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LU-11599 ldlm: printing negative time on logs for recovery
[fs/lustre-release.git] / lustre / ldlm / ldlm_lib.c
index c3f6551..9b5c425 100644 (file)
  *
  * 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
- *
- * 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.
+ * http://www.gnu.org/licenses/gpl-2.0.html
  *
  * GPL HEADER END
  */
@@ -27,7 +23,7 @@
  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
  *
- * Copyright (c) 2010, 2013, Intel Corporation.
+ * Copyright (c) 2010, 2017, Intel Corporation.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
@@ -43,6 +39,8 @@
 
 #define DEBUG_SUBSYSTEM S_LDLM
 
+#include <linux/jiffies.h>
+#include <linux/kthread.h>
 #include <libcfs/libcfs.h>
 #include <obd.h>
 #include <obd_class.h>
 static int import_set_conn(struct obd_import *imp, struct obd_uuid *uuid,
                            int priority, int create)
 {
-        struct ptlrpc_connection *ptlrpc_conn;
-        struct obd_import_conn *imp_conn = NULL, *item;
-        int rc = 0;
-        ENTRY;
+       struct ptlrpc_connection *ptlrpc_conn;
+       struct obd_import_conn *imp_conn = NULL, *item;
+       lnet_nid_t nid4refnet = LNET_NID_ANY;
+       int rc = 0;
+       ENTRY;
 
-        if (!create && !priority) {
-                CDEBUG(D_HA, "Nothing to do\n");
-                RETURN(-EINVAL);
-        }
+       if (!create && !priority) {
+               CDEBUG(D_HA, "Nothing to do\n");
+               RETURN(-EINVAL);
+       }
 
-        ptlrpc_conn = ptlrpc_uuid_to_connection(uuid);
-        if (!ptlrpc_conn) {
-                CDEBUG(D_HA, "can't find connection %s\n", uuid->uuid);
-                RETURN (-ENOENT);
-        }
+       if (imp->imp_connection &&
+           imp->imp_connection->c_remote_uuid.uuid[0] == 0)
+               /* nid4refnet is used to restrict network connections */
+               nid4refnet = imp->imp_connection->c_self;
+       ptlrpc_conn = ptlrpc_uuid_to_connection(uuid, nid4refnet);
+       if (!ptlrpc_conn) {
+               CDEBUG(D_HA, "can't find connection %s\n", uuid->uuid);
+               RETURN(-ENOENT);
+       }
 
-        if (create) {
-                OBD_ALLOC(imp_conn, sizeof(*imp_conn));
-                if (!imp_conn) {
-                        GOTO(out_put, rc = -ENOMEM);
-                }
-        }
+       if (create) {
+               OBD_ALLOC(imp_conn, sizeof(*imp_conn));
+               if (!imp_conn)
+                       GOTO(out_put, rc = -ENOMEM);
+       }
 
        spin_lock(&imp->imp_lock);
        list_for_each_entry(item, &imp->imp_conn_list, oic_item) {
-                if (obd_uuid_equals(uuid, &item->oic_uuid)) {
-                        if (priority) {
+               if (obd_uuid_equals(uuid, &item->oic_uuid)) {
+                       if (priority) {
                                list_del(&item->oic_item);
                                list_add(&item->oic_item,
-                                             &imp->imp_conn_list);
-                                item->oic_last_attempt = 0;
-                        }
-                        CDEBUG(D_HA, "imp %p@%s: found existing conn %s%s\n",
-                               imp, imp->imp_obd->obd_name, uuid->uuid,
-                               (priority ? ", moved to head" : ""));
+                                        &imp->imp_conn_list);
+                               item->oic_last_attempt = 0;
+                       }
+                       CDEBUG(D_HA, "imp %p@%s: found existing conn %s%s\n",
+                              imp, imp->imp_obd->obd_name, uuid->uuid,
+                              (priority ? ", moved to head" : ""));
                        spin_unlock(&imp->imp_lock);
-                        GOTO(out_free, rc = 0);
-                }
-        }
+                       GOTO(out_free, rc = 0);
+               }
+       }
        /* No existing import connection found for \a uuid. */
-        if (create) {
-                imp_conn->oic_conn = ptlrpc_conn;
-                imp_conn->oic_uuid = *uuid;
-                imp_conn->oic_last_attempt = 0;
-                if (priority)
+       if (create) {
+               imp_conn->oic_conn = ptlrpc_conn;
+               imp_conn->oic_uuid = *uuid;
+               imp_conn->oic_last_attempt = 0;
+               if (priority)
                        list_add(&imp_conn->oic_item, &imp->imp_conn_list);
-                else
+               else
                        list_add_tail(&imp_conn->oic_item,
-                                          &imp->imp_conn_list);
-                CDEBUG(D_HA, "imp %p@%s: add connection %s at %s\n",
-                       imp, imp->imp_obd->obd_name, uuid->uuid,
-                       (priority ? "head" : "tail"));
-        } else {
+                                     &imp->imp_conn_list);
+               CDEBUG(D_HA, "imp %p@%s: add connection %s at %s\n",
+                      imp, imp->imp_obd->obd_name, uuid->uuid,
+                      (priority ? "head" : "tail"));
+       } else {
                spin_unlock(&imp->imp_lock);
                GOTO(out_free, rc = -ENOENT);
        }
 
        spin_unlock(&imp->imp_lock);
-        RETURN(0);
+       RETURN(0);
 out_free:
-        if (imp_conn)
-                OBD_FREE(imp_conn, sizeof(*imp_conn));
+       if (imp_conn)
+               OBD_FREE(imp_conn, sizeof(*imp_conn));
 out_put:
-        ptlrpc_connection_put(ptlrpc_conn);
-        RETURN(rc);
+       ptlrpc_connection_put(ptlrpc_conn);
+       RETURN(rc);
 }
 
 int import_set_conn_priority(struct obd_import *imp, struct obd_uuid *uuid)
@@ -166,14 +168,17 @@ int client_import_del_conn(struct obd_import *imp, struct obd_uuid *uuid)
                         ptlrpc_connection_put(imp->imp_connection);
                         imp->imp_connection = NULL;
 
-                        dlmexp = class_conn2export(&imp->imp_dlm_handle);
-                        if (dlmexp && dlmexp->exp_connection) {
-                                LASSERT(dlmexp->exp_connection ==
-                                        imp_conn->oic_conn);
-                                ptlrpc_connection_put(dlmexp->exp_connection);
-                                dlmexp->exp_connection = NULL;
-                        }
-                }
+                       dlmexp = class_conn2export(&imp->imp_dlm_handle);
+                       if (dlmexp && dlmexp->exp_connection) {
+                               LASSERT(dlmexp->exp_connection ==
+                                       imp_conn->oic_conn);
+                               ptlrpc_connection_put(dlmexp->exp_connection);
+                               dlmexp->exp_connection = NULL;
+                       }
+
+                       if (dlmexp != NULL)
+                               class_export_put(dlmexp);
+               }
 
                list_del(&imp_conn->oic_item);
                 ptlrpc_connection_put(imp_conn->oic_conn);
@@ -256,20 +261,24 @@ static int osc_on_mdt(char *obdname)
  * 1 - client UUID
  * 2 - server UUID
  * 3 - inactive-on-startup
+ * 4 - restrictive net
  */
 int client_obd_setup(struct obd_device *obddev, struct lustre_cfg *lcfg)
 {
-        struct client_obd *cli = &obddev->u.cli;
-        struct obd_import *imp;
-        struct obd_uuid server_uuid;
-        int rq_portal, rp_portal, connect_op;
-        char *name = obddev->obd_type->typ_name;
-        ldlm_ns_type_t ns_type = LDLM_NS_TYPE_UNKNOWN;
-        int rc;
-        ENTRY;
+       struct client_obd *cli = &obddev->u.cli;
+       struct obd_import *imp;
+       struct obd_uuid server_uuid;
+       int rq_portal, rp_portal, connect_op;
+       char *name = obddev->obd_type->typ_name;
+       enum ldlm_ns_type ns_type = LDLM_NS_TYPE_UNKNOWN;
+       char *cli_name = lustre_cfg_buf(lcfg, 0);
+       struct ptlrpc_connection fake_conn = { .c_self = 0,
+                                              .c_remote_uuid.uuid[0] = 0 };
+       int rc;
+       ENTRY;
 
-        /* In a more perfect world, we would hang a ptlrpc_client off of
-         * obd_type and just use the values from there. */
+       /* In a more perfect world, we would hang a ptlrpc_client off of
+        * obd_type and just use the values from there. */
        if (!strcmp(name, LUSTRE_OSC_NAME)) {
                rq_portal = OST_REQUEST_PORTAL;
                rp_portal = OSC_REPLY_PORTAL;
@@ -282,7 +291,12 @@ int client_obd_setup(struct obd_device *obddev, struct lustre_cfg *lcfg)
                rq_portal = MDS_REQUEST_PORTAL;
                rp_portal = MDC_REPLY_PORTAL;
                connect_op = MDS_CONNECT;
-               cli->cl_sp_me = LUSTRE_SP_CLI;
+               if (is_lwp_on_ost(cli_name))
+                       cli->cl_sp_me = LUSTRE_SP_OST;
+               else if (is_lwp_on_mdt(cli_name))
+                       cli->cl_sp_me = LUSTRE_SP_MDT;
+               else
+                       cli->cl_sp_me = LUSTRE_SP_CLI;
                cli->cl_sp_to = LUSTRE_SP_MDT;
                ns_type = LDLM_NS_TYPE_MDC;
        } else if (!strcmp(name, LUSTRE_OSP_NAME)) {
@@ -300,7 +314,7 @@ int client_obd_setup(struct obd_device *obddev, struct lustre_cfg *lcfg)
                        rq_portal = OST_REQUEST_PORTAL;
                }
                rp_portal = OSC_REPLY_PORTAL;
-               cli->cl_sp_me = LUSTRE_SP_CLI;
+               cli->cl_sp_me = LUSTRE_SP_MDT;
         } else if (!strcmp(name, LUSTRE_MGC_NAME)) {
                 rq_portal = MGS_REQUEST_PORTAL;
                 rp_portal = MGC_REPLY_PORTAL;
@@ -337,10 +351,12 @@ int client_obd_setup(struct obd_device *obddev, struct lustre_cfg *lcfg)
 
        init_rwsem(&cli->cl_sem);
        mutex_init(&cli->cl_mgc_mutex);
-        cli->cl_conn_count = 0;
-        memcpy(server_uuid.uuid, lustre_cfg_buf(lcfg, 2),
-               min_t(unsigned int, LUSTRE_CFG_BUFLEN(lcfg, 2),
-                     sizeof(server_uuid)));
+       cli->cl_seq = NULL;
+       init_rwsem(&cli->cl_seq_rwsem);
+       cli->cl_conn_count = 0;
+       memcpy(server_uuid.uuid, lustre_cfg_buf(lcfg, 2),
+              min_t(unsigned int, LUSTRE_CFG_BUFLEN(lcfg, 2),
+                    sizeof(server_uuid)));
 
        cli->cl_dirty_pages = 0;
        cli->cl_avail_grant = 0;
@@ -353,7 +369,7 @@ int client_obd_setup(struct obd_device *obddev, struct lustre_cfg *lcfg)
        INIT_LIST_HEAD(&cli->cl_loi_hp_ready_list);
        INIT_LIST_HEAD(&cli->cl_loi_write_list);
        INIT_LIST_HEAD(&cli->cl_loi_read_list);
-       client_obd_list_lock_init(&cli->cl_loi_list_lock);
+       spin_lock_init(&cli->cl_loi_list_lock);
        atomic_set(&cli->cl_pending_w_pages, 0);
        atomic_set(&cli->cl_pending_r_pages, 0);
        cli->cl_r_in_flight = 0;
@@ -372,11 +388,18 @@ int client_obd_setup(struct obd_device *obddev, struct lustre_cfg *lcfg)
        atomic_long_set(&cli->cl_lru_busy, 0);
        atomic_long_set(&cli->cl_lru_in_list, 0);
        INIT_LIST_HEAD(&cli->cl_lru_list);
-       client_obd_list_lock_init(&cli->cl_lru_list_lock);
+       spin_lock_init(&cli->cl_lru_list_lock);
        atomic_long_set(&cli->cl_unstable_count, 0);
+       INIT_LIST_HEAD(&cli->cl_shrink_list);
+       INIT_LIST_HEAD(&cli->cl_grant_chain);
+
+       INIT_LIST_HEAD(&cli->cl_flight_waiters);
+       cli->cl_rpcs_in_flight = 0;
 
        init_waitqueue_head(&cli->cl_destroy_waitq);
        atomic_set(&cli->cl_destroy_in_flight, 0);
+
+       cli->cl_supp_cksum_types = OBD_CKSUM_CRC32;
 #ifdef ENABLE_CHECKSUM
        /* Turn on checksumming by default. */
        cli->cl_checksum = 1;
@@ -385,35 +408,53 @@ int client_obd_setup(struct obd_device *obddev, struct lustre_cfg *lcfg)
         * Set cl_chksum* to CRC32 for now to avoid returning screwed info
         * through procfs.
         */
-       cli->cl_cksum_type = cli->cl_supp_cksum_types = OBD_CKSUM_CRC32;
+       cli->cl_cksum_type = cli->cl_supp_cksum_types;
 #endif
        atomic_set(&cli->cl_resends, OSC_DEFAULT_RESENDS);
 
-       /* This value may be reduced at connect time in
-        * ptlrpc_connect_interpret() . We initialize it to only
-        * 1MB until we know what the performance looks like.
-        * In the future this should likely be increased. LU-1431 */
-       cli->cl_max_pages_per_rpc = min_t(int, PTLRPC_MAX_BRW_PAGES,
-                                         LNET_MTU >> PAGE_CACHE_SHIFT);
+       /* Set it to possible maximum size. It may be reduced by ocd_brw_size
+        * from OFD after connecting. */
+       cli->cl_max_pages_per_rpc = PTLRPC_MAX_BRW_PAGES;
+
+       cli->cl_max_short_io_bytes = OBD_MAX_SHORT_IO_BYTES;
 
