Re: [PATCH v2 1/3] brd: protect page with rcu

[Yu Kuai <yukuai1@xxxxxxxxxxxxxxx>]

Hi,

在 2025/04/28 20:52, Christoph Hellwig 写道:
> On Sun, Apr 27, 2025 at 04:39:23PM +0800, Yu Kuai wrote:
> >   	page = brd_lookup_page(brd, sector);
> >   
> >   	kaddr = bvec_kmap_local(&bv);
> >   	if (op_is_write(opf)) {
> > -		BUG_ON(!page);
> > -		memcpy_to_page(page, offset, kaddr, bv.bv_len);
> > +		if (page)
> > +			memcpy_to_page(page, offset, kaddr, bv.bv_len);
>
> This could use a comment on why page can be NULL here.
OK

> >   	} else if (page) {
> >   		memcpy_from_page(kaddr, page, offset, bv.bv_len);
> >   	} else {
> >   		memset(kaddr, 0, bv.bv_len);
>
> And why the above change my if/else cascade doesn't really make much sense
> any more and this should become:
>
> 	} else {
> 		if (page)
> 	 		memcpy_from_page(kaddr, page, offset, bv.bv_len);
> 		else
> 	 		memset(kaddr, 0, bv.bv_len);
>   	}
OK, I will send a new version soon.

Thanks for the review!
Kuai

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