X-Git-Url: https://git.whamcloud.com/?a=blobdiff_plain;f=lustre%2Ftarget%2Ftgt_lastrcvd.c;h=8b0f9a015e7ea4ffbb37d68ac49cccebc645d1ae;hb=892078e3b566c04471e7dcf2c28e66f2f3584f93;hp=03014a197316762e0f796e40eff61d9e9de137c8;hpb=77e44127bb39f5d1dc1f4e61274e5df7bf707603;p=fs%2Flustre-release.git

diff --git a/lustre/target/tgt_lastrcvd.c b/lustre/target/tgt_lastrcvd.c
index 03014a1..8b0f9a0 100644
--- a/lustre/target/tgt_lastrcvd.c
+++ b/lustre/target/tgt_lastrcvd.c
@@ -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, 2012, Whamcloud, Inc.
+ * Copyright (c) 2011, 2014, Intel Corporation.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
@@ -44,6 +44,317 @@
 
 #include "tgt_internal.h"
 
+
+/* Allocate a bitmap for a chunk of reply data slots */
+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));
+	if (bm == NULL)
+		return -ENOMEM;
+
+	spin_lock(&lut->lut_client_bitmap_lock);
+
+	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) *
+			 sizeof(long));
+		return 0;
+	}
+
+	lut->lut_reply_bitmap[chunk] = bm;
+
+	spin_unlock(&lut->lut_client_bitmap_lock);
+
+	return 0;
+}
+
+/* Look for an available reply data slot in the bitmap
+ * of the target @lut
+ * Allocate bitmap chunk when first used
+ * XXX algo could be improved if this routine limits performance
+ */
+static int tgt_find_free_reply_slot(struct lu_target *lut)
+{
+	unsigned long *bmp;
+	int chunk = 0;
+	int rc;
+	int b;
+
+	for (chunk = 0; chunk < LUT_REPLY_SLOTS_MAX_CHUNKS; chunk++) {
+		/* allocate the bitmap chunk if necessary */
+		if (unlikely(lut->lut_reply_bitmap[chunk] == NULL)) {
+			rc = tgt_bitmap_chunk_alloc(lut, chunk);
+			if (rc != 0)
+				return rc;
+		}
+		bmp = lut->lut_reply_bitmap[chunk];
+
+		/* look for an available slot in this chunk */
+		do {
+			b = find_first_zero_bit(bmp, LUT_REPLY_SLOTS_PER_CHUNK);
+			if (b >= LUT_REPLY_SLOTS_PER_CHUNK)
+				break;
+
+			/* found one */
+			if (test_and_set_bit(b, bmp) == 0)
+				return chunk * LUT_REPLY_SLOTS_PER_CHUNK + b;
+		} while (true);
+	}
+
+	return -ENOSPC;
+}
+
+/* Mark the reply data slot @idx 'used' in the corresponding bitmap chunk
+ * of the target @lut
+ * Allocate the bitmap chunk if necessary
+ */
+static int tgt_set_reply_slot(struct lu_target *lut, int idx)
+{
+	int chunk;
+	int b;
+	int rc;
+
+	chunk = idx / LUT_REPLY_SLOTS_PER_CHUNK;
+	b = idx % LUT_REPLY_SLOTS_PER_CHUNK;
+
+	LASSERT(chunk < LUT_REPLY_SLOTS_MAX_CHUNKS);
+	LASSERT(b < LUT_REPLY_SLOTS_PER_CHUNK);
+
+	/* allocate the bitmap chunk if necessary */
+	if (unlikely(lut->lut_reply_bitmap[chunk] == NULL)) {
+		rc = tgt_bitmap_chunk_alloc(lut, chunk);
+		if (rc != 0)
+			return rc;
+	}
+
+	/* mark the slot 'used' in this chunk */
+	if (test_and_set_bit(b, lut->lut_reply_bitmap[chunk]) != 0) {
+		CERROR("%s: slot %d already set in bitmap\n",
+		       tgt_name(lut), idx);
+		return -EALREADY;
+	}
+
+	return 0;
+}
+
+
+/* Mark the reply data slot @idx 'unused' in the corresponding bitmap chunk
+ * of the target @lut
+ */
+static int tgt_clear_reply_slot(struct lu_target *lut, int idx)
+{
+	int chunk;
+	int b;
+
+	chunk = idx / LUT_REPLY_SLOTS_PER_CHUNK;
+	b = idx % LUT_REPLY_SLOTS_PER_CHUNK;
+
+	LASSERT(chunk < LUT_REPLY_SLOTS_MAX_CHUNKS);
+	LASSERT(b < LUT_REPLY_SLOTS_PER_CHUNK);
+
+	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);
+		return -EALREADY;
+	}
+
+	return 0;
+}
+
+
+/* Read header of reply_data file of target @tgt into structure @lrh */
+static int tgt_reply_header_read(const struct lu_env *env,
+				 struct lu_target *tgt,
+				 struct lsd_reply_header *lrh)
+{
+	int			 rc;
+	struct lsd_reply_header	 buf;
+	struct tgt_thread_info	*tti = tgt_th_info(env);
+
+	tti->tti_off = 0;
+	tti->tti_buf.lb_buf = &buf;
+	tti->tti_buf.lb_len = sizeof(buf);
+
+	rc = dt_record_read(env, tgt->lut_reply_data, &tti->tti_buf,
+			    &tti->tti_off);
+	if (rc != 0)
+		return rc;
+
+	lrh->lrh_magic = le32_to_cpu(buf.lrh_magic);
+	lrh->lrh_header_size = le32_to_cpu(buf.lrh_header_size);
+	lrh->lrh_reply_size = le32_to_cpu(buf.lrh_reply_size);
+
+	CDEBUG(D_HA, "%s: read %s header. magic=0x%08x "
+	       "header_size=%d reply_size=%d\n",
+		tgt->lut_obd->obd_name, REPLY_DATA,
+		lrh->lrh_magic, lrh->lrh_header_size, lrh->lrh_reply_size);
+
+	return 0;
+}
+
+/* Write header into replay_data file of target @tgt from structure @lrh */
+static int tgt_reply_header_write(const struct lu_env *env,
+				  struct lu_target *tgt,
+				  struct lsd_reply_header *lrh)
+{
+	int			 rc;
+	struct lsd_reply_header	 buf;
+	struct tgt_thread_info	*tti = tgt_th_info(env);
+	struct thandle		*th;
+	struct dt_object	*dto;
+
+	CDEBUG(D_HA, "%s: write %s header. magic=0x%08x "
+	       "header_size=%d reply_size=%d\n",
+		tgt->lut_obd->obd_name, REPLY_DATA,
+		lrh->lrh_magic, lrh->lrh_header_size, lrh->lrh_reply_size);
+
+	buf.lrh_magic = cpu_to_le32(lrh->lrh_magic);
+	buf.lrh_header_size = cpu_to_le32(lrh->lrh_header_size);
+	buf.lrh_reply_size = cpu_to_le32(lrh->lrh_reply_size);
+
+	th = dt_trans_create(env, tgt->lut_bottom);
+	if (IS_ERR(th))
+		return PTR_ERR(th);
+	th->th_sync = 1;
+
+	tti->tti_off = 0;
+	tti->tti_buf.lb_buf = &buf;
+	tti->tti_buf.lb_len = sizeof(buf);
+
+	rc = dt_declare_record_write(env, tgt->lut_reply_data,
+				     &tti->tti_buf, tti->tti_off, th);
+	if (rc)
+		GOTO(out, rc);
+
+	rc = dt_trans_start(env, tgt->lut_bottom, th);
+	if (rc)
+		GOTO(out, rc);
+
+	dto = dt_object_locate(tgt->lut_reply_data, th->th_dev);
+	rc = dt_record_write(env, dto, &tti->tti_buf, &tti->tti_off, th);
+out:
+	dt_trans_stop(env, tgt->lut_bottom, th);
+	return rc;
+}
+
+/* Write the reply data @lrd into reply_data file of target @tgt
+ * at offset @off
+ */
+static int tgt_reply_data_write(const struct lu_env *env, struct lu_target *tgt,
+				struct lsd_reply_data *lrd, loff_t off,
+				struct thandle *th)
+{
+	struct tgt_thread_info	*tti = tgt_th_info(env);
+	struct dt_object	*dto;
+	struct lsd_reply_data	*buf = &tti->tti_lrd;
+
+	lrd->lrd_result = ptlrpc_status_hton(lrd->lrd_result);
+
+	buf->lrd_transno	 = cpu_to_le64(lrd->lrd_transno);
+	buf->lrd_xid		 = cpu_to_le64(lrd->lrd_xid);
+	buf->lrd_data		 = cpu_to_le64(lrd->lrd_data);
+	buf->lrd_result		 = cpu_to_le32(lrd->lrd_result);
+	buf->lrd_client_gen	 = cpu_to_le32(lrd->lrd_client_gen);
+
+	lrd->lrd_result = ptlrpc_status_ntoh(lrd->lrd_result);
+
+	tti->tti_off = off;
+	tti->tti_buf.lb_buf = buf;
+	tti->tti_buf.lb_len = sizeof(*buf);
+
+	dto = dt_object_locate(tgt->lut_reply_data, th->th_dev);
+	return dt_record_write(env, dto, &tti->tti_buf, &tti->tti_off, th);
+}
+
+/* Read the reply data from reply_data file of target @tgt at offset @off
+ * into structure @lrd
+ */
+static int tgt_reply_data_read(const struct lu_env *env, struct lu_target *tgt,
+			       struct lsd_reply_data *lrd, loff_t off)
+{
+	int			 rc;
+	struct tgt_thread_info	*tti = tgt_th_info(env);
+	struct lsd_reply_data	*buf = &tti->tti_lrd;
+
+	tti->tti_off = off;
+	tti->tti_buf.lb_buf = buf;
+	tti->tti_buf.lb_len = sizeof(*buf);
+
+	rc = dt_record_read(env, tgt->lut_reply_data, &tti->tti_buf,
+			    &tti->tti_off);
+	if (rc != 0)
+		return rc;
+
+	lrd->lrd_transno	 = le64_to_cpu(buf->lrd_transno);
+	lrd->lrd_xid		 = le64_to_cpu(buf->lrd_xid);
+	lrd->lrd_data		 = le64_to_cpu(buf->lrd_data);
+	lrd->lrd_result		 = le32_to_cpu(buf->lrd_result);
+	lrd->lrd_client_gen	 = le32_to_cpu(buf->lrd_client_gen);
+
+	return 0;
+}
+
+
+/* Free the in-memory reply data structure @trd and release
+ * the corresponding slot in the reply_data file of target @lut
+ * Called with ted_lcd_lock held
+ */
+static void tgt_free_reply_data(struct lu_target *lut,
+				struct tg_export_data *ted,
+				struct tg_reply_data *trd)
+{
+	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,
+	       trd->trd_reply.lrd_transno, trd->trd_reply.lrd_client_gen,
+	       trd->trd_index);
+
+	LASSERT(mutex_is_locked(&ted->ted_lcd_lock));
+
+	list_del(&trd->trd_list);
+	ted->ted_reply_cnt--;
+	tgt_clear_reply_slot(lut, trd->trd_index);
+	OBD_FREE_PTR(trd);
+}
+
+/* Release the reply data @trd from target @lut
+ * The reply data with the highest transno for this export
+ * is retained to ensure correctness of target recovery
+ * Called with ted_lcd_lock held
+ */
+static void tgt_release_reply_data(struct lu_target *lut,
+				   struct tg_export_data *ted,
+				   struct tg_reply_data *trd)
+{
+	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,
+	       trd->trd_reply.lrd_transno, trd->trd_reply.lrd_client_gen,
+	       trd->trd_index);
+
+	LASSERT(mutex_is_locked(&ted->ted_lcd_lock));
+
+	/* Do not free the reply data corresponding to the
+	 * highest transno of this export.
+	 * This ensures on-disk reply data is kept and
+	 * last committed transno can be restored from disk in case
+	 * of target recovery
+	 */
+	if (trd->trd_reply.lrd_transno == ted->ted_lcd->lcd_last_transno) {
+		/* free previous retained reply */
+		if (ted->ted_reply_last != NULL)
+			tgt_free_reply_data(lut, ted, ted->ted_reply_last);
+		/* retain the reply */
+		list_del_init(&trd->trd_list);
+		ted->ted_reply_last = trd;
+	} else {
+		tgt_free_reply_data(lut, ted, trd);
+	}
+}
+
 static inline struct lu_buf *tti_buf_lsd(struct tgt_thread_info *tti)
 {
 	tti->tti_buf.lb_buf = &tti->tti_lsd;
@@ -61,107 +372,144 @@ static inline struct lu_buf *tti_buf_lcd(struct tgt_thread_info *tti)
 /**
  * Allocate in-memory data for client slot related to export.
  */
-int lut_client_alloc(struct obd_export *exp)
+int tgt_client_alloc(struct obd_export *exp)
 {
-        LASSERT(exp != exp->exp_obd->obd_self_export);
-
-        OBD_ALLOC_PTR(exp->exp_target_data.ted_lcd);
-        if (exp->exp_target_data.ted_lcd == NULL)
-                RETURN(-ENOMEM);
-        /* Mark that slot is not yet valid, 0 doesn't work here */
-        exp->exp_target_data.ted_lr_idx = -1;
-        RETURN(0);
+	ENTRY;
+	LASSERT(exp != exp->exp_obd->obd_self_export);
+
+	OBD_ALLOC_PTR(exp->exp_target_data.ted_lcd);
+	if (exp->exp_target_data.ted_lcd == NULL)
+		RETURN(-ENOMEM);
+	/* Mark that slot is not yet valid, 0 doesn't work here */
+	exp->exp_target_data.ted_lr_idx = -1;
+	INIT_LIST_HEAD(&exp->exp_target_data.ted_reply_list);
+	mutex_init(&exp->exp_target_data.ted_lcd_lock);
+	RETURN(0);
 }
-EXPORT_SYMBOL(lut_client_alloc);
+EXPORT_SYMBOL(tgt_client_alloc);
 