-       /* set cl_chunkbits default value to PAGE_CACHE_SHIFT,
+       /* set cl_chunkbits default value to PAGE_SHIFT,
         * it will be updated at OSC connection time. */
-       cli->cl_chunkbits = PAGE_CACHE_SHIFT;
+       cli->cl_chunkbits = PAGE_SHIFT;
 
        if (!strcmp(name, LUSTRE_MDC_NAME)) {
                cli->cl_max_rpcs_in_flight = OBD_MAX_RIF_DEFAULT;
-       } else if (totalram_pages >> (20 - PAGE_CACHE_SHIFT) <= 128 /* MB */) {
+       } else if (totalram_pages >> (20 - PAGE_SHIFT) <= 128 /* MB */) {
                cli->cl_max_rpcs_in_flight = 2;
-       } else if (totalram_pages >> (20 - PAGE_CACHE_SHIFT) <= 256 /* MB */) {
+       } else if (totalram_pages >> (20 - PAGE_SHIFT) <= 256 /* MB */) {
                cli->cl_max_rpcs_in_flight = 3;
-       } else if (totalram_pages >> (20 - PAGE_CACHE_SHIFT) <= 512 /* MB */) {
+       } else if (totalram_pages >> (20 - PAGE_SHIFT) <= 512 /* MB */) {
                cli->cl_max_rpcs_in_flight = 4;
        } else {
                if (osc_on_mdt(obddev->obd_name))
                        cli->cl_max_rpcs_in_flight = OBD_MAX_RIF_MAX;
                else
                        cli->cl_max_rpcs_in_flight = OBD_MAX_RIF_DEFAULT;
-        }
+       }
+
+       spin_lock_init(&cli->cl_mod_rpcs_lock);
+       spin_lock_init(&cli->cl_mod_rpcs_hist.oh_lock);
+       cli->cl_max_mod_rpcs_in_flight = 0;
+       cli->cl_mod_rpcs_in_flight = 0;
+       cli->cl_close_rpcs_in_flight = 0;
+       init_waitqueue_head(&cli->cl_mod_rpcs_waitq);
+       cli->cl_mod_tag_bitmap = NULL;
+
+       INIT_LIST_HEAD(&cli->cl_chg_dev_linkage);
+
+       if (connect_op == MDS_CONNECT) {
+               cli->cl_max_mod_rpcs_in_flight = cli->cl_max_rpcs_in_flight - 1;
+               OBD_ALLOC(cli->cl_mod_tag_bitmap,
+                         BITS_TO_LONGS(OBD_MAX_RIF_MAX) * sizeof(long));
+               if (cli->cl_mod_tag_bitmap == NULL)
+                       GOTO(err, rc = -ENOMEM);
+       }
+
         rc = ldlm_get_ref();
         if (rc) {
                 CERROR("ldlm_get_ref failed: %d\n", rc);
@@ -432,16 +473,30 @@ int client_obd_setup(struct obd_device *obddev, struct lustre_cfg *lcfg)
                LUSTRE_CFG_BUFLEN(lcfg, 1));
         class_import_put(imp);
 
-        rc = client_import_add_conn(imp, &server_uuid, 1);
-        if (rc) {
-                CERROR("can't add initial connection\n");
-                GOTO(err_import, rc);
-        }
+       if (lustre_cfg_buf(lcfg, 4)) {
+               __u32 refnet = libcfs_str2net(lustre_cfg_string(lcfg, 4));
+
+               if (refnet == LNET_NIDNET(LNET_NID_ANY)) {
+                       rc = -EINVAL;
+                       CERROR("%s: bad mount option 'network=%s': rc = %d\n",
+                              obddev->obd_name, lustre_cfg_string(lcfg, 4),
+                              rc);
+                       GOTO(err_import, rc);
+               }
+               fake_conn.c_self = LNET_MKNID(refnet, 0);
+               imp->imp_connection = &fake_conn;
+       }
+
+       rc = client_import_add_conn(imp, &server_uuid, 1);
+       if (rc) {
+               CERROR("can't add initial connection\n");
+               GOTO(err_import, rc);
+       }
+       imp->imp_connection = NULL;
 
-        cli->cl_import = imp;
-        /* cli->cl_max_mds_{easize,cookiesize} updated by mdc_init_ea_size() */
-        cli->cl_max_mds_easize = sizeof(struct lov_mds_md_v3);
-        cli->cl_max_mds_cookiesize = sizeof(struct llog_cookie);
+       cli->cl_import = imp;
+       /* cli->cl_max_mds_easize updated by mdc_init_ea_size() */
+       cli->cl_max_mds_easize = sizeof(struct lov_mds_md_v3);
 
         if (LUSTRE_CFG_BUFLEN(lcfg, 3) > 0) {
                 if (!strcmp(lustre_cfg_string(lcfg, 3), "inactive")) {
@@ -464,8 +519,6 @@ int client_obd_setup(struct obd_device *obddev, struct lustre_cfg *lcfg)
                 GOTO(err_import, rc = -ENOMEM);
         }
 
-        cli->cl_qchk_stat = CL_NOT_QUOTACHECKED;
-
         RETURN(rc);
 
 err_import:
@@ -473,6 +526,10 @@ err_import:
 err_ldlm:
         ldlm_put_ref();
 err:
+       if (cli->cl_mod_tag_bitmap != NULL)
+               OBD_FREE(cli->cl_mod_tag_bitmap,
+                        BITS_TO_LONGS(OBD_MAX_RIF_MAX) * sizeof(long));
+       cli->cl_mod_tag_bitmap = NULL;
         RETURN(rc);
 
 }
@@ -480,6 +537,7 @@ EXPORT_SYMBOL(client_obd_setup);
 
 int client_obd_cleanup(struct obd_device *obddev)
 {
+       struct client_obd *cli = &obddev->u.cli;
        ENTRY;
 
        ldlm_namespace_free_post(obddev->obd_namespace);
@@ -489,6 +547,12 @@ int client_obd_cleanup(struct obd_device *obddev)
        LASSERT(obddev->u.cli.cl_import == NULL);
 
        ldlm_put_ref();
+
+       if (cli->cl_mod_tag_bitmap != NULL)
+               OBD_FREE(cli->cl_mod_tag_bitmap,
+                        BITS_TO_LONGS(OBD_MAX_RIF_MAX) * sizeof(long));
+       cli->cl_mod_tag_bitmap = NULL;
+
        RETURN(0);
 }
 EXPORT_SYMBOL(client_obd_cleanup);
@@ -506,55 +570,57 @@ int client_connect_import(const struct lu_env *env,
        int                     rc;
        ENTRY;
 
-        *exp = NULL;
+       *exp = NULL;
        down_write(&cli->cl_sem);
-        if (cli->cl_conn_count > 0 )
+       if (cli->cl_conn_count > 0)
                 GOTO(out_sem, rc = -EALREADY);
 
-        rc = class_connect(&conn, obd, cluuid);
-        if (rc)
-                GOTO(out_sem, rc);
+       rc = class_connect(&conn, obd, cluuid);
+       if (rc)
+               GOTO(out_sem, rc);
 
-        cli->cl_conn_count++;
-        *exp = class_conn2export(&conn);
+       cli->cl_conn_count++;
+       *exp = class_conn2export(&conn);
 
-        LASSERT(obd->obd_namespace);
+       LASSERT(obd->obd_namespace);
 
-        imp->imp_dlm_handle = conn;
-        rc = ptlrpc_init_import(imp);
-        if (rc != 0)
-                GOTO(out_ldlm, rc);
+       imp->imp_dlm_handle = conn;
+       rc = ptlrpc_init_import(imp);
+       if (rc != 0)
+               GOTO(out_ldlm, rc);
 
-        ocd = &imp->imp_connect_data;
-        if (data) {
-                *ocd = *data;
-                imp->imp_connect_flags_orig = data->ocd_connect_flags;
-        }
+       ocd = &imp->imp_connect_data;
+       if (data) {
+               *ocd = *data;
+               imp->imp_connect_flags_orig = data->ocd_connect_flags;
+               imp->imp_connect_flags2_orig = data->ocd_connect_flags2;
+       }
 
-        rc = ptlrpc_connect_import(imp);
-        if (rc != 0) {
-                LASSERT (imp->imp_state == LUSTRE_IMP_DISCON);
-                GOTO(out_ldlm, rc);
-        }
+       rc = ptlrpc_connect_import(imp);
+       if (rc != 0) {
+               LASSERT(imp->imp_state == LUSTRE_IMP_DISCON);
+               GOTO(out_ldlm, rc);
+       }
        LASSERT(*exp != NULL && (*exp)->exp_connection);
 
-        if (data) {
-                LASSERTF((ocd->ocd_connect_flags & data->ocd_connect_flags) ==
-                         ocd->ocd_connect_flags, "old "LPX64", new "LPX64"\n",
-                         data->ocd_connect_flags, ocd->ocd_connect_flags);
-                data->ocd_connect_flags = ocd->ocd_connect_flags;
-        }
+       if (data) {
+               LASSERTF((ocd->ocd_connect_flags & data->ocd_connect_flags) ==
+                        ocd->ocd_connect_flags, "old %#llx, new %#llx\n",
+                        data->ocd_connect_flags, ocd->ocd_connect_flags);
+               data->ocd_connect_flags = ocd->ocd_connect_flags;
+               data->ocd_connect_flags2 = ocd->ocd_connect_flags2;
+       }
 
-        ptlrpc_pinger_add_import(imp);
+       ptlrpc_pinger_add_import(imp);
 
-        EXIT;
+       EXIT;
 
-        if (rc) {
+       if (rc) {
 out_ldlm:
-                cli->cl_conn_count--;
-                class_disconnect(*exp);
-                *exp = NULL;
-        }
+               cli->cl_conn_count--;
+               class_disconnect(*exp);
+               *exp = NULL;
+       }
 out_sem:
        up_write(&cli->cl_sem);
 
@@ -571,7 +637,7 @@ int client_disconnect_export(struct obd_export *exp)
         ENTRY;
 
         if (!obd) {
-                CERROR("invalid export for disconnect: exp %p cookie "LPX64"\n",
+               CERROR("invalid export for disconnect: exp %p cookie %#llx\n",
                        exp, exp ? exp->exp_handle.h_cookie : -1);
                 RETURN(-EINVAL);
         }
@@ -580,17 +646,17 @@ int client_disconnect_export(struct obd_export *exp)
         imp = cli->cl_import;
 
        down_write(&cli->cl_sem);
-        CDEBUG(D_INFO, "disconnect %s - %d\n", obd->obd_name,
-               cli->cl_conn_count);
+       CDEBUG(D_INFO, "disconnect %s - %zu\n", obd->obd_name,
+               cli->cl_conn_count);
 
-        if (!cli->cl_conn_count) {
+       if (cli->cl_conn_count == 0) {
                 CERROR("disconnecting disconnected device (%s)\n",
                        obd->obd_name);
                 GOTO(out_disconnect, rc = -EINVAL);
         }
 
         cli->cl_conn_count--;
-        if (cli->cl_conn_count)
+       if (cli->cl_conn_count != 0)
                 GOTO(out_disconnect, rc = 0);
 
        /* Mark import deactivated now, so we don't try to reconnect if any
@@ -647,8 +713,7 @@ int server_disconnect_export(struct obd_export *exp)
        if (exp->exp_imp_reverse)
                ptlrpc_cleanup_imp(exp->exp_imp_reverse);
 
-       if (exp->exp_obd->obd_namespace != NULL)
-               ldlm_cancel_locks_for_export(exp);
+       ldlm_bl_thread_wakeup();
 
         /* complete all outstanding replies */
        spin_lock(&exp->exp_lock);
@@ -661,7 +726,10 @@ int server_disconnect_export(struct obd_export *exp)
                spin_lock(&svcpt->scp_rep_lock);
 
                list_del_init(&rs->rs_exp_list);
+
                spin_lock(&rs->rs_lock);
+               /* clear rs_convert_lock to make sure rs is handled and put */
+               rs->rs_convert_lock = 0;
                ptlrpc_schedule_difficult_reply(rs);
                spin_unlock(&rs->rs_lock);
 
@@ -681,99 +749,226 @@ static int target_handle_reconnect(struct lustre_handle *conn,
                                    struct obd_export *exp,
                                    struct obd_uuid *cluuid)
 {
-        ENTRY;
-
-        if (exp->exp_connection && exp->exp_imp_reverse) {
-                struct lustre_handle *hdl;
-                struct obd_device *target;
-
-                hdl = &exp->exp_imp_reverse->imp_remote_handle;
-                target = exp->exp_obd;
-
-                /* Might be a re-connect after a partition. */
-                if (!memcmp(&conn->cookie, &hdl->cookie, sizeof conn->cookie)) {
-                        if (target->obd_recovering) {
-                                int timeout = cfs_duration_sec(cfs_time_sub(
-                                        cfs_timer_deadline(
-                                        &target->obd_recovery_timer),
-                                        cfs_time_current()));
-
-                                LCONSOLE_WARN("%s: Client %s (at %s) reconnect"
-                                        "ing, waiting for %d clients in recov"
-                                        "ery for %d:%.02d\n", target->obd_name,
-                                        obd_uuid2str(&exp->exp_client_uuid),
-                                        obd_export_nid2str(exp),
-                                        target->obd_max_recoverable_clients,
-                                        timeout / 60, timeout % 60);
-                        } else {
-                                LCONSOLE_WARN("%s: Client %s (at %s) "
-                                        "reconnecting\n", target->obd_name,
-                                        obd_uuid2str(&exp->exp_client_uuid),
-                                        obd_export_nid2str(exp));
-                        }
+       struct obd_device *target;
+       struct lustre_handle *hdl;
+       time64_t deadline;
+       time64_t timeout;
+       time64_t now;
+       int rc = 0;
 
-                        conn->cookie = exp->exp_handle.h_cookie;
-                        /* target_handle_connect() treats EALREADY and
-                         * -EALREADY differently.  EALREADY means we are
-                         * doing a valid reconnect from the same client. */
-                        RETURN(EALREADY);
-                } else {
-                       LCONSOLE_WARN("%s: already connected client %s (at %s) "
-                                     "with handle "LPX64". Rejecting client "
-                                     "with the same UUID trying to reconnect "
-                                     "with handle "LPX64"\n", target->obd_name,
-                                     obd_uuid2str(&exp->exp_client_uuid),
-                                     obd_export_nid2str(exp),
-                                     hdl->cookie, conn->cookie);
-                        memset(conn, 0, sizeof *conn);
-                        /* target_handle_connect() treats EALREADY and
-                         * -EALREADY differently.  -EALREADY is an error
-                         * (same UUID, different handle). */
-                        RETURN(-EALREADY);
-                }
-        }
+       ENTRY;
+       hdl = &exp->exp_imp_reverse->imp_remote_handle;
+       if (!exp->exp_connection || !lustre_handle_is_used(hdl)) {
+               conn->cookie = exp->exp_handle.h_cookie;
+               CDEBUG(D_HA, "connect export for UUID '%s' at %p,"
+                      " cookie %#llx\n", cluuid->uuid, exp, conn->cookie);
+               RETURN(0);
+       }
 
-        conn->cookie = exp->exp_handle.h_cookie;
-        CDEBUG(D_HA, "connect export for UUID '%s' at %p, cookie "LPX64"\n",
-               cluuid->uuid, exp, conn->cookie);
-        RETURN(0);
-}
+       target = exp->exp_obd;
+
+       /* Might be a re-connect after a partition. */
+       if (memcmp(&conn->cookie, &hdl->cookie, sizeof conn->cookie)) {
+               LCONSOLE_WARN("%s: already connected client %s (at %s) "
+                             "with handle %#llx. Rejecting client "
+                             "with the same UUID trying to reconnect "
+                             "with handle %#llx\n", target->obd_name,
+                             obd_uuid2str(&exp->exp_client_uuid),
+                             obd_export_nid2str(exp),
+                             hdl->cookie, conn->cookie);
+               memset(conn, 0, sizeof *conn);
+               /* target_handle_connect() treats EALREADY and
+                * -EALREADY differently.  -EALREADY is an error
+                * (same UUID, different handle). */
+               RETURN(-EALREADY);
+       }
 
