Re: [PATCH] hugetlbfs read() support

Badari Pulavarty
2007-07-20T21:13:41Z

On Fri, 2007-07-20 at 14:29 +1000, Nick Piggin wrote:
> Andrew Morton wrote:
> > On Thu, 19 Jul 2007 08:51:49 -0700 Badari Pulavarty <pbadari@us.ibm.com> wrote:
> >
> >
> >>>>+ }
> >>>>+
> >>>>+ offset += ret;
> >>>>+ retval += ret;
> >>>>+ len -= ret;
> >>>>+ index += offset >> HPAGE_SHIFT;
> >>>>+ offset &= ~HPAGE_MASK;
> >>>>+
> >>>>+ page_cache_release(page);
> >>>>+ if (ret == nr && len)
> >>>>+ continue;
> >>>>+ goto out;
> >>>>+ }
> >>>>+out:
> >>>>+ return retval;
> >>>>+}
> >>>
> >>>This code doesn't have all the ghastly tricks which we deploy to handle
> >>>concurrent truncate.
> >>
> >>Do I need to ? Baaahh!! I don't want to deal with them.
> >
> >
> > Nick, can you think of any serious consequences of a read/truncate race in
> > there? I can't..
>
> As it doesn't allow writes, then I _think_ it should be OK. If you
> ever did want to add write(2) support, then you would have transient
> zeroes problems.

I have no plans to add write() support - unless there is real reason
for doing so.

>
> But why not just hold i_mutex around the whole thing just to be safe?

Yeah. I can do that, just to be safe for future..

Thanks,
Badari