MDEV-17138 follow-up: Use MLOG_MEMSET for writing FIL_NULL

Always use the MLOG_MEMSET record for writing FIL_NULL,
because it is more compact.

storage/innobase/btr/btr0bulk.cc

@@ -107,12 +107,12 @@ PageBulk::init()
 		} else {
 			ut_ad(!dict_index_is_spatial(m_index));
 			page_create(new_block, &m_mtr,
-				    dict_table_is_comp(m_index->table),
+				    m_index->table->not_redundant(),
 				    false);
-			mlog_write_ulint(FIL_PAGE_PREV + new_page, FIL_NULL,
-					 MLOG_4BYTES, &m_mtr);
-			mlog_write_ulint(FIL_PAGE_NEXT + new_page, FIL_NULL,
-					 MLOG_4BYTES, &m_mtr);
+			compile_time_assert(FIL_PAGE_NEXT
+					    == FIL_PAGE_PREV + 4);
+			compile_time_assert(FIL_NULL == 0xffffffff);
+			mlog_memset(new_block, FIL_PAGE_PREV, 8, 0xff, &m_mtr);
 			mlog_write_ulint(PAGE_HEADER + PAGE_LEVEL + new_page,
 					 m_level, MLOG_2BYTES, &m_mtr);
 			mlog_write_ull(PAGE_HEADER + PAGE_INDEX_ID + new_page,

storage/innobase/btr/btr0cur.cc

@@ -7776,12 +7776,11 @@ btr_store_big_rec_extern_fields(
 				ut_a(err == Z_STREAM_END
 				     || c_stream.avail_out == 0);
 
-				/* Write the "next BLOB page" pointer */
-				mlog_write_ulint(page + FIL_PAGE_NEXT,
-						 FIL_NULL, MLOG_4BYTES, &mtr);
-				/* Initialize the unused "prev page" pointer */
-				mlog_write_ulint(page + FIL_PAGE_PREV,
-						 FIL_NULL, MLOG_4BYTES, &mtr);
+				compile_time_assert(FIL_PAGE_NEXT
+						    == FIL_PAGE_PREV + 4);
+				compile_time_assert(FIL_NULL == 0xffffffff);
+				mlog_memset(block, FIL_PAGE_PREV, 8, 0xff,
+					    &mtr);
 				/* Write a back pointer to the record
 				into the otherwise unused area.  This
 				information could be useful in

storage/innobase/dict/dict0crea.cc

@@ -906,10 +906,10 @@ dict_drop_index_tree(
 	btr_pcur_t*	pcur,
 	mtr_t*		mtr)
 {
-	const byte*	ptr;
-	ulint		len;
-	ulint		space;
-	ulint		root_page_no;
+	byte*	ptr;
+	ulint	len;
+	ulint	space;
+	ulint	root_page_no;
 
 	ut_ad(mutex_own(&dict_sys.mutex));
 	ut_a(!dict_table_is_comp(dict_sys.sys_indexes));
@@ -928,7 +928,8 @@ dict_drop_index_tree(
 		return(false);
 	}
 
-	mlog_write_ulint(const_cast<byte*>(ptr), FIL_NULL, MLOG_4BYTES, mtr);
+	compile_time_assert(FIL_NULL == 0xffffffff);
+	mlog_memset(ptr, 4, 0xff, mtr);
 
 	ptr = rec_get_nth_field_old(
 		rec, DICT_FLD__SYS_INDEXES__SPACE, &len);