-void target_client_add_cb(struct obd_device *obd, __u64 transno, void *cb_data,
-                          int error)
-{
-        struct obd_export *exp = cb_data;
+       if (!target->obd_recovering) {
+               LCONSOLE_WARN("%s: Client %s (at %s) reconnecting\n",
+                       target->obd_name, obd_uuid2str(&exp->exp_client_uuid),
+                       obd_export_nid2str(exp));
+               GOTO(out_already, rc);
+       }
 
-        CDEBUG(D_RPCTRACE, "%s: committing for initial connect of %s\n",
-               obd->obd_name, exp->exp_client_uuid.uuid);
+       now = ktime_get_seconds();
+       deadline = jiffies_to_msecs(target->obd_recovery_timer.expires) /
+                  MSEC_PER_SEC;
+       if (now < deadline) {
+               struct target_distribute_txn_data *tdtd;
+               int size = 0;
+               int count = 0;
+               char *buf = NULL;
+
+               timeout = deadline - now;
+               tdtd = class_exp2tgt(exp)->lut_tdtd;
+               if (tdtd && tdtd->tdtd_show_update_logs_retrievers)
+                       buf = tdtd->tdtd_show_update_logs_retrievers(
+                               tdtd->tdtd_show_retrievers_cbdata,
+                               &size, &count);
+
+               if (count > 0)
+                       LCONSOLE_WARN("%s: Recovery already passed deadline "
+                                     "%lld:%.02lld. It is due to DNE recovery "
+                                     "failed/stuck on the %d MDT(s):%s. "
+                                     "Please wait until all MDTs recovered "
+                                     "or abort the recovery by force.\n",
+                                     target->obd_name, timeout / 60,
+                                     timeout % 60, count,
+                                     buf ? buf : "unknown (not enough RAM)");
+               else
+                       LCONSOLE_WARN("%s: Recovery already passed deadline "
+                                     "%lld:%.02lld. If you do not want to wait "
+                                     "more, please abort the recovery by "
+                                     "force.\n", target->obd_name,
+                                     timeout / 60, timeout % 60);
+
+               if (buf != NULL)
+                       OBD_FREE(buf, size);
+       } else {
+               timeout = now - deadline;
+               LCONSOLE_WARN("%s: Recovery already passed deadline"
+                       " %lld:%.02lld, It is most likely due to DNE"
+                       " recovery is failed or stuck, please wait a"
+                       " few more minutes or abort the recovery.\n",
+                       target->obd_name, timeout / 60, timeout % 60);
+       }
 
-       spin_lock(&exp->exp_lock);
-       exp->exp_need_sync = 0;
-       spin_unlock(&exp->exp_lock);
-       class_export_cb_put(exp);
+out_already:
+       conn->cookie = exp->exp_handle.h_cookie;
+       /* target_handle_connect() treats EALREADY and
+        * -EALREADY differently.  EALREADY means we are
+        * doing a valid reconnect from the same client. */
+       RETURN(EALREADY);
 }
-EXPORT_SYMBOL(target_client_add_cb);
 
 static void
 check_and_start_recovery_timer(struct obd_device *obd,
                                struct ptlrpc_request *req, int new_client);
 
+/**
+ * update flags for import during reconnect process
+ */
+static int rev_import_flags_update(struct obd_import *revimp,
+                                  struct ptlrpc_request *req)
+{
+       int rc;
+       struct obd_connect_data *data;
+
+       data = req_capsule_client_get(&req->rq_pill, &RMF_CONNECT_DATA);
+
+       if (data->ocd_connect_flags & OBD_CONNECT_AT)
+               revimp->imp_msghdr_flags |= MSGHDR_AT_SUPPORT;
+       else
+               revimp->imp_msghdr_flags &= ~MSGHDR_AT_SUPPORT;
+
+       revimp->imp_msghdr_flags |= MSGHDR_CKSUM_INCOMPAT18;
+
+       rc = sptlrpc_import_sec_adapt(revimp, req->rq_svc_ctx, &req->rq_flvr);
+       if (rc) {
+               CERROR("%s: cannot get reverse import %s security: rc = %d\n",
+                       revimp->imp_client->cli_name,
+                       libcfs_id2str(req->rq_peer), rc);
+               return rc;
+       }
+
+       return 0;
+}
+
+/**
+ * Allocate a new reverse import for an export.
+ *
+ * \retval -errno in case error hit
+ * \retval 0 if reverse import correctly init
+ **/
+int rev_import_init(struct obd_export *export)
+{
+       struct obd_device *obd = export->exp_obd;
+       struct obd_import *revimp;
+
+       LASSERT(export->exp_imp_reverse == NULL);
+
+       revimp = class_new_import(obd);
+       if (revimp == NULL)
+               return -ENOMEM;
+
+       revimp->imp_remote_handle.cookie = 0ULL;
+       revimp->imp_client = &obd->obd_ldlm_client;
+       revimp->imp_dlm_fake = 1;
+
+       /* it is safe to connect import in new state as no sends possible */
+       spin_lock(&export->exp_lock);
+       export->exp_imp_reverse = revimp;
+       spin_unlock(&export->exp_lock);
+       class_import_put(revimp);
+
+       return 0;
+}
+EXPORT_SYMBOL(rev_import_init);
+
+/**
+ * Handle reconnect for an export.
+ *
+ * \param exp export to handle reconnect process
+ * \param req client reconnect request
+ *
+ * \retval -rc in case securitfy flavor can't be changed
+ * \retval 0 in case none problems
+ */
+static int rev_import_reconnect(struct obd_export *exp,
+                               struct ptlrpc_request *req)
+{
+       struct obd_import *revimp = exp->exp_imp_reverse;
+       struct lustre_handle *lh;
+       int rc;
+
+       /* avoid sending a request until import flags are changed */
+       ptlrpc_import_enter_resend(revimp);
+
+       if (revimp->imp_connection != NULL)
+               ptlrpc_connection_put(revimp->imp_connection);
+
+       /*
+        * client from recovery don't have a handle so we need to take from
+        * request. it may produce situation when wrong client connected
+        * to recovery as we trust a client uuid
+        */
+       lh = req_capsule_client_get(&req->rq_pill, &RMF_CONN);
+       revimp->imp_remote_handle = *lh;
+
+       /* unknown versions will be caught in
+        * ptlrpc_handle_server_req_in->lustre_unpack_msg() */
+       revimp->imp_msg_magic = req->rq_reqmsg->lm_magic;
+
+       revimp->imp_connection = ptlrpc_connection_addref(exp->exp_connection);
+
+       rc = rev_import_flags_update(revimp, req);
+       if (rc != 0) {
+               /* it is safe to still be in RECOVERY phase as we are not able
+                * to setup correct security flavor so requests are not able to
+                * be delivered correctly */
+               return rc;
+       }
+
+       /* resend all rpc's via new connection */
+       return ptlrpc_import_recovery_state_machine(revimp);
+}
+
 int target_handle_connect(struct ptlrpc_request *req)
 {
-       struct obd_device *target = NULL, *targref = NULL;
-        struct obd_export *export = NULL;
-        struct obd_import *revimp;
-       struct obd_import *tmp_imp = NULL;
-        struct lustre_handle conn;
-        struct lustre_handle *tmp;
-        struct obd_uuid tgtuuid;
+       struct obd_device *target = NULL;
+       struct obd_export *export = NULL;
+       /* connect handle - filled from target_handle_reconnect in
+        * reconnect case */
+       struct lustre_handle conn;
+       struct lustre_handle *tmp;
         struct obd_uuid cluuid;
-        struct obd_uuid remote_uuid;
         char *str;
         int rc = 0;
         char *target_start;
         int target_len;
-       bool     mds_conn = false, lw_client = false;
+       bool     mds_conn = false, lw_client = false, initial_conn = false;
+       bool     mds_mds_conn = false;
+       bool     new_mds_mds_conn = false;
         struct obd_connect_data *data, *tmpdata;
         int size, tmpsize;
         lnet_nid_t *client_nid = NULL;
@@ -787,11 +982,7 @@ int target_handle_connect(struct ptlrpc_request *req)
                 GOTO(out, rc = -EINVAL);
         }
 
-        obd_str2uuid(&tgtuuid, str);
-        target = class_uuid2obd(&tgtuuid);
-        if (!target)
-                target = class_name2obd(str);
-
+       target = class_dev_by_str(str);
        if (!target) {
                deuuidify(str, NULL, &target_start, &target_len);
                LCONSOLE_ERROR_MSG(0x137, "%s: not available for connect "
@@ -803,6 +994,9 @@ int target_handle_connect(struct ptlrpc_request *req)
        }
 
        spin_lock(&target->obd_dev_lock);
+
+       target->obd_conn_inprogress++;
+
        if (target->obd_stopping || !target->obd_set_up) {
                spin_unlock(&target->obd_dev_lock);
 
@@ -824,12 +1018,6 @@ int target_handle_connect(struct ptlrpc_request *req)
                GOTO(out, rc = -EAGAIN);
        }
 
-       /* Make sure the target isn't cleaned up while we're here. Yes,
-        * there's still a race between the above check and our incref here.
-        * Really, class_uuid2obd should take the ref. */
-       targref = class_incref(target, __FUNCTION__, current);
-
-       target->obd_conn_inprogress++;
        spin_unlock(&target->obd_dev_lock);
 
         str = req_capsule_client_get(&req->rq_pill, &RMF_CLUUID);
@@ -840,21 +1028,6 @@ int target_handle_connect(struct ptlrpc_request *req)
 
         obd_str2uuid(&cluuid, str);
 
-       /* XXX Extract a nettype and format accordingly. */
-       switch (sizeof(lnet_nid_t)) {
-       /* NB the casts only avoid compiler warnings. */
-        case 8:
-                snprintf(remote_uuid.uuid, sizeof remote_uuid,
-                         "NET_"LPX64"_UUID", (__u64)req->rq_peer.nid);
-                break;
-        case 4:
-                snprintf(remote_uuid.uuid, sizeof remote_uuid,
-                         "NET_%x_UUID", (__u32)req->rq_peer.nid);
-                break;
-        default:
-                LBUG();
-        }
-
         tmp = req_capsule_client_get(&req->rq_pill, &RMF_CONN);
         if (tmp == NULL)
                 GOTO(out, rc = -EPROTO);
@@ -871,35 +1044,73 @@ int target_handle_connect(struct ptlrpc_request *req)
         if (rc)
                 GOTO(out, rc);
 
+#if LUSTRE_VERSION_CODE < OBD_OCD_VERSION(3, 0, 53, 0)
+       /* Don't allow clients to connect that are using old 1.8 format
+        * protocol conventions (LUSTRE_MSG_MAGIC_v1, !MSGHDR_CKSUM_INCOMPAT18,
+        * ldlm_flock_policy_wire format, MDT_ATTR_xTIME_SET, etc).  The
+        * FULL20 flag should be set on all connections since 2.0, but no
+        * longer affects behaviour.
+        *
+        * Later this check will be disabled and the flag can be retired
+        * completely once interop with 3.0 is no longer needed.
+        */
+       if (!(data->ocd_connect_flags & OBD_CONNECT_FULL20))
+               GOTO(out, rc = -EPROTO);
+
+       /* Don't allow liblustre clients to connect.
+        * - testing was disabled in v2_2_50_0-61-g6a75d65
+        * - building was disabled in v2_5_58_0-28-g7277179
+        * - client code was deleted in v2_6_50_0-101-gcdfbc72,
+        * - clients were refused connect for version difference > 0.0.1.32  */
        if (lustre_msg_get_op_flags(req->rq_reqmsg) & MSG_CONNECT_LIBCLIENT) {
-               if (data->ocd_version < LUSTRE_VERSION_CODE -
-                                              LUSTRE_VERSION_ALLOWED_OFFSET ||
-                   data->ocd_version > LUSTRE_VERSION_CODE +
-                                              LUSTRE_VERSION_ALLOWED_OFFSET) {
-                       DEBUG_REQ(D_WARNING, req, "Refusing %s (%d.%d.%d.%d) "
-                                 "libclient connection attempt",
-                                 data->ocd_version < LUSTRE_VERSION_CODE ?
-                                 "old" : "new",
-                                 OBD_OCD_VERSION_MAJOR(data->ocd_version),
-                                 OBD_OCD_VERSION_MINOR(data->ocd_version),
-                                 OBD_OCD_VERSION_PATCH(data->ocd_version),
-                                 OBD_OCD_VERSION_FIX(data->ocd_version));
-                       data = req_capsule_server_sized_get(&req->rq_pill,
-                                                           &RMF_CONNECT_DATA,
-                                   offsetof(typeof(*data), ocd_version) +
-                                            sizeof(data->ocd_version));
-                       if (data) {
-                               data->ocd_connect_flags = OBD_CONNECT_VERSION;
-                               data->ocd_version = LUSTRE_VERSION_CODE;
-                       }
-                       GOTO(out, rc = -EPROTO);
-               }
+               DEBUG_REQ(D_WARNING, req, "Refusing libclient connection");
+               GOTO(out, rc = -EPROTO);
        }
+#endif
+
+       /* Note: lw_client is needed in MDS-MDS failover during update log
+        * processing, so we needs to allow lw_client to be connected at
+        * anytime, instead of only the initial connection */
+       lw_client = (data->ocd_connect_flags & OBD_CONNECT_LIGHTWEIGHT) != 0;
 
        if (lustre_msg_get_op_flags(req->rq_reqmsg) & MSG_CONNECT_INITIAL) {
+               initial_conn = true;
                mds_conn = (data->ocd_connect_flags & OBD_CONNECT_MDS) != 0;
-               lw_client = (data->ocd_connect_flags &
-                            OBD_CONNECT_LIGHTWEIGHT) != 0;
+               mds_mds_conn = (data->ocd_connect_flags &
+                               OBD_CONNECT_MDS_MDS) != 0;
+
+               /* OBD_CONNECT_MNE_SWAB is defined as OBD_CONNECT_MDS_MDS
+                * for Imperative Recovery connection from MGC to MGS.
+                *
+                * Via check OBD_CONNECT_FID, we can distinguish whether
+                * the OBD_CONNECT_MDS_MDS/OBD_CONNECT_MNE_SWAB is from
+                * MGC or MDT, since MGC does not use OBD_CONNECT_FID.
+                */
+               if (!lw_client &&
+                   (data->ocd_connect_flags & OBD_CONNECT_MDS_MDS) &&
+                   (data->ocd_connect_flags & OBD_CONNECT_FID) &&
+                   (data->ocd_connect_flags & OBD_CONNECT_VERSION)) {
+                       __u32 major = OBD_OCD_VERSION_MAJOR(data->ocd_version);
+                       __u32 minor = OBD_OCD_VERSION_MINOR(data->ocd_version);
+                       __u32 patch = OBD_OCD_VERSION_PATCH(data->ocd_version);
+
+                       /* We do not support the MDT-MDT interoperations with
+                        * different version MDT because of protocol changes. */
+                       if (unlikely(major != LUSTRE_MAJOR ||
+                                    minor != LUSTRE_MINOR ||
+                                    abs(patch - LUSTRE_PATCH) > 3)) {
+                               LCONSOLE_WARN("%s (%u.%u.%u.%u) refused the "
+                                       "connection from different version MDT "
+                                       "(%d.%d.%d.%d) %s %s\n",
+                                       target->obd_name, LUSTRE_MAJOR,
+                                       LUSTRE_MINOR, LUSTRE_PATCH, LUSTRE_FIX,
+                                       major, minor, patch,
+                                       OBD_OCD_VERSION_FIX(data->ocd_version),
+                                       libcfs_nid2str(req->rq_peer.nid), str);
+
+                               GOTO(out, rc = -EPROTO);
+                       }
+               }
        }
 
