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LU-7593 target: umount vs tgt_last_rcvd_update deadlock
[fs/lustre-release.git] / lustre / target / tgt_lastrcvd.c
index 2a45895..55e5995 100644 (file)
@@ -27,7 +27,7 @@
  * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
  *
- * Copyright (c) 2011, 2014, Intel Corporation.
+ * Copyright (c) 2011, 2015, Intel Corporation.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
@@ -50,7 +50,8 @@ static int tgt_bitmap_chunk_alloc(struct lu_target *lut, int chunk)
 {
        unsigned long *bm;
 
-       OBD_ALLOC(bm, BITS_TO_LONGS(LUT_REPLY_SLOTS_PER_CHUNK) * sizeof(long));
+       OBD_ALLOC_LARGE(bm, BITS_TO_LONGS(LUT_REPLY_SLOTS_PER_CHUNK) *
+                       sizeof(long));
        if (bm == NULL)
                return -ENOMEM;
 
@@ -59,7 +60,7 @@ static int tgt_bitmap_chunk_alloc(struct lu_target *lut, int chunk)
        if (lut->lut_reply_bitmap[chunk] != NULL) {
                /* someone else already allocated the bitmap for this chunk */
                spin_unlock(&lut->lut_client_bitmap_lock);
-               OBD_FREE(bm, BITS_TO_LONGS(LUT_REPLY_SLOTS_PER_CHUNK) *
+               OBD_FREE_LARGE(bm, BITS_TO_LONGS(LUT_REPLY_SLOTS_PER_CHUNK) *
                         sizeof(long));
                return 0;
        }
@@ -155,6 +156,12 @@ static int tgt_clear_reply_slot(struct lu_target *lut, int idx)
        LASSERT(chunk < LUT_REPLY_SLOTS_MAX_CHUNKS);
        LASSERT(b < LUT_REPLY_SLOTS_PER_CHUNK);
 
+       if (lut->lut_reply_bitmap[chunk] == NULL) {
+               CERROR("%s: slot %d not allocated\n",
+                      tgt_name(lut), idx);
+               return -ENOENT;
+       }
+
        if (test_and_clear_bit(b, lut->lut_reply_bitmap[chunk]) == 0) {
                CERROR("%s: slot %d already clear in bitmap\n",
                       tgt_name(lut), idx);
@@ -308,7 +315,7 @@ static void tgt_free_reply_data(struct lu_target *lut,
 {
        CDEBUG(D_TRACE, "%s: free reply data %p: xid %llu, transno %llu, "
               "client gen %u, slot idx %d\n",
-              tgt_name(lut), trd, trd->trd_reply.lrd_xid,
+              lut == NULL ? "" : tgt_name(lut), trd, trd->trd_reply.lrd_xid,
               trd->trd_reply.lrd_transno, trd->trd_reply.lrd_client_gen,
               trd->trd_index);
 
@@ -316,7 +323,8 @@ static void tgt_free_reply_data(struct lu_target *lut,
 
        list_del(&trd->trd_list);
        ted->ted_reply_cnt--;
-       tgt_clear_reply_slot(lut, trd->trd_index);
+       if (lut != NULL)
+               tgt_clear_reply_slot(lut, trd->trd_index);
        OBD_FREE_PTR(trd);
 }
 
@@ -331,7 +339,7 @@ static void tgt_release_reply_data(struct lu_target *lut,
 {
        CDEBUG(D_TRACE, "%s: release reply data %p: xid %llu, transno %llu, "
               "client gen %u, slot idx %d\n",
-              tgt_name(lut), trd, trd->trd_reply.lrd_xid,
+              lut == NULL ? "" : tgt_name(lut), trd, trd->trd_reply.lrd_xid,
               trd->trd_reply.lrd_transno, trd->trd_reply.lrd_client_gen,
               trd->trd_index);
 
@@ -377,6 +385,9 @@ int tgt_client_alloc(struct obd_export *exp)
        ENTRY;
        LASSERT(exp != exp->exp_obd->obd_self_export);
 
+       spin_lock_init(&exp->exp_target_data.ted_nodemap_lock);
+       INIT_LIST_HEAD(&exp->exp_target_data.ted_nodemap_member);
+
        OBD_ALLOC_PTR(exp->exp_target_data.ted_lcd);
        if (exp->exp_target_data.ted_lcd == NULL)
                RETURN(-ENOMEM);
@@ -418,9 +429,12 @@ void tgt_client_free(struct obd_export *exp)
        OBD_FREE_PTR(ted->ted_lcd);
        ted->ted_lcd = NULL;
 
