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: <f12973bcf533a40ca7d7ed78846a0a10@manguebit.com>
Date: Tue, 15 Apr 2025 15:28:14 -0300
From: Paulo Alcantara <pc@...guebit.com>
To: Nicolas Baranger <nicolas.baranger@....fr>
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 Nicolas,

Sorry for the delay as I've got busy with some downstream work.

Nicolas Baranger <nicolas.baranger@....fr> writes:

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

I'm fully recovered now, thanks :-)

> 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

Thanks for the trace.  I was finally able to reproduce your issue and
will provide you with a fix soon.