         /* lctl gets a backstage, all-access pass. */
@@ -922,29 +1133,46 @@ int target_handle_connect(struct ptlrpc_request *req)
                class_export_put(export);
                export = NULL;
                rc = -EALREADY;
-       } else if ((mds_conn || lw_client) && export->exp_connection != NULL) {
+       } else if ((mds_conn || (lw_client && initial_conn) ||
+                  data->ocd_connect_flags & OBD_CONNECT_MDS_MDS) &&
+                  export->exp_connection != NULL) {
                spin_unlock(&export->exp_lock);
-               if (req->rq_peer.nid != export->exp_connection->c_peer.nid)
+               if (req->rq_peer.nid != export->exp_connection->c_peer.nid) {
                        /* MDS or LWP reconnected after failover. */
                        LCONSOLE_WARN("%s: Received %s connection from "
                            "%s, removing former export from %s\n",
                            target->obd_name, mds_conn ? "MDS" : "LWP",
                            libcfs_nid2str(req->rq_peer.nid),
                            libcfs_nid2str(export->exp_connection->c_peer.nid));
-               else
+               } else {
                        /* New MDS connection from the same NID. */
                        LCONSOLE_WARN("%s: Received new %s connection from "
                                "%s, removing former export from same NID\n",
                                target->obd_name, mds_conn ? "MDS" : "LWP",
                                libcfs_nid2str(req->rq_peer.nid));
-                class_fail_export(export);
-                class_export_put(export);
-                export = NULL;
-                rc = 0;
-        } else if (export->exp_connection != NULL &&
-                   req->rq_peer.nid != export->exp_connection->c_peer.nid &&
-                   (lustre_msg_get_op_flags(req->rq_reqmsg) &
-                    MSG_CONNECT_INITIAL)) {
+               }
+
+               if (req->rq_peer.nid == export->exp_connection->c_peer.nid &&
+                   data->ocd_connect_flags & OBD_CONNECT_MDS_MDS) {
+                       /* Because exports between MDTs will always be
+                        * kept, let's do not fail such export if they
+                        * come from the same NID, otherwise it might
+                        * cause eviction between MDTs, which might
+                        * cause namespace inconsistency */
+                       spin_lock(&export->exp_lock);
+                       export->exp_connecting = 1;
+                       export->exp_conn_cnt = 0;
+                       spin_unlock(&export->exp_lock);
+                       conn.cookie = export->exp_handle.h_cookie;
+                       rc = EALREADY;
+               } else {
+                       class_fail_export(export);
+                       class_export_put(export);
+                       export = NULL;
+                       rc = 0;
+               }
+       } else if (export->exp_connection != NULL && initial_conn &&
+                  req->rq_peer.nid != export->exp_connection->c_peer.nid) {
                spin_unlock(&export->exp_lock);
                /* In MDS failover we have static UUID but NID can change. */
                 LCONSOLE_WARN("%s: Client %s seen on new nid %s when "
@@ -975,28 +1203,29 @@ no_export:
                               target->obd_name, cluuid.uuid,
                               libcfs_nid2str(req->rq_peer.nid),
                              atomic_read(&export->exp_refcount));
-                GOTO(out, rc = -EBUSY);
-        } else if (lustre_msg_get_conn_cnt(req->rq_reqmsg) == 1) {
-                if (!strstr(cluuid.uuid, "mdt"))
-                        LCONSOLE_WARN("%s: Rejecting reconnect from the "
-                                      "known client %s (at %s) because it "
-                                      "is indicating it is a new client",
-                                      target->obd_name, cluuid.uuid,
-                                      libcfs_nid2str(req->rq_peer.nid));
-                GOTO(out, rc = -EALREADY);
-        } else {
-                OBD_FAIL_TIMEOUT(OBD_FAIL_TGT_DELAY_RECONNECT, 2 * obd_timeout);
-        }
+                       GOTO(out, rc = -EBUSY);
+       } else if (lustre_msg_get_conn_cnt(req->rq_reqmsg) == 1 &&
+                  rc != EALREADY) {
+               if (!strstr(cluuid.uuid, "mdt"))
+                       LCONSOLE_WARN("%s: Rejecting reconnect from the "
+                                     "known client %s (at %s) because it "
+                                     "is indicating it is a new client",
+                                     target->obd_name, cluuid.uuid,
+                                     libcfs_nid2str(req->rq_peer.nid));
+               GOTO(out, rc = -EALREADY);
+       } else {
+               OBD_FAIL_TIMEOUT(OBD_FAIL_TGT_DELAY_RECONNECT, 2 * obd_timeout);
+       }
 
         if (rc < 0) {
                 GOTO(out, rc);
         }
 
-        CDEBUG(D_HA, "%s: connection from %s@%s %st"LPU64" exp %p cur %ld last %ld\n",
-               target->obd_name, cluuid.uuid, libcfs_nid2str(req->rq_peer.nid),
-              target->obd_recovering ? "recovering/" : "", data->ocd_transno,
-              export, (long)cfs_time_current_sec(),
-              export ? (long)export->exp_last_request_time : 0);
+       CDEBUG(D_HA, "%s: connection from %s@%s %st%llu exp %p cur %lld last %lld\n",
+              target->obd_name, cluuid.uuid, libcfs_nid2str(req->rq_peer.nid),
+              target->obd_recovering ? "recovering/" : "", data->ocd_transno,
+              export, ktime_get_real_seconds(),
+              export ? export->exp_last_request_time : 0);
 
        /* If this is the first time a client connects, reset the recovery
         * timer. Discard lightweight connections which might be local. */
@@ -1019,44 +1248,60 @@ no_export:
 
         if (export == NULL) {
                /* allow lightweight connections during recovery */
-               if (target->obd_recovering && !lw_client) {
-                        cfs_time_t t;
-                       int     c; /* connected */
-                       int     i; /* in progress */
-                       int     k; /* known */
-                       int     s; /* stale/evicted */
+               /* allow "new" MDT to be connected during recovery, since we
+                * need retrieve recovery update records from it */
+               if (target->obd_recovering && !lw_client && !mds_mds_conn) {
+                       time64_t now;
+                       time64_t t;
+                       char *msg;
+                       int c; /* connected */
+                       int i; /* in progress */
+                       int k; /* known */
+                       int s; /* stale/evicted */
 
                        c = atomic_read(&target->obd_connected_clients);
                        i = atomic_read(&target->obd_lock_replay_clients);
                        k = target->obd_max_recoverable_clients;
                        s = target->obd_stale_clients;
-                       t = cfs_timer_deadline(&target->obd_recovery_timer);
-                       t = cfs_time_sub(t, cfs_time_current());
-                       t = cfs_duration_sec(t);
-                       LCONSOLE_WARN("%s: Denying connection for new client "
-                                     "%s (at %s), waiting for all %d known "
-                                     "clients (%d recovered, %d in progress, "
-                                     "and %d evicted) to recover in %d:%.02d\n",
+                       t = jiffies_to_msecs(target->obd_recovery_timer.expires);
+                       t /= MSEC_PER_SEC;
+                       now = ktime_get_seconds();
+                       if (now > t) {
+                               t = now - t;
+                               msg = "already passed deadline";
+                       } else {
+                               t -= now;
+                               msg = "to recover in";
+                       }
+
+                       LCONSOLE_WARN("%s: Denying connection for new client %s"
+                                     "(at %s), waiting for %d known clients "
+                                     "(%d recovered, %d in progress, and %d "
+                                     "evicted) %s %lld:%.02lld\n",
                                      target->obd_name, cluuid.uuid,
                                      libcfs_nid2str(req->rq_peer.nid), k,
-                                     c - i, i, s, (int)t / 60,
-                                     (int)t % 60);
-                        rc = -EBUSY;
-                } else {
+                                     c - i, i, s, msg, t / 60, t % 60);
+                       rc = -EBUSY;
+               } else {
 dont_check_exports:
-                        rc = obd_connect(req->rq_svc_thread->t_env,
-                                         &export, target, &cluuid, data,
-                                         client_nid);
+                       rc = obd_connect(req->rq_svc_thread->t_env,
+                                        &export, target, &cluuid, data,
+                                        client_nid);
                        if (mds_conn && OBD_FAIL_CHECK(OBD_FAIL_TGT_RCVG_FLAG))
                                lustre_msg_add_op_flags(req->rq_repmsg,
-                                               MSG_CONNECT_RECOVERING);
-                        if (rc == 0)
-                                conn.cookie = export->exp_handle.h_cookie;
-                }
-        } else {
-                rc = obd_reconnect(req->rq_svc_thread->t_env,
-                                   export, target, &cluuid, data, client_nid);
-        }
+                                                       MSG_CONNECT_RECOVERING);
+                       if (rc == 0) {
+                               conn.cookie = export->exp_handle.h_cookie;
+                               rc = rev_import_init(export);
+                       }
+
+                       if (mds_mds_conn)
+                               new_mds_mds_conn = true;
+               }
+       } else {
+               rc = obd_reconnect(req->rq_svc_thread->t_env,
+                                  export, target, &cluuid, data, client_nid);
+       }
        if (rc)
                GOTO(out, rc);
 
@@ -1076,11 +1321,6 @@ dont_check_exports:
                 memcpy(tmpdata, data, min(tmpsize, size));
         }
 
-        /* If all else goes well, this is our RPC return code. */
-        req->rq_status = 0;
-
-        lustre_msg_set_handle(req->rq_repmsg, &conn);
-
         /* If the client and the server are the same node, we will already
          * have an export that really points to the client's DLM export,
          * because we have a shared handles table.
@@ -1095,46 +1335,40 @@ dont_check_exports:
                spin_unlock(&export->exp_lock);
                CDEBUG(D_RPCTRACE, "%s: %s already connected at greater "
                       "or equal conn_cnt: %d >= %d\n",
-                       cluuid.uuid, libcfs_nid2str(req->rq_peer.nid),
-                       export->exp_conn_cnt,
-                       lustre_msg_get_conn_cnt(req->rq_reqmsg));
-
-                GOTO(out, rc = -EALREADY);
-        }
-        LASSERT(lustre_msg_get_conn_cnt(req->rq_reqmsg) > 0);
-        export->exp_conn_cnt = lustre_msg_get_conn_cnt(req->rq_reqmsg);
+                      cluuid.uuid, libcfs_nid2str(req->rq_peer.nid),
+                      export->exp_conn_cnt,
+                      lustre_msg_get_conn_cnt(req->rq_reqmsg));
 
-       /* Don't evict liblustre clients for not pinging. */
-        if (lustre_msg_get_op_flags(req->rq_reqmsg) & MSG_CONNECT_LIBCLIENT) {
-                export->exp_libclient = 1;
-               spin_unlock(&export->exp_lock);
-
-               spin_lock(&target->obd_dev_lock);
-               list_del_init(&export->exp_obd_chain_timed);
-               spin_unlock(&target->obd_dev_lock);
-       } else {
-               spin_unlock(&export->exp_lock);
+               GOTO(out, rc = -EALREADY);
        }
+       LASSERT(lustre_msg_get_conn_cnt(req->rq_reqmsg) > 0);
+       export->exp_conn_cnt = lustre_msg_get_conn_cnt(req->rq_reqmsg);
+       spin_unlock(&export->exp_lock);
 
-        if (export->exp_connection != NULL) {
+       if (export->exp_connection != NULL) {
                /* Check to see if connection came from another NID. */
-                if ((export->exp_connection->c_peer.nid != req->rq_peer.nid) &&
+               if ((export->exp_connection->c_peer.nid != req->rq_peer.nid) &&
                    !hlist_unhashed(&export->exp_nid_hash))
-                        cfs_hash_del(export->exp_obd->obd_nid_hash,
-                                     &export->exp_connection->c_peer.nid,
-                                     &export->exp_nid_hash);
+                       cfs_hash_del(export->exp_obd->obd_nid_hash,
+                                    &export->exp_connection->c_peer.nid,
+                                    &export->exp_nid_hash);
 
-                ptlrpc_connection_put(export->exp_connection);
-        }
+               ptlrpc_connection_put(export->exp_connection);
+       }
 
-        export->exp_connection = ptlrpc_connection_get(req->rq_peer,
-                                                       req->rq_self,
-                                                       &remote_uuid);
-       if (hlist_unhashed(&export->exp_nid_hash)) {
-                cfs_hash_add(export->exp_obd->obd_nid_hash,
-                             &export->exp_connection->c_peer.nid,
-                             &export->exp_nid_hash);
-        }
+       export->exp_connection = ptlrpc_connection_get(req->rq_peer,
+                                                      req->rq_self,
+                                                      &cluuid);
+       if (hlist_unhashed(&export->exp_nid_hash))
+               cfs_hash_add(export->exp_obd->obd_nid_hash,
+                            &export->exp_connection->c_peer.nid,
+                            &export->exp_nid_hash);
+
+       lustre_msg_set_handle(req->rq_repmsg, &conn);
+
+       rc = rev_import_reconnect(export, req);
+       if (rc != 0)
+               GOTO(out, rc);
 
        if (target->obd_recovering && !export->exp_in_recovery && !lw_client) {
                 int has_transno;
@@ -1169,6 +1403,14 @@ dont_check_exports:
 
                atomic_inc(&target->obd_req_replay_clients);
                atomic_inc(&target->obd_lock_replay_clients);
+               /* Note: MDS-MDS connection is allowed to be connected during
+                * recovery, no matter if the exports needs to be recoveried.
+                * Because we need retrieve updates logs from all other MDTs.
+                * So if the MDS-MDS export is new, obd_max_recoverable_clients
+                * also needs to be increased to match other recovery checking
+                * condition. */
+               if (new_mds_mds_conn)
+                       target->obd_max_recoverable_clients++;
                if (atomic_inc_return(&target->obd_connected_clients) ==
                    target->obd_max_recoverable_clients)
                        wake_up(&target->obd_next_transno_waitq);
@@ -1178,59 +1420,7 @@ dont_check_exports:
        if (target->obd_recovering && !lw_client)
                 lustre_msg_add_op_flags(req->rq_repmsg, MSG_CONNECT_RECOVERING);
 
