[dm-devel] [PATCH][RFC] dm: Do not open log and cow device read-write for read-only mappings

[Alasdair G Kergon]

On Mon, Feb 14, 2011 at 03:09:40PM +0100, Tejun Heo wrote:
> But if the underlying device is marked ro, dm shouldn't update it at
> all.  The device should be opened ro and ro policy should be enforced.

Indeed, but dm isn't tracking this today because it didn't need to up-to
now.

I can think of a few scenarios where dm can have the underlying device open
read-write when it only needs read-only.   (E.g. we track and cater for
read-only->read-write transitions but not the opposite and don't propagate
changes through the stack.)

We'll do an audit...
 
Alasdair