g. remember the maximum latency in each minute of the last 4 minutes.) */
+int at_measured(struct adaptive_timeout *at, unsigned int val)
+{
+        unsigned int old = at->at_current;
+        time_t now = cfs_time_current_sec();
+        time_t binlimit = max_t(time_t, at_history / AT_BINS, 1);
+
+        LASSERT(at);
+        CDEBUG(D_OTHER, "add %u to %p time=%lu v=%u (%u %u %u %u)\n",
+               val, at, now - at->at_binstart, at->at_current,
+               at->at_hist[0], at->at_hist[1], at->at_hist[2], at->at_hist[3]);
+
+        if (val == 0)
+                /* 0's don't count, because we never want our timeout to
+                   drop to 0, and because 0 could mean an error */
+                return 0;
+
+        cfs_spin_lock(&at->at_lock);
+
+        if (unlikely(at->at_binstart == 0)) {
+                /* Special case to remove default from history */
+                at->at_current = val;
+                at->at_worst_ever = val;
+                at->at_worst_time = now;
+                at->at_hist[0] = val;
+                at->at_binstart = now;
+        } else if (now - at->at_binstart < binlimit ) {
+                /* in bin 0 */
+                at->at_hist[0] = max(val, at->at_hist[0]);
+                at->at_current = max(val, at->at_current);
+        } else {
+                int i, shift;
+                unsigned int maxv = val;
+                /* move bins over */
+                shift = (now - at->at_binstart) / binlimit;
+                LASSERT(shift > 0);
+                for(i = AT_BINS - 1; i >= 0; i--) {
+                        if (i >= shift) {
+                                at->at_hist[i] = at->at_hist[i - shift];
+                                maxv = max(maxv, at->at_hist[i]);
+                        } else {
+                                at->at_hist[i] = 0;
+                        }
+                }
+                at->at_hist[0] = val;
+                at->at_current = maxv;
+                at->at_binstart += shift * binlimit;
+        }
+
+        if (at->at_current > at->at_worst_ever) {
+                at->at_worst_ever = at->at_current;
+                at->at_worst_time = now;
+        }
+
+        if (at->at_flags & AT_FLG_NOHIST)
+                /* Only keep last reported val; keeping the rest of the history
+                   for proc only */
+                at->at_current = val;
+
+        if (at_max > 0)
+                at->at_current =  min(at->at_current, at_max);
+        at->at_current =  max(at->at_current, at_min);
+
+        if (at->at_current != old)
+                CDEBUG(D_OTHER, "AT %p change: old=%u new=%u delta=%d "
+                       "(val=%u) hist %u %u %u %u\n", at,
+                       old, at->at_current, at->at_current - old, val,
+                       at->at_hist[0], at->at_hist[1], at->at_hist[2],
+                       at->at_hist[3]);
+
+        /* if we changed, report the old value */
+        old = (at->at_current != old) ? old : 0;
+
+        cfs_spin_unlock(&at->at_lock);
+        return old;
+}
+
+/* Find the imp_at index for a given portal; assign if space available */
+int import_at_get_index(struct obd_import *imp, int portal)
+{
+        struct imp_at *at = &imp->imp_at;
+        int i;
+
+        for (i = 0; i < IMP_AT_MAX_PORTALS; i++) {
+                if (at->iat_portal[i] == portal)
+                        return i;
+                if (at->iat_portal[i] == 0)
+                        /* unused */
+                        break;
+        }
+
+        /* Not found in list, add it under a lock */
+        cfs_spin_lock(&imp->imp_lock);
+
+        /* Check unused under lock */
+        for (; i < IMP_AT_MAX_PORTALS; i++) {
+                if (at->iat_portal[i] == portal)
+                        goto out;
+                if (at->iat_portal[i] == 0)
+                        /* unused */
+                        break;
+        }
+
+        /* Not enough portals? */
+        LASSERT(i < IMP_AT_MAX_PORTALS);
+
+        at->iat_portal[i] = portal;
+out:
+        cfs_spin_unlock(&imp->imp_lock);
+        return i;
+}