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Reverted #974 for now as it causes problems for people.
[fs/lustre-release.git] / lustre / ptlrpc / recover.c
index ef91aad..ed969fe 100644 (file)
 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
  * vim:expandtab:shiftwidth=8:tabstop=8:
  *
- * Lustre Light Super operations
+ * Portal-RPC reconnection and replay operations, for use in recovery.
  *
- * This code is issued under the GNU General Public License.
- * See the file COPYING in this distribution
+ *  Copyright (c) 2002, 2003 Cluster File Systems, Inc.
+ *   Author: Mike Shaver <shaver@clusterfs.com>
  *
- * Copryright (C) 1996 Peter J. Braam <braam@stelias.com>
- * Copryright (C) 1999 Stelias Computing Inc. <braam@stelias.com>
- * Copryright (C) 1999 Seagate Technology Inc.
- * Copryright (C) 2001 Mountain View Data, Inc.
- * Copryright (C) 2002 Cluster File Systems, Inc.
+ *   This file is part of Lustre, http://www.lustre.org.
  *
+ *   Lustre is free 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 is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with Lustre; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
-#include <linux/config.h>
-#include <linux/module.h>
-#include <linux/kmod.h>
-
-#define DEBUG_SUBSYSTEM S_LLITE
+#define DEBUG_SUBSYSTEM S_RPC
+#ifdef __KERNEL__
+# include <linux/config.h>
+# include <linux/module.h>
+# include <linux/kmod.h>
+#else
+# include <liblustre.h>
+#endif
 
-#include <linux/lustre_lite.h>
+#include <linux/obd_support.h>
 #include <linux/lustre_ha.h>
+#include <linux/lustre_net.h>
+#include <linux/lustre_import.h>
+#include <linux/lustre_export.h>
+#include <linux/obd.h>
+#include <linux/obd_ost.h>
+#include <linux/obd_class.h>
+#include <linux/obd_lov.h> /* for IOC_LOV_SET_OSC_ACTIVE */
+
+#include "ptlrpc_internal.h"
+
+static int ptlrpc_recover_import_no_retry(struct obd_import *, char *);
 
-int ll_reconnect(struct ptlrpc_connection *conn) 
+void ptlrpc_run_recovery_over_upcall(struct obd_device *obd)
 {
-        struct list_head *tmp;
-        int rc = -EINVAL;
-
-        /* XXX c_lock semantics! */
-        conn->c_level = LUSTRE_CONN_CON;
-
-        /* XXX this code MUST be shared with class_obd_connect! */
-        list_for_each(tmp, &conn->c_imports) {
-                struct obd_import *imp = list_entry(tmp, struct obd_import,
-                                                    imp_chain);
-                struct obd_device *obd = imp->imp_obd;
-                struct client_obd *cli = &obd->u.cli;
-                int rq_opc = (obd->obd_type->typ_ops->o_brw)
-                        ? OST_CONNECT : MDS_CONNECT;
-                int size[] = { sizeof(cli->cl_target_uuid),
-                               sizeof(obd->obd_uuid) };
-                char *tmp[] = {cli->cl_target_uuid, obd->obd_uuid };
-                struct lustre_handle old_hdl;
-                struct ptlrpc_request *request; 
-                struct obd_export *ldlmexp;
-
-                LASSERT(imp->imp_connection == conn);
-                request = ptlrpc_prep_req(imp, rq_opc, 2, size, tmp);
-                request->rq_level = LUSTRE_CONN_NEW;
-                request->rq_replen = lustre_msg_size(0, NULL);
-                /*
-                 * This address is the export that represents our client-side
-                 * LDLM service (for ASTs).  We should only have one on this
-                 * list, so we just grab the first one.
-                 *
-                 * XXX tear down export, call class_obd_connect!
-                 */
-                ldlmexp = list_entry(obd->obd_exports.next, struct obd_export,
-                                     exp_obd_chain);
-                request->rq_reqmsg->addr = (__u64)(unsigned long)ldlmexp;
-                request->rq_reqmsg->cookie = ldlmexp->exp_cookie;
-                rc = ptlrpc_queue_wait(request);
-                rc = ptlrpc_check_status(request, rc);
-                if (rc) {
-                        CERROR("cannot connect to %s@%s: rc = %d\n",
-                               cli->cl_target_uuid, conn->c_remote_uuid, rc);
-                        ptlrpc_free_req(request);
-                        GOTO(out_disc, rc = -ENOTCONN);
-                }
+        char *argv[4];
+        char *envp[3];
+        int rc;
 
