On Fri, May 03, 2013 at 04:37:41PM -0400, Chris Mason wrote:
> Quoting Josef Bacik (2013-05-03 16:33:44)
> > On Mon, Apr 29, 2013 at 07:38:01AM -0600, David Sterba wrote:
> > > After commit a65917156e34594 ("Btrfs: stop using highmem for
> > > extent_buffers") we don't need to call kmap_atomic anymore and can
> > > reduce the move_pages helper to a simple memmove.
> > >
> > > There's only one caller of memcpy_extent_buffer, we can use the
> > > memmove_ variant here.
> > >
> >
> > This makes -l 64k blow the hell up, just try generic/001. I'm kicking this
> > patch out. Thanks,
>
> Sorry Dave, I only now remember having this same problem the last time I
> tried to get rid of memcpy.
The patch evolved from a minor cleanup inside copy_page into a
functional change that looked ok to me after checking that memmove
behaves like memcpy if it's safe (both generic and arch-specific
implementations). Well, apparently not, but I still see some space for
micro-optimizations around copy_pages/move_pages.
david
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