# Re: \[PATCH v2 15/26\] block: Add bio\_copy\_data()

- From: Tejun Heo \<tj@kernel.org\>
- Date: 2012-09-21 00:09:54 
- List: linux-bcache
- Page: https://ratatoskr.run/linux-bcache/2012/09/3926574
- Thread: https://ratatoskr.run/linux-bcache/2012/09/3920950/t.md

```text
On Thu, Sep 20, 2012 at 05:06:32PM -0700, Tejun Heo wrote:
> Hello,
> 
> On Mon, Sep 10, 2012 at 05:22:26PM -0700, Kent Overstreet wrote:
> > +void bio_copy_data(struct bio *dst, struct bio *src)
> > +{
> ...
> > +		src_p = kmap_atomic(src_bv->bv_page);
> > +		dst_p = kmap_atomic(dst_bv->bv_page);
> > +
> > +		memcpy(dst_p + dst_bv->bv_offset,
> > +		       src_p + src_bv->bv_offset,
> > +		       bytes);
> > +
> > +		kunmap_atomic(dst_p);
> > +		kunmap_atomic(src_p);
> 
> Wrap these in preempt_disable/enable() to allow the function to be
> called from any context?

Ooh, and maybe return the amount of copied data?

-- 
tejun
```