-                old_hdl = imp->imp_handle;
-                imp->imp_handle.addr = request->rq_repmsg->addr;
-                imp->imp_handle.cookie = request->rq_repmsg->cookie;
-                CDEBUG(D_HA, "reconnected to %s@%s (%Lx/%Lx, was %Lx/%Lx)!\n",
-                       cli->cl_target_uuid, conn->c_remote_uuid,
-                       imp->imp_handle.addr, imp->imp_handle.cookie,
-                       old_hdl.addr, old_hdl.cookie);
-                ptlrpc_free_req(request);
-        }
-        conn->c_level = LUSTRE_CONN_RECOVD;
+        ENTRY;
+        argv[0] = obd_lustre_upcall;
+        argv[1] = "RECOVERY_OVER";
+        argv[2] = obd->obd_uuid.uuid;
+        argv[3] = NULL;
+
+        envp[0] = "HOME=/";
+        envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
+        envp[2] = NULL;
 
- out_disc:
-        return rc;
+        rc = USERMODEHELPER(argv[0], argv, envp);
+        if (rc < 0) {
+                CERROR("Error invoking recovery upcall %s %s %s: %d; check "
+                       "/proc/sys/lustre/upcall\n",
+                       argv[0], argv[1], argv[2], rc);
+
+        } else {
+                CERROR("Invoked upcall %s %s %s",
+                       argv[0], argv[1], argv[2]);
+        }
 }
 
-static int ll_recover_upcall(struct ptlrpc_connection *conn)
+void ptlrpc_run_failed_import_upcall(struct obd_import* imp)
 {
-        char *argv[3];
+#ifdef __KERNEL__
+        char *argv[7];
         char *envp[3];
         int rc;
 
         ENTRY;
-        conn->c_level = LUSTRE_CONN_RECOVD;
-
-        argv[0] = obd_recovery_upcall;
-        argv[1] = conn->c_remote_uuid;
-        argv[2] = NULL;
+        argv[0] = obd_lustre_upcall;
+        argv[1] = "FAILED_IMPORT";
+        argv[2] = imp->imp_target_uuid.uuid;
+        argv[3] = imp->imp_obd->obd_name;
+        argv[4] = imp->imp_connection->c_remote_uuid.uuid;
+        argv[5] = imp->imp_obd->obd_uuid.uuid;
+        argv[6] = NULL;
 
         envp[0] = "HOME=/";
         envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
         envp[2] = NULL;
 
-        rc = call_usermodehelper(argv[0], argv, envp);
+        rc = USERMODEHELPER(argv[0], argv, envp);
         if (rc < 0) {
-                /*
-                 * Tragically, this will never be run, because call_umh doesn't
-                 * report errors like -ENOENT to its caller.
-                 */
-                CERROR("Error invoking recovery upcall (%s): %d\n",
-                       obd_recovery_upcall, rc);
-                CERROR("Check /proc/sys/lustre/recovery_upcall?\n");
+                CERROR("Error invoking recovery upcall %s %s %s %s %s: %d; "
+                       "check /proc/sys/lustre/lustre_upcall\n",
+                       argv[0], argv[1], argv[2], argv[3], argv[4],rc);
+
         } else {
-                CDEBUG(D_HA, "Invoked upcall %s for connection %s\n",
-                       argv[0], argv[1]);
+                CERROR("Invoked upcall %s %s %s %s %s\n",
+                       argv[0], argv[1], argv[2], argv[3], argv[4]);
         }
-        RETURN(rc);
+#else
+        ptlrpc_recover_import(imp, NULL);
+#endif
 }
 
-static int ll_recover_reconnect(struct ptlrpc_connection *conn)
+int ptlrpc_replay(struct obd_import *imp)
 {
         int rc = 0;
         struct list_head *tmp, *pos;
         struct ptlrpc_request *req;
+        unsigned long flags;
         ENTRY;
 
-        /* 1. reconnect */
-        rc = ll_reconnect(conn);
-        if (rc)
-                RETURN(rc);
-        
-        /* 2. walk the request list */
-        spin_lock(&conn->c_lock);
+        /* It might have committed some after we last spoke, so make sure we
+         * get rid of them now.
+         */
+        spin_lock_irqsave(&imp->imp_lock, flags);
+        ptlrpc_free_committed(imp);
+        spin_unlock_irqrestore(&imp->imp_lock, flags);
 
