From 9c9c247da187c13464780fb8f5770f6bfdb5f9cd Mon Sep 17 00:00:00 2001
From: Alexey Kopytov <akopytov@gmail.com>
Date: Thu, 29 Jun 2017 11:19:09 +0300
Subject: [PATCH] Bug #86865: InnoDB does unnecessary work when extending a
 tablespace

Do not call fil_write_zeros() in fil_space_extend() if posix_fallocate()
is available and was successful.
---
 storage/innobase/fil/fil0fil.cc | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/storage/innobase/fil/fil0fil.cc b/storage/innobase/fil/fil0fil.cc
index 943eeabc178..f4c6d519225 100644
--- a/storage/innobase/fil/fil0fil.cc
+++ b/storage/innobase/fil/fil0fil.cc
@@ -5056,6 +5056,7 @@ fil_space_extend(
 
 		os_offset_t     len;
 		dberr_t		err = DB_SUCCESS;
+		bool		need_write_zeros = !node->atomic_write;
 
 		len = ((node->size + n_node_extend) * page_size) - node_start;
 		ut_ad(len > 0);
@@ -5081,11 +5082,16 @@ fil_space_extend(
 				" numbers are described at " REFMAN
 				" operating-system-error-codes.html";
 
-			err = DB_IO_ERROR;
+			need_write_zeros = true;
+		} else {
+			/* Physically writing zeroes is redundant if
+			posix_fallocate() successfully extended the
+			tablespace */
+			need_write_zeros = false;
 		}
 #endif /* NO_FALLOCATE || !UNIV_LINUX */
 
-		if (!node->atomic_write || err == DB_IO_ERROR) {
+		if (need_write_zeros) {
 
 			bool	read_only_mode;