-        tmp = req_capsule_client_get(&req->rq_pill, &RMF_CONN);
-        conn = *tmp;
-
-       /* Return -ENOTCONN in case of errors to let client reconnect. */
-       revimp = class_new_import(target);
-       if (revimp == NULL) {
-               CERROR("fail to alloc new reverse import.\n");
-               GOTO(out, rc = -ENOTCONN);
-       }
-
-       spin_lock(&export->exp_lock);
-       if (export->exp_imp_reverse != NULL)
-               /* destroyed import can be still referenced in ctxt */
-               tmp_imp = export->exp_imp_reverse;
-       export->exp_imp_reverse = revimp;
-       spin_unlock(&export->exp_lock);
-
-        revimp->imp_connection = ptlrpc_connection_addref(export->exp_connection);
-        revimp->imp_client = &export->exp_obd->obd_ldlm_client;
-        revimp->imp_remote_handle = conn;
-        revimp->imp_dlm_fake = 1;
-        revimp->imp_state = LUSTRE_IMP_FULL;
-
-       /* Unknown versions will be caught in
-        * ptlrpc_handle_server_req_in->lustre_unpack_msg(). */
-        revimp->imp_msg_magic = req->rq_reqmsg->lm_magic;
-
-       if ((data->ocd_connect_flags & OBD_CONNECT_AT) &&
-           (revimp->imp_msg_magic != LUSTRE_MSG_MAGIC_V1))
-               revimp->imp_msghdr_flags |= MSGHDR_AT_SUPPORT;
-       else
-               revimp->imp_msghdr_flags &= ~MSGHDR_AT_SUPPORT;
-
-       if ((data->ocd_connect_flags & OBD_CONNECT_FULL20) &&
-            (revimp->imp_msg_magic != LUSTRE_MSG_MAGIC_V1))
-                revimp->imp_msghdr_flags |= MSGHDR_CKSUM_INCOMPAT18;
-        else
-                revimp->imp_msghdr_flags &= ~MSGHDR_CKSUM_INCOMPAT18;
-
-       rc = sptlrpc_import_sec_adapt(revimp, req->rq_svc_ctx, &req->rq_flvr);
-       if (rc) {
-               CERROR("Failed to get sec for reverse import: %d\n", rc);
-               spin_lock(&export->exp_lock);
-               export->exp_imp_reverse = NULL;
-               spin_unlock(&export->exp_lock);
-               class_destroy_import(revimp);
-       }
-
-       class_import_put(revimp);
-
 out:
-       if (tmp_imp != NULL)
-               client_destroy_import(tmp_imp);
        if (export) {
                spin_lock(&export->exp_lock);
                export->exp_connecting = 0;
@@ -1238,18 +1428,15 @@ out:
 
                class_export_put(export);
        }
-       if (targref) {
+       if (target != NULL) {
                spin_lock(&target->obd_dev_lock);
                target->obd_conn_inprogress--;
                spin_unlock(&target->obd_dev_lock);
-
-               class_decref(targref, __func__, current);
+               class_decref(target, "find", current);
        }
-       if (rc)
-               req->rq_status = rc;
+       req->rq_status = rc;
        RETURN(rc);
 }
-EXPORT_SYMBOL(target_handle_connect);
 
 int target_handle_disconnect(struct ptlrpc_request *req)
 {
@@ -1265,7 +1452,6 @@ int target_handle_disconnect(struct ptlrpc_request *req)
 
         RETURN(0);
 }
-EXPORT_SYMBOL(target_handle_disconnect);
 
 void target_destroy_export(struct obd_export *exp)
 {
@@ -1318,6 +1504,7 @@ static int target_exp_enqueue_req_replay(struct ptlrpc_request *req)
         __u64                  transno = lustre_msg_get_transno(req->rq_reqmsg);
         struct obd_export     *exp = req->rq_export;
         struct ptlrpc_request *reqiter;
+       struct ptlrpc_request *dup_req = NULL;
         int                    dup = 0;
 
         LASSERT(exp);
@@ -1326,6 +1513,7 @@ static int target_exp_enqueue_req_replay(struct ptlrpc_request *req)
        list_for_each_entry(reqiter, &exp->exp_req_replay_queue,
                                 rq_replay_list) {
                 if (lustre_msg_get_transno(reqiter->rq_reqmsg) == transno) {
+                       dup_req = reqiter;
                         dup = 1;
                         break;
                 }
@@ -1337,6 +1525,16 @@ static int target_exp_enqueue_req_replay(struct ptlrpc_request *req)
                      (MSG_RESENT | MSG_REPLAY)) != (MSG_RESENT | MSG_REPLAY))
                         CERROR("invalid flags %x of resent replay\n",
                                lustre_msg_get_flags(req->rq_reqmsg));
+
+               if (lustre_msg_get_flags(req->rq_reqmsg) & MSG_REPLAY) {
+                       __u32 new_conn;
+
+                       new_conn = lustre_msg_get_conn_cnt(req->rq_reqmsg);
+                       if (new_conn >
+                           lustre_msg_get_conn_cnt(dup_req->rq_reqmsg))
+                               lustre_msg_set_conn_cnt(dup_req->rq_reqmsg,
+                                                       new_conn);
+               }
         } else {
                list_add_tail(&req->rq_replay_list,
                                   &exp->exp_req_replay_queue);
@@ -1356,24 +1554,27 @@ static void target_exp_dequeue_req_replay(struct ptlrpc_request *req)
        spin_unlock(&req->rq_export->exp_lock);
 }
 
-static void target_finish_recovery(struct obd_device *obd)
+static void target_finish_recovery(struct lu_target *lut)
 {
+       struct obd_device *obd = lut->lut_obd;
         ENTRY;
 
        /* Only log a recovery message when recovery has occurred. */
        if (obd->obd_recovery_start) {
-               time_t elapsed_time = max_t(time_t, 1, cfs_time_current_sec() -
-                                       obd->obd_recovery_start);
-               LCONSOLE_INFO("%s: Recovery over after %d:%.02d, of %d clients "
+               time64_t now = ktime_get_real_seconds();
+               time64_t elapsed_time;
+
+               elapsed_time = max_t(time64_t, now - obd->obd_recovery_start, 1);
+               LCONSOLE_INFO("%s: Recovery over after %lld:%.02lld, of %d clients "
                        "%d recovered and %d %s evicted.\n", obd->obd_name,
-                       (int)elapsed_time / 60, (int)elapsed_time % 60,
+                       (s64)elapsed_time / 60, (s64)elapsed_time % 60,
                        obd->obd_max_recoverable_clients,
                        atomic_read(&obd->obd_connected_clients),
                        obd->obd_stale_clients,
                        obd->obd_stale_clients == 1 ? "was" : "were");
        }
 
-        ldlm_reprocess_all_ns(obd->obd_namespace);
+       ldlm_reprocess_recovery_done(obd->obd_namespace);
        spin_lock(&obd->obd_recovery_task_lock);
        if (!list_empty(&obd->obd_req_replay_queue) ||
            !list_empty(&obd->obd_lock_replay_queue) ||
@@ -1390,15 +1591,16 @@ static void target_finish_recovery(struct obd_device *obd)
        }
        spin_unlock(&obd->obd_recovery_task_lock);
 
-        obd->obd_recovery_end = cfs_time_current_sec();
+       obd->obd_recovery_end = ktime_get_real_seconds();
 
        /* When recovery finished, cleanup orphans on MDS and OST. */
-        if (OBT(obd) && OBP(obd, postrecov)) {
-                int rc = OBP(obd, postrecov)(obd);
-                if (rc < 0)
-                        LCONSOLE_WARN("%s: Post recovery failed, rc %d\n",
-                                      obd->obd_name, rc);
-        }
+       if (obd->obd_type && OBP(obd, postrecov)) {
+               int rc = OBP(obd, postrecov)(obd);
+
+               if (rc < 0)
+                       LCONSOLE_WARN("%s: Post recovery failed, rc %d\n",
+                                     obd->obd_name, rc);
+       }
         EXIT;
 }
 
@@ -1456,7 +1658,6 @@ void target_cleanup_recovery(struct obd_device *obd)
 {
         struct ptlrpc_request *req, *n;
        struct list_head clean_list;
-        ENTRY;
 
        INIT_LIST_HEAD(&clean_list);
        spin_lock(&obd->obd_dev_lock);
@@ -1474,7 +1675,7 @@ void target_cleanup_recovery(struct obd_device *obd)
        spin_unlock(&obd->obd_recovery_task_lock);
 
        list_for_each_entry_safe(req, n, &clean_list, rq_list) {
-               LASSERT(req->rq_reply_state == 0);
+               LASSERT(req->rq_reply_state == NULL);
                target_exp_dequeue_req_replay(req);
                target_request_copy_put(req);
        }
@@ -1485,7 +1686,7 @@ void target_cleanup_recovery(struct obd_device *obd)
        spin_unlock(&obd->obd_recovery_task_lock);
 
        list_for_each_entry_safe(req, n, &clean_list, rq_list) {
-                LASSERT(req->rq_reply_state == 0);
+               LASSERT(req->rq_reply_state == NULL);
                 target_request_copy_put(req);
         }
 
@@ -1497,9 +1698,8 @@ EXPORT_SYMBOL(target_cleanup_recovery);
 void target_cancel_recovery_timer(struct obd_device *obd)
 {
         CDEBUG(D_HA, "%s: cancel recovery timer\n", obd->obd_name);
-        cfs_timer_disarm(&obd->obd_recovery_timer);
+       del_timer(&obd->obd_recovery_timer);
 }
-EXPORT_SYMBOL(target_cancel_recovery_timer);
 
 static void target_start_recovery_timer(struct obd_device *obd)
 {
@@ -1519,19 +1719,18 @@ static void target_start_recovery_timer(struct obd_device *obd)
                return;
        }
 
-       cfs_timer_arm(&obd->obd_recovery_timer,
-                     cfs_time_shift(obd->obd_recovery_timeout));
-       obd->obd_recovery_start = cfs_time_current_sec();
+       mod_timer(&obd->obd_recovery_timer,
+                 jiffies + cfs_time_seconds(obd->obd_recovery_timeout));
+       obd->obd_recovery_start = ktime_get_real_seconds();
        spin_unlock(&obd->obd_dev_lock);
 
-        LCONSOLE_WARN("%s: Will be in recovery for at least %d:%.02d, "
-                      "or until %d client%s reconnect%s\n",
-                      obd->obd_name,
-                      obd->obd_recovery_timeout / 60,
-                      obd->obd_recovery_timeout % 60,
-                      obd->obd_max_recoverable_clients,
-                      (obd->obd_max_recoverable_clients == 1) ? "" : "s",
-                      (obd->obd_max_recoverable_clients == 1) ? "s": "");
+       LCONSOLE_WARN("%s: Will be in recovery for at least %llu:%02llu, or until %d client%s reconnect%s\n",
+                     obd->obd_name,
+                     obd->obd_recovery_timeout / 60,
+                     obd->obd_recovery_timeout % 60,
+                     obd->obd_max_recoverable_clients,
+                     (obd->obd_max_recoverable_clients == 1) ? "" : "s",
+                     (obd->obd_max_recoverable_clients == 1) ? "s": "");
 }
 
 /**
@@ -1540,45 +1739,48 @@ static void target_start_recovery_timer(struct obd_device *obd)
  * if @extend is true, extend recovery window to have @drt remaining at least;
  * otherwise, make sure the recovery timeout value is not less than @drt.
  */
-static void extend_recovery_timer(struct obd_device *obd, int drt, bool extend)
+static void extend_recovery_timer(struct obd_device *obd, time64_t drt,
+                                 bool extend)
 {
-       cfs_time_t now;
-       cfs_time_t end;
-       cfs_duration_t left;
-       int to;
+       time64_t now;
+       time64_t end;
+       time64_t left;
+       time64_t to;
 
        spin_lock(&obd->obd_dev_lock);
        if (!obd->obd_recovering || obd->obd_abort_recovery) {
                spin_unlock(&obd->obd_dev_lock);
-                return;
-        }
-        LASSERT(obd->obd_recovery_start != 0);
+               return;
+       }
+       LASSERT(obd->obd_recovery_start != 0);
 
-        now  = cfs_time_current_sec();
-        to   = obd->obd_recovery_timeout;
-        end  = obd->obd_recovery_start + to;
-        left = cfs_time_sub(end, now);
+       now = ktime_get_real_seconds();
+       to = obd->obd_recovery_timeout;
+       end = obd->obd_recovery_start + to;
+       left = end - now;
 
         if (extend && (drt > left)) {
                 to += drt - left;
         } else if (!extend && (drt > to)) {
                 to = drt;
-                /* reduce drt by already passed time */
-                drt -= obd->obd_recovery_timeout - left;
         }
 
-        if (to > obd->obd_recovery_time_hard)
-                to = obd->obd_recovery_time_hard;
-       if (obd->obd_recovery_timeout < to ||
-           obd->obd_recovery_timeout == obd->obd_recovery_time_hard) {
+       if (to > obd->obd_recovery_time_hard) {
+               to = obd->obd_recovery_time_hard;
+               CWARN("%s: extended recovery timer reaching hard limit: %lld, extend: %d\n",
+                     obd->obd_name, to, extend);
+       }
+
+       if (obd->obd_recovery_timeout < to) {
                 obd->obd_recovery_timeout = to;
-                cfs_timer_arm(&obd->obd_recovery_timer,
-                              cfs_time_shift(drt));
+               end = obd->obd_recovery_start + to;
+               mod_timer(&obd->obd_recovery_timer,
+                         jiffies + cfs_time_seconds(end - now));
         }
        spin_unlock(&obd->obd_dev_lock);
 
-       CDEBUG(D_HA, "%s: recovery timer will expire in %u seconds\n",
-              obd->obd_name, (unsigned)drt);
+       CDEBUG(D_HA, "%s: recovery timer will expire in %lld seconds\n",
+               obd->obd_name, (s64)(end - now));
 }
 
 /* Reset the timer with each new client connection */
@@ -1597,7 +1799,7 @@ check_and_start_recovery_timer(struct obd_device *obd,
                                struct ptlrpc_request *req,
                                int new_client)
 {
-        int service_time = lustre_msg_get_service_time(req->rq_reqmsg);
+       time64_t service_time = lustre_msg_get_service_time(req->rq_reqmsg);
         struct obd_device_target *obt = &obd->u.obt;
 
         if (!new_client && service_time)
@@ -1609,9 +1811,14 @@ check_and_start_recovery_timer(struct obd_device *obd,
         target_start_recovery_timer(obd);
 
        /* Convert the service time to RPC timeout,
-        * and reuse service_time to limit stack usage. */
+        * and reuse service_time to limit stack usage.
+        */
        service_time = at_est2timeout(service_time);
 
+       if (OBD_FAIL_CHECK(OBD_FAIL_TGT_SLUGGISH_NET) &&
+           service_time < at_extra)
+               service_time = at_extra;
+
        /* We expect other clients to timeout within service_time, then try
         * to reconnect, then try the failover server.  The max delay between
         * connect attempts is SWITCH_MAX + SWITCH_INC + INITIAL. */
@@ -1635,6 +1842,14 @@ static inline int exp_req_replay_healthy(struct obd_export *exp)
        return (!exp->exp_req_replay_needed ||
                atomic_read(&exp->exp_replay_count) > 0);
 }
+
+
+static inline int exp_req_replay_healthy_or_from_mdt(struct obd_export *exp)
+{
+       return (exp_connect_flags(exp) & OBD_CONNECT_MDS_MDS) ||
+              exp_req_replay_healthy(exp);
+}
+
 /** if export done lock_replay or has replay in queue */
 static inline int exp_lock_replay_healthy(struct obd_export *exp)
 {
@@ -1652,23 +1867,21 @@ static inline int exp_finished(struct obd_export *exp)
         return (exp->exp_in_recovery && !exp->exp_lock_replay_needed);
 }
 
