[PATCH] XFS writeout fix

[XFS] Check that a page has dirty buffers before finding it acceptable for
rewrite clustering.  This prevents writing excessive amounts of clean data
when doing random rewrites of a cached file.
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

fs/xfs/linux-2.6/xfs_aops.c

@@ -616,7 +616,7 @@ xfs_is_delayed_page(
 				acceptable = (type == IOMAP_UNWRITTEN);
 			else if (buffer_delay(bh))
 				acceptable = (type == IOMAP_DELAY);
-			else if (buffer_mapped(bh))
+			else if (buffer_dirty(bh) && buffer_mapped(bh))
 				acceptable = (type == 0);
 			else
 				break;