Re: [PATCH v4 09/11] libmultipath: retain_attached_hw_handler obsolete with 4.3+

[Martin Wilck <mwilck@suse.com>]

On Fri, 2017-06-23 at 19:25 +0200, Xose Vazquez Perez wrote:
> On 06/22/2017 04:59 PM, Martin Wilck wrote:
> 
> > Kernels 4.3 and newer (commit 1bab0de0 "dm-mpath, scsi_dh: don't
> > let dm detach device handlers") imply "retain_attached_hw_handler
> > yes".
> > 
> > Clarify this in the propsel code, log messages, and documentation.
> > 
> > Signed-off-by: Martin Wilck <mwilck@suse.com>
> > Reviewed-by: Hannes Reinecke <hare@suse.com>
> > ---
> >  libmultipath/configure.c   |  3 ++-
> >  libmultipath/dmparser.c    |  3 ++-
> >  libmultipath/propsel.c     |  7 ++++++-
> >  libmultipath/util.c        | 36
> > ++++++++++++++++++++++++++++++++++++
> >  libmultipath/util.h        |  2 ++
> >  multipath/multipath.conf.5 | 15 +++++++++++----
> >  6 files changed, 59 insertions(+), 7 deletions(-)
> 
> [...]
> > --- a/libmultipath/propsel.c
> > +++ b/libmultipath/propsel.c
> > @@ -628,7 +628,12 @@ int select_retain_hwhandler(struct config
> > *conf, struct multipath *mp)
> >  
> >  	if (!VERSION_GE(conf->version, minv_dm_retain)) {
> >  		mp->retain_hwhandler = RETAIN_HWHANDLER_OFF;
> > -		origin = "(setting: WARNING, requires kernel
> > version >= 1.5.0)";
> > +		origin = "(setting: WARNING, requires kernel dm-
> > mpath version >= 1.5.0)";
> 
> It would be more informative replace the dm-mpath version with the
> kernel version. No one cares about subsystems versions.

I disagree. This code should also work for vendor kernels which may
e.g. contain patches to update dm-mpath without updating the main
kernel (utsname) version.

The reason I used get_linux_version_code() for the new check my patch
introduced was that unfortunately, the dm-mpath version has not been
changed when the "retain_attached_hwhandler" feature was removed in
4.3. The next dm-mpath version change (to 1.10) happened in 4.4.
Thus I couldn't use the dm-mpath version and had to fallback to
utsname.

Thinking about it, the new check should probably be (dm_mpath version
>= 1.10 OR kernel verson >= 4.3). IMO that can be handled in an
incremental patch.

Regards,
Martin

-- 
Dr. Martin Wilck <mwilck@suse.com>, Tel. +49 (0)911 74053 2107
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)

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