[Pkg-samba-maint] Bug#856463: Bug#856463: cifs-utils: Accessing files with length of 1067 bytes extremly slow

[Stephan Gampert | GIP]

Hello Mathieu,

thank you very much for your answer.

Unfortunately we need the symlinks, so removing the mfsymlinks option is 
not really an option for us.

We've already tried to use jessy. We had the same problem there.
We will test it with Debian stretch.

  > It is because the complete file is parsed whien its size is 1067 bytes.
....
  > However, the slowness is probably coming from the server side.

I've attached a wireshark trace of a "slow read". 10.0.9.149 is the
Debian-client, 10.0.21.11 is the Windows Server.

As you can see, all seems ok from package 1-25. The file is read once
(FID 0x009a) and is closed. I presume this is the parse for the symlink.

The next 4 packets seem strange for me. It looks like the Debian client
opens the file again 2 times in parallel (FID:0xc0f5 and FID 0x0017) and
the Server is sending a lock request back to the Debian-client (which is
not answered by the way).

Do you expect the Debian-client to open the file again 2 times in parallel?

Best regards

Stephan



Am 08.03.2017 um 17:34 schrieb Mathieu Parent:
> "Control: severity -1 wishlist
> Control: tag -1 upstream
>
> 2017-03-01 10:54 GMT+01:00 Stephan Gampert | GIP <stephan.gampert at gip.com>:
>> Subject: cifs-utils: Accessing files with length of 1067 bytes extremly slow
> [...]
>> we are using cifs-utils to access  Microsoft Windows 2012R2 File-Server
>> shares from Debian-workstations.
>>
>> The windows shares are mounted using fstab:
>> //fileserver/firstname.lastname  /home/firstname.lastname cifs
>> uid=firstname.lastname,gid=users,file_mode=0700,dir_mode=0700,users,user=firstname.lastname,domain=DOMAINNAME,mfsymlinks,noauto,sec=krb5
>> 0  0
>
>
>
>> Accessing some of the files is extremly slow (about 3-20 seconds):
>
> [...]
>> All of the "slow files" have a length of 1067 bytes.
>> As far as I know this is also the length of symlink files. Perhaps there is
>> a problem with symlink handling.
>
> It is because the complete file is parsed whien its size is 1067 bytes.
>
> See https://wiki.samba.org/index.php/UNIX_Extensions#Minshall.2BFrench_symlinks
> for more info.
>
> If you don't need symlink emulation, remove the "mfsymlinks" option.
>
> Otherwise, You should test with Debian jessie and Debian stretch.
> However, the slowness is probably coming from the server side.
>
> Regards
>

-- 
Stephan Gampert
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