linux-kernel - Re: [netfs/cifs - Linux 6.14] loop on file cat + file copy when files are on CIFS share

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Message-ID: <5087f9cb3dc1487423de34725352f57c@3xo.fr>
Date: Thu, 10 Apr 2025 10:43:49 +0200
From: Nicolas Baranger <nicolas.baranger@....fr>
To: Paulo Alcantara <pc@...guebit.com>
Cc: Christoph Hellwig <hch@...radead.org>, hch@....de, David Howells
 <dhowells@...hat.com>, netfs@...ts.linux.dev, linux-cifs@...r.kernel.org,
 linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, Steve French
 <smfrench@...il.com>, Jeff Layton <jlayton@...nel.org>, Christian Brauner
 <brauner@...nel.org>
Subject: Re: [netfs/cifs - Linux 6.14] loop on file cat + file copy when files
 are on CIFS share

Hi Paulo

Thanks for answer and help

> I'll look into it as soon as I recover from my illness.
Hope you're doing better

I had to rollback to linux 6.13.8 to be able to use the SMB share and 
here is what I constat
(don't know if it's a normal behavior but if yes, SMB seems to be a very 
very unefficient protocol)

I think the issue can be buffer related:
On Linux 6.13.8 the copy and cat of the 5 bytes 'toto' file containing 
only ascii string 'toto' is working fine but here is what I capture with 
tcpdump during transfert of toto file:
https://xba.soartist.net/t6.pcap
131 tcp packets to transfer a 5 byte file...
Isn't there a problem ?
Openning the pcap file with wireshark show a lot of lines:
25	0.005576	10.0.10.100	10.0.10.25	SMB2	1071	Read Response, Error: 
STATUS_END_OF_FILE
It seems that those lines appears after the 5 bytes 'toto' file had been 
transferred, and it continue until the last ACK recieved

I will try to reboot on Linux 6.14.0 mainline to see if I have the same 
behavior or to see what I get in the packet capture
(system is in production, I cannot reboot on a failing kernel when I 
want, it should be organised... sorry)

Let me know if you reproduced the issue

Kind regards
Nicolas Baranger



Le 2025-04-04 15:54, Paulo Alcantara a écrit :

> Hi Nicolas,
> 
> I'll look into it as soon as I recover from my illness.  Sorry for the 
> delay.
> 
> On 4 April 2025 08:50:27 UTC, Nicolas Baranger 
> <nicolas.baranger@....fr> wrote: Hi Christoph
> 
> Thanks for answer and help
> Did someone reproduced the issue (very easy) ?
> 
> CIFS SHARE is mounted as /mnt/fbx/FBX-24T
> echo toto >/mnt/fbx/FBX-24T/toto
> 
> ls -l /mnt/fbx/FBX-24T/toto
> -rw-rw-rw- 1 root root 5 20 mars  09:20 /mnt/fbx/FBX-24T/toto
> 
> cat /mnt/fbx/FBX-24T/toto
> toto
> toto
> toto
> toto
> toto
> toto
> toto
> ^C
> 
> CIFS mount options:
> grep cifs /proc/mounts
> //10.0.10.100/FBX24T /mnt/fbx/FBX-24T cifs 
> rw,nosuid,nodev,noexec,relatime,vers=3.1.1,cache=none,upcall_target=app,username=fbx,domain=HOMELAN,uid=0,noforceuid,gid=0,noforcegid,addr=10.0.10.100,file_mode=0666,dir_mode=0755,iocharset=utf8,soft,nounix,serverino,mapposix,mfsymlinks,reparse=nfs,nativesocket,symlink=mfsymlinks,rsize=65536,wsize=65536,bsize=16777216,retrans=1,echo_interval=60,actimeo=1,closetimeo=1 
> 0 0
> 
> KERNEL: uname -a
> Linux 14RV-SERVER.14rv.lan 6.14.0-rc2-amd64 #0 SMP PREEMPT_DYNAMIC Wed 
> Feb 12 18:23:00 CET 2025 x86_64 GNU/Linux
> 
> Kind regards
> Nicolas Baranger
> 
> Le 2025-03-28 11:45, Christoph Hellwig a écrit :
> 
> Hi Nicolas,
> 
> please wait a bit, many file system developers where at a conference
> this week.