Re: [PATCH V10 07/19] btrfs: use bvec_last_segment to get bio's last page

Ming Lei
2018-11-19T08:09:27Z

On Fri, Nov 16, 2018 at 02:37:10PM +0100, Christoph Hellwig wrote:
> On Thu, Nov 15, 2018 at 04:52:54PM +0800, Ming Lei wrote:
> > index 2955a4ea2fa8..161e14b8b180 100644
> > --- a/fs/btrfs/compression.c
> > +++ b/fs/btrfs/compression.c
> > @@ -400,8 +400,11 @@ blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
> > static u64 bio_end_offset(struct bio *bio)
> > {
> > struct bio_vec *last = bio_last_bvec_all(bio);
> > + struct bio_vec bv;
> >
> > - return page_offset(last->bv_page) + last->bv_len + last->bv_offset;
> > + bvec_last_segment(last, &bv);
> > +
> > + return page_offset(bv.bv_page) + bv.bv_len + bv.bv_offset;
>
> I don't think we need this. If last is a multi-page bvec bv_offset
> will already contain the correct offset from the first page.

Yeah, it is true for this specific case, looks we can drop this patch.

thanks,
Ming