[dm-devel] [PATCH] add endio fn to request structures

[Mike Christie]

Jens,

Some storage devices have a mode where they require a special
command be sent inorder to perform failover. IBM's fastt is one of
these devices we are trying to add support for using the dm-multipath
framework.

The problem is that dm works at the bio level and we need to send down
something like a block pc or special request. So from dm multipath we could
have a thread and do a blk_execute_rq, or if we had some sort of end_request
function similar to the bio's and bh's endio function we could send the
failover command asynchronously. The attached patch adds an end_request fn
to the request structure for this purpose.

Maybe the fact that I have to ask for such a change should indidcate that
I am doing something brain dead, in which case please be gentle in your review
of my patch :)


-- 
Mike Christie
mikenc at us.ibm.com
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