 /**
  * Free in-memory data for client slot related to export.
  */
-void lut_client_free(struct obd_export *exp)
+void tgt_client_free(struct obd_export *exp)
 {
-        struct tg_export_data *ted = &exp->exp_target_data;
-        struct lu_target *lut = class_exp2tgt(exp);
+	struct tg_export_data	*ted = &exp->exp_target_data;
+	struct lu_target	*lut = class_exp2tgt(exp);
+	struct tg_reply_data	*trd, *tmp;
 
-        LASSERT(exp != exp->exp_obd->obd_self_export);
+	LASSERT(exp != exp->exp_obd->obd_self_export);
 
-        OBD_FREE_PTR(ted->ted_lcd);
-        ted->ted_lcd = NULL;
+	/* free reply data */
+	mutex_lock(&ted->ted_lcd_lock);
+	list_for_each_entry_safe(trd, tmp, &ted->ted_reply_list, trd_list) {
+		tgt_release_reply_data(lut, ted, trd);
+	}
+	if (ted->ted_reply_last != NULL) {
+		tgt_free_reply_data(lut, ted, ted->ted_reply_last);
+		ted->ted_reply_last = NULL;
+	}
+	mutex_unlock(&ted->ted_lcd_lock);
+
+	if (!hlist_unhashed(&exp->exp_gen_hash))
+		cfs_hash_del(exp->exp_obd->obd_gen_hash,
+			     &ted->ted_lcd->lcd_generation,
+			     &exp->exp_gen_hash);
+
+	OBD_FREE_PTR(ted->ted_lcd);
+	ted->ted_lcd = NULL;
+
+	/* Slot may be not yet assigned */
+	if (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)) {
+		CERROR("%s: client %u bit already clear in bitmap\n",
+		       exp->exp_obd->obd_name, ted->ted_lr_idx);
+		LBUG();
+	}
 
-        /* Slot may be not yet assigned */
-        if (ted->ted_lr_idx < 0)
-                return;
-        /* Clear bit when lcd is freed */
-	LASSERT(lut->lut_client_bitmap);
-        if (!cfs_test_and_clear_bit(ted->ted_lr_idx, lut->lut_client_bitmap)) {
-                CERROR("%s: client %u bit already clear in bitmap\n",
-                       exp->exp_obd->obd_name, ted->ted_lr_idx);
-                LBUG();
-        }
+	if (tgt_is_multimodrpcs_client(exp) && !exp->exp_obd->obd_stopping)
+		atomic_dec(&lut->lut_num_clients);
 }
-EXPORT_SYMBOL(lut_client_free);
+EXPORT_SYMBOL(tgt_client_free);
 
-int lut_client_data_read(const struct lu_env *env, struct lu_target *tg,
+int tgt_client_data_read(const struct lu_env *env, struct lu_target *tgt,
 			 struct lsd_client_data *lcd, loff_t *off, int index)
 {
-	struct tgt_thread_info *tti = tgt_th_info(env);
-	int rc;
+	struct tgt_thread_info	*tti = tgt_th_info(env);
+	int			 rc;
 
 	tti_buf_lcd(tti);
-	rc = dt_record_read(env, tg->lut_last_rcvd, &tti->tti_buf, off);
+	rc = dt_record_read(env, tgt->lut_last_rcvd, &tti->tti_buf, off);
 	if (rc == 0) {
-		check_lcd(tg->lut_obd->obd_name, index, &tti->tti_lcd);
+		check_lcd(tgt->lut_obd->obd_name, index, &tti->tti_lcd);
 		lcd_le_to_cpu(&tti->tti_lcd, lcd);
+		lcd->lcd_last_result = ptlrpc_status_ntoh(lcd->lcd_last_result);
+		lcd->lcd_last_close_result =
+			ptlrpc_status_ntoh(lcd->lcd_last_close_result);
 	}
 
 	CDEBUG(D_INFO, "%s: read lcd @%lld uuid = %s, last_transno = "LPU64
 	       ", last_xid = "LPU64", last_result = %u, last_data = %u, "
 	       "last_close_transno = "LPU64", last_close_xid = "LPU64", "
-	       "last_close_result = %u, rc = %d\n", tg->lut_obd->obd_name,
+	       "last_close_result = %u, rc = %d\n", tgt->lut_obd->obd_name,
 	       *off, lcd->lcd_uuid, lcd->lcd_last_transno, lcd->lcd_last_xid,
 	       lcd->lcd_last_result, lcd->lcd_last_data,
 	       lcd->lcd_last_close_transno, lcd->lcd_last_close_xid,
 	       lcd->lcd_last_close_result, rc);
 	return rc;
 }
-EXPORT_SYMBOL(lut_client_data_read);
 
-int lut_client_data_write(const struct lu_env *env, struct lu_target *tg,
+int tgt_client_data_write(const struct lu_env *env, struct lu_target *tgt,
 			  struct lsd_client_data *lcd, loff_t *off,
 			  struct thandle *th)
 {
 	struct tgt_thread_info *tti = tgt_th_info(env);
+	struct dt_object	*dto;
 
+	lcd->lcd_last_result = ptlrpc_status_hton(lcd->lcd_last_result);
+	lcd->lcd_last_close_result =
+		ptlrpc_status_hton(lcd->lcd_last_close_result);
 	lcd_cpu_to_le(lcd, &tti->tti_lcd);
 	tti_buf_lcd(tti);
 
-	return dt_record_write(env, tg->lut_last_rcvd, &tti->tti_buf, off, th);
+	dto = dt_object_locate(tgt->lut_last_rcvd, th->th_dev);
+	return dt_record_write(env, dto, &tti->tti_buf, off, th);
 }
-EXPORT_SYMBOL(lut_client_data_write);
 
 /**
  * Update client data in last_rcvd
  */
-int lut_client_data_update(const struct lu_env *env, struct obd_export *exp)
+static int tgt_client_data_update(const struct lu_env *env,
+				  struct obd_export *exp)
 {
-	struct tg_export_data *ted = &exp->exp_target_data;
-	struct lu_target      *tg = class_exp2tgt(exp);
-	struct tgt_thread_info *tti = tgt_th_info(env);
-	struct thandle	      *th;
-	int		       rc = 0;
+	struct tg_export_data	*ted = &exp->exp_target_data;
+	struct lu_target	*tgt = class_exp2tgt(exp);
+	struct tgt_thread_info	*tti = tgt_th_info(env);
+	struct thandle		*th;
+	int			 rc = 0;
 
 	ENTRY;
 
-	th = dt_trans_create(env, tg->lut_bottom);
+	if (unlikely(tgt == NULL)) {
+		CDEBUG(D_ERROR, "%s: No target for connected export\n",
+			  class_exp2obd(exp)->obd_name);
+		RETURN(-EINVAL);
+	}
+
+	th = dt_trans_create(env, tgt->lut_bottom);
 	if (IS_ERR(th))
 		RETURN(PTR_ERR(th));
 
-	rc = dt_declare_record_write(env, tg->lut_last_rcvd,
-				     sizeof(struct lsd_client_data),
+	tti_buf_lcd(tti);
+	rc = dt_declare_record_write(env, tgt->lut_last_rcvd,
+				     &tti->tti_buf,
 				     ted->ted_lr_off, th);
 	if (rc)
 		GOTO(out, rc);
 
