[dm-devel] [RFC PATCH v2] dm mpath: add a queue_if_no_path timeout

[Frank Mayhar]

On Thu, 2013-10-31 at 14:31 +0000, Alasdair G Kergon wrote:
> On Thu, Oct 31, 2013 at 07:16:51AM -0700, Frank Mayhar wrote:
> > Unfortunately the clones don't appear to be associated with a request
> > queue; they're just put on multipath's internal queue.
> 
> (And also remember to test table swap/push back.)

That brings up something I wanted to ask.  I've dug through the code and
this particular thing isn't clear to me.  So how does it handle the
queued I/Os when switching tables?  I see nothing in the table_load()
path that would deal with this.  I'm guessing that the requests are
pushed back to the block layer and are later resubmitted and requeued on
the new multipath queue, but I don't see how that works.

Code references would be very welcome.
-- 
Frank Mayhar
310-460-4042