MDEV-15529 IMPORT TABLESPACE unnecessarily uses the doublewrite buffer

fil_space_t::atomic_write_supported: Always set this flag for
TEMPORARY TABLESPACE and during IMPORT TABLESPACE. The page
writes during these operations are by definition not crash-safe
because they are not written to the redo log.

fil_space_t::use_doublewrite(): Determine if doublewrite should
be used.

buf_dblwr_update(): Add assertions, and let the caller check whether
doublewrite buffering is desired.

buf_flush_write_block_low(): Disable the doublewrite buffer for
the temporary tablespace and for IMPORT TABLESPACE.

fil_space_set_imported(), fil_node_open_file(), fil_space_create():
Initialize or revise the space->atomic_write_supported flag.

buf_page_io_complete(), buf_flush_write_complete(): Add the parameter
dblwr, to indicate whether doublewrite was used for writes.

buf_dblwr_sync_datafiles(): Remove an unnecessary flush of
persistent tablespaces when flushing temporary tablespaces.
(Move the call to buf_dblwr_flush_buffered_writes().)

3 files changed, 18 insertions, 12 deletions

diff --git a/storage/innobase/include/buf0buf.h b/storage/innobase/include/buf0buf.h
index 063eb6b6fab..1001f2ca807 100644
--- a/storage/innobase/include/buf0buf.h
+++ b/storage/innobase/include/buf0buf.h
@@ -1,7 +1,7 @@
 /*****************************************************************************
 
 Copyright (c) 1995, 2016, Oracle and/or its affiliates. All Rights Reserved.
-Copyright (c) 2013, 2017, MariaDB Corporation.
+Copyright (c) 2013, 2018, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -1271,9 +1271,9 @@ buf_page_init_for_read(
 	bool			unzip);
 
 /** Complete a read or write request of a file page to or from the buffer pool.
-@param[in,out]		bpage		Page to complete
-@param[in]		evict		whether or not to evict the page
-					from LRU list.
+@param[in,out]	bpage	page to complete
+@param[in]	dblwr	whether the doublewrite buffer was used (on write)
+@param[in]	evict	whether or not to evict the page from LRU list
 @return whether the operation succeeded
 @retval	DB_SUCCESS		always when writing, or if a read page was OK
 @retval	DB_PAGE_CORRUPTED	if the checksum fails on a page read
@@ -1282,7 +1282,7 @@ buf_page_init_for_read(
 				not match */
 UNIV_INTERN
 dberr_t
-buf_page_io_complete(buf_page_t* bpage, bool evict = false)
+buf_page_io_complete(buf_page_t* bpage, bool dblwr = false, bool evict = false)
 	MY_ATTRIBUTE((nonnull));
 
 /********************************************************************//**
diff --git a/storage/innobase/include/buf0flu.h b/storage/innobase/include/buf0flu.h
index ccf1d991b09..c3b518c4295 100644
--- a/storage/innobase/include/buf0flu.h
+++ b/storage/innobase/include/buf0flu.h
@@ -70,12 +70,10 @@ buf_flush_relocate_on_flush_list(
 /*=============================*/
 	buf_page_t*	bpage,	/*!< in/out: control block being moved */
 	buf_page_t*	dpage);	/*!< in/out: destination block */
-/********************************************************************//**
-Updates the flush system data structures when a write is completed. */
-void
-buf_flush_write_complete(
-/*=====================*/
-	buf_page_t*	bpage);	/*!< in: pointer to the block in question */
+/** Update the flush system data structures when a write is completed.
+@param[in,out]	bpage	flushed page
+@param[in]	dblwr	whether the doublewrite buffer was used */
+void buf_flush_write_complete(buf_page_t* bpage, bool dblwr);
 /** Initialize a page for writing to the tablespace.
 @param[in]	block		buffer block; NULL if bypassing the buffer pool
 @param[in,out]	page		page frame
diff --git a/storage/innobase/include/fil0fil.h b/storage/innobase/include/fil0fil.h
index c2152ce11d0..249755f1ff6 100644
--- a/storage/innobase/include/fil0fil.h
+++ b/storage/innobase/include/fil0fil.h
@@ -36,9 +36,10 @@ Created 10/25/1995 Heikki Tuuri
 #include "ibuf0types.h"
 
 #include <list>
-#include <vector>
 
 // Forward declaration
+extern ibool srv_use_doublewrite_buf;
+extern struct buf_dblwr_t* buf_dblwr;
 struct trx_t;
 class page_id_t;
 class truncate_t;
@@ -200,6 +201,13 @@ struct fil_space_t {
 	{
 		return stop_new_ops || is_being_truncated;
 	}
+
+	/** @return whether doublewrite buffering is needed */
+	bool use_doublewrite() const
+	{
+		return !atomic_write_supported
+			&& srv_use_doublewrite_buf && buf_dblwr;
+	}
 };
 
 /** Value of fil_space_t::magic_n */