Revert "MDEV-6928: Add trx pointer to struct mtr_t"

This reverts commit 3486135bb5c9e21fd678821dee35484a81351cfb.

The commit comment ended in the words: "This is needed later."
Apparently the "later" never arrived.

21 files changed, 90 insertions, 115 deletions

diff --git a/storage/innobase/api/api0api.cc b/storage/innobase/api/api0api.cc
index 739ea9f7572..bb6de2b8051 100644
--- a/storage/innobase/api/api0api.cc
+++ b/storage/innobase/api/api0api.cc
@@ -398,7 +398,7 @@ ib_read_tuple(
 
 			data = btr_rec_copy_externally_stored_field(
 				copy, offsets, zip_size, i, &len,
-				tuple->heap, NULL);
+				tuple->heap);
 
 			ut_a(len != UNIV_SQL_NULL);
 		}
diff --git a/storage/innobase/btr/btr0cur.cc b/storage/innobase/btr/btr0cur.cc
index 9ca2cc8e50b..2dd7dceb261 100644
--- a/storage/innobase/btr/btr0cur.cc
+++ b/storage/innobase/btr/btr0cur.cc
@@ -3681,8 +3681,7 @@ btr_estimate_n_rows_in_range(
 	const dtuple_t*	tuple1,	/*!< in: range start, may also be empty tuple */
 	ulint		mode1,	/*!< in: search mode for range start */
 	const dtuple_t*	tuple2,	/*!< in: range end, may also be empty tuple */
-	ulint		mode2,	/*!< in: search mode for range end */
-	trx_t*		trx)	/*!< in: trx */
+	ulint		mode2)	/*!< in: search mode for range end */
 {
 	btr_path_t	path1[BTR_PATH_ARRAY_N_SLOTS];
 	btr_path_t	path2[BTR_PATH_ARRAY_N_SLOTS];
@@ -3700,7 +3699,7 @@ btr_estimate_n_rows_in_range(
 
 	table_n_rows = dict_table_get_n_rows(index->table);
 
-	mtr_start_trx(&mtr, trx);
+	mtr_start(&mtr);
 
 	cursor.path_arr = path1;
 
@@ -3718,7 +3717,7 @@ btr_estimate_n_rows_in_range(
 
 	mtr_commit(&mtr);
 
-	mtr_start_trx(&mtr, trx);
+	mtr_start(&mtr);
 
 	cursor.path_arr = path2;
 
@@ -5329,8 +5328,7 @@ btr_copy_blob_prefix(
 	ulint		len,	/*!< in: length of buf, in bytes */
 	ulint		space_id,/*!< in: space id of the BLOB pages */
 	ulint		page_no,/*!< in: page number of the first BLOB page */
-	ulint		offset,	/*!< in: offset on the first BLOB page */
-	trx_t*		trx)	/*!< in: transaction handle */
+	ulint		offset)	/*!< in: offset on the first BLOB page */
 {
 	ulint	copied_len	= 0;
 
@@ -5342,7 +5340,7 @@ btr_copy_blob_prefix(
 		ulint		part_len;
 		ulint		copy_len;
 
-		mtr_start_trx(&mtr, trx);
+		mtr_start(&mtr);
 
 		block = buf_page_get(space_id, 0, page_no, RW_S_LATCH, &mtr);
 		buf_block_dbg_add_level(block, SYNC_EXTERN_STORAGE);
@@ -5545,8 +5543,7 @@ btr_copy_externally_stored_field_prefix_low(
 				zero for uncompressed BLOBs */
 	ulint		space_id,/*!< in: space id of the first BLOB page */
 	ulint		page_no,/*!< in: page number of the first BLOB page */
-	ulint		offset,	/*!< in: offset on the first BLOB page */
-	trx_t*		trx)	/*!< in: transaction handle */
+	ulint		offset)	/*!< in: offset on the first BLOB page */
 {
 	if (UNIV_UNLIKELY(len == 0)) {
 		return(0);
@@ -5557,7 +5554,7 @@ btr_copy_externally_stored_field_prefix_low(
 					     space_id, page_no, offset));
 	} else {
 		return(btr_copy_blob_prefix(buf, len, space_id,
-					    page_no, offset, trx));
+					    page_no, offset));
 	}
 }
 
@@ -5578,8 +5575,7 @@ btr_copy_externally_stored_field_prefix(
 				field containing also the reference to
 				the external part; must be protected by
 				a lock or a page latch */
-	ulint		local_len,/*!< in: length of data, in bytes */
-	trx_t*		trx)	/*!< in: transaction handle */
+	ulint		local_len)/*!< in: length of data, in bytes */
 {
 	ulint	space_id;
 	ulint	page_no;
@@ -5618,7 +5614,7 @@ btr_copy_externally_stored_field_prefix(
 							     len - local_len,
 							     zip_size,
 							     space_id, page_no,
-							     offset, trx));
+							     offset));
 }
 
