[sisyphus] smbfs locking in 2.4.20

["Grigory Batalov" <grisxa@mail.ru>]

 Bart Oldeman из Dosemu Team обнаружил, что в ядре 2.4.20
отсутствует блокировка файлов на smbfs. Скорее всего,
он тестировал "чистое" ядро или от Алана Кокса.

 А как обстоят дела в нашем 2.4.20-alt2/altX ?
Если у нас есть walkaround, нельзя ли его присоветовать
коллегам из Dosemu ?


Begin forwarded message:

Date: Mon, 10 Feb 2003 16:28:18 -0500 (EST)
From: Bart Oldeman <oldeman@math.ohio-state.edu>
To: Gregor Ibic <gregor.ibic@intelicom.si>
Subject: WARNING: smbfs and locking (was RE: [PATCH] (locking) (was Re: dosemu and CLIPPER locks (again))))


On Mon, 10 Feb 2003, Gregor Ibic wrote:

> I cant, it is locked. It says resource deadlock avoided.

ok I browsed around a bit and looked at the kernel source, here's the real
answer.

Current (linux kernel 2.4.20) smbfs doesn't support locking at all.

you may look at
http://www.hojdpunkten.ac.se/054/samba
to see some experimental patches though.
NFS *does* support locking though.

So if you see locking "working" with smbfs it is actually by accident and
not by design.

This means that it is very well possible to corrupt your DOS databases
if you access them via smbfs, and there's nothing that DOSEMU can do about
it.

Now, why does a Win client access the file when DOSEMU "locks" it? This is
because there actually is no lock at all!

And the other way around, what happens is that: DOSEMU tries to apply a
lock to the file, the filesystem fails, and the DOS app hence claims that
access is denied.

Bart

-- 
 Grigory Batalov.