-        CDEBUG(D_HA, "connection %p to %s has last_xid "LPD64"\n",
-               conn, conn->c_remote_uuid, conn->c_last_xid);
+        CDEBUG(D_HA, "import %p from %s has committed "LPD64"\n",
+               imp, imp->imp_target_uuid.uuid, imp->imp_peer_committed_transno);
 
-        list_for_each_safe(tmp, pos, &conn->c_sending_head) { 
+        list_for_each(tmp, &imp->imp_replay_list) {
                 req = list_entry(tmp, struct ptlrpc_request, rq_list);
-                
-                /* replay what needs to be replayed */
-                if (req->rq_flags & PTL_RPC_FL_REPLAY) {
-                        CDEBUG(D_HA, "FL_REPLAY: xid "LPD64" op %d @ %d\n",
-                               req->rq_xid, req->rq_reqmsg->opc,
-                               req->rq_import->imp_client->cli_request_portal);
-                        rc = ptlrpc_replay_req(req);
-#if 0
-#error We should not hold a spinlock over such a lengthy operation.
-#error If necessary, drop spinlock, do operation, re-get spinlock, restart loop.
-#error If we need to avoid re-processint items, then delete them from the list
-#error as they are replayed and re-add at the tail of this list, so the next
-#error item to process will always be at the head of the list.
-#endif
-                        if (rc) {
-                                CERROR("recovery replay error %d for req %Ld\n",
-                                       rc, req->rq_xid);
-                                GOTO(out, rc);
-                        }
-                }
+                DEBUG_REQ(D_HA, req, "RETAINED: ");
+        }
 
-                /* server has seen req, we have reply: skip */
-                if ((req->rq_flags & PTL_RPC_FL_REPLIED)  &&
-                    req->rq_xid <= conn->c_last_xid) { 
-                        CDEBUG(D_HA, "REPLIED SKIP: xid "LPD64" op %d @ %d\n",
-                               req->rq_xid, req->rq_reqmsg->opc,
-                               req->rq_import->imp_client->cli_request_portal);
-                        continue;
-                }
+        /* Do I need to hold a lock across this iteration?  We shouldn't be
+         * racing with any additions to the list, because we're in recovery
+         * and are therefore not processing additional requests to add.  Calls
+         * to ptlrpc_free_committed might commit requests, but nothing "newer"
+         * than the one we're replaying (it can't be committed until it's
+         * replayed, and we're doing that here).  l_f_e_safe protects against
+         * problems with the current request being committed, in the unlikely
+         * event of that race.  So, in conclusion, I think that it's safe to
+         * perform this list-walk without the imp_lock held.
+         *
+         * But, the {mdc,osc}_replay_open callbacks both iterate
+         * request lists, and have comments saying they assume the
+         * imp_lock is being held by ptlrpc_replay, but it's not. it's
+         * just a little race...
+         */
+        list_for_each_safe(tmp, pos, &imp->imp_replay_list) {
+                req = list_entry(tmp, struct ptlrpc_request, rq_list);
+
+                DEBUG_REQ(D_HA, req, "REPLAY:");
 
-                /* server has lost req, we have reply: resend, ign reply */
-                if ((req->rq_flags & PTL_RPC_FL_REPLIED)  &&
-                    req->rq_xid > conn->c_last_xid) { 
-                        CDEBUG(D_HA, "REPLIED RESEND: xid "LPD64" op %d @ %d\n",
-                               req->rq_xid, req->rq_reqmsg->opc,
-                               req->rq_import->imp_client->cli_request_portal);
-                        rc = ptlrpc_replay_req(req); 
-                        if (rc) {
-                                CERROR("request resend error %d for req %Ld\n", 
-                                       rc, req->rq_xid); 
-                                GOTO(out, rc);
-                        }
+                rc = ptlrpc_replay_req(req);
+
+                if (rc) {
+                        CERROR("recovery replay error %d for req "LPD64"\n",
+                               rc, req->rq_xid);
+                        RETURN(rc);
                 }
+        }
+
+        RETURN(0);
+}
 
