Strange md/unionfs issue

[Gavin Atkinson]

On Sat, 10 Oct 2009, David Ehrmann wrote:

> I have a system running on a flash disk.  To prevent it from wearing out 
> quickly, I don't run with a swap and mount /tmp and /var from memory. 
> Because /var needs some directories and contains files I probably should save 
> from time to time, I mount it from flash, mount /var to /var_real so I can 
> access the underlying files, and then I mount an md device on top of /var as 
> a unionfs.  Initially, it seems to work, but seconds later, the unionfs seems 
> to fail.

When the mount "fails", is it still shown in the output of mount(1)?

It appears that this problem is the same as is reported in PR kern/131441, 
which has so far not had any activity.  It appears that this bug has 
existed since at least 7.1-RELEASE.

I've included Goto-san in the CC-list, as he may be able to see if this is 
a bug in unionfs or in nullfs.

Thanks,

Gavin