-	rc = dt_trans_start_local(env, tg->lut_bottom, th);
+	rc = dt_trans_start_local(env, tgt->lut_bottom, th);
 	if (rc)
 		GOTO(out, rc);
 	/*
@@ -170,121 +518,122 @@ int lut_client_data_update(const struct lu_env *env, struct obd_export *exp)
 	 * transaction so that many connecting clients will not bring
 	 * server down with lots of sync writes.
 	 */
-	rc = lut_new_client_cb_add(th, exp);
+	rc = tgt_new_client_cb_add(th, exp);
 	if (rc) {
 		/* can't add callback, do sync now */
 		th->th_sync = 1;
 	} else {
-		cfs_spin_lock(&exp->exp_lock);
+		spin_lock(&exp->exp_lock);
 		exp->exp_need_sync = 1;
-		cfs_spin_unlock(&exp->exp_lock);
+		spin_unlock(&exp->exp_lock);
 	}
 
 	tti->tti_off = ted->ted_lr_off;
-	rc = lut_client_data_write(env, tg, ted->ted_lcd, &tti->tti_off, th);
+	rc = tgt_client_data_write(env, tgt, ted->ted_lcd, &tti->tti_off, th);
 	EXIT;
 out:
-	dt_trans_stop(env, tg->lut_bottom, th);
+	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", tg->lut_obd->obd_name,
-	       tg->lut_lsd.lsd_uuid, tg->lut_lsd.lsd_last_transno, rc);
+	       "last_transno = "LPU64": rc = %d\n", tgt->lut_obd->obd_name,
+	       tgt->lut_lsd.lsd_uuid, tgt->lut_lsd.lsd_last_transno, rc);
 
 	return rc;
 }
 
-int lut_server_data_read(const struct lu_env *env, struct lu_target *tg)
+int tgt_server_data_read(const struct lu_env *env, struct lu_target *tgt)
 {
-	struct tgt_thread_info *tti = tgt_th_info(env);
-	int rc;
+	struct tgt_thread_info	*tti = tgt_th_info(env);
+	int			 rc;
 
 	tti->tti_off = 0;
 	tti_buf_lsd(tti);
-	rc = dt_record_read(env, tg->lut_last_rcvd, &tti->tti_buf, &tti->tti_off);
+	rc = dt_record_read(env, tgt->lut_last_rcvd, &tti->tti_buf,
+			    &tti->tti_off);
 	if (rc == 0)
-		lsd_le_to_cpu(&tti->tti_lsd, &tg->lut_lsd);
+		lsd_le_to_cpu(&tti->tti_lsd, &tgt->lut_lsd);
 
 	CDEBUG(D_INFO, "%s: read last_rcvd server data for UUID = %s, "
-	       "last_transno = "LPU64": rc = %d\n", tg->lut_obd->obd_name,
-	       tg->lut_lsd.lsd_uuid, tg->lut_lsd.lsd_last_transno, rc);
+	       "last_transno = "LPU64": rc = %d\n", tgt->lut_obd->obd_name,
+	       tgt->lut_lsd.lsd_uuid, tgt->lut_lsd.lsd_last_transno, rc);
         return rc;
 }
-EXPORT_SYMBOL(lut_server_data_read);
 
-int lut_server_data_write(const struct lu_env *env, struct lu_target *tg,
+int tgt_server_data_write(const struct lu_env *env, struct lu_target *tgt,
 			  struct thandle *th)
 {
-	struct tgt_thread_info *tti = tgt_th_info(env);
-	int rc;
+	struct tgt_thread_info	*tti = tgt_th_info(env);
+	struct dt_object	*dto;
+	int			 rc;
+
 	ENTRY;
 
 	tti->tti_off = 0;
 	tti_buf_lsd(tti);
-	lsd_cpu_to_le(&tg->lut_lsd, &tti->tti_lsd);
+	lsd_cpu_to_le(&tgt->lut_lsd, &tti->tti_lsd);
 
-	rc = dt_record_write(env, tg->lut_last_rcvd, &tti->tti_buf,
-			     &tti->tti_off, th);
+	dto = dt_object_locate(tgt->lut_last_rcvd, th->th_dev);
+	rc = dt_record_write(env, dto, &tti->tti_buf, &tti->tti_off, th);
 
 	CDEBUG(D_INFO, "%s: write last_rcvd server data for UUID = %s, "
-	       "last_transno = "LPU64": rc = %d\n", tg->lut_obd->obd_name,
-	       tg->lut_lsd.lsd_uuid, tg->lut_lsd.lsd_last_transno, rc);
+	       "last_transno = "LPU64": rc = %d\n", tgt->lut_obd->obd_name,
+	       tgt->lut_lsd.lsd_uuid, tgt->lut_lsd.lsd_last_transno, rc);
 
 	RETURN(rc);
 }
-EXPORT_SYMBOL(lut_server_data_write);
 
 /**
  * Update server data in last_rcvd
  */
-int lut_server_data_update(const struct lu_env *env, struct lu_target *tg,
+int tgt_server_data_update(const struct lu_env *env, struct lu_target *tgt,
 			   int sync)
 {
-	struct tgt_thread_info *tti = tgt_th_info(env);
-	struct thandle	*th;
-	int		    rc = 0;
+	struct tgt_thread_info	*tti = tgt_th_info(env);
+	struct thandle		*th;
+	int			 rc = 0;
 
 	ENTRY;
 
 	CDEBUG(D_SUPER,
 	       "%s: mount_count is "LPU64", last_transno is "LPU64"\n",
-	       tg->lut_lsd.lsd_uuid, tg->lut_obd->u.obt.obt_mount_count,
-	       tg->lut_last_transno);
+	       tgt->lut_lsd.lsd_uuid, tgt->lut_obd->u.obt.obt_mount_count,
+	       tgt->lut_last_transno);
 
 	/* Always save latest transno to keep it fresh */
-	cfs_spin_lock(&tg->lut_translock);
-	tg->lut_lsd.lsd_last_transno = tg->lut_last_transno;
-	cfs_spin_unlock(&tg->lut_translock);
+	spin_lock(&tgt->lut_translock);
+	tgt->lut_lsd.lsd_last_transno = tgt->lut_last_transno;
+	spin_unlock(&tgt->lut_translock);
 
-	th = dt_trans_create(env, tg->lut_bottom);
+	th = dt_trans_create(env, tgt->lut_bottom);
 	if (IS_ERR(th))
 		RETURN(PTR_ERR(th));
 
 	th->th_sync = sync;
 
-	rc = dt_declare_record_write(env, tg->lut_last_rcvd,
-				     sizeof(struct lr_server_data),
-				     tti->tti_off, th);
+	tti_buf_lsd(tti);
+	rc = dt_declare_record_write(env, tgt->lut_last_rcvd,
+				     &tti->tti_buf, tti->tti_off, th);
 	if (rc)
 		GOTO(out, rc);
 
-	rc = dt_trans_start(env, tg->lut_bottom, th);
+	rc = dt_trans_start(env, tgt->lut_bottom, th);
 	if (rc)
 		GOTO(out, rc);
 
-	rc = lut_server_data_write(env, tg, th);
+	rc = tgt_server_data_write(env, tgt, th);
 out:
-	dt_trans_stop(env, tg->lut_bottom, th);
+	dt_trans_stop(env, tgt->lut_bottom, th);
 
 	CDEBUG(D_INFO, "%s: update last_rcvd server data for UUID = %s, "
-	       "last_transno = "LPU64": rc = %d\n", tg->lut_obd->obd_name,
-	       tg->lut_lsd.lsd_uuid, tg->lut_lsd.lsd_last_transno, rc);
+	       "last_transno = "LPU64": rc = %d\n", tgt->lut_obd->obd_name,
+	       tgt->lut_lsd.lsd_uuid, tgt->lut_lsd.lsd_last_transno, rc);
 	RETURN(rc);
 }
-EXPORT_SYMBOL(lut_server_data_update);
+EXPORT_SYMBOL(tgt_server_data_update);
 
-int lut_truncate_last_rcvd(const struct lu_env *env, struct lu_target *tg,
+int tgt_truncate_last_rcvd(const struct lu_env *env, struct lu_target *tgt,
 			   loff_t size)
 {
-	struct dt_object *dt = tg->lut_last_rcvd;
+	struct dt_object *dt = tgt->lut_last_rcvd;
 	struct thandle	 *th;
 	struct lu_attr	  attr;
 	int		  rc;
@@ -294,7 +643,7 @@ int lut_truncate_last_rcvd(const struct lu_env *env, struct lu_target *tg,
 	attr.la_size = size;
 	attr.la_valid = LA_SIZE;
 
-	th = dt_trans_create(env, tg->lut_bottom);
+	th = dt_trans_create(env, tgt->lut_bottom);
 	if (IS_ERR(th))
 		RETURN(PTR_ERR(th));
 	rc = dt_declare_punch(env, dt, size, OBD_OBJECT_EOF, th);
@@ -303,147 +652,156 @@ int lut_truncate_last_rcvd(const struct lu_env *env, struct lu_target *tg,
 	rc = dt_declare_attr_set(env, dt, &attr, th);
 	if (rc)
 		GOTO(cleanup, rc);
-	rc = dt_trans_start_local(env, tg->lut_bottom, th);
+	rc = dt_trans_start_local(env, tgt->lut_bottom, th);
 	if (rc)
 		GOTO(cleanup, rc);
 
-	rc = dt_punch(env, dt, size, OBD_OBJECT_EOF, th, BYPASS_CAPA);
+	rc = dt_punch(env, dt, size, OBD_OBJECT_EOF, th);
 	if (rc == 0)
-		rc = dt_attr_set(env, dt, &attr, th, BYPASS_CAPA);
+		rc = dt_attr_set(env, dt, &attr, th);
 
 cleanup:
-	dt_trans_stop(env, tg->lut_bottom, th);
+	dt_trans_stop(env, tgt->lut_bottom, th);
 
 	RETURN(rc);
 }
-EXPORT_SYMBOL(lut_truncate_last_rcvd);
 
-void lut_client_epoch_update(const struct lu_env *env, struct obd_export *exp)
+static void tgt_client_epoch_update(const struct lu_env *env,
+				    struct obd_export *exp)
 {
-        struct lsd_client_data *lcd = exp->exp_target_data.ted_lcd;
-        struct lu_target *lut = class_exp2tgt(exp);
-
-        LASSERT(lut->lut_bottom);
-        /** VBR: set client last_epoch to current epoch */
-        if (lcd->lcd_last_epoch >= lut->lut_lsd.lsd_start_epoch)
-                return;
-        lcd->lcd_last_epoch = lut->lut_lsd.lsd_start_epoch;
-        lut_client_data_update(env, exp);
+	struct lsd_client_data	*lcd = exp->exp_target_data.ted_lcd;
+	struct lu_target	*tgt = class_exp2tgt(exp);
+
+	LASSERT(tgt && tgt->lut_bottom);
+	/** VBR: set client last_epoch to current epoch */
+	if (lcd->lcd_last_epoch >= tgt->lut_lsd.lsd_start_epoch)
+		return;
+	lcd->lcd_last_epoch = tgt->lut_lsd.lsd_start_epoch;
+	tgt_client_data_update(env, exp);
 }
 
 /**
  * Update boot epoch when recovery ends
  */
-void lut_boot_epoch_update(struct lu_target *lut)
+void tgt_boot_epoch_update(struct lu_target *tgt)
 {
-        struct lu_env env;
-        struct ptlrpc_request *req;
-        __u32 start_epoch;
-        cfs_list_t client_list;
-        int rc;
+	struct lu_env		 env;
+	struct ptlrpc_request	*req;
+	__u32			 start_epoch;
+	struct list_head	 client_list;
+	int			 rc;
 