 /*******************************************************************//**
@@ -5637,8 +5633,7 @@ btr_copy_externally_stored_field(
 	ulint		zip_size,/*!< in: nonzero=compressed BLOB page size,
 				zero for uncompressed BLOBs */
 	ulint		local_len,/*!< in: length of data */
-	mem_heap_t*	heap,	/*!< in: mem heap */
-	trx_t*		trx)	/*!< in: transaction handle */
+	mem_heap_t*	heap)	/*!< in: mem heap */
 {
 	ulint	space_id;
 	ulint	page_no;
@@ -5669,8 +5664,7 @@ btr_copy_externally_stored_field(
 							      extern_len,
 							      zip_size,
 							      space_id,
-							      page_no, offset,
-							      trx);
+							      page_no, offset);
 
 	return(buf);
 }
@@ -5689,8 +5683,7 @@ btr_rec_copy_externally_stored_field(
 				zero for uncompressed BLOBs */
 	ulint		no,	/*!< in: field number */
 	ulint*		len,	/*!< out: length of the field */
-	mem_heap_t*	heap,	/*!< in: mem heap */
-	trx_t*		trx)	/*!< in: transaction handle */
+	mem_heap_t*	heap)	/*!< in: mem heap */
 {
 	ulint		local_len;
 	const byte*	data;
@@ -5721,7 +5714,6 @@ btr_rec_copy_externally_stored_field(
 	}
 
 	return(btr_copy_externally_stored_field(len, data,
-						zip_size, local_len, heap,
-						trx));
+						zip_size, local_len, heap));
 }
 #endif /* !UNIV_HOTBACKUP */
diff --git a/storage/innobase/btr/btr0pcur.cc b/storage/innobase/btr/btr0pcur.cc
index 01d2e1bb8e2..82a2b6dbf6b 100644
--- a/storage/innobase/btr/btr0pcur.cc
+++ b/storage/innobase/btr/btr0pcur.cc
@@ -486,7 +486,7 @@ btr_pcur_move_backward_from_page(
 
 	mtr_commit(mtr);
 
-	mtr_start_trx(mtr, mtr->trx);
+	mtr_start(mtr);
 
 	btr_pcur_restore_position(latch_mode2, cursor, mtr);
 
diff --git a/storage/innobase/fts/fts0fts.cc b/storage/innobase/fts/fts0fts.cc
index cc7bf73a671..1d753e3657b 100644
--- a/storage/innobase/fts/fts0fts.cc
+++ b/storage/innobase/fts/fts0fts.cc
@@ -3361,8 +3361,7 @@ fts_fetch_doc_from_rec(
 					dict_table_zip_size(table),
 					clust_pos, &doc->text.f_len,
 					static_cast<mem_heap_t*>(
-						doc->self_heap->arg),
-					NULL);
+						doc->self_heap->arg));
 		} else {
 			doc->text.f_str = (byte*) rec_get_nth_field(
 				clust_rec, offsets, clust_pos,
@@ -7599,8 +7598,7 @@ fts_init_recover_doc(
 				&doc.text.f_len,
 				static_cast<byte*>(dfield_get_data(dfield)),
 				zip_size, len,
-				static_cast<mem_heap_t*>(doc.self_heap->arg),
-				NULL);
+				static_cast<mem_heap_t*>(doc.self_heap->arg));
 		} else {
 			doc.text.f_str = static_cast<byte*>(
 				dfield_get_data(dfield));
diff --git a/storage/innobase/fts/fts0que.cc b/storage/innobase/fts/fts0que.cc
index 20354b2f900..3a543836837 100644
--- a/storage/innobase/fts/fts0que.cc
+++ b/storage/innobase/fts/fts0que.cc
@@ -1917,8 +1917,7 @@ fts_query_fetch_document(
 		if (dfield_is_ext(dfield)) {
 			data = btr_copy_externally_stored_field(
 				&cur_len, data, phrase->zip_size,
-				dfield_get_len(dfield), phrase->heap,
-				NULL);
+				dfield_get_len(dfield), phrase->heap);
 		} else {
 			cur_len = dfield_get_len(dfield);
 		}
diff --git a/storage/innobase/handler/ha_innodb.cc b/storage/innobase/handler/ha_innodb.cc
index ac43bd6eed3..ad3849589a2 100644
--- a/storage/innobase/handler/ha_innodb.cc
+++ b/storage/innobase/handler/ha_innodb.cc
@@ -11163,7 +11163,7 @@ ha_innobase::records_in_range(
 
 		n_rows = btr_estimate_n_rows_in_range(index, range_start,
 						      mode1, range_end,
-						      mode2, prebuilt->trx);
+						      mode2);
 	} else {
 
