[dm-devel] Improve processing efficiency for addition and deletion of multipath devices

[Martin Wilck]

On Mon, 2016-11-28 at 12:46 -0600, Benjamin Marzinski wrote:
> On Thu, Nov 24, 2016 at 10:21:10AM +0100, Martin Wilck wrote:
> > 
> > from the udev db. Therefore IMO we just have to look at the last
> > received event for a given path:
> > 
> >  - DELETE => discard the device
> >  - ADD => use the udev properties coming with the event
> >  - CHANGE => query udev db for current set of properties
> 
> The issue is that when we get a change event, there may be udev
> environment variables that tell us what that specific event is for.
> For
> instance, a change in the Read-only status of the path device. Future
> change events will not have those environment variables set.

And the udev db will not have records of the environment variables of
previous change events? IOW, in your example, we can't derive the read-
only status of a device by looking at the current set of udev
properties of the device, only by tracking the full uevent history?

Regards
Martin

-- 
Dr. Martin Wilck <mwilck at suse.com>, Tel. +49 (0)911 74053 2107
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