-       /* Slot may be not yet assigned */
-       if (ted->ted_lr_idx < 0)
+       /* Target may have been freed (see LU-7430)
+        * Slot may be not yet assigned */
+       if (exp->exp_obd->u.obt.obt_magic != OBT_MAGIC ||
+           ted->ted_lr_idx < 0)
                return;
+
        /* Clear bit when lcd is freed */
        LASSERT(lut && lut->lut_client_bitmap);
        if (!test_and_clear_bit(ted->ted_lr_idx, lut->lut_client_bitmap)) {
@@ -503,6 +517,7 @@ static int tgt_client_data_update(const struct lu_env *env,
                RETURN(PTR_ERR(th));
 
        tti_buf_lcd(tti);
+       mutex_lock(&ted->ted_lcd_lock);
        rc = dt_declare_record_write(env, tgt->lut_last_rcvd,
                                     &tti->tti_buf,
                                     ted->ted_lr_off, th);
@@ -532,6 +547,7 @@ static int tgt_client_data_update(const struct lu_env *env,
        rc = tgt_client_data_write(env, tgt, ted->ted_lcd, &tti->tti_off, th);
        EXIT;
 out:
+       mutex_unlock(&ted->ted_lcd_lock);
        dt_trans_stop(env, tgt->lut_bottom, th);
        CDEBUG(D_INFO, "%s: update last_rcvd client data for UUID = %s, "
               "last_transno = "LPU64": rc = %d\n", tgt->lut_obd->obd_name,
@@ -745,7 +761,7 @@ void tgt_boot_epoch_update(struct lu_target *tgt)
 }
 
 /**
- * commit callback, need to update last_commited value
+ * commit callback, need to update last_committed value
  */
 struct tgt_last_committed_callback {
        struct dt_txn_commit_cb  llcc_cb;
@@ -761,21 +777,29 @@ static void tgt_cb_last_committed(struct lu_env *env, struct thandle *th,
 
        ccb = container_of0(cb, struct tgt_last_committed_callback, llcc_cb);
 
+       LASSERT(ccb->llcc_exp);
        LASSERT(ccb->llcc_tgt != NULL);
        LASSERT(ccb->llcc_exp->exp_obd == ccb->llcc_tgt->lut_obd);
 
+       /* Fast path w/o spinlock, if exp_last_committed was updated
+        * with higher transno, no need to take spinlock and check,
+        * also no need to update obd_last_committed. */
+       if (ccb->llcc_transno <= ccb->llcc_exp->exp_last_committed)
+               goto out;
        spin_lock(&ccb->llcc_tgt->lut_translock);
        if (ccb->llcc_transno > ccb->llcc_tgt->lut_obd->obd_last_committed)
                ccb->llcc_tgt->lut_obd->obd_last_committed = ccb->llcc_transno;
 
-       LASSERT(ccb->llcc_exp);
        if (ccb->llcc_transno > ccb->llcc_exp->exp_last_committed) {
                ccb->llcc_exp->exp_last_committed = ccb->llcc_transno;
                spin_unlock(&ccb->llcc_tgt->lut_translock);
+
                ptlrpc_commit_replies(ccb->llcc_exp);
+               tgt_cancel_slc_locks(ccb->llcc_transno);
        } else {
                spin_unlock(&ccb->llcc_tgt->lut_translock);
        }
+out:
        class_export_cb_put(ccb->llcc_exp);
        if (ccb->llcc_transno)
                CDEBUG(D_HA, "%s: transno "LPD64" is committed\n",
@@ -1047,10 +1071,8 @@ int tgt_client_del(const struct lu_env *env, struct obd_export *exp)
                RETURN(rc);
        }
 
-       mutex_lock(&ted->ted_lcd_lock);
        memset(ted->ted_lcd->lcd_uuid, 0, sizeof ted->ted_lcd->lcd_uuid);
        rc = tgt_client_data_update(env, exp);
-       mutex_unlock(&ted->ted_lcd_lock);
 