 		n_rows = HA_POS_ERROR;
diff --git a/storage/innobase/include/btr0cur.h b/storage/innobase/include/btr0cur.h
index 77de98d5812..28b74070556 100644
--- a/storage/innobase/include/btr0cur.h
+++ b/storage/innobase/include/btr0cur.h
@@ -566,8 +566,7 @@ btr_estimate_n_rows_in_range(
 	const dtuple_t*	tuple1,	/*!< in: range start, may also be empty tuple */
 	ulint		mode1,	/*!< in: search mode for range start */
 	const dtuple_t*	tuple2,	/*!< in: range end, may also be empty tuple */
-	ulint		mode2,	/*!< in: search mode for range end */
-	trx_t*		trx);	/*!< in: trx */
+	ulint		mode2);	/*!< in: search mode for range end */
 /*******************************************************************//**
 Estimates the number of different key values in a given index, for
 each n-column prefix of the index where 1 <= n <= dict_index_get_n_unique(index).
@@ -703,8 +702,7 @@ btr_copy_externally_stored_field_prefix(
 				field containing also the reference to
 				the external part; must be protected by
 				a lock or a page latch */
-	ulint		local_len,/*!< in: length of data, in bytes */
-	trx_t*		trx);	/*!< in: transaction handle */
+	ulint		local_len);/*!< in: length of data, in bytes */
 /*******************************************************************//**
 Copies an externally stored field of a record to mem heap.  The
 clustered index record must be protected by a lock or a page latch.
@@ -721,8 +719,7 @@ btr_copy_externally_stored_field(
 	ulint		zip_size,/*!< in: nonzero=compressed BLOB page size,
 				zero for uncompressed BLOBs */
 	ulint		local_len,/*!< in: length of data */
-	mem_heap_t*	heap,	/*!< in: mem heap */
-	trx_t*		trx);	/*!< in: transaction handle */
+	mem_heap_t*	heap);	/*!< in: mem heap */
 /*******************************************************************//**
 Copies an externally stored field of a record to mem heap.
 @return	the field copied to heap, or NULL if the field is incomplete */
@@ -737,8 +734,7 @@ btr_rec_copy_externally_stored_field(
 				zero for uncompressed BLOBs */
 	ulint		no,	/*!< in: field number */
 	ulint*		len,	/*!< out: length of the field */
-	mem_heap_t*	heap,	/*!< in: mem heap */
-	trx_t*		trx);	/*!< in: transaction handle */
+	mem_heap_t*	heap);	/*!< in: mem heap */
 /*******************************************************************//**
 Flags the data tuple fields that are marked as extern storage in the
 update vector.  We use this function to remember which fields we must
diff --git a/storage/innobase/include/mtr0mtr.h b/storage/innobase/include/mtr0mtr.h
index c6c1c89188d..abb5fd7b2dc 100644
--- a/storage/innobase/include/mtr0mtr.h
+++ b/storage/innobase/include/mtr0mtr.h
@@ -36,7 +36,6 @@ Created 11/26/1995 Heikki Tuuri
 #include "ut0byte.h"
 #include "mtr0types.h"
 #include "page0types.h"
-#include "trx0types.h"
 
 /* Logging modes for a mini-transaction */
 #define MTR_LOG_ALL		21	/* default mode: log all operations
@@ -206,22 +205,10 @@ functions).  The page number parameter was originally written as 0. @{ */
 Starts a mini-transaction. */
 UNIV_INLINE
 void
-mtr_start_trx(
-/*======*/
-	mtr_t*	mtr,	/*!< out: mini-transaction */
-	trx_t*	trx)	/*!< in: transaction */
-	MY_ATTRIBUTE((nonnull (1)));
-/***************************************************************//**
-Starts a mini-transaction. */
-UNIV_INLINE
-void
 mtr_start(
 /*======*/
 	mtr_t*	mtr)	/*!< out: mini-transaction */
-{
-	mtr_start_trx(mtr, NULL);
-}
-	MY_ATTRIBUTE((nonnull))
+	MY_ATTRIBUTE((nonnull));
 /***************************************************************//**
 Commits a mini-transaction. */
 UNIV_INTERN
@@ -417,7 +404,6 @@ struct mtr_t{
 #ifdef UNIV_DEBUG
 	ulint		magic_n;
 #endif /* UNIV_DEBUG */
-	trx_t*		trx;	/*!< transaction */
 };
 
 #ifdef UNIV_DEBUG
diff --git a/storage/innobase/include/mtr0mtr.ic b/storage/innobase/include/mtr0mtr.ic
index 37cea34d4eb..3f897ae1d10 100644
--- a/storage/innobase/include/mtr0mtr.ic
+++ b/storage/innobase/include/mtr0mtr.ic
@@ -43,10 +43,9 @@ mtr_block_dirtied(
 Starts a mini-transaction. */
 UNIV_INLINE
 void
-mtr_start_trx(
+mtr_start(
 /*======*/
-	mtr_t*	mtr,	/*!< out: mini-transaction */
-	trx_t*	trx)	/*!< in: transaction */
+	mtr_t*	mtr)	/*!< out: mini-transaction */
 {
 	UNIV_MEM_INVALID(mtr, sizeof *mtr);
 
