Re: [PATCH] gnttab: propagate Reserved flag from old to new page in gnttab_copy_grant_page.

[Ian Campbell <Ian.Campbell@citrix.com>]

On Tue, 2010-02-23 at 17:04 +0000, Jan Beulich wrote:
> >>> Ian Campbell <ian.campbell@citrix.com> 23.02.10 17:40 >>>
> >--- a/drivers/xen/grant-table.c
> >+++ b/drivers/xen/grant-table.c
> >@@ -558,9 +558,12 @@ int gnttab_copy_grant_page(grant_ref_t ref, struct page **pagep)
> > 	new_page->mapping = page->mapping;
> > 	new_page->index = page->index;
> > 	set_bit(PG_foreign, &new_page->flags);
> >+	if (PageReserved(page))
> >+		set_bit(PG_reserved, &new_page->flags);
> 
> Why not SetPageReserved()?

I was just following the pattern above with PG_foreign. I guess that is
subtly different since either mapping or index (I forget which) would
need to be the second argument to SetPageForeign (probably an accessor
is required for that dtor field).

This function is grubbing around at a low level with many of the struct
page fields -- I guess doing it this way makes it a little more obvious
that something subtle is going on but I'm not fussed about changing it.

I'll follow up with something which fixes this up for both reserved and
foreign.

Ian.