        CDEBUG(rc == 0 ? D_INFO : D_ERROR,
               "%s: zeroing out client %s at idx %u (%llu), rc %d\n",
@@ -1060,6 +1082,58 @@ int tgt_client_del(const struct lu_env *env, struct obd_export *exp)
 }
 EXPORT_SYMBOL(tgt_client_del);
 
+int tgt_add_reply_data(const struct lu_env *env, struct lu_target *tgt,
+                      struct tg_export_data *ted, struct tg_reply_data *trd,
+                      struct thandle *th, bool update_lrd_file)
+{
+       struct lsd_reply_data   *lrd;
+       int     i;
+
+       lrd = &trd->trd_reply;
+       /* update export last transno */
+       mutex_lock(&ted->ted_lcd_lock);
+       if (lrd->lrd_transno > ted->ted_lcd->lcd_last_transno)
+               ted->ted_lcd->lcd_last_transno = lrd->lrd_transno;
+       mutex_unlock(&ted->ted_lcd_lock);
+
+       /* find a empty slot */
+       i = tgt_find_free_reply_slot(tgt);
+       if (unlikely(i < 0)) {
+               CERROR("%s: couldn't find a slot for reply data: "
+                      "rc = %d\n", tgt_name(tgt), i);
+               RETURN(i);
+       }
+       trd->trd_index = i;
+
+       if (update_lrd_file) {
+               loff_t  off;
+               int     rc;
+
+               /* write reply data to disk */
+               off = sizeof(struct lsd_reply_header) + sizeof(*lrd) * i;
+               rc = tgt_reply_data_write(env, tgt, lrd, off, th);
+               if (unlikely(rc != 0)) {
+                       CERROR("%s: can't update %s file: rc = %d\n",
+                              tgt_name(tgt), REPLY_DATA, rc);
+                       RETURN(rc);
+               }
+       }
+       /* add reply data to target export's reply list */
+       mutex_lock(&ted->ted_lcd_lock);
+       list_add(&trd->trd_list, &ted->ted_reply_list);
+       ted->ted_reply_cnt++;
+       if (ted->ted_reply_cnt > ted->ted_reply_max)
+               ted->ted_reply_max = ted->ted_reply_cnt;
+       mutex_unlock(&ted->ted_lcd_lock);
+
+       CDEBUG(D_TRACE, "add reply %p: xid %llu, transno %llu, "
+              "tag %hu, client gen %u, slot idx %d\n",
+              trd, lrd->lrd_xid, lrd->lrd_transno,
+              trd->trd_tag, lrd->lrd_client_gen, i);
+       RETURN(0);
+}
+EXPORT_SYMBOL(tgt_add_reply_data);
+
 /*
  * last_rcvd & last_committed update callbacks
  */
@@ -1068,22 +1142,30 @@ static int tgt_last_rcvd_update(const struct lu_env *env, struct lu_target *tgt,
                                struct thandle *th, struct ptlrpc_request *req)
 {
        struct tgt_thread_info  *tti = tgt_th_info(env);
+       struct tgt_session_info *tsi = tgt_ses_info(env);
+       struct obd_export       *exp = tsi->tsi_exp;
        struct tg_export_data   *ted;
        __u64                   *transno_p;
        int                      rc = 0;
-       bool                     lw_client, update = false;
+       bool                     lw_client;
 
        ENTRY;
 
-       ted = &req->rq_export->exp_target_data;
 
-       lw_client = exp_connect_flags(req->rq_export) & OBD_CONNECT_LIGHTWEIGHT;
+       LASSERT(exp != NULL);
+       ted = &exp->exp_target_data;
+
+       lw_client = exp_connect_flags(exp) & OBD_CONNECT_LIGHTWEIGHT;
        if (ted->ted_lr_idx < 0 && !lw_client)
                /* ofd connect may cause transaction before export has
                 * last_rcvd slot */
                RETURN(0);
 
-       tti->tti_transno = lustre_msg_get_transno(req->rq_reqmsg);
+       if (req != NULL)
+               tti->tti_transno = lustre_msg_get_transno(req->rq_reqmsg);
+       else
+               /* From update replay, tti_transno should be set already */
+               LASSERT(tti->tti_transno != 0);
 
        spin_lock(&tgt->lut_translock);
        if (th->th_result != 0) {
@@ -1110,12 +1192,13 @@ static int tgt_last_rcvd_update(const struct lu_env *env, struct lu_target *tgt,
        CDEBUG(D_INODE, "transno = "LPU64", last_committed = "LPU64"\n",
               tti->tti_transno, tgt->lut_obd->obd_last_committed);
 
