[dm-devel] Why is device mapper unable to remove a mapped device which is open?

[Alasdair G Kergon]

On Fri, Sep 22, 2006 at 04:26:16PM -0400, goggin, edward wrote:
> Why shouldn't the kernel's reference counting for the
> mapped device's md structure account for properly 
> handling the de-allocation of the md structure upon
> the last close in this case?

This behaviour has flipped a couple of times during the
development.

It would be fine if devices could never be suspended.
You can't close a suspended device you've written to
until it gets resumed.  If you've removed it you can't
resume it because it has gone.

It's similar in a way to how the kernel used to (at least I assume someone
fixed it?) let you unlink a swap file and then it was impossible to
'swapoff' because you couldn't reference the device any more.
 
Alasdair
-- 
agk at redhat.com