Re: [PATCH 2/10] seperate max sectors and max hw sectors

[Mike Christie <michaelc@cs.wisc.edu>]

Jens Axboe wrote:
> On Tue, Nov 08 2005, Mike Christie wrote:
> 
>>Seperate max_hw_sectors and max_sectors.
>>
>>LLDs call blk_queue_max_hw_sectors() to set max_hw_sectors.
>>blk_queue_max_sectors will also set max_sectors to a safe
>>default value.
>>
>>blk_init_queue still calls blk_queue_max_sectors so if there
>>are any LLDs that do not call blk_queue_max_hw_sectors() and
>>were expecting both the max_sectors and max_hw_sectors to be
>>255 they do not have to do anything.
>>
>>I was not able to test every driver I touched, but I think the
>>only place I may have messed up is MD so some testing is needed.
> 
> 
> ->max_sectors will become less of a driver property and more of a
> block/vm propery, so I think the best way to do this is just to have
> blk_queue_max_sectors() set ->max_hw_sectors directly and lower
> ->max_sectors appropriately if it is lower. That also comes with the
> bonus of not having to modify drivers.
> 

Ugggh. I did this in reverse to make the naming nicer. So I added a 
blk_queue_max_hw_sectors() which sets ->max_sectors to some Block layer 
default and ->max_hw_sectors to the hw limit (for SCSI this is the scsi 
host template ->max_sectors). Is this ok? It is more clear for driver 
writers that they are setting max_hw_sectors when calling 
blk_queue_max_hw_sectors(). I also converted all the 
blk_queue_max_sectors() to blk_queue_max_hw_sectors().