-       req->rq_transno = tti->tti_transno;
-       lustre_msg_set_transno(req->rq_repmsg, tti->tti_transno);
+       if (req != NULL) {
+               req->rq_transno = tti->tti_transno;
+               lustre_msg_set_transno(req->rq_repmsg, tti->tti_transno);
+       }
 
        /* if can't add callback, do sync write */
-       th->th_sync |= !!tgt_last_commit_cb_add(th, tgt, req->rq_export,
-                                               tti->tti_transno);
+       th->th_sync |= !!tgt_last_commit_cb_add(th, tgt, exp, tti->tti_transno);
 
        if (lw_client) {
                /* All operations performed by LW clients are synchronous and
@@ -1123,54 +1206,53 @@ static int tgt_last_rcvd_update(const struct lu_env *env, struct lu_target *tgt,
                spin_lock(&tgt->lut_translock);
                if (tti->tti_transno > tgt->lut_lsd.lsd_last_transno) {
                        tgt->lut_lsd.lsd_last_transno = tti->tti_transno;
-                       update = true;
+                       spin_unlock(&tgt->lut_translock);
+                       /* Although lightweight (LW) connections have no slot
+                        * in the last_rcvd, we still want to maintain
+                        * the in-memory lsd_client_data structure in order to
+                        * properly handle reply reconstruction. */
+                       rc = tgt_server_data_write(env, tgt, th);
+               } else {
+                       spin_unlock(&tgt->lut_translock);
                }
-               spin_unlock(&tgt->lut_translock);
-               /* Although lightweight (LW) connections have no slot in
-                * last_rcvd, we still want to maintain the in-memory
-                * lsd_client_data structure in order to properly handle reply
-                * reconstruction. */
        } else if (ted->ted_lr_off == 0) {
                CERROR("%s: client idx %d has offset %lld\n",
                       tgt_name(tgt), ted->ted_lr_idx, ted->ted_lr_off);
                RETURN(-EINVAL);
        }
 
-       /* if the export has already been disconnected, we have no last_rcvd
-        * slot, update server data with latest transno then */
-       if (ted->ted_lcd == NULL) {
-               CWARN("commit transaction for disconnected client %s: rc %d\n",
-                     req->rq_export->exp_client_uuid.uuid, rc);
-               GOTO(srv_update, rc = 0);
-       }
-
        /* Target that supports multiple reply data */
-       if (tgt_is_multimodrpcs_client(req->rq_export)) {
+       if (tgt_is_multimodrpcs_client(exp)) {
                struct tg_reply_data    *trd;
                struct lsd_reply_data   *lrd;
                __u64                   *pre_versions;
-               int                      i;
-               loff_t                   off;
+               bool                    write_update;
 
                OBD_ALLOC_PTR(trd);
                if (unlikely(trd == NULL))
-                       GOTO(srv_update, rc = -ENOMEM);
-
-               /* update export last transno */
-               mutex_lock(&ted->ted_lcd_lock);
-               if (tti->tti_transno > ted->ted_lcd->lcd_last_transno)
-                       ted->ted_lcd->lcd_last_transno = tti->tti_transno;
-               mutex_unlock(&ted->ted_lcd_lock);
+                       RETURN(-ENOMEM);
 
                /* fill reply data information */
                lrd = &trd->trd_reply;
                lrd->lrd_transno = tti->tti_transno;
-               lrd->lrd_xid = req->rq_xid;
-               lrd->lrd_result = th->th_result;
+               if (req != NULL) {
+                       lrd->lrd_xid = req->rq_xid;
+                       trd->trd_tag = lustre_msg_get_tag(req->rq_reqmsg);
+                       pre_versions = lustre_msg_get_versions(req->rq_repmsg);
+                       lrd->lrd_result = th->th_result;
+                       lrd->lrd_client_gen = ted->ted_lcd->lcd_generation;
+                       write_update = true;
+               } else {
+                       LASSERT(tsi->tsi_xid != 0);
+                       lrd->lrd_xid = tsi->tsi_xid;
+                       lrd->lrd_result = tsi->tsi_result;
+                       lrd->lrd_client_gen = tsi->tsi_client_gen;
+                       trd->trd_tag = 0;
+                       pre_versions = NULL;
+                       write_update = false;
+               }
+
                lrd->lrd_data = opdata;
-               lrd->lrd_client_gen = ted->ted_lcd->lcd_generation;
-               trd->trd_tag = lustre_msg_get_tag(req->rq_reqmsg);
-               pre_versions = lustre_msg_get_versions(req->rq_repmsg);
                if (pre_versions) {
                        trd->trd_pre_versions[0] = pre_versions[0];
                        trd->trd_pre_versions[1] = pre_versions[1];
@@ -1178,40 +1260,16 @@ static int tgt_last_rcvd_update(const struct lu_env *env, struct lu_target *tgt,
                        trd->trd_pre_versions[3] = pre_versions[3];
                }
 
