[PATCH 05/15] block: add a max_user_discard_sectors queue limit

[Christoph Hellwig]

On Wed, Jan 24, 2024 at 08:44:16AM -0700, Keith Busch wrote:
> > > > +		min_not_zero(q->limits.max_hw_discard_sectors,
> > > > +			     q->limits.max_user_discard_sectors);
> > > 
> > > Shouldn't writing 0 disable discards?
> > 
> > I mirror the max_user_sectors behavior here, where 0 disables the
> > user limiting.  But yes, that would be a behavior change.
> 
> But a user should be able to disable discards, right? Unless you really
> want to match max_user_sectors, I think you could default the user
> setting here to UINT_MAX and use "min" instead of "min_not_zero".

Not a fan of having different semantics for the different attributes,
but given that we've had this or 9 years we better stick to it, so
I'll change it.