-        if (lut->lut_obd->obd_stopping)
-                return;
+	if (tgt->lut_obd->obd_stopping)
+		return;
 
 	rc = lu_env_init(&env, LCT_DT_THREAD);
-        if (rc) {
-                CERROR("Can't initialize environment rc=%d\n", rc);
-                return;
-        }
-
-        cfs_spin_lock(&lut->lut_translock);
-        start_epoch = lr_epoch(lut->lut_last_transno) + 1;
-        lut->lut_last_transno = (__u64)start_epoch << LR_EPOCH_BITS;
-        lut->lut_lsd.lsd_start_epoch = start_epoch;
-        cfs_spin_unlock(&lut->lut_translock);
-
-        CFS_INIT_LIST_HEAD(&client_list);
-        /**
-         * The recovery is not yet finished and final queue can still be updated
-         * with resend requests. Move final list to separate one for processing
-         */
-        cfs_spin_lock(&lut->lut_obd->obd_recovery_task_lock);
-        cfs_list_splice_init(&lut->lut_obd->obd_final_req_queue, &client_list);
-        cfs_spin_unlock(&lut->lut_obd->obd_recovery_task_lock);
-
-        /**
-         * go through list of exports participated in recovery and
-         * set new epoch for them
-         */
-        cfs_list_for_each_entry(req, &client_list, rq_list) {
-                LASSERT(!req->rq_export->exp_delayed);
-                if (!req->rq_export->exp_vbr_failed)
-                        lut_client_epoch_update(&env, req->rq_export);
-        }
-        /** return list back at once */
-        cfs_spin_lock(&lut->lut_obd->obd_recovery_task_lock);
-        cfs_list_splice_init(&client_list, &lut->lut_obd->obd_final_req_queue);
-        cfs_spin_unlock(&lut->lut_obd->obd_recovery_task_lock);
-        /** update server epoch */
-        lut_server_data_update(&env, lut, 1);
-        lu_env_fini(&env);
-}
-EXPORT_SYMBOL(lut_boot_epoch_update);
+	if (rc) {
+		CERROR("%s: can't initialize environment: rc = %d\n",
+		        tgt->lut_obd->obd_name, rc);
+		return;
+	}
+
+	spin_lock(&tgt->lut_translock);
+	start_epoch = lr_epoch(tgt->lut_last_transno) + 1;
+	tgt->lut_last_transno = (__u64)start_epoch << LR_EPOCH_BITS;
+	tgt->lut_lsd.lsd_start_epoch = start_epoch;
+	spin_unlock(&tgt->lut_translock);
+
+	INIT_LIST_HEAD(&client_list);
+	/**
+	 * The recovery is not yet finished and final queue can still be updated
+	 * with resend requests. Move final list to separate one for processing
+	 */
+	spin_lock(&tgt->lut_obd->obd_recovery_task_lock);
+	list_splice_init(&tgt->lut_obd->obd_final_req_queue, &client_list);
+	spin_unlock(&tgt->lut_obd->obd_recovery_task_lock);
+
+	/**
+	 * go through list of exports participated in recovery and
+	 * set new epoch for them
+	 */
+	list_for_each_entry(req, &client_list, rq_list) {
+		LASSERT(!req->rq_export->exp_delayed);
+		if (!req->rq_export->exp_vbr_failed)
+			tgt_client_epoch_update(&env, req->rq_export);
+	}
+	/** return list back at once */
+	spin_lock(&tgt->lut_obd->obd_recovery_task_lock);
+	list_splice_init(&client_list, &tgt->lut_obd->obd_final_req_queue);
+	spin_unlock(&tgt->lut_obd->obd_recovery_task_lock);
+
+	/** Clear MULTI RPCS incompatibility flag if
+	 * - target is MDT and
+	 * - there is no client to recover or the recovery was aborted
+	 */
+	if (!strncmp(tgt->lut_obd->obd_type->typ_name, LUSTRE_MDT_NAME, 3) &&
+	    (tgt->lut_obd->obd_max_recoverable_clients == 0 ||
+	    tgt->lut_obd->obd_abort_recovery))
+		tgt->lut_lsd.lsd_feature_incompat &= ~OBD_INCOMPAT_MULTI_RPCS;
+
+	/** update server epoch */
+	tgt_server_data_update(&env, tgt, 1);
+	lu_env_fini(&env);
+}
 
 /**
  * commit callback, need to update last_commited value
  */
-struct lut_last_committed_callback {
-        struct dt_txn_commit_cb llcc_cb;
-        struct lu_target       *llcc_lut;
-        struct obd_export      *llcc_exp;
-        __u64                   llcc_transno;
+struct tgt_last_committed_callback {
+	struct dt_txn_commit_cb	 llcc_cb;
+	struct lu_target	*llcc_tgt;
+	struct obd_export	*llcc_exp;
+	__u64			 llcc_transno;
 };
 
-void lut_cb_last_committed(struct lu_env *env, struct thandle *th,
-                           struct dt_txn_commit_cb *cb, int err)
+static void tgt_cb_last_committed(struct lu_env *env, struct thandle *th,
+				  struct dt_txn_commit_cb *cb, int err)
 {
-        struct lut_last_committed_callback *ccb;
+	struct tgt_last_committed_callback *ccb;
 
-        ccb = container_of0(cb, struct lut_last_committed_callback, llcc_cb);
+	ccb = container_of0(cb, struct tgt_last_committed_callback, llcc_cb);
 
-	LASSERT(ccb->llcc_lut != NULL);
-	LASSERT(ccb->llcc_exp->exp_obd == ccb->llcc_lut->lut_obd);
+	LASSERT(ccb->llcc_tgt != NULL);
+	LASSERT(ccb->llcc_exp->exp_obd == ccb->llcc_tgt->lut_obd);
 
-        cfs_spin_lock(&ccb->llcc_lut->lut_translock);
-        if (ccb->llcc_transno > ccb->llcc_lut->lut_obd->obd_last_committed)
-                ccb->llcc_lut->lut_obd->obd_last_committed = ccb->llcc_transno;
+	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;
-                cfs_spin_unlock(&ccb->llcc_lut->lut_translock);
-                ptlrpc_commit_replies(ccb->llcc_exp);
-        } else {
-                cfs_spin_unlock(&ccb->llcc_lut->lut_translock);
-        }
-        class_export_cb_put(ccb->llcc_exp);
-        if (ccb->llcc_transno)
-                CDEBUG(D_HA, "%s: transno "LPD64" is committed\n",
-                       ccb->llcc_lut->lut_obd->obd_name, ccb->llcc_transno);
-        OBD_FREE_PTR(ccb);
+	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);
+	} else {
+		spin_unlock(&ccb->llcc_tgt->lut_translock);
+	}
+	class_export_cb_put(ccb->llcc_exp);
+	if (ccb->llcc_transno)
+		CDEBUG(D_HA, "%s: transno "LPD64" is committed\n",
+		       ccb->llcc_tgt->lut_obd->obd_name, ccb->llcc_transno);
+	OBD_FREE_PTR(ccb);
 }
 
-int lut_last_commit_cb_add(struct thandle *th, struct lu_target *lut,
-                           struct obd_export *exp, __u64 transno)
+int tgt_last_commit_cb_add(struct thandle *th, struct lu_target *tgt,
+			   struct obd_export *exp, __u64 transno)
 {
-	struct lut_last_committed_callback *ccb;
-	struct dt_txn_commit_cb		   *dcb;
-	int				   rc;
+	struct tgt_last_committed_callback	*ccb;
+	struct dt_txn_commit_cb			*dcb;
+	int					 rc;
 
 	OBD_ALLOC_PTR(ccb);
 	if (ccb == NULL)
 		return -ENOMEM;
 
-	ccb->llcc_lut	  = lut;
-	ccb->llcc_exp	  = class_export_cb_get(exp);
+	ccb->llcc_tgt = tgt;
+	ccb->llcc_exp = class_export_cb_get(exp);
 	ccb->llcc_transno = transno;
 
-	dcb	       = &ccb->llcc_cb;
-	dcb->dcb_func  = lut_cb_last_committed;
-	CFS_INIT_LIST_HEAD(&dcb->dcb_linkage);
-	strncpy(dcb->dcb_name, "lut_cb_last_committed", MAX_COMMIT_CB_STR_LEN);
-	dcb->dcb_name[MAX_COMMIT_CB_STR_LEN - 1] = '\0';
+	dcb = &ccb->llcc_cb;
+	dcb->dcb_func = tgt_cb_last_committed;
+	INIT_LIST_HEAD(&dcb->dcb_linkage);
+	strlcpy(dcb->dcb_name, "tgt_cb_last_committed", sizeof(dcb->dcb_name));
 
 	rc = dt_trans_cb_add(th, dcb);
 	if (rc) {
@@ -451,57 +809,57 @@ int lut_last_commit_cb_add(struct thandle *th, struct lu_target *lut,
 		OBD_FREE_PTR(ccb);
 	}
 
-	if ((exp->exp_connect_flags & OBD_CONNECT_LIGHTWEIGHT) != 0)
+	if (exp_connect_flags(exp) & OBD_CONNECT_LIGHTWEIGHT)
 		/* report failure to force synchronous operation */
 		return -EPERM;
 
 	return rc;
 }
-EXPORT_SYMBOL(lut_last_commit_cb_add);
 
-struct lut_new_client_callback {
-        struct dt_txn_commit_cb lncc_cb;
-        struct obd_export      *lncc_exp;
+struct tgt_new_client_callback {
+	struct dt_txn_commit_cb	 lncc_cb;
+	struct obd_export	*lncc_exp;
 };
 
-void lut_cb_new_client(struct lu_env *env, struct thandle *th,
-                       struct dt_txn_commit_cb *cb, int err)
+static void tgt_cb_new_client(struct lu_env *env, struct thandle *th,
+			      struct dt_txn_commit_cb *cb, int err)
 {
-        struct lut_new_client_callback *ccb;
+	struct tgt_new_client_callback *ccb;
+
+	ccb = container_of0(cb, struct tgt_new_client_callback, lncc_cb);
 
-        ccb = container_of0(cb, struct lut_new_client_callback, lncc_cb);
+	LASSERT(ccb->lncc_exp->exp_obd);
 
-        LASSERT(ccb->lncc_exp->exp_obd);
+	CDEBUG(D_RPCTRACE, "%s: committing for initial connect of %s\n",
+	       ccb->lncc_exp->exp_obd->obd_name,
+	       ccb->lncc_exp->exp_client_uuid.uuid);
 
-        CDEBUG(D_RPCTRACE, "%s: committing for initial connect of %s\n",
-               ccb->lncc_exp->exp_obd->obd_name,
-               ccb->lncc_exp->exp_client_uuid.uuid);
+	spin_lock(&ccb->lncc_exp->exp_lock);
 
-        cfs_spin_lock(&ccb->lncc_exp->exp_lock);
-        ccb->lncc_exp->exp_need_sync = 0;
-        cfs_spin_unlock(&ccb->lncc_exp->exp_lock);
-        class_export_cb_put(ccb->lncc_exp);
+	ccb->lncc_exp->exp_need_sync = 0;
 
-        OBD_FREE_PTR(ccb);
+	spin_unlock(&ccb->lncc_exp->exp_lock);
+	class_export_cb_put(ccb->lncc_exp);
+
+	OBD_FREE_PTR(ccb);
 }
 
-int lut_new_client_cb_add(struct thandle *th, struct obd_export *exp)
+int tgt_new_client_cb_add(struct thandle *th, struct obd_export *exp)
 {
-	struct lut_new_client_callback *ccb;
-	struct dt_txn_commit_cb	       *dcb;
-	int			       rc;
+	struct tgt_new_client_callback	*ccb;
+	struct dt_txn_commit_cb		*dcb;
+	int				 rc;
 