-               /* find a empty slot */
-               i = tgt_find_free_reply_slot(tgt);
-               if (unlikely(i < 0)) {
-                       CERROR("%s: couldn't find a slot for reply data: "
-                              "rc = %d\n", tgt_name(tgt), i);
-                       GOTO(srv_update, rc = i);
-               }
-               trd->trd_index = i;
-
-               /* write reply data to disk */
-               off = sizeof(struct lsd_reply_header) + sizeof(*lrd) * i;
-               rc = tgt_reply_data_write(env, tgt, lrd, off, th);
-               if (unlikely(rc != 0)) {
-                       CERROR("%s: can't update %s file: rc = %d\n",
-                              tgt_name(tgt), REPLY_DATA, rc);
-                       RETURN(rc);
-               }
-
-               /* add reply data to target export's reply list */
-               mutex_lock(&ted->ted_lcd_lock);
-               list_add(&trd->trd_list, &ted->ted_reply_list);
-               ted->ted_reply_cnt++;
-               if (ted->ted_reply_cnt > ted->ted_reply_max)
-                       ted->ted_reply_max = ted->ted_reply_cnt;
-               mutex_unlock(&ted->ted_lcd_lock);
-
-               CDEBUG(D_TRACE, "add reply %p: xid %llu, transno %llu, "
-                      "tag %hu, client gen %u, slot idx %d\n",
-                      trd, lrd->lrd_xid, lrd->lrd_transno,
-                      trd->trd_tag, lrd->lrd_client_gen, i);
-
-               GOTO(srv_update, rc = 0);
+               rc = tgt_add_reply_data(env, tgt, ted, trd, th, write_update);
+               if (rc < 0)
+                       OBD_FREE_PTR(trd);
+               return rc;
        }
 
+       /* Enough for update replay, let's return */
+       if (req == NULL)
+               RETURN(rc);
+
        mutex_lock(&ted->ted_lcd_lock);
        LASSERT(ergo(tti->tti_transno == 0, th->th_result != 0));
        if (lustre_msg_get_opc(req->rq_reqmsg) == MDS_CLOSE) {
@@ -1238,21 +1296,27 @@ static int tgt_last_rcvd_update(const struct lu_env *env, struct lu_target *tgt,
 
        /* Update transno in slot only if non-zero number, i.e. no errors */
        if (likely(tti->tti_transno != 0)) {
-               if (*transno_p > tti->tti_transno &&
-                   !tgt->lut_no_reconstruct) {
-                       CERROR("%s: trying to overwrite bigger transno:"
-                              "on-disk: "LPU64", new: "LPU64" replay: %d. "
-                              "see LU-617.\n", tgt_name(tgt), *transno_p,
-                              tti->tti_transno, req_is_replay(req));
-                       if (req_is_replay(req)) {
-                               spin_lock(&req->rq_export->exp_lock);
-                               req->rq_export->exp_vbr_failed = 1;
-                               spin_unlock(&req->rq_export->exp_lock);
+               /* Don't overwrite bigger transaction number with lower one.
+                * That is not sign of problem in all cases, but in any case
+                * this value should be monotonically increased only. */
+               if (*transno_p > tti->tti_transno) {
+                       if (!tgt->lut_no_reconstruct) {
+                               CERROR("%s: trying to overwrite bigger transno:"
+                                      "on-disk: "LPU64", new: "LPU64" replay: "
+                                      "%d. See LU-617.\n", tgt_name(tgt),
+                                      *transno_p, tti->tti_transno,
+                                      req_is_replay(req));
+                               if (req_is_replay(req)) {
+                                       spin_lock(&req->rq_export->exp_lock);
+                                       req->rq_export->exp_vbr_failed = 1;
+                                       spin_unlock(&req->rq_export->exp_lock);
+                               }
+                               mutex_unlock(&ted->ted_lcd_lock);
+                               RETURN(req_is_replay(req) ? -EOVERFLOW : 0);
                        }
-                       mutex_unlock(&ted->ted_lcd_lock);
-                       RETURN(req_is_replay(req) ? -EOVERFLOW : 0);
+               } else {
+                       *transno_p = tti->tti_transno;
                }
-               *transno_p = tti->tti_transno;
        }
 
