[dm-devel] [RFC PATCH v3] dm mpath: add a queue_if_no_path timeout

[Mike Snitzer]

On Wed, Nov 06 2013 at 10:43am -0500,
Frank Mayhar <fmayhar at google.com> wrote:

> On Wed, 2013-11-06 at 07:54 +0100, Hannes Reinecke wrote:
> > On 11/05/2013 05:02 PM, Frank Mayhar wrote:
> > > This is the patch submitted by Jun'ichi Nomura, originally based on
> > > Mike's patch with some small changes by me.  Jun'ichi's description
> > > follows, along with my changes:
> > > 
> > > On Tue, 2013-11-05 at 07:18 -0800, Frank Mayhar wrote:
> > >> On Fri, 2013-11-01 at 04:17 +0000, Junichi Nomura wrote:
> > >>> I slightly modified the patch:
> > >>>   - fixed the timeout handler to correctly find
> > >>>     clone request and "struct multipath"
> > >>>   - the timeout handler just disables "queue_if_no_path"
> > >>>     instead of killing the request directly
> > >>>   - "dmsetup status" to show the parameter
> > >>>   - changed an interface between dm core and target
> > >>>   - added some debugging printk (you can remove them)
> > >>> and checked the timeout occurs, at least.
> > >>>
> > >>> I'm not sure if this feature is good or not though.
> > >>> (The timer behavior is not intuitive, I think)
> > >> Thanks!  I integrated your new patch and tested it.  Sure enough, it
> > >> seems to work.  I've made a few tweaks (added a module tunable and
> > >> support for setting the timer in multipath_message(), removed your debug
> > >> printks) and will submit the modified patch for discussion shortly.
> > > 
> > > Comments?
> > > 
> > Yeah. Seems to be my eternal fate; initiating fixes and not getting
> > mentioned at all.
> > Sigh.
> > 
> > I dimly remember having sent the original patch for the blk timeout
> > function ... hence a short notice would've been nice.
> 
> Sorry, I did ding you early on (and I think Mike dinged you as well),
> but you were apparently busy with other things at the time.

Hi Frank,

I wouldn't worry about this.  You didn't even supply a patch header.. so
it isn't like Hannes was obviously left out.  Fact is this patch has had
4 iterations, the first of which from Hannes didn't compile or even make
sense.  Anyway, he'll get attribution through Suggested-by unless he
wins the race to produces the first upstream-worthy variant of this line
of work.

So far it has all been RFC-style patches.. your most recent one that
builds on Jun'ichi's patch with a module param and timeout default:  We
generally don't add module params to targets (but I can appreciate why
you might want that.. just not seeing the need).  And having a message
to change the timeout conflicts with my desire to conditionally
establish a timed_out method only if a timeout was specified (like my
last reply in this thread suggested).

Mike