@@ -59,7 +58,6 @@ mtr_start_trx(
 	mtr->made_dirty = FALSE;
 	mtr->n_log_recs = 0;
 	mtr->n_freed_pages = 0;
-	mtr->trx = trx;
 
 	ut_d(mtr->state = MTR_ACTIVE);
 	ut_d(mtr->magic_n = MTR_MAGIC_N);
diff --git a/storage/innobase/include/trx0undo.h b/storage/innobase/include/trx0undo.h
index 42ac62916e0..266ca32548c 100644
--- a/storage/innobase/include/trx0undo.h
+++ b/storage/innobase/include/trx0undo.h
@@ -246,13 +246,22 @@ Truncates an undo log from the end. This function is used during a rollback
 to free space from an undo log. */
 UNIV_INTERN
 void
-trx_undo_truncate_end(
+trx_undo_truncate_end_func(
 /*=======================*/
-	trx_t*		trx,	/*!< in: transaction whose undo log it is */
+#ifdef UNIV_DEBUG
+	const trx_t*	trx,	/*!< in: transaction whose undo log it is */
+#endif /* UNIV_DEBUG */
 	trx_undo_t*	undo,	/*!< in/out: undo log */
 	undo_no_t	limit)	/*!< in: all undo records with undo number
 				>= this value should be truncated */
 	MY_ATTRIBUTE((nonnull));
+#ifdef UNIV_DEBUG
+# define trx_undo_truncate_end(trx,undo,limit)		\
+	trx_undo_truncate_end_func(trx,undo,limit)
+#else /* UNIV_DEBUG */
+# define trx_undo_truncate_end(trx,undo,limit)		\
+	trx_undo_truncate_end_func(undo,limit)
+#endif /* UNIV_DEBUG */
 
 /***********************************************************************//**
 Truncates an undo log from the start. This function is used during a purge
diff --git a/storage/innobase/row/row0ext.cc b/storage/innobase/row/row0ext.cc
index ad852577ad2..32b78391d6a 100644
--- a/storage/innobase/row/row0ext.cc
+++ b/storage/innobase/row/row0ext.cc
@@ -78,8 +78,7 @@ row_ext_cache_fill(
 			crashed during the execution of
 			btr_free_externally_stored_field(). */
 			ext->len[i] = btr_copy_externally_stored_field_prefix(
-				buf, ext->max_len, zip_size, field, f_len,
-				NULL);
+				buf, ext->max_len, zip_size, field, f_len);
 		}
 	}
 }
diff --git a/storage/innobase/row/row0ftsort.cc b/storage/innobase/row/row0ftsort.cc
index 27d6cdf124c..8a3d4573879 100644
--- a/storage/innobase/row/row0ftsort.cc
+++ b/storage/innobase/row/row0ftsort.cc
@@ -675,8 +675,7 @@ loop:
 				doc.text.f_str =
 					btr_copy_externally_stored_field(
 						&doc.text.f_len, data,
-						zip_size, data_len, blob_heap,
-						NULL);
+						zip_size, data_len, blob_heap);
 			} else {
 				doc.text.f_str = data;
 				doc.text.f_len = data_len;
diff --git a/storage/innobase/row/row0ins.cc b/storage/innobase/row/row0ins.cc
index 0e28f8f63e6..dbf43cca058 100644
--- a/storage/innobase/row/row0ins.cc
+++ b/storage/innobase/row/row0ins.cc
@@ -1305,7 +1305,7 @@ row_ins_foreign_check_on_constraint(
 
 	row_mysql_freeze_data_dictionary(thr_get_trx(thr));
 
-	mtr_start_trx(mtr, trx);
+	mtr_start(mtr);
 
 	/* Restore pcur position */
 
@@ -1333,7 +1333,7 @@ nonstandard_exit_func:
 	btr_pcur_store_position(pcur, mtr);
 
 	mtr_commit(mtr);
-	mtr_start_trx(mtr, trx);
+	mtr_start(mtr);
 
 	btr_pcur_restore_position(BTR_SEARCH_LEAF, pcur, mtr);
 
@@ -1543,7 +1543,7 @@ run_again:
 		}
 	}
 
-	mtr_start_trx(&mtr, trx);
+	mtr_start(&mtr);
 
 	/* Store old value on n_fields_cmp */
 
@@ -2330,7 +2330,7 @@ row_ins_clust_index_entry_low(
 	      || n_uniq == dict_index_get_n_unique(index));
 	ut_ad(!n_uniq || n_uniq == dict_index_get_n_unique(index));
 