 	OBD_ALLOC_PTR(ccb);
 	if (ccb == NULL)
 		return -ENOMEM;
 
-	ccb->lncc_exp  = class_export_cb_get(exp);
+	ccb->lncc_exp = class_export_cb_get(exp);
 
-	dcb	       = &ccb->lncc_cb;
-	dcb->dcb_func  = lut_cb_new_client;
-	CFS_INIT_LIST_HEAD(&dcb->dcb_linkage);
-	strncpy(dcb->dcb_name, "lut_cb_new_client", MAX_COMMIT_CB_STR_LEN);
-	dcb->dcb_name[MAX_COMMIT_CB_STR_LEN - 1] = '\0';
+	dcb = &ccb->lncc_cb;
+	dcb->dcb_func = tgt_cb_new_client;
+	INIT_LIST_HEAD(&dcb->dcb_linkage);
+	strlcpy(dcb->dcb_name, "tgt_cb_new_client", sizeof(dcb->dcb_name));
 
 	rc = dt_trans_cb_add(th, dcb);
 	if (rc) {
@@ -517,133 +875,160 @@ int lut_new_client_cb_add(struct thandle *th, struct obd_export *exp)
  * We use a bitmap to locate a free space in the last_rcvd file and initialize
  * tg_export_data.
  */
-int lut_client_new(const struct lu_env *env, struct obd_export *exp)
+int tgt_client_new(const struct lu_env *env, struct obd_export *exp)
 {
-	struct tg_export_data *ted = &exp->exp_target_data;
-	struct lu_target *tg = class_exp2tgt(exp);
-	int rc = 0, idx;
+	struct tg_export_data	*ted = &exp->exp_target_data;
+	struct lu_target	*tgt = class_exp2tgt(exp);
+	int			 rc = 0, idx;
 
 	ENTRY;
 
-	LASSERT(tg->lut_client_bitmap != NULL);
-	if (!strcmp(ted->ted_lcd->lcd_uuid, tg->lut_obd->obd_uuid.uuid))
+	LASSERT(tgt && tgt->lut_client_bitmap != NULL);
+	if (!strcmp(ted->ted_lcd->lcd_uuid, tgt->lut_obd->obd_uuid.uuid))
 		RETURN(0);
 
-	cfs_mutex_init(&ted->ted_lcd_lock);
-
-	if ((exp->exp_connect_flags & OBD_CONNECT_LIGHTWEIGHT) != 0)
+	if (exp_connect_flags(exp) & OBD_CONNECT_LIGHTWEIGHT)
 		RETURN(0);
 
 	/* the bitmap operations can handle cl_idx > sizeof(long) * 8, so
 	 * there's no need for extra complication here
 	 */
-	idx = cfs_find_first_zero_bit(tg->lut_client_bitmap, LR_MAX_CLIENTS);
+	idx = find_first_zero_bit(tgt->lut_client_bitmap, LR_MAX_CLIENTS);
 repeat:
 	if (idx >= LR_MAX_CLIENTS ||
 	    OBD_FAIL_CHECK(OBD_FAIL_MDS_CLIENT_ADD)) {
 		CERROR("%s: no room for %u clients - fix LR_MAX_CLIENTS\n",
-		       tg->lut_obd->obd_name,  idx);
+		       tgt->lut_obd->obd_name,  idx);
 		RETURN(-EOVERFLOW);
 	}
-	if (cfs_test_and_set_bit(idx, tg->lut_client_bitmap)) {
-		idx = cfs_find_next_zero_bit(tg->lut_client_bitmap,
+	if (test_and_set_bit(idx, tgt->lut_client_bitmap)) {
+		idx = find_next_zero_bit(tgt->lut_client_bitmap,
 					     LR_MAX_CLIENTS, idx);
 		goto repeat;
 	}
 
-	CDEBUG(D_INFO, "%s: client at idx %d with UUID '%s' added\n",
-	       tg->lut_obd->obd_name, idx, ted->ted_lcd->lcd_uuid);
-
 	ted->ted_lr_idx = idx;
-	ted->ted_lr_off = tg->lut_lsd.lsd_client_start +
-			  idx * tg->lut_lsd.lsd_client_size;
+	ted->ted_lr_off = tgt->lut_lsd.lsd_client_start +
+			  idx * tgt->lut_lsd.lsd_client_size;
 
 	LASSERTF(ted->ted_lr_off > 0, "ted_lr_off = %llu\n", ted->ted_lr_off);
 
-	CDEBUG(D_INFO, "%s: new client at index %d (%llu) with UUID '%s'\n",
-	       tg->lut_obd->obd_name, ted->ted_lr_idx, ted->ted_lr_off,
-	       ted->ted_lcd->lcd_uuid);
+	if (tgt_is_multimodrpcs_client(exp)) {
+		/* Set MULTI RPCS incompatibility flag to prevent previous
+		 * Lustre versions to mount a target with reply_data file */
+		atomic_inc(&tgt->lut_num_clients);
+		if (!(tgt->lut_lsd.lsd_feature_incompat &
+		      OBD_INCOMPAT_MULTI_RPCS)) {
+			tgt->lut_lsd.lsd_feature_incompat |=
+							OBD_INCOMPAT_MULTI_RPCS;
+			rc = tgt_server_data_update(env, tgt, 1);
+			if (rc < 0) {
+				CERROR("%s: unable to set MULTI RPCS "
+				       "incompatibility flag\n",
+				       exp->exp_obd->obd_name);
+				RETURN(rc);
+			}
+		}
+
+		/* assign client slot generation */
+		ted->ted_lcd->lcd_generation =
+				atomic_inc_return(&tgt->lut_client_generation);
+	} else {
+		ted->ted_lcd->lcd_generation = 0;
+	}
+
+	CDEBUG(D_INFO, "%s: new client at index %d (%llu) with UUID '%s' "
+	       "generation %d\n",
+	       tgt->lut_obd->obd_name, ted->ted_lr_idx, ted->ted_lr_off,
+	       ted->ted_lcd->lcd_uuid, ted->ted_lcd->lcd_generation);
 
 	if (OBD_FAIL_CHECK(OBD_FAIL_TGT_CLIENT_ADD))
 		RETURN(-ENOSPC);
 
-	rc = lut_client_data_update(env, exp);
+	rc = tgt_client_data_update(env, exp);
 	if (rc)
 		CERROR("%s: Failed to write client lcd at idx %d, rc %d\n",
-		       tg->lut_obd->obd_name, idx, rc);
+		       tgt->lut_obd->obd_name, idx, rc);
 
 	RETURN(rc);
 }
-EXPORT_SYMBOL(lut_client_new);
+EXPORT_SYMBOL(tgt_client_new);
 
-/* Add client data to the MDS.  We use a bitmap to locate a free space
- * in the last_rcvd file if cl_off is -1 (i.e. a new client).
- * Otherwise, we just have to read the data from the last_rcvd file and
- * we know its offset.
+/* Add an existing client to the MDS in-memory state based on
+ * a client that was previously found in the last_rcvd file and
+ * already has an assigned slot (idx >= 0).
  *
  * It should not be possible to fail adding an existing client - otherwise
  * mdt_init_server_data() callsite needs to be fixed.
  */
-int lut_client_add(const struct lu_env *env,  struct obd_export *exp, int idx)
+int tgt_client_add(const struct lu_env *env,  struct obd_export *exp, int idx)
 {
-	struct tg_export_data *ted = &exp->exp_target_data;
-	struct lu_target *tg = class_exp2tgt(exp);
+	struct tg_export_data	*ted = &exp->exp_target_data;
+	struct lu_target	*tgt = class_exp2tgt(exp);
 
 	ENTRY;
 
-	LASSERT(tg->lut_client_bitmap != NULL);
+	LASSERT(tgt && tgt->lut_client_bitmap != NULL);
 	LASSERTF(idx >= 0, "%d\n", idx);
 
-	if (!strcmp(ted->ted_lcd->lcd_uuid, tg->lut_obd->obd_uuid.uuid) ||
-	    (exp->exp_connect_flags & OBD_CONNECT_LIGHTWEIGHT) != 0)
+	if (!strcmp(ted->ted_lcd->lcd_uuid, tgt->lut_obd->obd_uuid.uuid) ||
+	    exp_connect_flags(exp) & OBD_CONNECT_LIGHTWEIGHT)
 		RETURN(0);
 
-	if (cfs_test_and_set_bit(idx, tg->lut_client_bitmap)) {
+	if (test_and_set_bit(idx, tgt->lut_client_bitmap)) {
 		CERROR("%s: client %d: bit already set in bitmap!!\n",
-		       tg->lut_obd->obd_name,  idx);
+		       tgt->lut_obd->obd_name,  idx);
 		LBUG();
 	}
+	atomic_inc(&tgt->lut_num_clients);
 
-	CDEBUG(D_INFO, "%s: client at idx %d with UUID '%s' added\n",
-	       tg->lut_obd->obd_name, idx, ted->ted_lcd->lcd_uuid);
+	CDEBUG(D_INFO, "%s: client at idx %d with UUID '%s' added, "
+	       "generation %d\n",
+	       tgt->lut_obd->obd_name, idx, ted->ted_lcd->lcd_uuid,
+	       ted->ted_lcd->lcd_generation);
 
 	ted->ted_lr_idx = idx;
-	ted->ted_lr_off = tg->lut_lsd.lsd_client_start +
-			  idx * tg->lut_lsd.lsd_client_size;
+	ted->ted_lr_off = tgt->lut_lsd.lsd_client_start +
+			  idx * tgt->lut_lsd.lsd_client_size;
 
-	cfs_mutex_init(&ted->ted_lcd_lock);
+	mutex_init(&ted->ted_lcd_lock);
 
 	LASSERTF(ted->ted_lr_off > 0, "ted_lr_off = %llu\n", ted->ted_lr_off);
 
 	RETURN(0);
 }
-EXPORT_SYMBOL(lut_client_add);
 
-int lut_client_del(const struct lu_env *env, struct obd_export *exp)
+int tgt_client_del(const struct lu_env *env, struct obd_export *exp)
 {
-	struct tg_export_data *ted = &exp->exp_target_data;
-	struct lu_target      *tg = class_exp2tgt(exp);
-	int		       rc;
+	struct tg_export_data	*ted = &exp->exp_target_data;
+	struct lu_target	*tgt = class_exp2tgt(exp);
+	int			 rc;
 
 	ENTRY;
 
 	LASSERT(ted->ted_lcd);
 
+	if (unlikely(tgt == NULL)) {
+		CDEBUG(D_ERROR, "%s: No target for connected export\n",
+		       class_exp2obd(exp)->obd_name);
+		RETURN(-EINVAL);
+	}
+
 	/* XXX if lcd_uuid were a real obd_uuid, I could use obd_uuid_equals */
 	if (!strcmp((char *)ted->ted_lcd->lcd_uuid,
-		    (char *)tg->lut_obd->obd_uuid.uuid) ||
-	    (exp->exp_connect_flags & OBD_CONNECT_LIGHTWEIGHT) != 0)
+		    (char *)tgt->lut_obd->obd_uuid.uuid) ||
+	    exp_connect_flags(exp) & OBD_CONNECT_LIGHTWEIGHT)
 		RETURN(0);
 
