samba - Mar 2002 - Regarding killing an application that still has file opened on a smbfs mount.

Hi,

I have a question regarding killing an app that still holds on to a file in 
a smbfs mount.

When I do that, I get this message on the console:

smb_get_length: recv error = 512
smb_request: result -512 setting invalid
smb_retry: successful, new pid = xxxx, generation=xxx

The above message is repeated.

I'm using the kernel from redhat 7.1 kernel version 2.4.2(ac).

What do these messages mean? Is this the correct behaviour for the smbfs? 
Need to know because I'm running a stackable fs on top of smbfs, and trying 
to see how to handle this situation.

When this happens the non-root user cannot do much (ls, smbumount etc..).
But if this mountpoint is mounted by root, then she can just "umount"
the
mountpoint.

For a non-root user who is doing the mount through smbmount (suid), she can 
kill the smbmount process that is running in the background. BTW why is it 
that the smbmount program is running in the background (can see from a ps)?

Thank you in advance.

Louis Lam







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On Wed, 27 Mar 2002, Louis Lam wrote:
> When I do that, I get this message on the console:
> 
> smb_get_length: recv error = 512
> smb_request: result -512 setting invalid
smbfs was trying to read a response and was waiting for the length of the
SMB to be returned. If the server disappears you may end up with a process 
that will sleep for a long time.

This interruption is returned by the network layer as -512 (-ERESTARTSYS).
This event is logged because it is believed to be an error.
> smb_retry: successful, new pid = xxxx, generation=xxx
When there is a network error smbfs closes the tcp socket and signals
smbmount. smbmount is sleeping, when it gets a signal it reconnects to the
server and passes the socket to smbfs.

> I'm using the kernel from redhat 7.1 kernel version 2.4.2(ac).
I think smbfs in the RH7.1 kernel has some stability problems. Any reason
not to use the updated kernel rpm?
> What do these messages mean? Is this the correct behaviour for the smbfs? 
Yes, they are normal when killing the process.

> When this happens the non-root user cannot do much (ls, smbumount etc..).
> But if this mountpoint is mounted by root, then she can just
"umount" the
> mountpoint.
After the successful "retry" the mount should be working again. But
for
you it isn't?

> For a non-root user who is doing the mount through smbmount (suid), she can
> kill the smbmount process that is running in the background. BTW why is it 
> that the smbmount program is running in the background (can see from a ps)?
Killing the smbmount process is bad. It runs as a daemon and reconnects
when asked to. If it disappears smbfs may send it's wakeup signal to some
innocent process (the smbfs-smbmount relationship has a few flaws ...)

/Urban

>
>After the successful "retry" the mount should be working again.
But for
>you it isn't?
>
It seems that after the retry, the mount is still not working (e.g.user 
cannot go and do "ls" on the mountpoint).

What else can cause this to happen?

Initially we had to keep the configuration of Redhat 7.1 due to some 
application that we've developed that worked on redhat 7.1 only. But
I'll
try it on later versions of smbfs found in newer kernel releases.

Thank you in advance,
Louis Lam



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Hi,

ok, here is the way to reproduce the problem.

1. Do smbmount a share from the server.

2. "vi" a file(or some other program that holds on to a file on the
share)

3. kill the vi application(simulating non-graceful exit)
>Does it block?
If I try to "ls" that mountpoint or even try to smbumount, the process
will
block.
>Does it cause more errors?
If you mean getting more of these messages:
smb_get_length: recv error = 512
smb_request: result -512 setting invalid
smb_retry: successful, new pid = xxxx, generation=xxx

These messages are repeated continuously.

>There should be a connection between localhost and port 139 on the server.
>If you look at it with netstat it should be ESTABLISHED.
Indeed there was, when I do a netstat, I get the following:

On the client:

Proto Recv-Q Send-Q Local Address     Foreign Address      State
----- ------ ------ -------------     ---------------      ------
tcp   0      0      10.20.30.16:1025  kitchen:netbios-ssn  ESTABLISHED

On the Server:

Proto Recv-Q Send-Q Local Address        Foreign Address      State
----- ------ ------ -------------        ---------------      ------
tcp   0      0      kitchen:netbios-ssn  10.20.30.16:1024   ESTABLISHED


I don't see anything about port 139 though. Is that the netbios-ssn?



Thank you in advance.

Louis Lam






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