-                /* server has seen req, we have lost reply: -ERESTARTSYS */
-                if ( !(req->rq_flags & PTL_RPC_FL_REPLIED)  &&
-                     req->rq_xid <= conn->c_last_xid) { 
-                        CDEBUG(D_HA, "RESTARTSYS: xid "LPD64" op %d @ %d\n",
-                               req->rq_xid, req->rq_reqmsg->opc,
-                               req->rq_import->imp_client->cli_request_portal);
-                        ptlrpc_restart_req(req);
+int ptlrpc_resend(struct obd_import *imp)
+{
+        struct list_head *tmp, *pos;
+        struct ptlrpc_request *req;
+        unsigned long flags;
+
+        ENTRY;
+
+        /* As long as we're in recovery, nothing should be added to the sending
+         * list, so we don't need to hold the lock during this iteration and
+         * resend process.
+         */
+        /* Well... what if lctl recover is called twice at the same time?
+         */
+        spin_lock_irqsave(&imp->imp_lock, flags);
+        LASSERT(imp->imp_state == LUSTRE_IMP_RECOVER);
+        spin_unlock_irqrestore(&imp->imp_lock, flags);
+
+        list_for_each_safe(tmp, pos, &imp->imp_sending_list) {
+                req = list_entry(tmp, struct ptlrpc_request, rq_list);
+                ptlrpc_resend_req(req);
+        }
+
+        RETURN(0);
+}
+
+void ptlrpc_wake_delayed(struct obd_import *imp)
+{
+        unsigned long flags;
+        struct list_head *tmp, *pos;
+        struct ptlrpc_request *req;
+
+        spin_lock_irqsave(&imp->imp_lock, flags);
+        list_for_each_safe(tmp, pos, &imp->imp_delayed_list) {
+                req = list_entry(tmp, struct ptlrpc_request, rq_list);
+
+                ptlrpc_put_connection(req->rq_connection);
+                req->rq_connection =
+                       ptlrpc_connection_addref(req->rq_import->imp_connection);
+
+                if (req->rq_set) {
+                        DEBUG_REQ(D_HA, req, "waking (set %p):", req->rq_set);
+                        wake_up(&req->rq_set->set_waitq);
+                } else {
+                        DEBUG_REQ(D_HA, req, "waking:");
+                        wake_up(&req->rq_reply_waitq);
                 }
+        }
+        spin_unlock_irqrestore(&imp->imp_lock, flags);
+}
+
+inline void ptlrpc_invalidate_import_state(struct obd_import *imp)
+{
+        struct obd_device *obd = imp->imp_obd;
+        struct ldlm_namespace *ns = obd->obd_namespace;
+
+        ptlrpc_abort_inflight(imp);
+
+#if 0
+        obd_invalidate_import(obd, imp);
+#endif
+
+        ldlm_namespace_cleanup(ns, LDLM_FL_LOCAL_ONLY | LDLM_FL_CANCEL);
+}
+
+void ptlrpc_handle_failed_import(struct obd_import *imp)
+{
+        ENTRY;
+        if (!imp->imp_replayable) {
+                CDEBUG(D_HA,
+                       "import %s@%s for %s not replayable, deactivating\n",
+                       imp->imp_target_uuid.uuid,
+                       imp->imp_connection->c_remote_uuid.uuid,
+                       imp->imp_obd->obd_name);
+                ptlrpc_set_import_active(imp, 0);
+        }
+
+        ptlrpc_run_failed_import_upcall(imp);
+        EXIT;
+}
+
+void ptlrpc_request_handle_notconn(struct ptlrpc_request *failed_req)
+{
+        int rc;
+        struct obd_import *imp= failed_req->rq_import;
+        unsigned long flags;
+        ENTRY;
+
+        CDEBUG(D_HA, "import %s of %s@%s abruptly disconnected: reconnecting\n",
+               imp->imp_obd->obd_name,
+               imp->imp_target_uuid.uuid,
+               imp->imp_connection->c_remote_uuid.uuid);
+
+        rc = ptlrpc_recover_import_no_retry(imp, NULL);
+
+        if (failed_req->rq_import_generation != imp->imp_generation) {
+                spin_lock_irqsave (&failed_req->rq_lock, flags);
+                failed_req->rq_err = 1;
+                spin_unlock_irqrestore (&failed_req->rq_lock, flags);
+        }
+        else {
+                ptlrpc_resend_req(failed_req);
+                if (rc && rc != -EALREADY)
+                        ptlrpc_handle_failed_import(imp);
+                        
+        }
+        EXIT;
+}
+
+int ptlrpc_set_import_active(struct obd_import *imp, int active)
+{
+        struct obd_device *obd = imp->imp_obd;
+        unsigned long flags;
+
+        LASSERT(obd);
 
