Apple has a bug in credit handling with their smbfs, it seems :-)

[Jeremy Allison]

On Wed, Jan 23, 2019 at 09:16:31PM +0100, Stefan Metzmacher wrote:
> Am 23.01.19 um 20:44 schrieb Jeremy Allison via samba-technical:
> > On Mon, Jan 21, 2019 at 07:22:48PM -0800, Richard Sharpe via samba-technical wrote:
> >> Hi folks,
> >>
> >> Apple has a bug in their handling of credits when Samba returns
> >> STATUS_PENDING for a SESSION SETUP request.
> >>
> >> Such responses only seem to occur when the Samba server is under heavy load.
> >>
> >> Samba issues one credit in such cases, and, as per the spec issues
> >> zero credits in the final successful response to the SESSION SETUP.
> >>
> >> The Mac then issues a TREE CREATE, consuming one credit and getting one credit.
> >>
> >> The Mac then issues a compound CREATE and CLOSE. This is a protocol
> >> violation and Samba drops the connection.
> >>
> >> I have communicated this issue to Apple, but I also created the
> >> attached patch to mitigate the issue while Apple thinks about fixing
> >> their code.
> >>
> >> Is it worth doing this? Is it going to work?
> > 
> > So this is sending credits on the SESSION SETUP
> > interim reply, and then also on the final SESSION SETUP
> > reply, yeah ?
> > 
> > Have you tested this against the Apple client ?
> > 
> > It's really ugly and a protocol violation :-).
> > 
> > How often does this problem occur ? If it did
> > go in it'd have to be configured off by default
> > but I'm not convinced yet :-).
> 
> I'd propose to skip the STATUS_PENDING using
> smb2_request_set_async_internal() and leave the credit handling as is.

Trouble with that is the client may then timeout.