Re: [PATCH v9 5/8] fsdax: Add dax_iomap_cow_copy() for dax_iomap_zero

[Shiyang Ruan]

On 2021/9/16 14:16, Christoph Hellwig wrote:
> On Wed, Sep 15, 2021 at 06:44:58PM +0800, Shiyang Ruan wrote:
> > +	rc = dax_direct_access(iomap->dax_dev, pgoff, 1, &kaddr, NULL);
> > +	if (rc < 0)
> > +		goto out;
> > +	memset(kaddr + offset, 0, size);
> > +	if (srcmap->addr != IOMAP_HOLE && srcmap->addr != iomap->addr) {
>
> Should we also check that ->dax_dev for iomap and srcmap are different
> first to deal with case of file system with multiple devices?

I have not thought of this case.  Isn't it possible to CoW between 
different devices?


--
Thanks,
Ruan

> Otherwise looks good:
>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>