-                /* service has not seen req, no reply: resend */
-                if ( !(req->rq_flags & PTL_RPC_FL_REPLIED)  &&
-                     req->rq_xid > conn->c_last_xid) {
-                        CDEBUG(D_HA, "RESEND: xid "LPD64" op %d @ %d\n",
-                               req->rq_xid, req->rq_reqmsg->opc,
-                               req->rq_import->imp_client->cli_request_portal);
-                        ptlrpc_resend_req(req);
+        /* When deactivating, mark import invalid, and abort in-flight
+         * requests. */
+        if (!active) {
+                spin_lock_irqsave(&imp->imp_lock, flags);
+                /* This is a bit of a hack, but invalidating replayable
+                 * imports makes a temporary reconnect failure into a much more
+                 * ugly -- and hard to remedy -- situation. */
+                if (!imp->imp_replayable) {
+                        CDEBUG(D_HA, "setting import %s INVALID\n",
+                               imp->imp_target_uuid.uuid);
+                        imp->imp_invalid = 1;
                 }
+                imp->imp_generation++;
+                spin_unlock_irqrestore(&imp->imp_lock, flags);
+                ptlrpc_invalidate_import_state(imp);
+        }
 
+        /* When activating, mark import valid */
+        if (active) {
+                CDEBUG(D_HA, "setting import %s VALID\n",
+                       imp->imp_target_uuid.uuid);
+                spin_lock_irqsave(&imp->imp_lock, flags);
+                imp->imp_invalid = 0;
+                spin_unlock_irqrestore(&imp->imp_lock, flags);
         }
 
-        conn->c_level = LUSTRE_CONN_FULL;
-        recovd_conn_fixed(conn);
+        if (obd->obd_observer)
+                RETURN(obd_notify(obd->obd_observer, obd, active));
 
-        CERROR("recovery complete on conn %p(%s), waking delayed reqs\n",
-               conn, conn->c_remote_uuid);
-        /* Finally, continue what we delayed since recovery started */
-        list_for_each_safe(tmp, pos, &conn->c_delayed_head) { 
-                req = list_entry(tmp, struct ptlrpc_request, rq_list);
-                ptlrpc_continue_req(req);
+        RETURN(0);
+}
+
+void ptlrpc_fail_import(struct obd_import *imp, int generation)
+{
+        unsigned long flags;
+        int in_recovery = 0;
+        ENTRY;
+
+        LASSERT (!imp->imp_dlm_fake);
+
+        spin_lock_irqsave(&imp->imp_lock, flags);
+        if (imp->imp_state != LUSTRE_IMP_FULL) {
+                in_recovery = 1;
+        } else {
+                CDEBUG(D_HA, "%s: new state: DISCON\n", 
+                       imp->imp_client->cli_name);
+                imp->imp_state = LUSTRE_IMP_DISCON;
         }
+        spin_unlock_irqrestore(&imp->imp_lock, flags);
 
+        if (in_recovery) {
+                EXIT;
+                return;
+        }
+
+        ptlrpc_handle_failed_import(imp);
         EXIT;
- out:
-        spin_unlock(&conn->c_lock);
-        return rc;
 }
 
-static int ll_retry_recovery(struct ptlrpc_connection *conn)
+static int signal_completed_replay(struct obd_import *imp)
 {
-        CDEBUG(D_HA, "Recovery has failed on conn %p\n", conn);
-#if 0
-        /* XXX use a timer, sideshow bob */
-        recovd_conn_fail(conn);
-        /* XXX this is disabled until I fix it so that we don't just keep
-         * XXX retrying in the case of a missing upcall.
-         */
-#endif
-        return 0;
+        struct ptlrpc_request *req;
+        int rc;
+        ENTRY;
+
+        req = ptlrpc_prep_req(imp, OBD_PING, 0, NULL, NULL);
+        if (!req)
+                RETURN(-ENOMEM);
+
+        req->rq_replen = lustre_msg_size(0, NULL);
+        req->rq_send_state = LUSTRE_IMP_REPLAY;
+        req->rq_reqmsg->flags |= MSG_LAST_REPLAY;
+        req->rq_timeout *= 3; 
+
+        rc = ptlrpc_queue_wait(req);
+
+        ptlrpc_req_finished(req);
+        RETURN(rc);
 }
 
