[Pkg-samba-maint] Bug#408001: umount.cifs: mtab locking needs improvement

[Radu Cristescu]

Package: smbfs
Version: 3.0.23d-4
Severity: important

The mtab locking code gives up too easily. If it can't obtain the lock
it just bails out without retrying, sometimes resulting in a dirty mtab
with the mount entry still there.

This causes autofs to think that the mount is still active and it
doesn't try to mount the autofs entry again when accessed.

I looked in the source code for umount (package: mount) and umount.cifs
(package: smbfs) for how each does the mtab locking. umount tries to get
the lock for a few seconds before giving up. umount.cifs just gives up.
So, if there are two umount processes running and one of them is
umount.cifs, and they both need to update mtab, umount.cifs will leave
its mtab entry there because it wasn't patient enough when trying to get
the lock.

I don't have a patch right now, but if nobody takes action by the end of
the week I may do one. It's probably just copy/pasting from umount into
umount.cifs with a few changes.

The relevant functions in umount.cifs source code:
File: source/client/umount.cifs.c
Functions: lock_mtab, unlock_mtab

The relevant functions in umount source code:
File: mount/fstab.c
Functions: lock_mtab, unlock_mtab

The other functions seem to do their jobs right so far.

-- System Information:
Debian Release: 4.0
  APT prefers testing
  APT policy: (990, 'testing'), (50, 'unstable'), (1, 'experimental')
Architecture: i386 (i686)
Shell:  /bin/sh linked to /bin/bash
Kernel: Linux 2.6.18-3-k7
Locale: LANG=en_US, LC_CTYPE=en_US (charmap=ANSI_X3.4-1968)

Versions of packages smbfs depends on:
ii  libc6    2.3.6.ds1-8                     GNU C Library: Shared libraries
ii  libcomer 1.39+1.40-WIP-2006.11.14+dfsg-1 common error description 
library
ii  libkrb53 1.4.4-6                         MIT Kerberos runtime libraries
ii  libldap2 2.1.30-13.2                     OpenLDAP libraries
ii  netbase  4.28                            Basic TCP/IP networking system
ii  samba-co 3.0.23d-4                       Samba common files used by 
both th

smbfs recommends no packages.

-- no debconf information