Re: [PATCH] NFS: Fix "BUG at fs/aio.c:554!"

[Nick Piggin <npiggin@gmail.com>]

On Thu, Jan 20, 2011 at 10:49 AM, Trond Myklebust
<Trond.Myklebust@netapp.com> wrote:
> On Thu, 2011-01-20 at 10:37 +1100, Nick Piggin wrote:
>> On Thu, Jan 20, 2011 at 10:31 AM, Trond Myklebust
>> <Trond.Myklebust@netapp.com> wrote:
>> > On Thu, 2011-01-20 at 10:26 +1100, Nick Piggin wrote:
>> >> On Thu, Jan 20, 2011 at 10:25 AM, Trond Myklebust
>>
>> >> > Also, why is EIO the correct reply when no bytes were read/written? Why
>> >> > shouldn't the VFS aio code be able to cope with a zero byte reply?
>> >>
>> >> What would it do?
>> >
>> > Just return that zero byte reply to userland.
>> >
>> > zero bytes is a valid reply for ordinary read() and write(), so why
>> > should we have to do anything different for aio_read()/aio_write()?
>>
>> It doesn't give userspace much to do. zero reply from read means
>> EOF. Zero reply from write is pretty useless, I don't think we do it
>> in the buffered write path -- we either ensure we write at least
>> something or have a meaningful error to return.
>
> zero reply from read means EOF _or_ user supplied a zero length buffer.
>
> zero reply from write may also be useless, but it is a valid value. It
> can simply mean the user supplied a zero length buffer.

OK, yes. I'm ignoring zero length request.