[linux-cifs-client] CIFS mounted share: scandir returns incomplete list

[Sam Liddicott]

* Hervé Fache wrote, On 01/09/08 08:43:
> In my case there are 677 files in the DOS file name format in that
> directory...
I think the problem shows up when more than once SMB packet is used to
contain the responses, it may occur on a smaller number of files,
depending on the negotiated max-xmit.
>
> Could you let me know how to log packets for this machine ('abrolhos')
> and protocol? I could leave the backup server logging all the time
> until the problem happens again and send you the relevant log when it
> does then...
something like: tcpdump -n -i eth0 -w dump.pcap -s 1500 port 445

but if you can run wireshark directly on the machine, or a machine on
that switch segment  you can use a capture filter like:
host SERVER.IP and port 445

Once you have a capture you can open it with wireshark and use a display
filter:
smb and (smb.trans2.cmd == 0x1 or smb.trans2.cmd == 0x2)

and then export the filtered packets.

>
> Also, isn't there a way maybe to send the number of entries as read on
> the CIFS server so we can at least detect the inconsistency? Or does
> it break the protocol?
The number of returned entries is part of the response in the first
nttrans response packet.
Somehow the re-combined nttrans response isn't correctly read; wireshark
doesn't seem to manage to properly re-constitute nttrans responses either.

Sam
>
> Hervé
>
> 2008/8/31 Sam Liddicott <sam at liddicott.com <mailto:sam at liddicott.com>>
>
>     I've noticed similar behavior on samba4 with vfs-cifs. By
>     modifying the request to reduce the number of entries that
>     find-first or find-next require I can make the problem "go away".
>
>     I think the problem is related to the encoding or decoding of
>     multi-part nttrans requests.
>
>     I believe that Stefan Metzemacher is aware of alignment issues in
>     the packing of large nttrans responses; your experience suggest a
>     problem also in unpacking large response.
>
>     I've been to busy to follow this up, having to make do with the
>     workaround I mention, but hope to spend time on it the latter part
>     of this week.
>
>     However if you bring it up on irc when I'm online (samjam) and
>     metze (I can't really speak for him) we may get somewhere. If you
>     have some packet dumps that can be put through wireshark it may help.
>
>     The problem occurs for me when there are more than a thousand
>     longish filenames in a directory.
>
>     sam
>
>     ------------------------------------------------------------------------
>     From: Hervé Fache <Herve at lucidia.net <mailto:Herve at lucidia.net>>
>     Sent: 31 August 2008 13:51
>     To: linux-cifs-client at lists.samba.org
>     <mailto:linux-cifs-client at lists.samba.org>
>     Subject: [linux-cifs-client] CIFS mounted share: scandir returns
>     incomplete list
>
>
>     Hello there,
>
>     I have a backup system on my Linux server which mounts shares to
>     back them up. To backup Windows shares, I use the CIFS mount type.
>
>     Every so often (hadn't happened in a few weeks until today),
>     scandir returns an incomplete list of contents, without any error
>     code being returned. Also, errno is not set. The problem happens
>     on a machine connected via WiFi (Intel 2200BG).
>
>     If you have any clues or if I can turn on some debug to track the
>     issue, please let me know.
>
>     Also, if you have ideas on how I could work around this issue, all
>     ideas are welcome!
>     Hervé
>
>

-------------- next part --------------
HTML attachment scrubbed and removed