Re: dm table: Reject unconfigured device

[Milan Broz <mbroz@redhat.com>]

On 03/29/2011 08:22 PM, Mike Snitzer wrote:
> 
> Part of me was thinking it best to check this, and error out, as early
> as possible (e.g. in drivers/md/dm-table.c:open_dev()).  But I like the
> additional info that is naturally provided in device_area_is_invalid().

Another option is change loop device by assigning request
fn early (it will reject IO if unbounded, once configured it
has request fn defined forever).

But then you get lot of errors instead of crash on access, like
Buffer I/O error on device dm-0, logical block 0

So rejecting unconfigured device use this way seems to me
like better idea.
(If there is no request function, how DM can map it?)

Milan