-int ll_recover(struct recovd_data *rd, int phase)
+int ptlrpc_recover_import(struct obd_import *imp, char *new_uuid)
 {
-        struct ptlrpc_connection *conn = class_rd2conn(rd);
+        int rc;
+        ENTRY;
+        
+        rc = ptlrpc_recover_import_no_retry(imp, new_uuid);
+
+        if (rc && rc != -EALREADY) {
+                unsigned long flags;
+                CDEBUG(D_HA, "recovery of %s on %s failed (%d); restarting\n",
+                       imp->imp_target_uuid.uuid,
+                       new_uuid ? new_uuid :
+                       (char *)imp->imp_connection->c_remote_uuid.uuid, rc);
+                spin_lock_irqsave(&imp->imp_lock, flags);
+                imp->imp_state = LUSTRE_IMP_FULL;
+                spin_unlock_irqrestore(&imp->imp_lock, flags);
+                ptlrpc_fail_import(imp, imp->imp_generation);
+        }
+        RETURN(rc);
+}
 
-        LASSERT(conn);
+static int ptlrpc_recover_import_no_retry(struct obd_import *imp,
+                                          char *new_uuid)
+{
+        int rc;
+        unsigned long flags;
+        int in_recovery = 0;
+        int was_invalid = 0;
         ENTRY;
 
-        switch (phase) {
-            case PTLRPC_RECOVD_PHASE_PREPARE:
-                RETURN(ll_recover_upcall(conn));
-            case PTLRPC_RECOVD_PHASE_RECOVER:
-                RETURN(ll_recover_reconnect(conn));
-            case PTLRPC_RECOVD_PHASE_FAILURE:
-                RETURN(ll_retry_recovery(conn));
+        spin_lock_irqsave(&imp->imp_lock, flags);
+        if (imp->imp_state == LUSTRE_IMP_FULL) {
+                CDEBUG(D_HA, "%s: new state: DISCON\n", 
+                       imp->imp_client->cli_name);
+                imp->imp_state = LUSTRE_IMP_DISCON;
+        } 
+        
+        if (imp->imp_state != LUSTRE_IMP_DISCON) {
+                in_recovery = 1;
+        } else if (imp->imp_invalid) {
+                imp->imp_invalid = 0;
+                was_invalid = 1;
         }
 
