[dm-devel] [PATCH 4/5] dax, iomap: Start using dax native zero_page_range()

[Vivek Goyal]

On Wed, Feb 05, 2020 at 10:33:56AM -0800, Christoph Hellwig wrote:
> On Mon, Feb 03, 2020 at 03:00:28PM -0500, Vivek Goyal wrote:
> > +	id = dax_read_lock();
> > +	rc = dax_zero_page_range(dax_dev, pgoff, offset, size);
> > +	dax_read_unlock(id);
> > +	return rc;
> 
> Is there a good reason not to move the locking into dax_zero_page_range?

Thinking more about it. If we keep locking outside, then we don't have
to take lock again when we recurse into dax_zero_page_range() in device
mapper path. IIUC, just taking lock once at top level is enough. If that's
the case then it probably is better to keep locking outside of
dax_zero_page_range().

Thanks
Vivek