-/** Checking routines for recovery */
-static int check_for_clients(struct obd_device *obd)
+static inline int exp_finished_or_from_mdt(struct obd_export *exp)
 {
-       unsigned int clnts = atomic_read(&obd->obd_connected_clients);
-
-       if (obd->obd_abort_recovery || obd->obd_recovery_expired)
-               return 1;
-       LASSERT(clnts <= obd->obd_max_recoverable_clients);
-       return (clnts + obd->obd_stale_clients ==
-               obd->obd_max_recoverable_clients);
+       return (exp_connect_flags(exp) & OBD_CONNECT_MDS_MDS) ||
+               exp_finished(exp);
 }
 
-static int check_for_next_transno(struct obd_device *obd)
+static int check_for_next_transno(struct lu_target *lut)
 {
        struct ptlrpc_request *req = NULL;
+       struct obd_device *obd = lut->lut_obd;
+       struct target_distribute_txn_data *tdtd = lut->lut_tdtd;
        int wake_up = 0, connected, completed, queue_len;
-       __u64 next_transno, req_transno;
+       __u64 req_transno = 0;
+       __u64 update_transno = 0;
+       __u64 next_transno = 0;
        ENTRY;
 
        spin_lock(&obd->obd_recovery_task_lock);
@@ -1676,17 +1889,18 @@ static int check_for_next_transno(struct obd_device *obd)
                req = list_entry(obd->obd_req_replay_queue.next,
                                     struct ptlrpc_request, rq_list);
                req_transno = lustre_msg_get_transno(req->rq_reqmsg);
-       } else {
-               req_transno = 0;
        }
 
+       if (tdtd != NULL)
+               update_transno = distribute_txn_get_next_transno(tdtd);
+
        connected = atomic_read(&obd->obd_connected_clients);
        completed = connected - atomic_read(&obd->obd_req_replay_clients);
        queue_len = obd->obd_requests_queued_for_recovery;
        next_transno = obd->obd_next_recovery_transno;
 
        CDEBUG(D_HA, "max: %d, connected: %d, completed: %d, queue_len: %d, "
-              "req_transno: "LPU64", next_transno: "LPU64"\n",
+              "req_transno: %llu, next_transno: %llu\n",
               obd->obd_max_recoverable_clients, connected, completed,
               queue_len, req_transno, next_transno);
 
@@ -1696,26 +1910,30 @@ static int check_for_next_transno(struct obd_device *obd)
        } else if (obd->obd_recovery_expired) {
                CDEBUG(D_HA, "waking for expired recovery\n");
                wake_up = 1;
-       } else if (req_transno == next_transno) {
-               CDEBUG(D_HA, "waking for next ("LPD64")\n", next_transno);
+       } else if (tdtd != NULL && req != NULL &&
+                  is_req_replayed_by_update(req)) {
+               LASSERTF(req_transno < next_transno, "req_transno %llu"
+                        "next_transno%llu\n", req_transno, next_transno);
+               CDEBUG(D_HA, "waking for duplicate req (%llu)\n",
+                      req_transno);
+               wake_up = 1;
+       } else if (req_transno == next_transno ||
+                  (update_transno != 0 && update_transno <= next_transno)) {
+               CDEBUG(D_HA, "waking for next (%lld)\n", next_transno);
                wake_up = 1;
        } else if (queue_len > 0 &&
                   queue_len == atomic_read(&obd->obd_req_replay_clients)) {
-               int d_lvl = D_HA;
                /** handle gaps occured due to lost reply or VBR */
                LASSERTF(req_transno >= next_transno,
-                        "req_transno: "LPU64", next_transno: "LPU64"\n",
+                        "req_transno: %llu, next_transno: %llu\n",
                         req_transno, next_transno);
-               if (req_transno > obd->obd_last_committed &&
-                   !obd->obd_version_recov)
-                       d_lvl = D_ERROR;
-               CDEBUG(d_lvl,
+               CDEBUG(D_HA,
                       "%s: waking for gap in transno, VBR is %s (skip: "
-                      LPD64", ql: %d, comp: %d, conn: %d, next: "LPD64
-                      ", last_committed: "LPD64")\n",
+                      "%lld, ql: %d, comp: %d, conn: %d, next: %lld"
+                      ", next_update %lld last_committed: %lld)\n",
                       obd->obd_name, obd->obd_version_recov ? "ON" : "OFF",
                       next_transno, queue_len, completed, connected,
-                      req_transno, obd->obd_last_committed);
+                      req_transno, update_transno, obd->obd_last_committed);
                obd->obd_next_recovery_transno = req_transno;
                wake_up = 1;
        } else if (atomic_read(&obd->obd_req_replay_clients) == 0) {
@@ -1723,7 +1941,7 @@ static int check_for_next_transno(struct obd_device *obd)
                wake_up = 1;
        } else if (OBD_FAIL_CHECK(OBD_FAIL_MDS_RECOVERY_ACCEPTS_GAPS)) {
                CDEBUG(D_HA, "accepting transno gaps is explicitly allowed"
-                      " by fail_lock, waking up ("LPD64")\n", next_transno);
+                      " by fail_lock, waking up (%lld)\n", next_transno);
                obd->obd_next_recovery_transno = req_transno;
                wake_up = 1;
        }
@@ -1731,8 +1949,9 @@ static int check_for_next_transno(struct obd_device *obd)
        return wake_up;
 }
 
-static int check_for_next_lock(struct obd_device *obd)
+static int check_for_next_lock(struct lu_target *lut)
 {
+       struct obd_device *obd = lut->lut_obd;
        int wake_up = 0;
 
        spin_lock(&obd->obd_recovery_task_lock);
@@ -1759,14 +1978,97 @@ static int check_for_next_lock(struct obd_device *obd)
  * check its status with help of check_routine
  * evict dead clients via health_check
  */
-static int target_recovery_overseer(struct obd_device *obd,
-                                   int (*check_routine)(struct obd_device *),
+static int target_recovery_overseer(struct lu_target *lut,
+                                   int (*check_routine)(struct lu_target *),
                                    int (*health_check)(struct obd_export *))
 {
+       struct obd_device       *obd = lut->lut_obd;
+       struct target_distribute_txn_data *tdtd;
+       time64_t last = 0;
+       time64_t now;
 repeat:
-       wait_event(obd->obd_next_transno_waitq, check_routine(obd));
+       if (obd->obd_recovering && obd->obd_recovery_start == 0) {
+               now = ktime_get_seconds();
+               if (now - last > 600) {
+                       LCONSOLE_INFO("%s: in recovery but waiting for "
+                                     "the first client to connect\n",
+                                     obd->obd_name);
+                       last = now;
+               }
+       }
+       if (obd->obd_recovery_start != 0 && ktime_get_real_seconds() >=
+             (obd->obd_recovery_start + obd->obd_recovery_time_hard)) {
+               __u64 next_update_transno = 0;
+
+               /* Only abort the recovery if there are no update recovery
+                * left in the queue */
+               spin_lock(&obd->obd_recovery_task_lock);
+               if (lut->lut_tdtd != NULL) {
+                       next_update_transno =
+                               distribute_txn_get_next_transno(lut->lut_tdtd);
+
+                       tdtd = lut->lut_tdtd;
+                       /* If next_update_transno == 0, it probably because
+                        * updatelog retrieve threads did not get any records
+                        * yet, let's wait those threads stopped */
+                       if (next_update_transno == 0) {
+                               struct l_wait_info lwi = { 0 };
+
+                               l_wait_event(tdtd->tdtd_recovery_threads_waitq,
+                                      atomic_read(
+                                      &tdtd->tdtd_recovery_threads_count) == 0,
+                                      &lwi);
+
+                               next_update_transno =
+                                       distribute_txn_get_next_transno(
+                                                               lut->lut_tdtd);
+                       }
+               }
+
+               if (next_update_transno != 0 && !obd->obd_abort_recovery) {
+                       obd->obd_next_recovery_transno = next_update_transno;
+                       spin_unlock(&obd->obd_recovery_task_lock);
+                       /* Disconnect unfinished exports from clients, and
+                        * keep connection from MDT to make sure the update
+                        * recovery will still keep trying until some one
+                        * manually abort the recovery */
+                       class_disconnect_stale_exports(obd,
+                                               exp_finished_or_from_mdt);
+                       /* Abort all of replay and replay lock req from
+                        * clients */
+                       abort_req_replay_queue(obd);
+                       abort_lock_replay_queue(obd);
+                       CDEBUG(D_HA, "%s: there are still update replay (%#llx"
+                              ")in the queue.\n", obd->obd_name,
+                              next_update_transno);
+               } else {
+                       obd->obd_abort_recovery = 1;
+                       spin_unlock(&obd->obd_recovery_task_lock);
+                       CWARN("%s recovery is aborted by hard timeout\n",
+                             obd->obd_name);
+               }
+       }
+
+       while (wait_event_timeout(obd->obd_next_transno_waitq,
+                                 check_routine(lut),
+                                 msecs_to_jiffies(60 * MSEC_PER_SEC)) == 0)
+               /* wait indefinitely for event, but don't trigger watchdog */;
+
        if (obd->obd_abort_recovery) {
                CWARN("recovery is aborted, evict exports in recovery\n");
+               if (lut->lut_tdtd != NULL) {
+                       struct l_wait_info lwi = { 0 };
+
+                       tdtd = lut->lut_tdtd;
+                       /* Let's wait all of the update log recovery thread
+                        * finished */
+                       l_wait_event(tdtd->tdtd_recovery_threads_waitq,
+                        atomic_read(&tdtd->tdtd_recovery_threads_count) == 0,
+                            &lwi);
+                       /* Then abort the update recovery list */
+                       dtrq_list_destroy(lut->lut_tdtd);
+               }
+
                /** evict exports which didn't finish recovery yet */
                class_disconnect_stale_exports(obd, exp_finished);
                return 1;
@@ -1777,6 +2079,7 @@ repeat:
                              "evict stale exports\n", obd->obd_name);
                /** evict cexports with no replay in queue, they are stalled */
                class_disconnect_stale_exports(obd, health_check);
+
                /** continue with VBR */
                spin_lock(&obd->obd_dev_lock);
                obd->obd_version_recov = 1;
@@ -1792,45 +2095,13 @@ repeat:
        return 0;
 }
 
-static struct ptlrpc_request *target_next_replay_req(struct obd_device *obd)
-{
-       struct ptlrpc_request *req = NULL;
-       ENTRY;
-
-       CDEBUG(D_HA, "Waiting for transno "LPD64"\n",
-               obd->obd_next_recovery_transno);
-
-       CFS_FAIL_TIMEOUT(OBD_FAIL_TGT_REPLAY_DELAY2, cfs_fail_val);
-
-       if (target_recovery_overseer(obd, check_for_next_transno,
-                                    exp_req_replay_healthy)) {
-               abort_req_replay_queue(obd);
-               abort_lock_replay_queue(obd);
-       }
-
-       spin_lock(&obd->obd_recovery_task_lock);
-       if (!list_empty(&obd->obd_req_replay_queue)) {
-               req = list_entry(obd->obd_req_replay_queue.next,
-                                    struct ptlrpc_request, rq_list);
-               list_del_init(&req->rq_list);
-               obd->obd_requests_queued_for_recovery--;
-               spin_unlock(&obd->obd_recovery_task_lock);
-       } else {
-               spin_unlock(&obd->obd_recovery_task_lock);
-               LASSERT(list_empty(&obd->obd_req_replay_queue));
-               LASSERT(atomic_read(&obd->obd_req_replay_clients) == 0);
-               /** evict exports failed VBR */
-               class_disconnect_stale_exports(obd, exp_vbr_healthy);
-       }
-       RETURN(req);
-}
-
-static struct ptlrpc_request *target_next_replay_lock(struct obd_device *obd)
+static struct ptlrpc_request *target_next_replay_lock(struct lu_target *lut)
 {
+       struct obd_device       *obd = lut->lut_obd;
        struct ptlrpc_request *req = NULL;
 
        CDEBUG(D_HA, "Waiting for lock\n");
-       if (target_recovery_overseer(obd, check_for_next_lock,
+       if (target_recovery_overseer(lut, check_for_next_lock,
                                     exp_lock_replay_healthy))
                abort_lock_replay_queue(obd);
 
@@ -1895,7 +2166,7 @@ static void handle_recovery_req(struct ptlrpc_thread *thread,
 
         /* don't reset timer for final stage */
         if (!exp_finished(req->rq_export)) {
-                int to = obd_timeout;
+               time64_t to = obd_timeout;
 
                 /**
                  * Add request timeout to the recovery time so next request from
@@ -1924,6 +2195,253 @@ static void handle_recovery_req(struct ptlrpc_thread *thread,
        EXIT;
 }
 