-	mtr_start_trx(&mtr, thr_get_trx(thr));
+	mtr_start(&mtr);
 
 	if (mode == BTR_MODIFY_LEAF && dict_index_is_online_ddl(index)) {
 		mode = BTR_MODIFY_LEAF | BTR_ALREADY_S_LATCHED;
@@ -2543,10 +2543,9 @@ Starts a mini-transaction and checks if the index will be dropped.
 @return true if the index is to be dropped */
 static MY_ATTRIBUTE((nonnull, warn_unused_result))
 bool
-row_ins_sec_mtr_start_trx_and_check_if_aborted(
+row_ins_sec_mtr_start_and_check_if_aborted(
 /*=======================================*/
 	mtr_t*		mtr,	/*!< out: mini-transaction */
-	trx_t*		trx,	/*!< in: transaction handle */
 	dict_index_t*	index,	/*!< in/out: secondary index */
 	bool		check,	/*!< in: whether to check */
 	ulint		search_mode)
@@ -2554,7 +2553,7 @@ row_ins_sec_mtr_start_trx_and_check_if_aborted(
 {
 	ut_ad(!dict_index_is_clust(index));
 
-	mtr_start_trx(mtr, trx);
+	mtr_start(mtr);
 
 	if (!check) {
 		return(false);
@@ -2612,14 +2611,13 @@ row_ins_sec_index_entry_low(
 	ulint		n_unique;
 	mtr_t		mtr;
 	ulint*		offsets	= NULL;
-	trx_t*		trx = thr_get_trx(thr);
 
 	ut_ad(!dict_index_is_clust(index));
 	ut_ad(mode == BTR_MODIFY_LEAF || mode == BTR_MODIFY_TREE);
 
 	cursor.thr = thr;
 	ut_ad(thr_get_trx(thr)->id);
-	mtr_start_trx(&mtr, trx);
+	mtr_start(&mtr);
 
 	/* Ensure that we acquire index->lock when inserting into an
 	index with index->online_status == ONLINE_INDEX_COMPLETE, but
@@ -2680,8 +2678,8 @@ row_ins_sec_index_entry_low(
 
 		DEBUG_SYNC_C("row_ins_sec_index_unique");
 
-		if (row_ins_sec_mtr_start_trx_and_check_if_aborted(
-			    &mtr, trx, index, check, search_mode)) {
+		if (row_ins_sec_mtr_start_and_check_if_aborted(
+			    &mtr, index, check, search_mode)) {
 			goto func_exit;
 		}
 
@@ -2715,8 +2713,8 @@ row_ins_sec_index_entry_low(
 			return(err);
 		}
 
-		if (row_ins_sec_mtr_start_trx_and_check_if_aborted(
-			    &mtr, trx, index, check, search_mode)) {
+		if (row_ins_sec_mtr_start_and_check_if_aborted(
+			    &mtr, index, check, search_mode)) {
 			goto func_exit;
 		}
 
diff --git a/storage/innobase/row/row0log.cc b/storage/innobase/row/row0log.cc
index 995ff35cf47..0720b3ee8c4 100644
--- a/storage/innobase/row/row0log.cc
+++ b/storage/innobase/row/row0log.cc
@@ -1011,7 +1011,7 @@ row_log_table_get_pk_col(
 			mem_heap_alloc(heap, field_len));
 
 		len = btr_copy_externally_stored_field_prefix(
-			blob_field, field_len, zip_size, field, len, NULL);
+			blob_field, field_len, zip_size, field, len);
 		if (len >= max_len + 1) {
 			return(DB_TOO_BIG_INDEX_COL);
 		}
@@ -1404,7 +1404,7 @@ row_log_table_apply_convert_mrec(
 			data = btr_rec_copy_externally_stored_field(
 				mrec, offsets,
 				dict_table_zip_size(index->table),
-				i, &len, heap, NULL);
+				i, &len, heap);
 			ut_a(data);
 			dfield_set_data(dfield, data, len);
 blob_done:
diff --git a/storage/innobase/row/row0merge.cc b/storage/innobase/row/row0merge.cc
index e3d8a3a5936..49c9aa4b51f 100644
--- a/storage/innobase/row/row0merge.cc
+++ b/storage/innobase/row/row0merge.cc
@@ -273,7 +273,7 @@ row_merge_buf_redundant_convert(
 			    field_ref_zero, BTR_EXTERN_FIELD_REF_SIZE));
 
 		byte*	data = btr_copy_externally_stored_field(
-			&ext_len, field_data, zip_size, field_len, heap, NULL);
+			&ext_len, field_data, zip_size, field_len, heap);
 
 		ut_ad(ext_len < len);
 
