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().
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