Re: [PATCH] hugetlbfs read() support

[Nick Piggin]

Nishanth Aravamudan wrote:
> On 19.07.2007 [09:58:50 -0700], Andrew Morton wrote:
>
> > On Thu, 19 Jul 2007 08:51:49 -0700 Badari Pulavarty <pbadari@xxxxxxxxxx> 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..
> >
> >
> > > All I want is a simple read() to get my oprofile working.  Please
> > > advise.
> >
> > Did you consider changing oprofile userspace to read the executable
> > with mmap?
>
>
> It's not actually oprofile's code, though, it's libbfd (used by
> oprofile). And it works fine (presumably) for other binaries.

So... what's the problem with changing it? The fact that it is a
library doesn't really make a difference except that you'll also
help everyone else who links with it.

It won't break backwards compatibility, and it will work on older
kernels...

--
SUSE Labs, Novell Inc.
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