@@ -2445,7 +2445,7 @@ row_merge_copy_blobs(
 		BLOB pointers are read (row_merge_read_clustered_index())
 		and dereferenced (below). */
 		data = btr_rec_copy_externally_stored_field(
-			mrec, offsets, zip_size, i, &len, heap, NULL);
+			mrec, offsets, zip_size, i, &len, heap);
 		/* Because we have locked the table, any records
 		written by incomplete transactions must have been
 		rolled back already. There must not be any incomplete
diff --git a/storage/innobase/row/row0mysql.cc b/storage/innobase/row/row0mysql.cc
index 357af2ff1dc..7c0d104cd0b 100644
--- a/storage/innobase/row/row0mysql.cc
+++ b/storage/innobase/row/row0mysql.cc
@@ -1942,7 +1942,7 @@ row_unlock_for_mysql(
 		trx_id_t	rec_trx_id;
 		mtr_t		mtr;
 
-		mtr_start_trx(&mtr, trx);
+		mtr_start(&mtr);
 
 		/* Restore the cursor position and find the record */
 
@@ -3476,7 +3476,7 @@ row_truncate_table_for_mysql(
 				index = dict_table_get_next_index(index);
 			} while (index);
 
-			mtr_start_trx(&mtr, trx);
+			mtr_start(&mtr);
 			fsp_header_init(space,
 					FIL_IBD_FILE_INITIAL_SIZE, &mtr);
 			mtr_commit(&mtr);
@@ -3505,7 +3505,7 @@ row_truncate_table_for_mysql(
 	sys_index = dict_table_get_first_index(dict_sys->sys_indexes);
 	dict_index_copy_types(tuple, sys_index, 1);
 
-	mtr_start_trx(&mtr, trx);
+	mtr_start(&mtr);
 	btr_pcur_open_on_user_rec(sys_index, tuple, PAGE_CUR_GE,
 				  BTR_MODIFY_LEAF, &pcur, &mtr);
 	for (;;) {
@@ -3552,7 +3552,7 @@ row_truncate_table_for_mysql(
 			a page in this mini-transaction, and the rest of
 			this loop could latch another index page. */
 			mtr_commit(&mtr);
-			mtr_start_trx(&mtr, trx);
+			mtr_start(&mtr);
 			btr_pcur_restore_position(BTR_MODIFY_LEAF,
 						  &pcur, &mtr);
 		}
diff --git a/storage/innobase/row/row0sel.cc b/storage/innobase/row/row0sel.cc
index dde3ba826a7..c2954742f8e 100644
--- a/storage/innobase/row/row0sel.cc
+++ b/storage/innobase/row/row0sel.cc
@@ -135,8 +135,7 @@ row_sel_sec_rec_is_for_blob(
 
 	len = btr_copy_externally_stored_field_prefix(buf, prefix_len,
 						      zip_size,
-						      clust_field, clust_len,
-						      NULL);
+						      clust_field, clust_len);
 
 	if (UNIV_UNLIKELY(len == 0)) {
 		/* The BLOB was being deleted as the server crashed.
@@ -455,7 +454,7 @@ row_sel_fetch_columns(
 				data = btr_rec_copy_externally_stored_field(
 					rec, offsets,
 					dict_table_zip_size(index->table),
-					field_no, &len, heap, NULL);
+					field_no, &len, heap);
 
 				/* data == NULL means that the
 				externally stored field was not
@@ -1402,7 +1401,7 @@ table_loop:
 
 	/* Open a cursor to index, or restore an open cursor position */
 
-	mtr_start_trx(&mtr, thr_get_trx(thr));
+	mtr_start(&mtr);
 
 	if (consistent_read && plan->unique_search && !plan->pcur_is_open
 	    && !plan->must_get_clust
@@ -1442,7 +1441,7 @@ table_loop:
 		plan_reset_cursor(plan);
 
 		mtr_commit(&mtr);
-		mtr_start_trx(&mtr, thr_get_trx(thr));
+		mtr_start(&mtr);
 	}
 
 	if (search_latch_locked) {
@@ -2813,7 +2812,7 @@ row_sel_store_mysql_field_func(
 		data = btr_rec_copy_externally_stored_field(
 			rec, offsets,
 			dict_table_zip_size(prebuilt->table),
-			field_no, &len, heap, NULL);
+			field_no, &len, heap);
 
 		if (UNIV_UNLIKELY(!data)) {
 			/* The externally stored field was not written
@@ -3921,7 +3920,7 @@ row_search_for_mysql(
 		}
 	}
 
-	mtr_start_trx(&mtr, trx);
+	mtr_start(&mtr);
 
 	/*-------------------------------------------------------------*/
 	/* PHASE 2: Try fast adaptive hash index search if possible */
@@ -4052,7 +4051,7 @@ release_search_latch_if_needed:
 			}
 
 			mtr_commit(&mtr);
-			mtr_start_trx(&mtr, trx);
+			mtr_start(&mtr);
 		}
 	}
 
@@ -5041,7 +5040,7 @@ next_rec:
 		mtr_commit(&mtr);
 		mtr_has_extra_clust_latch = FALSE;
 
