[dm-devel] [PATCH ] multipath: Fall back to getuid_callout if ID_SERIAL attribute is missing.

[Merla, ShivaKrishna]

> -----Original Message-----
> From: Hannes Reinecke [mailto:hare at suse.de]
> Sent: Wednesday, June 18, 2014 1:18 AM
> To: Merla, ShivaKrishna; christophe.varoqui at opensvc.com
> Cc: dm-devel at redhat.com
> Subject: Re: [PATCH ] multipath: Fall back to getuid_callout if ID_SERIAL
> attribute is missing.
> 
> On 06/18/2014 02:17 AM, Merla, ShivaKrishna wrote:
> >   Sometimes whenever a path is added, scsi_id call during udev rule
> processing
> >   can fail and ID_SERIAL attribute will not be set. This causes multipathd to
> add
> >   the path as orphan. We have seen several instances of this happening
> during
> >   testing.
> >
> >        Jun 17 10:14:43 ictm-vader multipathd[474]: sda: uid_attribute =
> ID_SERIAL (config file default)
> >        Jun 17 10:14:43 ictm-vader multipathd[474]: sda: no ID_SERIAL attribute
> >        Jun 17 10:14:43 ictm-vader multipathd[474]: sda: uid = <empty> (udev)
> >        Jun 17 10:14:43 ictm-vader multipathd[474]: sda: no ID_SERIAL attribute
> >        Jun 17 10:14:43 ictm-vader multipathd[474]: sda: uid = <empty> (udev)
> >        Jun 17 10:14:43 ictm-vader multipathd[474]: sda: failed to get path uid
> >        Jun 17 10:14:43 ictm-vader multipathd[474]: sda: orphan path, failed to
> add path
> >
> >   This patch handles this case by allowing to fall back to explict
> getuid_callout
> >   incase if ID_SERIAL attribute is not set. This way support for deprecated
> >   getuid_callout is not lost for older versions where ID_SERIAL attribute is
> not
> >   present but also serves good purpose in the scenario mentioned above.
> >
> > Signed-off-by: Shiva Krishna Merla<shivakrishna.merla at netapp.com>
> 
> Hmm. I have a similar patch in my tree. Will be checking.
>
Hannes, did you get a chance to verify this?. We are seeing many scenarios
where scsi_id call can fail during udev processing and path will not be added
to map until scsi_id is successful on future udev change events. Falling back to 
getuid_callout will solve this particular problem.