samba - Aug 2025 - delayed mtime updates: configurable?

On Sun, 27 Jul 2025 18:45:17 +0200 hede via samba <samba at
lists.samba.org> wrote:
> Hi,
> 
> SMB 2.1 and up seems to have a delayed mtime update. If writing to a file
on the client, the modification time (mtime) for this file gets updated some
time after closing. Typically ~1 second after closing the file.
It's a feature, not a bug. Somehow. 

It's the deferred close feature implementation within cifs.ko which delays
the mtime update. With "closetimeo=0" the problem is gone.

Yet, the deferred close itself is not the problem here. It's the deferred
mtime update which is of harm here, which (by effect) is prevented with
disabling deferred close.

So my "feature request" would be to immediately update the mtime on
close, even if deferring the close operation itself. But I do not know if that
is reasonable.

thanks
hede

...adding linux-cifs to the loop...

On 8/1/25 11:35 AM, hede via samba wrote:
> On Sun, 27 Jul 2025 18:45:17 +0200 hede via samba
> <samba at lists.samba.org> wrote:
> 
>> Hi,
>> 
>> SMB 2.1 and up seems to have a delayed mtime update. If writing to
>> a file on the client, the modification time (mtime) for this file
>> gets updated some time after closing. Typically ~1 second after
>> closing the file.
> 
> It's a feature, not a bug. Somehow.
> 
> It's the deferred close feature implementation within cifs.ko which
> delays the mtime update. With "closetimeo=0" the problem is gone.
no idea what the client is doing here, but from a server perspective, 
with current Samba, the write will *immediately* update the mtime on 
disk and report this updated value whenever it is queried. When the 
handle is closed, the server doesn't update the mtime.

A network trace will tell you the truth about what's going on.

Cheers!
-slow

-- 
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