Merge lp:~laurynas-biveinis/percona-server/bug1227581-5.5 into lp:percona-server/5.5

[Laurynas Biveinis]

BT 37223

Backport the bug 1227581 fix from 5.6:

The issue is that buf_LRU_free_page() may perform a flush list
relocation for a dirty zip page, making it possible to observe a page
in BUF_BLOCK_REMOVE_HASH state on the flush list between
buf_LRU_block_remove_hashed() and buf_flush_relocate_on_flush_list()
calls, if another thread reads flush list pages without the LRU list
mutex.

Places where a thread iterates through the flush list without the LRU
list mutex and does not expect to see a BUF_BLOCK_REMOVE_HASH page are
buf_flush_page_and_try_neighbors() and
buf_get_latched_pages_number_instance(). The fix is to accept such
pages there:
- in buf_flush_page_and_try_neighbors() do not attempt to flush such
  page.
- in buf_get_latched_pages_number_instance(), silently accept such
  page as BUF_BLOCK_FILE_PAGE.

http://jenkins.percona.com/job/percona-server-5.5-param/897/

I have reviewed the 5.5 code BUF_BLOCK_REMOVE_HASH/buf_page_in_file() uses, and haven't found any new places to fix to what was fixed in 5.6. So this MP is an "automerge" of the 5.6 fix with the bits in new-in-5.6 code dropped, thus I'm submitting it as an G2.

[George Ormond Lorch III (gl-az)]

review: Approve (g2)

[Stewart Smith (stewart)]

review: Approve

=== modified file 'Percona-Server/storage/innobase/buf/buf0buf.c'
--- Percona-Server/storage/innobase/buf/buf0buf.c	2013-10-23 08:23:08 +0000
+++ Percona-Server/storage/innobase/buf/buf0buf.c	2013-11-27 13:06:35 +0000
@@ -4754,12 +4754,16 @@
 		case BUF_BLOCK_FILE_PAGE:
 			/* uncompressed page */
 			break;
+		case BUF_BLOCK_REMOVE_HASH:
+			/* We hold flush list but not LRU list mutex here.
+			Thus encountering BUF_BLOCK_REMOVE_HASH pages is
+			possible.  */
+			break;
 		case BUF_BLOCK_ZIP_FREE:
 		case BUF_BLOCK_ZIP_PAGE:
 		case BUF_BLOCK_NOT_USED:
 		case BUF_BLOCK_READY_FOR_USE:
 		case BUF_BLOCK_MEMORY:
-		case BUF_BLOCK_REMOVE_HASH:
 			ut_error;
 			break;
 		}

=== modified file 'Percona-Server/storage/innobase/buf/buf0flu.c'
--- Percona-Server/storage/innobase/buf/buf0flu.c	2013-10-23 08:23:08 +0000
+++ Percona-Server/storage/innobase/buf/buf0flu.c	2013-11-27 13:06:35 +0000
@@ -1605,6 +1605,16 @@
 		ut_ad(block_mutex);
 	}
 
+	if (UNIV_UNLIKELY(buf_page_get_state(bpage)
+			  == BUF_BLOCK_REMOVE_HASH)) {
+
+		/* In case we don't hold the LRU list mutex, we may see a page
+		that is about to be relocated on the flush list.  Do not
+		attempt to flush it.  */
+		ut_ad(flush_type == BUF_FLUSH_LIST);
+		return (flushed);
+	}
+
 	ut_a(buf_page_in_file(bpage));
 
 	if (buf_flush_ready_for_flush(bpage, flush_type)) {