Why do my cifs mounted drives become inaccessable after a few hours?

Question

I mount several drives on my machine.

//selah-think/UbuntuShare   /home/selah/Shares/UbuntuShare  cifs exec,credentials=/etc/cifspw,uid=1000,dir_mode=0755,file_mode=0644 0 0
//server123/Groups/LearningLab  /home/selah/Shares/LearningLab  cifs nounix,exec,credentials=/etc/cifspw,uid=1000,dir_mode=0755,file_mode=0644 0 0

Almost without fail, after a couple hours and/or after my machine has gone idle, these drives become inaccessable. Any command I issue that references these drives (such as ls) hangs for several minutes and Ctr-C does nothing to stop the hang. The only way I've found to fix it is to restart my machine.

I notice when I look in my CIFS file several messages like this which I think may be related:

[22588.034488] CIFS VFS: Unexpected lookup error -112
[22598.026480] CIFS VFS: Unexpected lookup error -112
[22608.003788] CIFS VFS: Unexpected lookup error -112

I'm using Ubuntu 12.04. Previously I used Ubuntu 10.04 and did not have the same problem accessing these drives.

Also I'm using mount.cifs version: 5.1

Any help appreciated... thanks!

Solution

I believe this problem has something to do with this bug: https://lists.ubuntu.com/archives/foundations-bugs/2011-May/000610.html

My solution for the time being is to use /bin/ls instead of ls when I'm looking through my directories so that ls doesn't hang.

Also, if I sudo umount hungshare and sudo mount hungshare that fixes the problem for another 10 hours.