[dm-devel] [RFC][PATCH] Simplify dm_get_device restriction combining
Mike Christie
mikenc at us.ibm.com
Tue Jan 20 15:52:01 UTC 2004
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
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