Merge remote-tracking branch 'origin/5.5' into 10.0

Author: cvicentiu

mysys/mf_iocache.c

@@ -258,7 +258,7 @@ int init_io_cache(IO_CACHE *info, File file, size_t cachesize,
   else
   {
     /* Clear mutex so that safe_mutex will notice that it's not initialized */
-    bzero((char*) &info->append_buffer_lock, sizeof(info));
+    bzero((char*) &info->append_buffer_lock, sizeof(info->append_buffer_lock));
   }
 #endif
 

sql/sql_cache.cc

@@ -2539,6 +2539,7 @@ void Query_cache::init()
   */
   if (global_system_variables.query_cache_type == 0)
   {
+    m_cache_status= DISABLE_REQUEST;
     free_cache();
     m_cache_status= DISABLED;
   }

sql/sql_update.cc

@@ -689,6 +689,8 @@ int mysql_update(THD *thd,
       if (reinit_io_cache(&tempfile,READ_CACHE,0L,0,0))
 	error=1; /* purecov: inspected */
       select->file=tempfile;			// Read row ptrs from this file
+      // select->file was copied, update self-references.
+      setup_io_cache(&select->file);
       if (error >= 0)
 	goto err;
     }