Re: [PATCH v7 3/8] fsdax: Replace mmap entry in case of CoW

[Shiyang Ruan]

On 2021/8/27 13:00, Dan Williams wrote:
> On Thu, Aug 26, 2021 at 8:22 PM Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx> wrote:
> > On 2021/8/23 20:57, Christoph Hellwig wrote:
> > > On Thu, Aug 19, 2021 at 03:54:01PM -0700, Dan Williams wrote:
> > > > static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf,
> > > >                                 const struct iomap_iter *iter, void
> > > > *entry, pfn_t pfn,
> > > >                                 unsigned long flags)
> > > >
> > > >
> > > > >    {
> > > > > +       struct address_space *mapping = vmf->vma->vm_file->f_mapping;
> > > > >           void *new_entry = dax_make_entry(pfn, flags);
> > > > > +       bool dirty = insert_flags & DAX_IF_DIRTY;
> > > > > +       bool cow = insert_flags & DAX_IF_COW;
> > > >
> > > > ...and then calculate these flags from the source data. I'm just
> > > > reacting to "yet more flags".
> > >
> > > Except for the overly long line above that seems like a good idea.
> > > The iomap_iter didn't exist for most of the time this patch has been
> > > around.
> >
> > So should I reuse the iter->flags to pass the insert_flags? (left shift
> > it to higher bits)
>
> No, the advice is to just pass the @iter to dax_insert_entry directly
> and calculate @dirty and @cow internally.

I see.  Yes, they can be calculated inside the dax_insert_entry() 
because it already has enough arguments.


--
Thanks,
Ruan.