[dm-devel] [PATCH v4 10/20] libmultipath: indicate wwid failure in dm_addmap_create()

[Martin Wilck]

On Thu, 2018-04-12 at 16:32 -0500, Benjamin Marzinski wrote:
> On Thu, Apr 12, 2018 at 10:22:19PM +0200, Martin Wilck wrote:
> > 
> > But I suppose I'm still missing your point.
> 
> Any failure in ev_add_path() before the call to domap() could cause
> multipath device creation to fail, without triggering this. For
> instance
> add_map_with_path() or setup_map() can fail for a host of reasons.

OK, got it, finally. The semantics of my failed marker were intended to
be exactly what they are now: we tried DM_DEVICE_CREATE for this WWID,
and failed. Other semantics are certainly possible, but much harder to
define cleanly.

I believe that catches a large portion of the real-world failures. And
in many cases, this failure means that one or more devices are busy.
(Oh, it could also mean that we tried to set 'hwhandler "1 alua"' for a
device that doesn't support ALUA, but I digress ;-)

Martin

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