+/** Checking routines for recovery */
+static int check_for_recovery_ready(struct lu_target *lut)
+{
+       struct obd_device *obd = lut->lut_obd;
+       unsigned int clnts = atomic_read(&obd->obd_connected_clients);
+
+       CDEBUG(D_HA, "connected %d stale %d max_recoverable_clients %d"
+              " abort %d expired %d\n", clnts, obd->obd_stale_clients,
+              obd->obd_max_recoverable_clients, obd->obd_abort_recovery,
+              obd->obd_recovery_expired);
+
+       if (!obd->obd_abort_recovery && !obd->obd_recovery_expired) {
+               LASSERT(clnts <= obd->obd_max_recoverable_clients);
+               if (clnts + obd->obd_stale_clients <
+                   obd->obd_max_recoverable_clients)
+                       return 0;
+       }
+
+       if (lut->lut_tdtd != NULL) {
+               if (!lut->lut_tdtd->tdtd_replay_ready &&
+                   !obd->obd_abort_recovery) {
+                       /* Let's extend recovery timer, in case the recovery
+                        * timer expired, and some clients got evicted */
+                       extend_recovery_timer(obd, obd->obd_recovery_timeout,
+                                             true);
+                       CDEBUG(D_HA, "%s update recovery is not ready, extend recovery %llu\n",
+                              obd->obd_name, obd->obd_recovery_timeout);
+                       return 0;
+               }
+       }
+
+       return 1;
+}
+
+enum {
+       REQUEST_RECOVERY = 1,
+       UPDATE_RECOVERY = 2,
+};
+
+static __u64 get_next_replay_req_transno(struct obd_device *obd)
+{
+       __u64 transno = 0;
+
+       if (!list_empty(&obd->obd_req_replay_queue)) {
+               struct ptlrpc_request *req;
+
+               req = list_entry(obd->obd_req_replay_queue.next,
+                                struct ptlrpc_request, rq_list);
+               transno = lustre_msg_get_transno(req->rq_reqmsg);
+       }
+
+       return transno;
+}
+
+static __u64 get_next_transno(struct lu_target *lut, int *type)
+{
+       struct obd_device *obd = lut->lut_obd;
+       struct target_distribute_txn_data *tdtd = lut->lut_tdtd;
+       __u64 transno = 0;
+       __u64 update_transno;
+       ENTRY;
+
+       transno = get_next_replay_req_transno(obd);
+       if (type != NULL)
+               *type = REQUEST_RECOVERY;
+
+       if (tdtd == NULL)
+               RETURN(transno);
+
+       update_transno = distribute_txn_get_next_transno(tdtd);
+       if (transno == 0 || (transno >= update_transno &&
+                            update_transno != 0)) {
+               transno = update_transno;
+               if (type != NULL)
+                       *type = UPDATE_RECOVERY;
+       }
+
+       RETURN(transno);
+}
+
+/**
+ * drop duplicate replay request
+ *
+ * Because the operation has been replayed by update recovery, the request
+ * with the same transno will be dropped and also notify the client to send
+ * next replay request.
+ *
+ * \param[in] env      execution environment
+ * \param[in] obd      failover obd device
+ * \param[in] req      request to be dropped
+ */
+static void drop_duplicate_replay_req(struct lu_env *env,
+                                     struct obd_device *obd,
+                                     struct ptlrpc_request *req)
+{
+       DEBUG_REQ(D_HA, req, "remove t%lld from %s because of duplicate"
+                 " update records are found.\n",
+                 lustre_msg_get_transno(req->rq_reqmsg),
+                 libcfs_nid2str(req->rq_peer.nid));
+
+       /* Right now, only for MDS reint operation update replay and
+        * normal request replay can have the same transno */
+       if (lustre_msg_get_opc(req->rq_reqmsg) == MDS_REINT) {
+               req_capsule_set(&req->rq_pill, &RQF_MDS_REINT);
+               req->rq_status = req_capsule_server_pack(&req->rq_pill);
+               if (likely(req->rq_export))
+                       target_committed_to_req(req);
+               lustre_msg_set_transno(req->rq_repmsg, req->rq_transno);
+               target_send_reply(req, req->rq_status, 0);
+       } else {
+               DEBUG_REQ(D_ERROR, req, "wrong opc" "from %s\n",
+               libcfs_nid2str(req->rq_peer.nid));
+       }
+       target_exp_dequeue_req_replay(req);
+       target_request_copy_put(req);
+       obd->obd_replayed_requests++;
+}
+
+static void replay_request_or_update(struct lu_env *env,
+                                    struct lu_target *lut,
+                                    struct target_recovery_data *trd,
+                                    struct ptlrpc_thread *thread)
+{
+       struct obd_device *obd = lut->lut_obd;
+       struct ptlrpc_request *req = NULL;
+       int                     type;
+       __u64                   transno;
+       ENTRY;
+
+       CDEBUG(D_HA, "Waiting for transno %lld\n",
+              obd->obd_next_recovery_transno);
+
+       /* Replay all of request and update by transno */
+       do {
+               struct target_distribute_txn_data *tdtd = lut->lut_tdtd;
+
+               CFS_FAIL_TIMEOUT(OBD_FAIL_TGT_REPLAY_DELAY2, cfs_fail_val);
+
+               /** It is needed to extend recovery window above
+                *  recovery_time_soft. Extending is possible only in the
+                *  end of recovery window (see more details in
+                *  handle_recovery_req()).
+                */
+               CFS_FAIL_TIMEOUT_MS(OBD_FAIL_TGT_REPLAY_DELAY, 300);
+
+               if (target_recovery_overseer(lut, check_for_next_transno,
+                                       exp_req_replay_healthy_or_from_mdt)) {
+                       abort_req_replay_queue(obd);
+                       abort_lock_replay_queue(obd);
+                       goto abort;
+               }
+
+               spin_lock(&obd->obd_recovery_task_lock);
+               transno = get_next_transno(lut, &type);
+               if (type == REQUEST_RECOVERY && transno != 0) {
+                       /* Drop replay request from client side, if the
+                        * replay has been executed by update with the
+                        * same transno */
+                       req = list_entry(obd->obd_req_replay_queue.next,
+                                       struct ptlrpc_request, rq_list);
+
+                       list_del_init(&req->rq_list);
+                       obd->obd_requests_queued_for_recovery--;
+                       spin_unlock(&obd->obd_recovery_task_lock);
+
+                       /* Let's check if the request has been redone by
+                        * update replay */
+                       if (is_req_replayed_by_update(req)) {
+                               struct distribute_txn_replay_req *dtrq;
+
+                               dtrq = distribute_txn_lookup_finish_list(tdtd,
+                                                                  req->rq_xid);
+                               LASSERT(dtrq != NULL);
+                               spin_lock(&tdtd->tdtd_replay_list_lock);
+                               list_del_init(&dtrq->dtrq_list);
+                               spin_unlock(&tdtd->tdtd_replay_list_lock);
+                               dtrq_destroy(dtrq);
+
+                               drop_duplicate_replay_req(env, obd, req);
+
+                               continue;
+                       }
+
+                       LASSERT(trd->trd_processing_task == current_pid());
+                       DEBUG_REQ(D_HA, req, "processing t%lld from %s",
+                                 lustre_msg_get_transno(req->rq_reqmsg),
+                                 libcfs_nid2str(req->rq_peer.nid));
+
+                       handle_recovery_req(thread, req,
+                                           trd->trd_recovery_handler);
+                       /**
+                        * bz18031: increase next_recovery_transno before
+                        * target_request_copy_put() will drop exp_rpc reference
+                        */
+                       spin_lock(&obd->obd_recovery_task_lock);
+                       obd->obd_next_recovery_transno++;
+                       spin_unlock(&obd->obd_recovery_task_lock);
+                       target_exp_dequeue_req_replay(req);
+                       target_request_copy_put(req);
+                       obd->obd_replayed_requests++;
+               } else if (type == UPDATE_RECOVERY && transno != 0) {
+                       struct distribute_txn_replay_req *dtrq;
+                       int rc;
+
+                       spin_unlock(&obd->obd_recovery_task_lock);
+
+                       LASSERT(tdtd != NULL);
+                       dtrq = distribute_txn_get_next_req(tdtd);
+                       lu_context_enter(&thread->t_env->le_ctx);
+                       rc = tdtd->tdtd_replay_handler(env, tdtd, dtrq);
+                       lu_context_exit(&thread->t_env->le_ctx);
+                       extend_recovery_timer(obd, obd_timeout, true);
+
+                       if (rc == 0 && dtrq->dtrq_xid != 0) {
+                               CDEBUG(D_HA, "Move x%llu t%llu"
+                                      " to finish list\n", dtrq->dtrq_xid,
+                                      dtrq->dtrq_master_transno);
+
+                               /* Add it to the replay finish list */
+                               spin_lock(&tdtd->tdtd_replay_list_lock);
+                               list_add(&dtrq->dtrq_list,
+                                        &tdtd->tdtd_replay_finish_list);
+                               spin_unlock(&tdtd->tdtd_replay_list_lock);
+
+                               spin_lock(&obd->obd_recovery_task_lock);
+                               if (transno == obd->obd_next_recovery_transno)
+                                       obd->obd_next_recovery_transno++;
+                               else if (transno >
+                                        obd->obd_next_recovery_transno)
+                                       obd->obd_next_recovery_transno =
+                                                               transno + 1;
+                               spin_unlock(&obd->obd_recovery_task_lock);
+                       } else {
+                               dtrq_destroy(dtrq);
+                       }
+               } else {
+                       spin_unlock(&obd->obd_recovery_task_lock);
+abort:
+                       LASSERT(list_empty(&obd->obd_req_replay_queue));
+                       LASSERT(atomic_read(&obd->obd_req_replay_clients) == 0);
+                       /** evict exports failed VBR */
+                       class_disconnect_stale_exports(obd, exp_vbr_healthy);
+                       break;
+               }
+       } while (1);
+}
+
 static int target_recovery_thread(void *arg)
 {
         struct lu_target *lut = arg;
@@ -1969,43 +2487,28 @@ static int target_recovery_thread(void *arg)
        spin_unlock(&obd->obd_dev_lock);
        complete(&trd->trd_starting);
 
-        /* first of all, we have to know the first transno to replay */
-        if (target_recovery_overseer(obd, check_for_clients,
-                                     exp_connect_healthy)) {
-                abort_req_replay_queue(obd);
-                abort_lock_replay_queue(obd);
-        }
+       /* first of all, we have to know the first transno to replay */
+       if (target_recovery_overseer(lut, check_for_recovery_ready,
+                                    exp_connect_healthy)) {
+               abort_req_replay_queue(obd);
+               abort_lock_replay_queue(obd);
+               if (lut->lut_tdtd != NULL)
+                       dtrq_list_destroy(lut->lut_tdtd);
+       }
 
-       /* next stage: replay requests */
+       /* next stage: replay requests or update */
        delta = jiffies;
-       CDEBUG(D_INFO, "1: request replay stage - %d clients from t"LPU64"\n",
+       CDEBUG(D_INFO, "1: request replay stage - %d clients from t%llu\n",
               atomic_read(&obd->obd_req_replay_clients),
               obd->obd_next_recovery_transno);
-       while ((req = target_next_replay_req(obd))) {
-               LASSERT(trd->trd_processing_task == current_pid());
-               DEBUG_REQ(D_HA, req, "processing t"LPD64" from %s",
-                         lustre_msg_get_transno(req->rq_reqmsg),
-                         libcfs_nid2str(req->rq_peer.nid));
-                handle_recovery_req(thread, req,
-                                    trd->trd_recovery_handler);
-                /**
-                 * bz18031: increase next_recovery_transno before
-                 * target_request_copy_put() will drop exp_rpc reference
-                 */
-               spin_lock(&obd->obd_recovery_task_lock);
-               obd->obd_next_recovery_transno++;
-               spin_unlock(&obd->obd_recovery_task_lock);
-                target_exp_dequeue_req_replay(req);
-                target_request_copy_put(req);
-                obd->obd_replayed_requests++;
-        }
+       replay_request_or_update(env, lut, trd, thread);
 
        /**
         * The second stage: replay locks
         */
        CDEBUG(D_INFO, "2: lock replay stage - %d clients\n",
               atomic_read(&obd->obd_lock_replay_clients));
-       while ((req = target_next_replay_lock(obd))) {
+       while ((req = target_next_replay_lock(lut))) {
                LASSERT(trd->trd_processing_task == current_pid());
                DEBUG_REQ(D_HA, req, "processing lock from %s: ",
                          libcfs_nid2str(req->rq_peer.nid));
@@ -2052,7 +2555,7 @@ static int target_recovery_thread(void *arg)
                libcfs_debug_dumplog();
        }
 
-        target_finish_recovery(obd);
+       target_finish_recovery(lut);
 
         lu_context_fini(&env->le_ctx);
         trd->trd_processing_task = 0;
@@ -2070,14 +2573,19 @@ static int target_start_recovery_thread(struct lu_target *lut,
        struct obd_device *obd = lut->lut_obd;
        int rc = 0;
        struct target_recovery_data *trd = &obd->obd_recovery_data;
+       int index;
 
        memset(trd, 0, sizeof(*trd));
        init_completion(&trd->trd_starting);
        init_completion(&trd->trd_finishing);
        trd->trd_recovery_handler = handler;
 
+       rc = server_name2index(obd->obd_name, &index, NULL);
+       if (rc < 0)
+               return rc;
+
        if (!IS_ERR(kthread_run(target_recovery_thread,
-                               lut, "tgt_recov"))) {
+                               lut, "tgt_recover_%d", index))) {
                wait_for_completion(&trd->trd_starting);
                LASSERT(obd->obd_recovering != 0);
        } else {
@@ -2112,13 +2620,13 @@ void target_recovery_fini(struct obd_device *obd)
 }
 EXPORT_SYMBOL(target_recovery_fini);
 
-static void target_recovery_expired(unsigned long castmeharder)
+static void target_recovery_expired(cfs_timer_cb_arg_t data)
 {
-       struct obd_device *obd = (struct obd_device *)castmeharder;
+       struct obd_device *obd = cfs_from_timer(obd, data, obd_recovery_timer);
        CDEBUG(D_HA, "%s: recovery timed out; %d clients are still in recovery"
-              " after %lds (%d clients connected)\n",
+              " after %llus (%d clients connected)\n",
               obd->obd_name, atomic_read(&obd->obd_lock_replay_clients),
-              cfs_time_current_sec()- obd->obd_recovery_start,
+              (s64)(ktime_get_real_seconds() - obd->obd_recovery_start),
               atomic_read(&obd->obd_connected_clients));
 
        obd->obd_recovery_expired = 1;
@@ -2127,27 +2635,31 @@ static void target_recovery_expired(unsigned long castmeharder)
 
 void target_recovery_init(struct lu_target *lut, svc_handler_t handler)
 {
-        struct obd_device *obd = lut->lut_obd;
-        if (obd->obd_max_recoverable_clients == 0) {
-                /** Update server last boot epoch */
-                tgt_boot_epoch_update(lut);
-                return;
-        }
+       struct obd_device *obd = lut->lut_obd;
+
+       if (lut->lut_bottom->dd_rdonly)
+               return;
+
+       if (obd->obd_max_recoverable_clients == 0) {
+               /** Update server last boot epoch */
+               tgt_boot_epoch_update(lut);
+               return;
+       }
 
        CDEBUG(D_HA, "RECOVERY: service %s, %d recoverable clients, "
-              "last_transno "LPU64"\n", obd->obd_name,
+              "last_transno %llu\n", obd->obd_name,
               obd->obd_max_recoverable_clients, obd->obd_last_committed);
         LASSERT(obd->obd_stopping == 0);
         obd->obd_next_recovery_transno = obd->obd_last_committed + 1;
         obd->obd_recovery_start = 0;
         obd->obd_recovery_end = 0;
 
-        cfs_timer_init(&obd->obd_recovery_timer, target_recovery_expired, obd);
-        target_start_recovery_thread(lut, handler);
+       cfs_timer_setup(&obd->obd_recovery_timer, target_recovery_expired,
+                       (unsigned long)obd, 0);
+       target_start_recovery_thread(lut, handler);
 }
 EXPORT_SYMBOL(target_recovery_init);
 
