Comment 3 for bug 303124

(sorry, mistake in the feedback to the system variables, fixed patch below)

In a nutshell, this patch allows the default log file size to be changed (in the compiled-in default, or my.cnf) for new installations, without breaking existing installations.

It does the following: if the iblogfiles already exist, and size differs from innodb_log_file_size, issue a warning but not abort; it'll also update the system variable with the actual log file size.

For an existing installation, the user can simply update the my.cnf with the actual file size to get rid of the warning, or do the procedure for changing the log file size.

=== modified file 'storage/xtradb/handler/ha_innodb.cc'
--- storage/xtradb/handler/ha_innodb.cc 2009-09-09 21:06:57 +0000
+++ storage/xtradb/handler/ha_innodb.cc 2009-10-14 03:40:05 +0000
@@ -2405,6 +2405,10 @@
  /* Get the current high water mark format. */
  innobase_file_format_check = (char*) trx_sys_file_format_max_get();

+ /* Get the current log file size. */
+ innobase_log_file_size = srv_log_file_size;
+ innobase_log_file_size *= UNIV_PAGE_SIZE;
+
  DBUG_RETURN(FALSE);
 error:
  DBUG_RETURN(TRUE);

=== modified file 'storage/xtradb/srv/srv0start.c'
--- storage/xtradb/srv/srv0start.c 2009-09-16 17:43:01 +0000
+++ storage/xtradb/srv/srv0start.c 2009-10-14 03:26:54 +0000
@@ -547,6 +547,21 @@
 }

 /*************************************************************************
+Calculates the number of database pages which are represented by the
+file size in bytes. */
+static
+ulint
+srv_calc_pages(
+/*============*/
+ /* out: file size in database pages */
+ ulint size, /* in: low 32 bits of file size in bytes */
+ ulint size_high) /* in: high 32 bits of file size in bytes */
+{
+ return((size >> UNIV_PAGE_SIZE_SHIFT)
+ | (size_high << (32 - UNIV_PAGE_SIZE_SHIFT));
+}
+
+/*************************************************************************
 Creates or opens the log files and closes them. */
 static
 ulint
@@ -623,7 +638,12 @@
     (ulong) srv_calc_high32(srv_log_file_size),
     (ulong) srv_calc_low32(srv_log_file_size));

- return(DB_ERROR);
+ if (log_file_has_been_opened) {
+
+ return(DB_ERROR);
+ }
+
+ srv_log_file_size = srv_calc_pages(size, size_high);
   }
  } else {
   *log_file_created = TRUE;