[dm-devel] dm: introduce a DM_ENFORCE_OPEN_COUNT flag.

[Mike Snitzer]

On Wed, Feb 02 2022 at  9:42P -0500,
Christoph Hellwig <hch at infradead.org> wrote:

> Withmy block hat on: nak to this.  No block driver has any business at
> all rejecting "too many openers".  In fact any opener but the first of
> a partition is already not counted as an opener, and I plan to complete
> hide the open count from the device driver.

I agree that this proposal exposes controls to userspace that simply
shouldn't be meaningful given the arbitrary nature of openers.  And
preventing openers can result in a race where systemd or some other
service opens before the intended primary consumer of the device.

Seriously brittle and even if finely tuned to have a suitable value
for some niche usecase like android: an absolute hack.

Sorry, not interested in taking this.