-
 static int target_process_req_flags(struct obd_device *obd,
                                     struct ptlrpc_request *req)
 {
@@ -2199,6 +2711,17 @@ int target_queue_recovery_request(struct ptlrpc_request *req,
         target_process_req_flags(obd, req);
 
         if (lustre_msg_get_flags(req->rq_reqmsg) & MSG_LOCK_REPLAY_DONE) {
+               if (unlikely(OBD_FAIL_CHECK(OBD_FAIL_TGT_RECOVERY_REQ_RACE))) {
+                       if (cfs_fail_val == 1) {
+                               cfs_race_state = 1;
+                               cfs_fail_val = 0;
+                               wake_up(&cfs_race_waitq);
+
+                               set_current_state(TASK_INTERRUPTIBLE);
+                               schedule_timeout(cfs_time_seconds(1));
+                       }
+               }
+
                 /* client declares he's ready to complete recovery
                  * so, we put the request on th final queue */
                target_request_copy_get(req);
@@ -2206,15 +2729,46 @@ int target_queue_recovery_request(struct ptlrpc_request *req,
                wake_up(&obd->obd_next_transno_waitq);
                spin_lock(&obd->obd_recovery_task_lock);
                if (obd->obd_recovering) {
+                       struct ptlrpc_request *tmp;
+                       struct ptlrpc_request *duplicate = NULL;
+
+                       if (likely(!req->rq_export->exp_replay_done)) {
+                               req->rq_export->exp_replay_done = 1;
+                               list_add_tail(&req->rq_list,
+                                             &obd->obd_final_req_queue);
+                               spin_unlock(&obd->obd_recovery_task_lock);
+                               RETURN(0);
+                       }
+
+                       /* XXX O(n), but only happens if final ping is
+                        * timed out, probably reorganize the list as
+                        * a hash list later */
+                       list_for_each_entry_safe(reqiter, tmp,
+                                                &obd->obd_final_req_queue,
+                                                rq_list) {
+                               if (reqiter->rq_export == req->rq_export) {
+                                       list_del_init(&reqiter->rq_list);
+                                       duplicate = reqiter;
+                                       break;
+                               }
+                       }
+
                        list_add_tail(&req->rq_list,
-                                         &obd->obd_final_req_queue);
+                                     &obd->obd_final_req_queue);
+                       req->rq_export->exp_replay_done = 1;
+                       spin_unlock(&obd->obd_recovery_task_lock);
+
+                       if (duplicate != NULL) {
+                               DEBUG_REQ(D_HA, duplicate,
+                                         "put prev final req\n");
+                               target_request_copy_put(duplicate);
+                       }
+                       RETURN(0);
                } else {
                        spin_unlock(&obd->obd_recovery_task_lock);
                        target_request_copy_put(req);
                        RETURN(obd->obd_stopping ? -ENOTCONN : 1);
                }
-               spin_unlock(&obd->obd_recovery_task_lock);
-               RETURN(0);
        }
        if (lustre_msg_get_flags(req->rq_reqmsg) & MSG_REQ_REPLAY_DONE) {
                /* client declares he's ready to replay locks */
@@ -2255,11 +2809,16 @@ int target_queue_recovery_request(struct ptlrpc_request *req,
          * Also, a resent, replayed request that has already been
          * handled will pass through here and be processed immediately.
          */
-        CDEBUG(D_HA, "Next recovery transno: "LPU64
-               ", current: "LPU64", replaying\n",
+       CDEBUG(D_HA, "Next recovery transno: %llu"
+              ", current: %llu, replaying\n",
                obd->obd_next_recovery_transno, transno);
+
+       /* If the request has been replayed by update replay, then sends this
+        * request to the recovery thread (replay_request_or_update()), where
+        * it will be handled */
        spin_lock(&obd->obd_recovery_task_lock);
-       if (transno < obd->obd_next_recovery_transno) {
+       if (transno < obd->obd_next_recovery_transno &&
+           !is_req_replayed_by_update(req)) {
                /* Processing the queue right now, don't re-add. */
                LASSERT(list_empty(&req->rq_list));
                spin_unlock(&obd->obd_recovery_task_lock);
@@ -2312,14 +2871,12 @@ added:
        wake_up(&obd->obd_next_transno_waitq);
        RETURN(0);
 }
-EXPORT_SYMBOL(target_queue_recovery_request);
 
 int target_handle_ping(struct ptlrpc_request *req)
 {
         obd_ping(req->rq_svc_thread->t_env, req->rq_export);
         return req_capsule_server_pack(&req->rq_pill);
 }
-EXPORT_SYMBOL(target_handle_ping);
 
 void target_committed_to_req(struct ptlrpc_request *req)
 {
@@ -2333,10 +2890,9 @@ void target_committed_to_req(struct ptlrpc_request *req)
                           "%d)", exp->exp_obd->obd_no_transno,
                           req->rq_repmsg == NULL);
 
-        CDEBUG(D_INFO, "last_committed "LPU64", transno "LPU64", xid "LPU64"\n",
+       CDEBUG(D_INFO, "last_committed %llu, transno %llu, xid %llu\n",
                exp->exp_last_committed, req->rq_transno, req->rq_xid);
 }
-EXPORT_SYMBOL(target_committed_to_req);
 
 #endif /* HAVE_SERVER_SUPPORT */
 
@@ -2367,24 +2923,30 @@ int target_pack_pool_reply(struct ptlrpc_request *req)
 
         RETURN(0);
 }
-EXPORT_SYMBOL(target_pack_pool_reply);
 
-int target_send_reply_msg(struct ptlrpc_request *req, int rc, int fail_id)
+static int target_send_reply_msg(struct ptlrpc_request *req,
+                                int rc, int fail_id)
 {
-        if (OBD_FAIL_CHECK_ORSET(fail_id & ~OBD_FAIL_ONCE, OBD_FAIL_ONCE)) {
-                DEBUG_REQ(D_ERROR, req, "dropping reply");
-                return (-ECOMM);
-        }
-
-        if (unlikely(rc)) {
-                DEBUG_REQ(D_NET, req, "processing error (%d)", rc);
-                req->rq_status = rc;
-                return (ptlrpc_send_error(req, 1));
-        } else {
-                DEBUG_REQ(D_NET, req, "sending reply");
-        }
+       if (OBD_FAIL_CHECK_ORSET(fail_id & ~OBD_FAIL_ONCE, OBD_FAIL_ONCE)) {
+               DEBUG_REQ(D_ERROR, req, "dropping reply");
+               return -ECOMM;
+       }
+       /* We can have a null rq_reqmsg in the event of bad signature or
+        * no context when unwrapping */
+       if (req->rq_reqmsg &&
+           unlikely(lustre_msg_get_opc(req->rq_reqmsg) == MDS_REINT &&
+           OBD_FAIL_CHECK(OBD_FAIL_MDS_REINT_MULTI_NET_REP)))
+               return -ECOMM;
+
+       if (unlikely(rc)) {
+               DEBUG_REQ(D_NET, req, "processing error (%d)", rc);
+               req->rq_status = rc;
+               return ptlrpc_send_error(req, 1);
+       } else {
+               DEBUG_REQ(D_NET, req, "sending reply");
+       }
 
-        return (ptlrpc_send_reply(req, PTLRPC_REPLY_MAYBE_DIFFICULT));
+       return ptlrpc_send_reply(req, PTLRPC_REPLY_MAYBE_DIFFICULT);
 }
 
 void target_send_reply(struct ptlrpc_request *req, int rc, int fail_id)
@@ -2434,7 +2996,7 @@ void target_send_reply(struct ptlrpc_request *req, int rc, int fail_id)
         rs->rs_opc       = lustre_msg_get_opc(req->rq_reqmsg);
 
        spin_lock(&exp->exp_uncommitted_replies_lock);
-       CDEBUG(D_NET, "rs transno = "LPU64", last committed = "LPU64"\n",
+       CDEBUG(D_NET, "rs transno = %llu, last committed = %llu\n",
               rs->rs_transno, exp->exp_last_committed);
        if (rs->rs_transno > exp->exp_last_committed) {
                /* not committed already */
@@ -2478,9 +3040,8 @@ void target_send_reply(struct ptlrpc_request *req, int rc, int fail_id)
        spin_unlock(&svcpt->scp_rep_lock);
        EXIT;
 }
-EXPORT_SYMBOL(target_send_reply);
 
-ldlm_mode_t lck_compat_array[] = {
+enum ldlm_mode lck_compat_array[] = {
        [LCK_EX]    = LCK_COMPAT_EX,
        [LCK_PW]    = LCK_COMPAT_PW,
        [LCK_PR]    = LCK_COMPAT_PR,
@@ -2495,12 +3056,12 @@ ldlm_mode_t lck_compat_array[] = {
  * Rather arbitrary mapping from LDLM error codes to errno values. This should
  * not escape to the user level.
  */
-int ldlm_error2errno(ldlm_error_t error)
+int ldlm_error2errno(enum ldlm_error error)
 {
-        int result;
+       int result;
 
-        switch (error) {
-        case ELDLM_OK:
+       switch (error) {
+       case ELDLM_OK:
        case ELDLM_LOCK_MATCHED:
                 result = 0;
                 break;
@@ -2522,22 +3083,22 @@ int ldlm_error2errno(ldlm_error_t error)
         case ELDLM_BAD_NAMESPACE:
                 result = -EBADF;
                 break;
-        default:
-                if (((int)error) < 0)  /* cast to signed type */
-                        result = error; /* as ldlm_error_t can be unsigned */
-                else {
-                        CERROR("Invalid DLM result code: %d\n", error);
-                        result = -EPROTO;
-                }
-        }
-        return result;
+       default:
+               if (((int)error) < 0) { /* cast to signed type */
+                       result = error; /* as ldlm_error can be unsigned */
+               } else {
+                       CERROR("Invalid DLM result code: %d\n", error);
+                       result = -EPROTO;
+               }
+       }
+       return result;
 }
 EXPORT_SYMBOL(ldlm_error2errno);
 
 /**
- * Dual to ldlm_error2errno(): maps errno values back to ldlm_error_t.
+ * Dual to ldlm_error2errno(): maps errno values back to enum ldlm_error.
  */
-ldlm_error_t ldlm_errno2error(int err_no)
+enum ldlm_error ldlm_errno2error(int err_no)
 {
         int error;
 
@@ -2568,7 +3129,6 @@ ldlm_error_t ldlm_errno2error(int err_no)
         }
         return error;
 }
-EXPORT_SYMBOL(ldlm_errno2error);
 
 #if LUSTRE_TRACKS_LOCK_EXP_REFS
 void ldlm_dump_export_locks(struct obd_export *exp)
@@ -2597,18 +3157,22 @@ static int target_bulk_timeout(void *data)
         RETURN(1);
 }
 
-static inline char *bulk2type(struct ptlrpc_bulk_desc *desc)
+static inline const char *bulk2type(struct ptlrpc_request *req)
 {
-        return desc->bd_type == BULK_GET_SINK ? "GET" : "PUT";
+       if (req->rq_bulk_read)
+               return "READ";
+       if (req->rq_bulk_write)
+               return "WRITE";
+       return "UNKNOWN";
 }
 
 int target_bulk_io(struct obd_export *exp, struct ptlrpc_bulk_desc *desc,
                    struct l_wait_info *lwi)
 {
-       struct ptlrpc_request   *req = desc->bd_req;
-       time_t                   start = cfs_time_current_sec();
-       time_t                   deadline;
-       int                      rc = 0;
+       struct ptlrpc_request *req = desc->bd_req;
+       time64_t start = ktime_get_real_seconds();
+       time64_t deadline;
+       int rc = 0;
 
        ENTRY;
 
@@ -2626,15 +3190,21 @@ int target_bulk_io(struct obd_export *exp, struct ptlrpc_bulk_desc *desc,
            exp->exp_conn_cnt > lustre_msg_get_conn_cnt(req->rq_reqmsg)) {
                rc = -ENOTCONN;
        } else {
-               if (desc->bd_type == BULK_PUT_SINK)
+               if (req->rq_bulk_read)
                        rc = sptlrpc_svc_wrap_bulk(req, desc);
+
+               if (OCD_HAS_FLAG(&exp->exp_connect_data, BULK_MBITS))
+                       req->rq_mbits = lustre_msg_get_mbits(req->rq_reqmsg);
+               else /* old version, bulk matchbits is rq_xid */
+                       req->rq_mbits = req->rq_xid;
+
                if (rc == 0)
                        rc = ptlrpc_start_bulk_transfer(desc);
        }
 
        if (rc < 0) {
                DEBUG_REQ(D_ERROR, req, "bulk %s failed: rc %d",
-                         bulk2type(desc), rc);
+                         bulk2type(req), rc);
                RETURN(rc);
        }
 
@@ -2649,12 +3219,13 @@ int target_bulk_io(struct obd_export *exp, struct ptlrpc_bulk_desc *desc,
                deadline = req->rq_deadline;
 
        do {
-               long timeoutl = deadline - cfs_time_current_sec();
-               cfs_duration_t timeout = timeoutl <= 0 ?
-                                        CFS_TICK : cfs_time_seconds(timeoutl);
-               time_t  rq_deadline;
+               time64_t timeoutl = deadline - ktime_get_real_seconds();
+               long timeout_jiffies = timeoutl <= 0 ?
+                                      1 : cfs_time_seconds(timeoutl);
+               time64_t rq_deadline;
 
-               *lwi = LWI_TIMEOUT_INTERVAL(timeout, cfs_time_seconds(1),
+               *lwi = LWI_TIMEOUT_INTERVAL(timeout_jiffies,
+                                           cfs_time_seconds(1),
                                            target_bulk_timeout, desc);
                rc = l_wait_event(desc->bd_waitq,
                                  !ptlrpc_server_bulk_active(desc) ||
@@ -2664,40 +3235,45 @@ int target_bulk_io(struct obd_export *exp, struct ptlrpc_bulk_desc *desc,
                                  lwi);
                LASSERT(rc == 0 || rc == -ETIMEDOUT);
                /* Wait again if we changed rq_deadline. */
-               rq_deadline = ACCESS_ONCE(req->rq_deadline);
+               rq_deadline = READ_ONCE(req->rq_deadline);
                deadline = start + bulk_timeout;
                if (deadline > rq_deadline)
                        deadline = rq_deadline;
-       } while ((rc == -ETIMEDOUT) &&
-                (deadline > cfs_time_current_sec()));
+       } while (rc == -ETIMEDOUT &&
+                deadline > ktime_get_real_seconds());
 
        if (rc == -ETIMEDOUT) {
-               DEBUG_REQ(D_ERROR, req, "timeout on bulk %s after %ld%+lds",
-                         bulk2type(desc), deadline - start,
-                         cfs_time_current_sec() - deadline);
+               DEBUG_REQ(D_ERROR, req, "timeout on bulk %s after %lld%+llds",
+                         bulk2type(req), deadline - start,
+                         ktime_get_real_seconds() - deadline);
                ptlrpc_abort_bulk(desc);
        } else if (exp->exp_failed) {
                DEBUG_REQ(D_ERROR, req, "Eviction on bulk %s",
-                         bulk2type(desc));
+                         bulk2type(req));
                rc = -ENOTCONN;
                ptlrpc_abort_bulk(desc);
        } else if (exp->exp_conn_cnt >
                   lustre_msg_get_conn_cnt(req->rq_reqmsg)) {
                DEBUG_REQ(D_ERROR, req, "Reconnect on bulk %s",
-                         bulk2type(desc));
+                         bulk2type(req));
                /* We don't reply anyway. */
                rc = -ETIMEDOUT;
                ptlrpc_abort_bulk(desc);
-       } else if (desc->bd_failure ||
-                  desc->bd_nob_transferred != desc->bd_nob) {
-               DEBUG_REQ(D_ERROR, req, "%s bulk %s %d(%d)",
-                         desc->bd_failure ? "network error on" : "truncated",
-                         bulk2type(desc), desc->bd_nob_transferred,
-                         desc->bd_nob);
-               /* XXX Should this be a different errno? */
+       } else if (desc->bd_failure) {
+               DEBUG_REQ(D_ERROR, req, "network error on bulk %s",
+                         bulk2type(req));
+               /* XXX should this be a different errno? */
                rc = -ETIMEDOUT;
-       } else if (desc->bd_type == BULK_GET_SINK) {
-               rc = sptlrpc_svc_unwrap_bulk(req, desc);
+       } else {
+               if (req->rq_bulk_write)
+                       rc = sptlrpc_svc_unwrap_bulk(req, desc);
+               if (rc == 0 && desc->bd_nob_transferred != desc->bd_nob) {
+                       DEBUG_REQ(D_ERROR, req, "truncated bulk %s %d(%d)",
+                                 bulk2type(req), desc->bd_nob_transferred,
+                                 desc->bd_nob);
+                       /* XXX should this be a different errno? */
+                       rc = -ETIMEDOUT;
+               }
        }
 
        RETURN(rc);