Bug#695492: [wheezy] Ctrl-C on program accessing CIFS mount breaks/hangs mount

[Jonathan Nieder <jrnieder@gmail.com>]

Hi John,

John Darrah wrote:

> When using a program like 'find' or 'cp' in an operation involving a CIFS mounted network
> location and then typing a Ctrl-C to terminate it will cause -all- CIFS mount points to
> become unusable. To fix this, you just unmount them and then re-mount again. This is repeatable
> as often as I choose.

That's beautiful.  Thanks for a clear report.

Can you say a little more about the server hosting this share (Windows
Server or samba?  What version?  etc).

>                       I might also note this behaviour has been around since I ran 2.6 series.

If you remember which version introduced it, that could help in
tracking this down.  (In other words, what are the newest working and
oldest non-working versions you've tried?)

[...]
> CIFS VFS: Unexpected lookup error -512
> CIFS VFS: No task to wake, unknown frame received! NumMids 0
> Received Data is: : dump of 37 bytes of data at 0xffff8800449f9c40
>  23000000 424d53ff 000022a4 c00580c0 . . . # <FF> S M B <A4> " . . <C0> . . <C0>
>  5bd80000 8faa367c 00000618 34d42803 . . <D8> [ | 6 <AA> . . . . . . ( <D4> 4
>  dfbb0800 da000000 . . <BB> <DF> .
> CIFS VFS: Unexpected SMB signature
> CIFS VFS: Unexpected SMB signature
[...]

There has been work on the upstream CIFS driver recently, including
making that message more precise.  Could you try 3.6.y from
experimental and let us know how it goes?

If it's fixed, the next step will be to try to find which patch fixed
it and apply the same to wheezy.  If it's broken, we can take this
upstream.  So either result is progress.

Hope that helps,
Jonathan