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

This reverts commit 3486135b.

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

storage/innobase/include/mtr0mtr.h

@@ -37,8 +37,6 @@ Created 11/26/1995 Heikki Tuuri
 
 /** Start a mini-transaction. */
 #define mtr_start(m)		(m)->start()
-/** Start a mini-transaction. */
-#define mtr_start_trx(m, t)		(m)->start((t))
 
 /** Start a synchronous mini-transaction */
 #define mtr_start_sync(m)	(m)->start(true)
@@ -217,9 +215,6 @@ struct mtr_t {
 
 		/** Owning mini-transaction */
 		mtr_t*		m_mtr;
-
-		/* Transaction handle */
-		trx_t*			m_trx;
 	};
 
 	mtr_t()
@@ -239,15 +234,7 @@ struct mtr_t {
 	/** Start a mini-transaction.
 	@param sync		true if it is a synchronous mini-transaction
 	@param read_only	true if read only mini-transaction */
-	void start(bool sync = true, bool read_only = false)
-	{
-		start(NULL, sync, read_only);
-	}
-
-	/** Start a mini-transaction.
-	@param sync		true if it is a synchronous mini-transaction
-	@param read_only	true if read only mini-transaction */
-	void start(trx_t* trx, bool sync = true, bool read_only = false);
+	void start(bool sync = true, bool read_only = false);
 
 	/** @return whether this is an asynchronous mini-transaction. */
 	bool is_async() const

storage/innobase/mtr/mtr0mtr.cc

@@ -492,7 +492,7 @@ mtr_write_log(
 @param sync		true if it is a synchronous mini-transaction
 @param read_only	true if read only mini-transaction */
 void
-mtr_t::start(trx_t* trx, bool sync, bool read_only)
+mtr_t::start(bool sync, bool read_only)
 {
 	UNIV_MEM_INVALID(this, sizeof(*this));
 
@@ -517,7 +517,6 @@ mtr_t::start(trx_t* trx, bool sync, bool read_only)
 	m_impl.m_undo_space = NULL;
 	m_impl.m_sys_space = NULL;
 	m_impl.m_flush_observer = NULL;
-	m_impl.m_trx = trx;
 
 	ut_d(m_impl.m_magic_n = MTR_MAGIC_N);
 }

storage/innobase/row/row0umod.cc

@@ -306,7 +306,7 @@ 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();
 		if (index->table->is_temporary()) {
 			mtr.set_log_mode(MTR_LOG_NO_REDO);
 		} else {
@@ -366,7 +366,7 @@ 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();
 		if (index->table->is_temporary()) {
 			mtr.set_log_mode(MTR_LOG_NO_REDO);
 		} else {
@@ -384,7 +384,7 @@ 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();
 			if (index->table->is_temporary()) {
 				mtr.set_log_mode(MTR_LOG_NO_REDO);
 			} else {
@@ -498,7 +498,7 @@ 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_vers.start();
 
 	success = btr_pcur_restore_position(BTR_SEARCH_LEAF, &(node->pcur),
 					    &mtr_vers);

storage/innobase/row/row0upd.cc

@@ -248,7 +248,7 @@ row_upd_check_references_constraints(
 
 	DEBUG_SYNC_C("foreign_constraint_check_for_update");
 
-	mtr_start_trx(mtr, trx);
+	mtr->start();
 
 	if (trx->dict_operation_lock_mode == 0) {
 		got_s_lock = TRUE;
@@ -2298,7 +2298,7 @@ row_upd_sec_index_entry(
 	DEBUG_SYNC_C_IF_THD(trx->mysql_thd,
 			    "before_row_upd_sec_index_entry");
 
-	mtr_start_trx(&mtr, trx);
+	mtr.start();
 
 	switch (index->space) {
 	case SRV_TMP_SPACE_ID:
@@ -2858,7 +2858,7 @@ 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->set_named_space(index->space);
 
 	/* Disable REDO logging as lifetime of temp-tables is limited to
@@ -3045,7 +3045,7 @@ row_upd_clust_step(
 
 	/* We have to restore the cursor to its position */
 
-	mtr_start_trx(&mtr, thr_get_trx(thr));
+	mtr.start();
 	mtr.set_named_space(index->space);
 
 	/* Disable REDO logging as lifetime of temp-tables is limited to
@@ -3103,9 +3103,9 @@ row_upd_clust_step(
 		dict_drop_index_tree(
 			btr_pcur_get_rec(pcur), pcur, &mtr);
 
-		mtr_commit(&mtr);
+		mtr.commit();
 
-		mtr_start_trx(&mtr, thr_get_trx(thr));
+		mtr.start();
 		mtr.set_named_space(index->space);
 
 		success = btr_pcur_restore_position(BTR_MODIFY_LEAF, pcur,
@@ -3113,7 +3113,7 @@ row_upd_clust_step(
 		if (!success) {
 			err = DB_ERROR;
 
-			mtr_commit(&mtr);
+			mtr.commit();
 
 			return(err);
 		}
@@ -3128,7 +3128,7 @@ row_upd_clust_step(
 			0, btr_pcur_get_block(pcur),
 			rec, index, offsets, thr);
 		if (err != DB_SUCCESS) {
-			mtr_commit(&mtr);
+			mtr.commit();
 			goto exit_func;
 		}
 	}