Bug #14676249 : ROW_VERS_IMPL_X_LOCKED_LOW() MIGHT HIT !BPAGE->FILE_PAGE_WAS_FREED ASSERTION

 trx_undo_prev_version_build() should confirm existence of inherited (not-own) external pages.

Bug #14676084 : ROW_UNDO_MOD_UPD_DEL_SEC() DOESN'T NEED UNDO_ROW AND UNDO_EXT INITIALIZED
 mtr script could hit the assertion error !bpage->file_page_was_freed using this path.
 So, also fixed

rb://1337 approved by Marko Makela.

storage/innobase/row/row0umod.c

@@ -519,6 +519,7 @@ row_undo_mod_upd_del_sec(
 	ulint		err	= DB_SUCCESS;
 
 	ut_ad(node->rec_type == TRX_UNDO_UPD_DEL_REC);
+	ut_ad(!node->undo_row);
 	heap = mem_heap_create(1024);
 
 	while (node->index != NULL) {
@@ -580,6 +581,8 @@ row_undo_mod_del_mark_sec(
 	dict_index_t*	index;
 	ulint		err;
 
+	ut_ad(!node->undo_row);
+
 	heap = mem_heap_create(1024);
 
 	while (node->index != NULL) {

storage/innobase/row/row0undo.c

@@ -216,7 +216,7 @@ row_undo_search_clust_to_pcur(
 
 		node->row = row_build(ROW_COPY_DATA, clust_index, rec,
 				      offsets, NULL, ext, node->heap);
-		if (node->update) {
+		if (node->rec_type == TRX_UNDO_UPD_EXIST_REC) {
 			node->undo_row = dtuple_copy(node->row, node->heap);
 			row_upd_replace(node->undo_row, &node->undo_ext,
 					clust_index, node->update, node->heap);

storage/innobase/srv/srv0srv.c

@@ -58,6 +58,8 @@ Created 10/8/1995 Heikki Tuuri
 *******************************************************/
 
 /* Dummy comment */
+#include "m_string.h" /* for my_sys.h */
+#include "my_sys.h" /* DEBUG_SYNC_C */
 #include "srv0srv.h"
 
 #include "ut0mem.h"
@@ -1571,6 +1573,10 @@ srv_suspend_mysql_thread(
 
 	trx = thr_get_trx(thr);
 
+	if (trx->mysql_thd != 0) {
+		DEBUG_SYNC_C("srv_suspend_mysql_thread_enter");
+	}
+
 	os_event_set(srv_lock_timeout_thread_event);
 
 	mutex_enter(&kernel_mutex);

storage/innobase/trx/trx0rec.c

@@ -1634,6 +1634,25 @@ trx_undo_prev_version_build(
 	if (row_upd_changes_field_size_or_external(index, offsets, update)) {
 		ulint	n_ext;
 
+		/* We should confirm the existence of disowned external data,
+		if the previous version record is delete marked. If the trx_id
+		of the previous record is seen by purge view, we should treat
+		it as missing history, because the disowned external data
+		might be purged already.
+
+		The inherited external data (BLOBs) can be freed (purged)
+		after trx_id was committed, provided that no view was started
+		before trx_id. If the purge view can see the committed
+		delete-marked record by trx_id, no transactions need to access
+		the BLOB. */
+
+		if ((update->info_bits & REC_INFO_DELETED_FLAG)
+		    && read_view_sees_trx_id(purge_sys->view, trx_id)) {
+			/* treat as a fresh insert, not to
+			cause assertion error at the caller. */
+			return(DB_SUCCESS);
+		}
+
 		/* We have to set the appropriate extern storage bits in the
 		old version of the record: the extern bits in rec for those
 		fields that update does NOT update, as well as the bits for