        if (!lw_client) {
@@ -1264,11 +1328,7 @@ static int tgt_last_rcvd_update(const struct lu_env *env, struct lu_target *tgt,
                }
        }
        mutex_unlock(&ted->ted_lcd_lock);
-       EXIT;
-srv_update:
-       if (update)
-               rc = tgt_server_data_write(env, tgt, th);
-       return rc;
+       RETURN(rc);
 }
 
 /*
@@ -1405,7 +1465,6 @@ static int tgt_clients_data_init(const struct lu_env *env,
                    lcd->lcd_generation != 0) {
                        /* compute the highest valid client generation */
                        generation = max(generation, lcd->lcd_generation);
-
                        /* fill client_generation <-> export hash table */
                        rc = cfs_hash_add_unique(hash, &lcd->lcd_generation,
                                                 &exp->exp_gen_hash);
@@ -1420,6 +1479,12 @@ static int tgt_clients_data_init(const struct lu_env *env,
 
                class_export_put(exp);
 
+               rc = rev_import_init(exp);
+               if (rc != 0) {
+                       class_unlink_export(exp);
+                       GOTO(err_out, rc);
+               }
+
                /* Need to check last_rcvd even for duplicated exports. */
                CDEBUG(D_OTHER, "client at idx %d has last_transno = "LPU64"\n",
                       cl_idx, last_transno);
@@ -1659,19 +1724,32 @@ int tgt_txn_start_cb(const struct lu_env *env, struct thandle *th,
        if (tsi->tsi_exp == NULL)
                return 0;
 
-       dto = dt_object_locate(tgt->lut_last_rcvd, th->th_dev);
-       tti_buf_lcd(tti);
-
-       rc = dt_declare_record_write(env, dto, &tti->tti_buf,
-                                    tsi->tsi_exp->exp_target_data.ted_lr_off,
-                                    th);
-       if (rc)
-               return rc;
-
-       tti_buf_lsd(tti);
-       rc = dt_declare_record_write(env, dto, &tti->tti_buf, 0, th);
-       if (rc)
-               return rc;
+       if (tgt_is_multimodrpcs_client(tsi->tsi_exp)) {
+               /*
+                * Use maximum possible file offset for declaration to ensure
+                * ZFS will reserve enough credits for a write anywhere in this
+                * file, since we don't know where in the file the write will be
+                * because a replay slot has not been assigned.  This should be
+                * replaced by dmu_tx_hold_append() when available.
+                */
+               tti->tti_off = atomic_read(&tgt->lut_num_clients) * 8 *
+                               sizeof(struct lsd_reply_data);
+               tti->tti_buf.lb_buf = NULL;
+               tti->tti_buf.lb_len = sizeof(struct lsd_reply_data);
+               dto = dt_object_locate(tgt->lut_reply_data, th->th_dev);
+               rc = dt_declare_record_write(env, dto, &tti->tti_buf,
+                                            tti->tti_off, th);
+               if (rc)
+                       return rc;
+       } else {
+               dto = dt_object_locate(tgt->lut_last_rcvd, th->th_dev);
+               tti_buf_lcd(tti);
+               tti->tti_off = tsi->tsi_exp->exp_target_data.ted_lr_off;
+               rc = dt_declare_record_write(env, dto, &tti->tti_buf,
+                                            tti->tti_off, th);
+               if (rc)
+                       return rc;
+       }
 
        if (tsi->tsi_vbr_obj != NULL &&
            !lu_object_remote(&tsi->tsi_vbr_obj->do_lu)) {
@@ -1701,7 +1779,7 @@ int tgt_txn_stop_cb(const struct lu_env *env, struct thandle *th,
        if (tsi->tsi_exp == NULL)
                return 0;
 
