Bug#16405422 - RECOVERY FAILURE, ASSERT !RECV_NO_LOG_WRITE

eliminate a race condition over recv_sys->n_addrs which might result in a database corruption
in recovery, without reporting a recovery error.

recv_recover_page_func(): move the code segment that decrements recv_sys->n_addrs
  to the end of the function, after the call to mtr_commit()

rb://2282 approved by Inaam

storage/innobase/log/log0recv.c

@@ -1301,6 +1301,19 @@ recv_recover_page(
 		recv = UT_LIST_GET_NEXT(rec_list, recv);
 	}
 
+	if (!recover_backup && modification_to_page) {
+		ut_a(block);
+
+		buf_flush_recv_note_modification(block, start_lsn, end_lsn);
+	}
+
+	/* Make sure that committing mtr does not change the modification
+	lsn values of page */
+
+	mtr.modifications = FALSE;
+
+	mtr_commit(&mtr);
+
 	mutex_enter(&(recv_sys->mutex));
 
 	if (ut_dulint_cmp(recv_max_page_lsn, page_lsn) < 0) {
@@ -1314,18 +1327,6 @@ recv_recover_page(
 
 	mutex_exit(&(recv_sys->mutex));
 
-	if (!recover_backup && modification_to_page) {
-		ut_a(block);
-
-		buf_flush_recv_note_modification(block, start_lsn, end_lsn);
-	}
-
-	/* Make sure that committing mtr does not change the modification
-	lsn values of page */
-
-	mtr.modifications = FALSE;
-
-	mtr_commit(&mtr);
 }
 
 /***********************************************************************

storage/innodb_plugin/log/log0recv.c

@@ -1638,19 +1638,6 @@ recv_recover_page_func(
 	}
 #endif /* UNIV_ZIP_DEBUG */
 
-	mutex_enter(&(recv_sys->mutex));
-
-	if (recv_max_page_lsn < page_lsn) {
-		recv_max_page_lsn = page_lsn;
-	}
-
-	recv_addr->state = RECV_PROCESSED;
-
-	ut_a(recv_sys->n_addrs);
-	recv_sys->n_addrs--;
-
-	mutex_exit(&(recv_sys->mutex));
-
 #ifndef UNIV_HOTBACKUP
 	if (modification_to_page) {
 		ut_a(block);
@@ -1665,6 +1652,20 @@ recv_recover_page_func(
 	mtr.modifications = FALSE;
 
 	mtr_commit(&mtr);
+
+	mutex_enter(&(recv_sys->mutex));
+
+	if (recv_max_page_lsn < page_lsn) {
+		recv_max_page_lsn = page_lsn;
+	}
+
+	recv_addr->state = RECV_PROCESSED;
+
+	ut_a(recv_sys->n_addrs);
+	recv_sys->n_addrs--;
+
+	mutex_exit(&(recv_sys->mutex));
+
 }
 
 #ifndef UNIV_HOTBACKUP