Re: [dm-devel] [PATCH] fix default IO restrictions

[Christophe Saout <christophe saout de>]

Am Mo, den 26.01.2004 schrieb Mike Christie um 22:22:

> > I don't think that will happen. The values are already the allowed
> > maximum values. Or am I wrong?
> 
> I don't think they are the max values. SCSI will override them depending 
> on the HBA settings.

Hmm. Then I think there is something wrong anyway. Why are the max
constants not maximum values...

> > If the table isn't backed by a real device (like if it only contains an
> > error target) the resulting queue will use those "unrealstic" values
> > that exceed the system-wide limits. And a hardsect size of 0 bytes...
> 
> If you do not have a device, should you set sane IO restrictions in the 
> target accroding to your target implementation limits.

Interestingly the code that sets these defaults limits isn't very old.
It was a simplified version of my combine_default_restrictions function
that did what you are proposing. See the dm-devel archices around
November 2003.

The default limits were all zero before (the min_not_zero function took
care of everything) so if you think this is wrong I suggest that we
should either look into why the maximum values are not maximum values or
that we just revert the io_restrictions patch.