[PATCH] Fix XFS after clear_page_dirty() removal

XFS appears to call clear_page_dirty to get the mapping tree dirty tag
set correctly at the same time the page dirty flag is cleared.  I note
that this can be done by set_page_writeback() if we clear the dirty flag
on the page first when we are writing back the entire page.

Hence it seems to me that the XFS call to clear_page_dirty() could
easily be substituted by clear_page_dirty_for_io() followed by a call to
set_page_writeback() to get the mapping tree tags set correctly after
the page has been marked clean.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/xfs/linux-2.6/xfs_aops.c

@@ -341,9 +341,9 @@ xfs_start_page_writeback(
 {
 	ASSERT(PageLocked(page));
 	ASSERT(!PageWriteback(page));
-	set_page_writeback(page);
 	if (clear_dirty)
-		clear_page_dirty(page);
+		clear_page_dirty_for_io(page);
+	set_page_writeback(page);
 	unlock_page(page);
 	if (!buffers) {
 		end_page_writeback(page);