-       echo_client = (tgt_ses_req(tsi) == NULL);
+       echo_client = (tgt_ses_req(tsi) == NULL && tsi->tsi_xid == 0);
 
        if (tti->tti_has_trans && !echo_client) {
                if (tti->tti_mult_trans == 0) {
@@ -1742,7 +1820,6 @@ int tgt_reply_data_init(const struct lu_env *env, struct lu_target *tgt)
        loff_t                   off;
        struct cfs_hash         *hash = NULL;
        struct obd_export       *exp;
-       struct obd_export       *tmp;
        struct tg_export_data   *ted;
        int                      reply_data_recovered = 0;
 
@@ -1815,7 +1892,11 @@ int tgt_reply_data_init(const struct lu_env *env, struct lu_target *tgt)
 
                        /* create in-memory reply_data and link it to
                         * target export's reply list */
-                       tgt_set_reply_slot(tgt, idx);
+                       rc = tgt_set_reply_slot(tgt, idx);
+                       if (rc != 0) {
+                               mutex_unlock(&ted->ted_lcd_lock);
+                               GOTO(out, rc);
+                       }
                        trd->trd_reply = *lrd;
                        trd->trd_pre_versions[0] = 0;
                        trd->trd_pre_versions[1] = 0;
@@ -1855,20 +1936,6 @@ int tgt_reply_data_init(const struct lu_env *env, struct lu_target *tgt)
                }
                CDEBUG(D_INFO, "%s: %d reply data have been recovered\n",
                       tgt_name(tgt), reply_data_recovered);
-
-               /* delete entries from client_generation<->export hash */
-               spin_lock(&tgt->lut_obd->obd_dev_lock);
-               list_for_each_entry_safe(exp, tmp,
-                                        &tgt->lut_obd->obd_exports,
-                                        exp_obd_chain) {
-                       struct tg_export_data *ted = &exp->exp_target_data;
-
-                       if (!hlist_unhashed(&exp->exp_gen_hash))
-                               cfs_hash_del(hash,
-                                            &ted->ted_lcd->lcd_generation,
-                                            &exp->exp_gen_hash);
-               }
-               spin_unlock(&tgt->lut_obd->obd_dev_lock);
        }
 
        spin_lock(&tgt->lut_translock);
@@ -1891,25 +1958,39 @@ out:
        return rc;
 }
 
+struct tg_reply_data *tgt_lookup_reply_by_xid(struct tg_export_data *ted,
+                                             __u64 xid)
+{
+       struct tg_reply_data    *found = NULL;
+       struct tg_reply_data    *reply;
+
+       mutex_lock(&ted->ted_lcd_lock);
+       list_for_each_entry(reply, &ted->ted_reply_list, trd_list) {
+               if (reply->trd_reply.lrd_xid == xid) {
+                       found = reply;
+                       break;
+               }
+       }
+       mutex_unlock(&ted->ted_lcd_lock);
+       return found;
+}
+EXPORT_SYMBOL(tgt_lookup_reply_by_xid);
+
 /* Look for a reply data matching specified request @req
  * A copy is returned in @trd if the pointer is not NULL
  */
 bool tgt_lookup_reply(struct ptlrpc_request *req, struct tg_reply_data *trd)
 {
        struct tg_export_data   *ted = &req->rq_export->exp_target_data;
-       struct tg_reply_data    *reply, *tmp;
+       struct tg_reply_data    *reply;
        bool                     found = false;
 
-       mutex_lock(&ted->ted_lcd_lock);
-       list_for_each_entry_safe(reply, tmp, &ted->ted_reply_list, trd_list) {
-               if (reply->trd_reply.lrd_xid == req->rq_xid) {
-                       found = true;
-                       break;
-               }
+       reply = tgt_lookup_reply_by_xid(ted, req->rq_xid);
+       if (reply != NULL) {
+               found = true;
+               if (trd != NULL)
+                       *trd = *reply;
        }
-       if (found && trd != NULL)
-               *trd = *reply;
-       mutex_unlock(&ted->ted_lcd_lock);
 
        CDEBUG(D_TRACE, "%s: lookup reply xid %llu, found %d\n",
               tgt_name(class_exp2tgt(req->rq_export)), req->rq_xid,