[GFS2] Use vmalloc() in dir code

When allocating memory to sort directory entries, use vmalloc()
rather than kmalloc() since for larger directories, the required
size can easily be graeter than the 128k maximum of kmalloc().

Also adding the first steps towards getting the AOP_TRUNCATED_PAGE
return code get in the glock code by flagging all places where we
request a glock and we are holding a page lock.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/incore.h

@@ -156,7 +156,7 @@ struct gfs2_holder {
 	struct gfs2_glock *gh_gl;
 	struct task_struct *gh_owner;
 	unsigned int gh_state;
-	int gh_flags;
+	unsigned gh_flags;
 
 	int gh_error;
 	unsigned long gh_iflags;