 	CDEBUG(D_INFO, "%s: del client at idx %u, off %lld, UUID '%s'\n",
-	       tg->lut_obd->obd_name, ted->ted_lr_idx, ted->ted_lr_off,
+	       tgt->lut_obd->obd_name, ted->ted_lr_idx, ted->ted_lr_off,
 	       ted->ted_lcd->lcd_uuid);
 
 	/* Clear the bit _after_ zeroing out the client so we don't
 	   race with filter_client_add and zero out new clients.*/
-	if (!cfs_test_bit(ted->ted_lr_idx, tg->lut_client_bitmap)) {
+	if (!test_bit(ted->ted_lr_idx, tgt->lut_client_bitmap)) {
 		CERROR("%s: client %u: bit already clear in bitmap!!\n",
-		       tg->lut_obd->obd_name, ted->ted_lr_idx);
+		       tgt->lut_obd->obd_name, ted->ted_lr_idx);
 		LBUG();
 	}
 
@@ -654,23 +1039,967 @@ int lut_client_del(const struct lu_env *env, struct obd_export *exp)
 	/* Make sure the server's last_transno is up to date.
 	 * This should be done before zeroing client slot so last_transno will
 	 * be in server data or in client data in case of failure */
-	rc = lut_server_data_update(env, tg, 0);
+	rc = tgt_server_data_update(env, tgt, 0);
 	if (rc != 0) {
 		CERROR("%s: failed to update server data, skip client %s "
-		       "zeroing, rc %d\n", tg->lut_obd->obd_name,
+		       "zeroing, rc %d\n", tgt->lut_obd->obd_name,
 		       ted->ted_lcd->lcd_uuid, rc);
 		RETURN(rc);
 	}
 
