[GFS2] Export file_ra_state_init

Export file_ra_state_init so that its possible to use the already
exported functions which require a struct ra_state as an argument
from a module.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/mm/readahead.c b/mm/readahead.c
index 8d6eeaa..9f0b982 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -38,6 +38,7 @@
 	ra->ra_pages = mapping->backing_dev_info->ra_pages;
 	ra->prev_page = -1;
 }
+EXPORT_SYMBOL_GPL(file_ra_state_init);
 
 /*
  * Return max readahead size for this inode in number-of-pages.