-		mtr_start_trx(&mtr, trx);
+		mtr_start(&mtr);
 		if (sel_restore_position_for_mysql(&same_user_rec,
 						   BTR_SEARCH_LEAF,
 						   pcur, moves_up, &mtr)) {
@@ -5106,7 +5105,7 @@ lock_table_wait:
 		/* It was a lock wait, and it ended */
 
 		thr->lock_state = QUE_THR_LOCK_NOLOCK;
-		mtr_start_trx(&mtr, trx);
+		mtr_start(&mtr);
 
 		/* Table lock waited, go try to obtain table lock
 		again */
diff --git a/storage/innobase/row/row0umod.cc b/storage/innobase/row/row0umod.cc
index d8bb6955e60..92f7060b56b 100644
--- a/storage/innobase/row/row0umod.cc
+++ b/storage/innobase/row/row0umod.cc
@@ -299,7 +299,7 @@ row_undo_mod_clust(
 	pcur = &node->pcur;
 	index = btr_cur_get_index(btr_pcur_get_btr_cur(pcur));
 
-	mtr_start_trx(&mtr, thr_get_trx(thr));
+	mtr_start(&mtr);
 
 	online = dict_index_is_online_ddl(index);
 	if (online) {
@@ -328,7 +328,7 @@ row_undo_mod_clust(
 		/* We may have to modify tree structure: do a pessimistic
 		descent down the index tree */
 
-		mtr_start_trx(&mtr, thr_get_trx(thr));
+		mtr_start(&mtr);
 
 		err = row_undo_mod_clust_low(
 			node, &offsets, &offsets_heap,
@@ -373,7 +373,7 @@ row_undo_mod_clust(
 
 	if (err == DB_SUCCESS && node->rec_type == TRX_UNDO_UPD_DEL_REC) {
 
-		mtr_start_trx(&mtr, thr_get_trx(thr));
+		mtr_start(&mtr);
 
 		/* It is not necessary to call row_log_table,
 		because the record is delete-marked and would thus
@@ -386,7 +386,7 @@ row_undo_mod_clust(
 			/* We may have to modify tree structure: do a
 			pessimistic descent down the index tree */
 
-			mtr_start_trx(&mtr, thr_get_trx(thr));
+			mtr_start(&mtr);
 
 			err = row_undo_mod_remove_clust_low(node, thr, &mtr,
 							    BTR_MODIFY_TREE);
@@ -433,7 +433,7 @@ row_undo_mod_del_mark_or_remove_sec_low(
 	enum row_search_result	search_result;
 
 	log_free_check();
-	mtr_start_trx(&mtr, thr_get_trx(thr));
+	mtr_start(&mtr);
 	if (mode == BTR_MODIFY_TREE
 	    && index->space == IBUF_SPACE_ID
 	    && !dict_index_is_unique(index)) {
@@ -494,7 +494,7 @@ row_undo_mod_del_mark_or_remove_sec_low(
 	which cannot be purged yet, requires its existence. If some requires,
 	we should delete mark the record. */
 
-	mtr_start_trx(&mtr_vers, thr_get_trx(thr));
+	mtr_start(&mtr_vers);
 
 	success = btr_pcur_restore_position(BTR_SEARCH_LEAF, &(node->pcur),
 					    &mtr_vers);
@@ -610,7 +610,7 @@ row_undo_mod_del_unmark_sec_and_undo_update(
 	ut_ad(trx->id);
 
 	log_free_check();
-	mtr_start_trx(&mtr, thr_get_trx(thr));
+	mtr_start(&mtr);
 	if (mode == BTR_MODIFY_TREE
 	    && index->space == IBUF_SPACE_ID
 	    && !dict_index_is_unique(index)) {
diff --git a/storage/innobase/row/row0upd.cc b/storage/innobase/row/row0upd.cc
index 0a6804af5ea..4f1ce9a69ce 100644
--- a/storage/innobase/row/row0upd.cc
+++ b/storage/innobase/row/row0upd.cc
@@ -211,7 +211,7 @@ row_upd_check_references_constraints(
 
 	DEBUG_SYNC_C("foreign_constraint_check_for_update");
 
-	mtr_start_trx(mtr, trx);
+	mtr_start(mtr);
 
 	if (trx->dict_operation_lock_mode == 0) {
 		got_s_lock = TRUE;
@@ -985,7 +985,7 @@ row_upd_ext_fetch(
 	byte*	buf = static_cast<byte*>(mem_heap_alloc(heap, *len));
 
 	*len = btr_copy_externally_stored_field_prefix(
-		buf, *len, zip_size, data, local_len, NULL);
+		buf, *len, zip_size, data, local_len);
 
