[PATCH] file_ra_state_init speedup

Marcelo points out that this function's main caller already memsets the
structure, so avoid doing it again.

Also, an earlier knfsd patch withdrew file_ra_state_init()'s other caller, so
unexport this function.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

mm/readahead.c

@@ -28,16 +28,15 @@ struct backing_dev_info default_backing_dev_info = {
 EXPORT_SYMBOL_GPL(default_backing_dev_info);
 
 /*
- * Initialise a struct file's readahead state
+ * Initialise a struct file's readahead state.  Assumes that the caller has
+ * memset *ra to zero.
  */
 void
 file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping)
 {
-	memset(ra, 0, sizeof(*ra));
 	ra->ra_pages = mapping->backing_dev_info->ra_pages;
 	ra->average = ra->ra_pages / 2;
 }
-EXPORT_SYMBOL(file_ra_state_init);
 
 /*
  * Return max readahead size for this inode in number-of-pages.