-	cfs_mutex_lock(&ted->ted_lcd_lock);
+	mutex_lock(&ted->ted_lcd_lock);
 	memset(ted->ted_lcd->lcd_uuid, 0, sizeof ted->ted_lcd->lcd_uuid);
-	rc = lut_client_data_update(env, exp);
-	cfs_mutex_unlock(&ted->ted_lcd_lock);
+	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",
-	       tg->lut_obd->obd_name, ted->ted_lcd->lcd_uuid,
+	       tgt->lut_obd->obd_name, ted->ted_lcd->lcd_uuid,
 	       ted->ted_lr_idx, ted->ted_lr_off, rc);
 	RETURN(rc);
 }
-EXPORT_SYMBOL(lut_client_del);
+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
+ */
+static int tgt_last_rcvd_update(const struct lu_env *env, struct lu_target *tgt,
+				struct dt_object *obj, __u64 opdata,
+				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;
+
+	ENTRY;
+
+
+	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);
+
+	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) {
+		if (tti->tti_transno != 0) {
+			CERROR("%s: replay transno "LPU64" failed: rc = %d\n",
+			       tgt_name(tgt), tti->tti_transno, th->th_result);
+		}
+	} else if (tti->tti_transno == 0) {
+		tti->tti_transno = ++tgt->lut_last_transno;
+	} else {
+		/* should be replay */
+		if (tti->tti_transno > tgt->lut_last_transno)
+			tgt->lut_last_transno = tti->tti_transno;
+	}
+	spin_unlock(&tgt->lut_translock);
+
+	/** VBR: set new versions */
+	if (th->th_result == 0 && obj != NULL) {
+		struct dt_object *dto = dt_object_locate(obj, th->th_dev);
+		dt_version_set(env, dto, tti->tti_transno, th);
+	}
+
+	/* filling reply data */
+	CDEBUG(D_INODE, "transno = "LPU64", last_committed = "LPU64"\n",
+	       tti->tti_transno, tgt->lut_obd->obd_last_committed);
+
+	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, exp, tti->tti_transno);
+
+	if (lw_client) {
+		/* All operations performed by LW clients are synchronous and
+		 * we store the committed transno in the last_rcvd header */
+		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
+		 * 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",
+		      exp->exp_client_uuid.uuid, rc);
+		GOTO(srv_update, rc = 0);
+	}
+
+	/* Target that supports multiple reply data */
+	if (tgt_is_multimodrpcs_client(exp)) {
+		struct tg_reply_data	*trd;
+		struct lsd_reply_data	*lrd;
+		__u64			*pre_versions;
+		bool			write_update;
+
+		OBD_ALLOC_PTR(trd);
+		if (unlikely(trd == NULL))
+			GOTO(srv_update, rc = -ENOMEM);
+
+		/* fill reply data information */
+		lrd = &trd->trd_reply;
+		lrd->lrd_transno = tti->tti_transno;
+		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;
+		if (pre_versions) {
+			trd->trd_pre_versions[0] = pre_versions[0];
+			trd->trd_pre_versions[1] = pre_versions[1];
+			trd->trd_pre_versions[2] = pre_versions[2];
+			trd->trd_pre_versions[3] = pre_versions[3];
+		}
+
+		rc = tgt_add_reply_data(env, tgt, ted, trd, th, write_update);
+		GOTO(srv_update, rc);
+	}
+
+	/* Enough for update replay, let's return */
+	if (req == NULL)
+		GOTO(srv_update, 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) {
+		transno_p = &ted->ted_lcd->lcd_last_close_transno;
+		ted->ted_lcd->lcd_last_close_xid = req->rq_xid;
+		ted->ted_lcd->lcd_last_close_result = th->th_result;
+	} else {
+		/* VBR: save versions in last_rcvd for reconstruct. */
+		__u64 *pre_versions = lustre_msg_get_versions(req->rq_repmsg);
+
+		if (pre_versions) {
+			ted->ted_lcd->lcd_pre_versions[0] = pre_versions[0];
+			ted->ted_lcd->lcd_pre_versions[1] = pre_versions[1];
+			ted->ted_lcd->lcd_pre_versions[2] = pre_versions[2];
+			ted->ted_lcd->lcd_pre_versions[3] = pre_versions[3];
+		}
+		transno_p = &ted->ted_lcd->lcd_last_transno;
+		ted->ted_lcd->lcd_last_xid = req->rq_xid;
+		ted->ted_lcd->lcd_last_result = th->th_result;
+		/* XXX: lcd_last_data is __u32 but intent_dispostion is __u64,
+		 * see struct ldlm_reply->lock_policy_res1; */
+		ted->ted_lcd->lcd_last_data = opdata;
+	}
+
+	/* 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);
+			}
+			mutex_unlock(&ted->ted_lcd_lock);
+			RETURN(req_is_replay(req) ? -EOVERFLOW : 0);
+		}
+		*transno_p = tti->tti_transno;
+	}
+
+	if (!lw_client) {
+		tti->tti_off = ted->ted_lr_off;
+		rc = tgt_client_data_write(env, tgt, ted->ted_lcd, &tti->tti_off, th);
+		if (rc < 0) {
+			mutex_unlock(&ted->ted_lcd_lock);
+			RETURN(rc);
+		}
+	}
+	mutex_unlock(&ted->ted_lcd_lock);
+	EXIT;
+srv_update:
+	if (update)
+		rc = tgt_server_data_write(env, tgt, th);
+	return rc;
+}
+
+/*
+ * last_rcvd update for echo client simulation.
+ * It updates last_rcvd client slot and version of object in
+ * simple way but with all locks to simulate all drawbacks
+ */
+static int tgt_last_rcvd_update_echo(const struct lu_env *env,
+				     struct lu_target *tgt,
+				     struct dt_object *obj,
+				     struct thandle *th,
+				     struct obd_export *exp)
+{
+	struct tgt_thread_info	*tti = tgt_th_info(env);
+	struct tg_export_data	*ted = &exp->exp_target_data;
+	int			 rc = 0;
+
+	ENTRY;
+
+	tti->tti_transno = 0;
+
+	spin_lock(&tgt->lut_translock);
+	if (th->th_result == 0)
+		tti->tti_transno = ++tgt->lut_last_transno;
+	spin_unlock(&tgt->lut_translock);
+
+	/** VBR: set new versions */
+	if (th->th_result == 0 && obj != NULL)
+		dt_version_set(env, obj, tti->tti_transno, th);
+
+	/* if can't add callback, do sync write */
+	th->th_sync |= !!tgt_last_commit_cb_add(th, tgt, exp,
+						tti->tti_transno);
+
+	LASSERT(ted->ted_lr_off > 0);
+
+	mutex_lock(&ted->ted_lcd_lock);
+	LASSERT(ergo(tti->tti_transno == 0, th->th_result != 0));
+	ted->ted_lcd->lcd_last_transno = tti->tti_transno;
+	ted->ted_lcd->lcd_last_result = th->th_result;
+
+	tti->tti_off = ted->ted_lr_off;
+	rc = tgt_client_data_write(env, tgt, ted->ted_lcd, &tti->tti_off, th);
+	mutex_unlock(&ted->ted_lcd_lock);
+	RETURN(rc);
+}
+
+static int tgt_clients_data_init(const struct lu_env *env,
+				 struct lu_target *tgt,
+				 unsigned long last_size)
+{
+	struct obd_device	*obd = tgt->lut_obd;
+	struct lr_server_data	*lsd = &tgt->lut_lsd;
+	struct lsd_client_data	*lcd = NULL;
+	struct tg_export_data	*ted;
+	int			 cl_idx;
+	int			 rc = 0;
+	loff_t			 off = lsd->lsd_client_start;
+	__u32			 generation = 0;
+	struct cfs_hash		*hash = NULL;
+
+	ENTRY;
+
+	CLASSERT(offsetof(struct lsd_client_data, lcd_padding) +
+		 sizeof(lcd->lcd_padding) == LR_CLIENT_SIZE);
+
+	OBD_ALLOC_PTR(lcd);
+	if (lcd == NULL)
+		RETURN(-ENOMEM);
+
+	hash = cfs_hash_getref(tgt->lut_obd->obd_gen_hash);
+	if (hash == NULL)
+		GOTO(err_out, rc = -ENODEV);
+
+	for (cl_idx = 0; off < last_size; cl_idx++) {
+		struct obd_export	*exp;
+		__u64			 last_transno;
+
+		/* Don't assume off is incremented properly by
+		 * read_record(), in case sizeof(*lcd)
+		 * isn't the same as fsd->lsd_client_size.  */
+		off = lsd->lsd_client_start + cl_idx * lsd->lsd_client_size;
+		rc = tgt_client_data_read(env, tgt, lcd, &off, cl_idx);
+		if (rc) {
+			CERROR("%s: error reading last_rcvd %s idx %d off "
+			       "%llu: rc = %d\n", tgt_name(tgt), LAST_RCVD,
+			       cl_idx, off, rc);
+			rc = 0;
+			break; /* read error shouldn't cause startup to fail */
+		}
+
+		if (lcd->lcd_uuid[0] == '\0') {
+			CDEBUG(D_INFO, "skipping zeroed client at offset %d\n",
+			       cl_idx);
+			continue;
+		}
+
+		last_transno = lcd_last_transno(lcd);
+
+		/* These exports are cleaned up by disconnect, so they
+		 * need to be set up like real exports as connect does.
+		 */
+		CDEBUG(D_HA, "RCVRNG CLIENT uuid: %s idx: %d lr: "LPU64
+		       " srv lr: "LPU64" lx: "LPU64" gen %u\n", lcd->lcd_uuid,
+		       cl_idx, last_transno, lsd->lsd_last_transno,
+		       lcd_last_xid(lcd), lcd->lcd_generation);
+
+		exp = class_new_export(obd, (struct obd_uuid *)lcd->lcd_uuid);
+		if (IS_ERR(exp)) {
+			if (PTR_ERR(exp) == -EALREADY) {
+				/* export already exists, zero out this one */
+				CERROR("%s: Duplicate export %s!\n",
+				       tgt_name(tgt), lcd->lcd_uuid);
+				continue;
+			}
+			GOTO(err_out, rc = PTR_ERR(exp));
+		}
+
+		ted = &exp->exp_target_data;
+		*ted->ted_lcd = *lcd;
+
+		rc = tgt_client_add(env, exp, cl_idx);
+		LASSERTF(rc == 0, "rc = %d\n", rc); /* can't fail existing */
+		/* VBR: set export last committed version */
+		exp->exp_last_committed = last_transno;
+		spin_lock(&exp->exp_lock);
+		exp->exp_connecting = 0;
+		exp->exp_in_recovery = 0;
+		spin_unlock(&exp->exp_lock);
+		obd->obd_max_recoverable_clients++;
+
+		if (tgt->lut_lsd.lsd_feature_incompat &
+		    OBD_INCOMPAT_MULTI_RPCS &&
+		    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);
+			if (rc != 0) {
+				CERROR("%s: duplicate export for client "
+				       "generation %u\n",
+				       tgt_name(tgt), lcd->lcd_generation);
+				class_export_put(exp);
+				GOTO(err_out, rc);
+			}
+		}
+
+		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);
+
+		spin_lock(&tgt->lut_translock);
+		tgt->lut_last_transno = max(last_transno,
+					    tgt->lut_last_transno);
+		spin_unlock(&tgt->lut_translock);
+	}
+
+	/* record highest valid client generation */
+	atomic_set(&tgt->lut_client_generation, generation);
+
+err_out:
+	if (hash != NULL)
+		cfs_hash_putref(hash);
+	OBD_FREE_PTR(lcd);
+	RETURN(rc);
+}
+
+struct server_compat_data {
+	__u32 rocompat;
+	__u32 incompat;
+	__u32 rocinit;
+	__u32 incinit;
+};
+
+static struct server_compat_data tgt_scd[] = {
+	[LDD_F_SV_TYPE_MDT] = {
+		.rocompat = OBD_ROCOMPAT_LOVOBJID,
+		.incompat = OBD_INCOMPAT_MDT | OBD_INCOMPAT_COMMON_LR |
+			    OBD_INCOMPAT_FID | OBD_INCOMPAT_IAM_DIR |
+			    OBD_INCOMPAT_LMM_VER | OBD_INCOMPAT_MULTI_OI |
+			    OBD_INCOMPAT_MULTI_RPCS,
+		.rocinit = OBD_ROCOMPAT_LOVOBJID,
+		.incinit = OBD_INCOMPAT_MDT | OBD_INCOMPAT_COMMON_LR |
+			   OBD_INCOMPAT_MULTI_OI,
+	},
+	[LDD_F_SV_TYPE_OST] = {
+		.rocompat = OBD_ROCOMPAT_IDX_IN_IDIF,
+		.incompat = OBD_INCOMPAT_OST | OBD_INCOMPAT_COMMON_LR |
+			    OBD_INCOMPAT_FID,
+		.rocinit = OBD_ROCOMPAT_IDX_IN_IDIF,
+		.incinit = OBD_INCOMPAT_OST | OBD_INCOMPAT_COMMON_LR,
+	}
+};
+
+int tgt_server_data_init(const struct lu_env *env, struct lu_target *tgt)
+{
+	struct tgt_thread_info		*tti = tgt_th_info(env);
+	struct lr_server_data		*lsd = &tgt->lut_lsd;
+	unsigned long			 last_rcvd_size;
+	__u32				 index;
+	int				 rc, type;
+
+	rc = dt_attr_get(env, tgt->lut_last_rcvd, &tti->tti_attr);
+	if (rc)
+		RETURN(rc);
+
+	last_rcvd_size = (unsigned long)tti->tti_attr.la_size;
+
+	/* ensure padding in the struct is the correct size */
+	CLASSERT(offsetof(struct lr_server_data, lsd_padding) +
+		 sizeof(lsd->lsd_padding) == LR_SERVER_SIZE);
+
+	rc = server_name2index(tgt_name(tgt), &index, NULL);
+	if (rc < 0) {
+		CERROR("%s: Can not get index from name: rc = %d\n",
+		       tgt_name(tgt), rc);
+		RETURN(rc);
+	}
+	/* server_name2index() returns type */
+	type = rc;
+	if (type != LDD_F_SV_TYPE_MDT && type != LDD_F_SV_TYPE_OST) {
+		CERROR("%s: unknown target type %x\n", tgt_name(tgt), type);
+		RETURN(-EINVAL);
+	}
+
+	/* last_rcvd on OST doesn't provide reconstruct support because there
+	 * may be up to 8 in-flight write requests per single slot in
+	 * last_rcvd client data
+	 */
+	tgt->lut_no_reconstruct = (type == LDD_F_SV_TYPE_OST);
+
+	if (last_rcvd_size == 0) {
+		LCONSOLE_WARN("%s: new disk, initializing\n", tgt_name(tgt));
+
+		memcpy(lsd->lsd_uuid, tgt->lut_obd->obd_uuid.uuid,
+		       sizeof(lsd->lsd_uuid));
+		lsd->lsd_last_transno = 0;
+		lsd->lsd_mount_count = 0;
+		lsd->lsd_server_size = LR_SERVER_SIZE;
+		lsd->lsd_client_start = LR_CLIENT_START;
+		lsd->lsd_client_size = LR_CLIENT_SIZE;
+		lsd->lsd_subdir_count = OBJ_SUBDIR_COUNT;
+		lsd->lsd_osd_index = index;
+		lsd->lsd_feature_rocompat = tgt_scd[type].rocinit;
+		lsd->lsd_feature_incompat = tgt_scd[type].incinit;
+	} else {
+		rc = tgt_server_data_read(env, tgt);
+		if (rc) {
