Re: [dm-devel] [RFC][PATCH] Simplify dm_get_device restriction combining

[Mike Christie <mikenc us ibm com>]

Joe Thornber wrote:

> On Tue, Jan 20, 2004 at 08:32:44PM +0100, Christophe Saout wrote:
>
> > To use blk_queue_stack_limits dm would have to associate a request queue
> > with a table and swap it around too. I don't know if this is possible.
> > dm doesn't use most of the fields in the request_queue struct.
>
>
> This would be the wrong thing.

Right having the queue in the table would not work.

In the constructor the target calls dm_get_device on it's devices and 
combines the io restrictions for them. Then dm_table_add_target calls 
combine_restrictions_low to combine the newly added targets restrictions.

So, it looked like instead of combining the restrictions when you build 
the table you could defer it until you bind. dm_table_set_restrictions 
could just loop through its list of devices combining all the 
restrictions then.

Mike