 	/* We should never update records containing a half-deleted BLOB. */
 	ut_a(*len);
@@ -1682,7 +1682,7 @@ row_upd_sec_index_entry(
 	}
 #endif /* UNIV_DEBUG */
 
-	mtr_start_trx(&mtr, trx);
+	mtr_start(&mtr);
 
 	if (*index->name == TEMP_INDEX_PREFIX) {
 		/* The index->online_status may change if the
@@ -2149,7 +2149,7 @@ row_upd_clust_rec(
 	/* We may have to modify the tree structure: do a pessimistic descent
 	down the index tree */
 
-	mtr_start_trx(mtr, thr_get_trx(thr));
+	mtr_start(mtr);
 
 	/* NOTE: this transaction has an s-lock or x-lock on the record and
 	therefore other transactions cannot modify the record when we have no
@@ -2316,7 +2316,7 @@ row_upd_clust_step(
 
 	/* We have to restore the cursor to its position */
 
-	mtr_start_trx(&mtr, thr_get_trx(thr));
+	mtr_start(&mtr);
 
 	/* If the restoration does not succeed, then the same
 	transaction has deleted the record on which the cursor was,
@@ -2370,7 +2370,7 @@ row_upd_clust_step(
 
 		mtr_commit(&mtr);
 
-		mtr_start_trx(&mtr, thr_get_trx(thr));
+		mtr_start(&mtr);
 
 		success = btr_pcur_restore_position(BTR_MODIFY_LEAF, pcur,
 						    &mtr);
diff --git a/storage/innobase/trx/trx0rec.cc b/storage/innobase/trx/trx0rec.cc
index 2584d6bf3cb..9e54c429393 100644
--- a/storage/innobase/trx/trx0rec.cc
+++ b/storage/innobase/trx/trx0rec.cc
@@ -467,7 +467,7 @@ trx_undo_page_fetch_ext(
 {
 	/* Fetch the BLOB. */
 	ulint	ext_len = btr_copy_externally_stored_field_prefix(
-		ext_buf, prefix_len, zip_size, field, *len, NULL);
+		ext_buf, prefix_len, zip_size, field, *len);
 	/* BLOBs should always be nonempty. */
 	ut_a(ext_len);
 	/* Append the BLOB pointer to the prefix. */
@@ -1266,7 +1266,7 @@ trx_undo_report_row_operation(
 
 	rseg = trx->rseg;
 
-	mtr_start_trx(&mtr, trx);
+	mtr_start(&mtr);
 	mutex_enter(&trx->undo_mutex);
 
 	/* If the undo log is not assigned yet, assign one */
@@ -1342,7 +1342,7 @@ trx_undo_report_row_operation(
 				latches, such as SYNC_FSP and SYNC_FSP_PAGE. */
 
 				mtr_commit(&mtr);
-				mtr_start_trx(&mtr, trx);
+				mtr_start(&mtr);
 
 				mutex_enter(&rseg->mutex);
 				trx_undo_free_last_page(trx, undo, &mtr);
@@ -1379,7 +1379,7 @@ trx_undo_report_row_operation(
 		/* We have to extend the undo log by one page */
 
 		ut_ad(++loop_count < 2);
-		mtr_start_trx(&mtr, trx);
+		mtr_start(&mtr);
 
 		/* When we add a page to an undo log, this is analogous to
 		a pessimistic insert in a B-tree, and we must reserve the
diff --git a/storage/innobase/trx/trx0undo.cc b/storage/innobase/trx/trx0undo.cc
index 5638ccd17a6..d6bcd131a4f 100644
--- a/storage/innobase/trx/trx0undo.cc
+++ b/storage/innobase/trx/trx0undo.cc
@@ -1070,9 +1070,11 @@ Truncates an undo log from the end. This function is used during a rollback
 to free space from an undo log. */
 UNIV_INTERN
 void
-trx_undo_truncate_end(
+trx_undo_truncate_end_func(
 /*=======================*/
-	trx_t*		trx,	/*!< in: transaction whose undo log it is */
+#ifdef UNIV_DEBUG
+	const trx_t*	trx,	/*!< in: transaction whose undo log it is */
+#endif /* UNIV_DEBUG */
 	trx_undo_t*	undo,	/*!< in: undo log */
 	undo_no_t	limit)	/*!< in: all undo records with undo number
 				>= this value should be truncated */
@@ -1087,7 +1089,7 @@ trx_undo_truncate_end(
 	ut_ad(mutex_own(&(trx->rseg->mutex)));
 
 	for (;;) {
-		mtr_start_trx(&mtr, trx);
+		mtr_start(&mtr);
 
 		trunc_here = NULL;
 
@@ -1774,7 +1776,7 @@ trx_undo_assign_undo(
 
 	ut_ad(mutex_own(&(trx->undo_mutex)));
 
-	mtr_start_trx(&mtr, trx);
+	mtr_start(&mtr);
 
 	mutex_enter(&rseg->mutex);