-        LBUG();
-        RETURN(-ENOSYS);
+        spin_unlock_irqrestore(&imp->imp_lock, flags);
+
+        if (in_recovery == 1)
+                RETURN(-EALREADY);
+
+        down(&imp->imp_recovery_sem);
+        /* If recovery happened while we waited, we're done. */
+        if (imp->imp_state == LUSTRE_IMP_FULL)
+                GOTO(out, rc = 0);
+
+        LASSERT (imp->imp_state == LUSTRE_IMP_DISCON);
+
+        if (new_uuid) {
+                struct ptlrpc_connection *conn;
+                struct obd_uuid uuid;
+                struct ptlrpc_peer peer;
+                struct obd_export *dlmexp;
+
+                obd_str2uuid(&uuid, new_uuid);
+                if (ptlrpc_uuid_to_peer(&uuid, &peer)) {
+                        CERROR("no connection found for UUID %s\n", new_uuid);
+                        GOTO(out, rc = -EINVAL);
+                }
+
+                conn = ptlrpc_get_connection(&peer, &uuid);
+                if (!conn)
+                        GOTO(out, rc = -ENOMEM);
+
+                CDEBUG(D_HA, "switching import %s/%s from %s to %s\n",
+                       imp->imp_target_uuid.uuid, imp->imp_obd->obd_name,
+                       imp->imp_connection->c_remote_uuid.uuid,
+                       conn->c_remote_uuid.uuid);
+
+                /* Switch the import's connection and the DLM export's
+                 * connection (which are almost certainly the same, but we
+                 * keep distinct refs just to make things clearer. I think. */
+                if (imp->imp_connection)
+                        ptlrpc_put_connection(imp->imp_connection);
+                /* We hand off the ref from ptlrpc_get_connection. */
+                imp->imp_connection = conn;
+
+                dlmexp = class_conn2export(&imp->imp_dlm_handle);
+                if (dlmexp->exp_connection)
+                        ptlrpc_put_connection(dlmexp->exp_connection);
+                dlmexp->exp_connection = ptlrpc_connection_addref(conn);
+                class_export_put(dlmexp);
+
+        }
+
+ connect:
+        rc = ptlrpc_connect_import(imp);
+
+        if (rc < 0) {
+                CERROR("failed to reconnect to %s@%s: %d\n",
+                       imp->imp_target_uuid.uuid,
+                       imp->imp_connection->c_remote_uuid.uuid, rc);
+                GOTO(out, rc);
+        } 
+
+        if (imp->imp_state == LUSTRE_IMP_EVICTED) {
+                CDEBUG(D_HA, "evicted from %s@%s; invalidating\n",
+                       imp->imp_target_uuid.uuid,
+                       imp->imp_connection->c_remote_uuid.uuid);
+                ptlrpc_set_import_active(imp, 0);
+                CDEBUG(D_HA, "%s: new state: RECOVER\n", 
+                       imp->imp_client->cli_name);
+                imp->imp_state = LUSTRE_IMP_RECOVER;
+        } 
+        
+        if (imp->imp_state == LUSTRE_IMP_REPLAY) {
+                CDEBUG(D_HA, "replay requested by %s\n",
+                       imp->imp_target_uuid.uuid);
+                rc = ptlrpc_replay(imp);
+                if (rc)
+                        GOTO(out, rc);
+
+                rc = ldlm_replay_locks(imp);
+                if (rc)
+                        GOTO(out, rc);
+
+                rc = signal_completed_replay(imp);
+                if (rc)
+                        GOTO(out, rc);
+                CDEBUG(D_HA, "%s: new state: RECOVER\n", 
+                       imp->imp_client->cli_name);
+                imp->imp_state = LUSTRE_IMP_RECOVER;
+        } 
+
+        if (imp->imp_state == LUSTRE_IMP_RECOVER) {
+                CDEBUG(D_HA, "reconnected to %s@%s\n",
+                       imp->imp_target_uuid.uuid,
+                       imp->imp_connection->c_remote_uuid.uuid);
+
+                ptlrpc_set_import_active(imp, 1);
+                ptlrpc_resend(imp);
+                spin_lock_irqsave(&imp->imp_lock, flags);
+                CDEBUG(D_HA, "%s: new state: FULL\n", 
+                       imp->imp_client->cli_name);
+                imp->imp_state = LUSTRE_IMP_FULL;
+                spin_unlock_irqrestore(&imp->imp_lock, flags);
+                ptlrpc_wake_delayed(imp);
+        } 
+
+
+        LASSERT(imp->imp_state == LUSTRE_IMP_FULL);
+
+ out:
+        if (rc != 0) {
+                spin_lock_irqsave(&imp->imp_lock, flags);
+                imp->imp_state = LUSTRE_IMP_DISCON;
+                spin_unlock_irqrestore(&imp->imp_lock, flags);
+                
+                if (rc == -ENOTCONN) {
+                        CDEBUG(D_HA, "evicted/aborted by %s@%s during recovery;"
+                               "invalidating and reconnecting\n",
+                               imp->imp_target_uuid.uuid,
+                               imp->imp_connection->c_remote_uuid.uuid);
+                        GOTO(connect, -ENOTCONN);
+                } else if (was_invalid) {
+                        ptlrpc_set_import_active(imp, 0);
+                }
+        }
+        up(&imp->imp_recovery_sem);
+        RETURN(rc);
+}
+
+void ptlrpc_fail_export(struct obd_export *exp)
+{
+        int rc, already_failed;
+        unsigned long flags;
+
+        spin_lock_irqsave(&exp->exp_lock, flags);
+        already_failed = exp->exp_failed;
+        exp->exp_failed = 1;
+        spin_unlock_irqrestore(&exp->exp_lock, flags);
+
+        if (already_failed) {
+                CDEBUG(D_HA, "disconnecting dead export %p/%s; skipping\n",
+                       exp, exp->exp_client_uuid.uuid);
+                return;
+        }
+
+        CDEBUG(D_HA, "disconnecting export %p/%s\n",
+               exp, exp->exp_client_uuid.uuid);
+
+        /* Most callers into obd_disconnect are removing their own reference
+         * (request, for example) in addition to the one from the hash table.
+         * We don't have such a reference here, so make one. */
+        class_export_get(exp);
+        rc = obd_disconnect(exp, 0);
+        if (rc)
+                CERROR("disconnecting export %p failed: %d\n", exp, rc);
 }