xfs deadlock in stable kernel 3.0.4

[Stefan Priebe - Profihost AG]

Hi,

at least i'm now able to reproduce the issue. I hope this will help to 
investigate the issue and hopefully you can reproduce it as well.

I'm using vanilla 3.0.4 kernel + xfs as root filesystem and had detect 
hanging taks with 120s set. You'll then see that the bonnie++ command 
get's stuck in xlog_grant_log_space while creating or deleting files. I 
was using a SSD or a fast Raid 10 (24x SAS Disks) - i was not able to 
reproduce it on normal SATA disks even a 20x SATA Raid 10 didn't work.

I used bonnie++ (V 1.96) to reproduce it. Mostly in the 1st run the bug 
is triggered - sometimes I needed two runs.

bonnie++ -u root -s 0 -n 1024:32768:0:1024:4096 -d /

I hope that helps - as i now have a testing machine and can trigger the 
bug pretty fast (10-30min instead of hours). I can also add debug code 
if you want or have one.

Stefan