+			CERROR("%s: error reading LAST_RCVD: rc= %d\n",
+			       tgt_name(tgt), rc);
+			RETURN(rc);
+		}
+		if (strcmp(lsd->lsd_uuid, tgt->lut_obd->obd_uuid.uuid)) {
+			LCONSOLE_ERROR_MSG(0x157, "Trying to start OBD %s "
+					   "using the wrong disk %s. Were the"
+					   " /dev/ assignments rearranged?\n",
+					   tgt->lut_obd->obd_uuid.uuid,
+					   lsd->lsd_uuid);
+			RETURN(-EINVAL);
+		}
+
+		if (lsd->lsd_osd_index != index) {
+			LCONSOLE_ERROR_MSG(0x157, "%s: index %d in last rcvd "
+					   "is different with the index %d in"
+					   "config log, It might be disk"
+					   "corruption!\n", tgt_name(tgt),
+					   lsd->lsd_osd_index, index);
+			RETURN(-EINVAL);
+		}
+	}
+
+	if (lsd->lsd_feature_incompat & ~tgt_scd[type].incompat) {
+		CERROR("%s: unsupported incompat filesystem feature(s) %x\n",
+		       tgt_name(tgt),
+		       lsd->lsd_feature_incompat & ~tgt_scd[type].incompat);
+		RETURN(-EINVAL);
+	}
+
+	if (type == LDD_F_SV_TYPE_MDT)
+		lsd->lsd_feature_incompat |= OBD_INCOMPAT_FID;
+
+	if (lsd->lsd_feature_rocompat & ~tgt_scd[type].rocompat) {
+		CERROR("%s: unsupported read-only filesystem feature(s) %x\n",
+		       tgt_name(tgt),
+		       lsd->lsd_feature_rocompat & ~tgt_scd[type].rocompat);
+		RETURN(-EINVAL);
+	}
+	/** Interop: evict all clients at first boot with 1.8 last_rcvd */
+	if (type == LDD_F_SV_TYPE_MDT &&
+	    !(lsd->lsd_feature_compat & OBD_COMPAT_20)) {
+		if (last_rcvd_size > lsd->lsd_client_start) {
+			LCONSOLE_WARN("%s: mounting at first time on 1.8 FS, "
+				      "remove all clients for interop needs\n",
+				      tgt_name(tgt));
+			rc = tgt_truncate_last_rcvd(env, tgt,
+						    lsd->lsd_client_start);
+			if (rc)
+				RETURN(rc);
+			last_rcvd_size = lsd->lsd_client_start;
+		}
+		/** set 2.0 flag to upgrade/downgrade between 1.8 and 2.0 */
+		lsd->lsd_feature_compat |= OBD_COMPAT_20;
+	}
+
+	spin_lock(&tgt->lut_translock);
+	tgt->lut_last_transno = lsd->lsd_last_transno;
+	spin_unlock(&tgt->lut_translock);
+
+	lsd->lsd_mount_count++;
+
+	CDEBUG(D_INODE, "=======,=BEGIN DUMPING LAST_RCVD========\n");
+	CDEBUG(D_INODE, "%s: server last_transno: "LPU64"\n",
+	       tgt_name(tgt), tgt->lut_last_transno);
+	CDEBUG(D_INODE, "%s: server mount_count: "LPU64"\n",
+	       tgt_name(tgt), lsd->lsd_mount_count);
+	CDEBUG(D_INODE, "%s: server data size: %u\n",
+	       tgt_name(tgt), lsd->lsd_server_size);
+	CDEBUG(D_INODE, "%s: per-client data start: %u\n",
+	       tgt_name(tgt), lsd->lsd_client_start);
+	CDEBUG(D_INODE, "%s: per-client data size: %u\n",
+	       tgt_name(tgt), lsd->lsd_client_size);
+	CDEBUG(D_INODE, "%s: last_rcvd size: %lu\n",
+	       tgt_name(tgt), last_rcvd_size);
+	CDEBUG(D_INODE, "%s: server subdir_count: %u\n",
+	       tgt_name(tgt), lsd->lsd_subdir_count);
+	CDEBUG(D_INODE, "%s: last_rcvd clients: %lu\n", tgt_name(tgt),
+	       last_rcvd_size <= lsd->lsd_client_start ? 0 :
+	       (last_rcvd_size - lsd->lsd_client_start) /
+		lsd->lsd_client_size);
+	CDEBUG(D_INODE, "========END DUMPING LAST_RCVD========\n");
+
+	if (lsd->lsd_server_size == 0 || lsd->lsd_client_start == 0 ||
+	    lsd->lsd_client_size == 0) {
+		CERROR("%s: bad last_rcvd contents!\n", tgt_name(tgt));
+		RETURN(-EINVAL);
+	}
+
+	if (!tgt->lut_obd->obd_replayable)
+		CWARN("%s: recovery support OFF\n", tgt_name(tgt));
+
+	rc = tgt_clients_data_init(env, tgt, last_rcvd_size);
+	if (rc < 0)
+		GOTO(err_client, rc);
+
+	spin_lock(&tgt->lut_translock);
+	/* obd_last_committed is used for compatibility
+	 * with other lustre recovery code */
+	tgt->lut_obd->obd_last_committed = tgt->lut_last_transno;
+	spin_unlock(&tgt->lut_translock);
+
+	tgt->lut_obd->u.obt.obt_mount_count = lsd->lsd_mount_count;
+	tgt->lut_obd->u.obt.obt_instance = (__u32)lsd->lsd_mount_count;
+
+	/* save it, so mount count and last_transno is current */
+	rc = tgt_server_data_update(env, tgt, 0);
+	if (rc < 0)
+		GOTO(err_client, rc);
+
+	RETURN(0);
+
+err_client:
+	class_disconnect_exports(tgt->lut_obd);
+	return rc;
+}
+
+/* add credits for last_rcvd update */
+int tgt_txn_start_cb(const struct lu_env *env, struct thandle *th,
+		     void *cookie)
+{
+	struct lu_target	*tgt = cookie;
+	struct tgt_session_info	*tsi;
+	struct tgt_thread_info	*tti = tgt_th_info(env);
+	struct dt_object	*dto;
+	int			 rc;
+
+	/* if there is no session, then this transaction is not result of
+	 * request processing but some local operation */
+	if (env->le_ses == NULL)
+		return 0;
+
+	LASSERT(tgt->lut_last_rcvd);
+	tsi = tgt_ses_info(env);
+	/* OFD may start transaction without export assigned */
+	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 (tsi->tsi_vbr_obj != NULL &&
+	    !lu_object_remote(&tsi->tsi_vbr_obj->do_lu)) {
+		dto = dt_object_locate(tsi->tsi_vbr_obj, th->th_dev);
+		rc = dt_declare_version_set(env, dto, th);
+	}
+
+	return rc;
+}
+
+/* Update last_rcvd records with latests transaction data */
+int tgt_txn_stop_cb(const struct lu_env *env, struct thandle *th,
+		    void *cookie)
+{
+	struct lu_target	*tgt = cookie;
+	struct tgt_session_info	*tsi;
+	struct tgt_thread_info	*tti = tgt_th_info(env);
+	struct dt_object	*obj = NULL;
+	int			 rc;
+	bool			 echo_client;
+
+	if (env->le_ses == NULL)
+		return 0;
+
+	tsi = tgt_ses_info(env);
+	/* OFD may start transaction without export assigned */
+	if (tsi->tsi_exp == NULL)
+		return 0;
+
+	echo_client = (tgt_ses_req(tsi) == NULL && tsi->tsi_xid == 0);
+
+	if (tti->tti_has_trans && !echo_client) {
+		if (tti->tti_mult_trans == 0) {
+			CDEBUG(D_HA, "More than one transaction "LPU64"\n",
+			       tti->tti_transno);
+			RETURN(0);
+		}
+		/* we need another transno to be assigned */
+		tti->tti_transno = 0;
+	} else if (th->th_result == 0) {
+		tti->tti_has_trans = 1;
+	}
+
+	if (tsi->tsi_vbr_obj != NULL &&
+	    !lu_object_remote(&tsi->tsi_vbr_obj->do_lu)) {
+		obj = tsi->tsi_vbr_obj;
+	}
+
+	if (unlikely(echo_client)) /* echo client special case */
+		rc = tgt_last_rcvd_update_echo(env, tgt, obj, th,
+					       tsi->tsi_exp);
+	else
+		rc = tgt_last_rcvd_update(env, tgt, obj, tsi->tsi_opdata, th,
+					  tgt_ses_req(tsi));
+	return rc;
+}
+
+int tgt_reply_data_init(const struct lu_env *env, struct lu_target *tgt)
+{
+	struct tgt_thread_info	*tti = tgt_th_info(env);
+	struct lsd_reply_data	*lrd = &tti->tti_lrd;
+	unsigned long		 reply_data_size;
+	int			 rc;
+	struct lsd_reply_header	*lrh = NULL;
+	struct lsd_client_data  *lcd = NULL;
+	struct tg_reply_data	*trd = NULL;
+	int                      idx;
+	loff_t			 off;
+	struct cfs_hash		*hash = NULL;
+	struct obd_export	*exp;
+	struct tg_export_data   *ted;
+	int			 reply_data_recovered = 0;
+
+	rc = dt_attr_get(env, tgt->lut_reply_data, &tti->tti_attr);
+	if (rc)
+		GOTO(out, rc);
+	reply_data_size = (unsigned long)tti->tti_attr.la_size;
+
+	OBD_ALLOC_PTR(lrh);
+	if (lrh == NULL)
+		GOTO(out, rc = -ENOMEM);
+
+	if (reply_data_size == 0) {
+		CDEBUG(D_INFO, "%s: new reply_data file, initializing\n",
+		       tgt_name(tgt));
+		lrh->lrh_magic = LRH_MAGIC;
+		lrh->lrh_header_size = sizeof(struct lsd_reply_header);
+		lrh->lrh_reply_size = sizeof(struct lsd_reply_data);
+		rc = tgt_reply_header_write(env, tgt, lrh);
+		if (rc) {
+			CERROR("%s: error writing %s: rc = %d\n",
+			       tgt_name(tgt), REPLY_DATA, rc);
+			GOTO(out, rc);
+		}
+	} else {
+		rc = tgt_reply_header_read(env, tgt, lrh);
+		if (rc) {
+			CERROR("%s: error reading %s: rc = %d\n",
+			       tgt_name(tgt), REPLY_DATA, rc);
+			GOTO(out, rc);
+		}
+		if (lrh->lrh_magic != LRH_MAGIC ||
+		    lrh->lrh_header_size != sizeof(struct lsd_reply_header) ||
+		    lrh->lrh_reply_size != sizeof(struct lsd_reply_data)) {
+			CERROR("%s: invalid header in %s\n",
+			       tgt_name(tgt), REPLY_DATA);
+			GOTO(out, rc = -EINVAL);
+		}
+
+		hash = cfs_hash_getref(tgt->lut_obd->obd_gen_hash);
+		if (hash == NULL)
+			GOTO(out, rc = -ENODEV);
+
+		OBD_ALLOC_PTR(lcd);
+		if (lcd == NULL)
+			GOTO(out, rc = -ENOMEM);
+
+		OBD_ALLOC_PTR(trd);
+		if (trd == NULL)
+			GOTO(out, rc = -ENOMEM);
+
+		/* Load reply_data from disk */
+		for (idx = 0, off = sizeof(struct lsd_reply_header);
+		     off < reply_data_size;
+		     idx++, off += sizeof(struct lsd_reply_data)) {
+			rc = tgt_reply_data_read(env, tgt, lrd, off);
+			if (rc) {
+				CERROR("%s: error reading %s: rc = %d\n",
+				       tgt_name(tgt), REPLY_DATA, rc);
+				GOTO(out, rc);
+			}
+
+			exp = cfs_hash_lookup(hash, &lrd->lrd_client_gen);
+			if (exp == NULL) {
+				/* old reply data from a disconnected client */
+				continue;
+			}
+			ted = &exp->exp_target_data;
+			mutex_lock(&ted->ted_lcd_lock);
+
+			/* create in-memory reply_data and link it to
+			 * target export's reply list */
+			tgt_set_reply_slot(tgt, idx);
+			trd->trd_reply = *lrd;
+			trd->trd_pre_versions[0] = 0;
+			trd->trd_pre_versions[1] = 0;
+			trd->trd_pre_versions[2] = 0;
+			trd->trd_pre_versions[3] = 0;
+			trd->trd_index = idx;
+			trd->trd_tag = 0;
+			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;
+
+			CDEBUG(D_HA, "%s: restore reply %p: xid %llu, "
+			       "transno %llu, client gen %u, slot idx %d\n",
+			       tgt_name(tgt), trd, lrd->lrd_xid,
+			       lrd->lrd_transno, lrd->lrd_client_gen,
+			       trd->trd_index);
+
+			/* update export last committed transation */
+			exp->exp_last_committed = max(exp->exp_last_committed,
+						      lrd->lrd_transno);
+
+			mutex_unlock(&ted->ted_lcd_lock);
+			class_export_put(exp);
+
+			/* update target last committed transaction */
+			spin_lock(&tgt->lut_translock);
+			tgt->lut_last_transno = max(tgt->lut_last_transno,
+						    lrd->lrd_transno);
+			spin_unlock(&tgt->lut_translock);
+
+			reply_data_recovered++;
+
+			OBD_ALLOC_PTR(trd);
+			if (trd == NULL)
+				GOTO(out, rc = -ENOMEM);
+		}
+		CDEBUG(D_INFO, "%s: %d reply data have been recovered\n",
+		       tgt_name(tgt), reply_data_recovered);
+	}
+
+	spin_lock(&tgt->lut_translock);
+	/* obd_last_committed is used for compatibility
+	 * with other lustre recovery code */
+	tgt->lut_obd->obd_last_committed = tgt->lut_last_transno;
+	spin_unlock(&tgt->lut_translock);
+
+	rc = 0;
+
+out:
+	if (hash != NULL)
+		cfs_hash_putref(hash);
+	if (lcd != NULL)
+		OBD_FREE_PTR(lcd);
+	if (trd != NULL)
+		OBD_FREE_PTR(trd);
+	if (lrh != NULL)
+		OBD_FREE_PTR(lrh);
+	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;
+	bool			 found = false;
+
+	reply = tgt_lookup_reply_by_xid(ted, req->rq_xid);
+	if (reply != NULL) {
+		found = true;
+		if (trd != NULL)
+			*trd = *reply;
+	}
+
+	CDEBUG(D_TRACE, "%s: lookup reply xid %llu, found %d\n",
+	       tgt_name(class_exp2tgt(req->rq_export)), req->rq_xid,
+	       found ? 1 : 0);
+
+	return found;
+}
+EXPORT_SYMBOL(tgt_lookup_reply);
+
+int tgt_handle_received_xid(struct obd_export *exp, __u64 rcvd_xid)
+{
+	struct tg_export_data	*ted = &exp->exp_target_data;
+	struct lu_target	*lut = class_exp2tgt(exp);
+	struct tg_reply_data	*trd, *tmp;
+
+	mutex_lock(&ted->ted_lcd_lock);
+	list_for_each_entry_safe(trd, tmp, &ted->ted_reply_list, trd_list) {
+		if (trd->trd_reply.lrd_xid > rcvd_xid)
+			continue;
+		ted->ted_release_xid++;
+		tgt_release_reply_data(lut, ted, trd);
+	}
+	mutex_unlock(&ted->ted_lcd_lock);
+
+	return 0;
+}
+
+int tgt_handle_tag(struct obd_export *exp, __u16 tag)
+{
+	struct tg_export_data	*ted = &exp->exp_target_data;
+	struct lu_target	*lut = class_exp2tgt(exp);
+	struct tg_reply_data	*trd, *tmp;
+
+	if (tag == 0)
+		return 0;
+
+	mutex_lock(&ted->ted_lcd_lock);
+	list_for_each_entry_safe(trd, tmp, &ted->ted_reply_list, trd_list) {
+		if (trd->trd_tag != tag)
+			continue;
+		ted->ted_release_tag++;
+		tgt_release_reply_data(lut, ted, trd);
+		break;
+	}
+	mutex_unlock(&ted->ted_lcd_lock);
+
+	return 0;
+}
+