Merge lp:~akopytov/percona-xtrabackup/bug1055547-2.0 into lp:percona-xtrabackup/2.0

[Alexey Kopytov]

Bug #1055547: xtrabackup as SST fails when innodb_flush_method is
                  O_DIRECT

    XtraBackup sometimes calls os_file_read() / os_file_write() calls on the
    log file to read/update log file header. The problem was that those
    calls honor the innodb_flush_method value and thus may do O_DIRECT I/O,
    which has strict alignment rules on both I/O operations themselves and
    user-space buffers, i.e. they must be aligned on the filesystem block
    size. I/O operations could never become a problem, because we always
    read/write from/to the start of the file. However, user-space buffers
    used for those operations were aligned to LOG_FILE_HDR_SIZE (2048 bytes),
    which is not necessarily greater than the FS block size.

    Fixed by making sure buffers are aligned to UNIV_PAGE_SIZE_MAX (16
    KB). Which may be redundant, since it is unlikely that FS block sizes >
    4 KB are ever used or even supported. However, that constant is used to
    be on the safe side and similar to other buffers alignment.

http://jenkins.percona.com/view/XtraBackup/job/percona-xtrabackup-2.0-param/365/

[Sergei Glushchenko (sergei.glushchenko)]

Approve

review: Approve (g2)

=== modified file 'src/xtrabackup.cc'
--- src/xtrabackup.cc	2013-03-01 06:54:51 +0000
+++ src/xtrabackup.cc	2013-03-07 17:54:38 +0000
@@ -4652,9 +4652,9 @@
 	datafiles_iter_t *it;
 
 	log_hdr_buf_ = static_cast<byte *>
-		(ut_malloc(LOG_FILE_HDR_SIZE + OS_FILE_LOG_BLOCK_SIZE));
+		(ut_malloc(LOG_FILE_HDR_SIZE + UNIV_PAGE_SIZE_MAX));
 	log_hdr_buf = static_cast<byte *>
-		(ut_align(log_hdr_buf_, OS_FILE_LOG_BLOCK_SIZE));
+		(ut_align(log_hdr_buf_, UNIV_PAGE_SIZE_MAX));
 
 	/* get current checkpoint_lsn */
 	/* Look for the latest checkpoint from any of the log groups */
@@ -5588,9 +5588,9 @@
 		}
 
 		log_buf_ = static_cast<byte *>
-			(ut_malloc(LOG_FILE_HDR_SIZE * 2));
+			(ut_malloc(LOG_FILE_HDR_SIZE + UNIV_PAGE_SIZE_MAX));
 		log_buf = static_cast<byte *>
-			(ut_align(log_buf_, LOG_FILE_HDR_SIZE));
+			(ut_align(log_buf_, UNIV_PAGE_SIZE_MAX));
 
 		success = os_file_read(src_file, log_buf, 0, 0, LOG_FILE_HDR_SIZE);
 		if (!success) {
@@ -6514,8 +6514,9 @@
 
 	xb_file_set_nocache(src_file, src_path, "OPEN");
 
-	log_buf_ = static_cast<byte *>(ut_malloc(LOG_FILE_HDR_SIZE * 2));
-	log_buf = static_cast<byte *>(ut_align(log_buf_, LOG_FILE_HDR_SIZE));
+	log_buf_ = static_cast<byte *>(ut_malloc(LOG_FILE_HDR_SIZE +
+						 UNIV_PAGE_SIZE_MAX));
+	log_buf = static_cast<byte *>(ut_align(log_buf_, UNIV_PAGE_SIZE_MAX));
 
 	success = os_file_read(src_file, log_buf, 0, 0, LOG_FILE_HDR_SIZE);
 	if (!success) {