Bug 62565

Summary: udev: 60-persistent-storage.rules ignores NBD
Product: systemd Reporter: Marius Vollmer <marius.vollmer>
Component: generalAssignee: systemd-bugs
Status: VERIFIED NOTABUG QA Contact: systemd-bugs
Severity: normal    
Priority: medium    
Version: unspecified   
Hardware: Other   
OS: All   
Whiteboard:
i915 platform: i915 features:

Description Marius Vollmer 2013-03-20 17:15:45 UTC
I think a NBD device is just like any other block device, isn't it?  I was expecting it to have things like ID_FS_TYPE set on it.
Comment 1 Kay Sievers 2013-03-20 17:41:14 UTC
The nbd devices are set up loop devices, we first have dead device
nodes, then later we attach stuff behind them. At the time of the udev
creation event, nothing works at nbd devices.

Userspace has no idea when to probe for the device, or when stuff changes,
it needs proper kernel support for that to work, which is as far as I know
not existing.

It is currently blacklisted for that reason, and removing the blacklist
could only happen if the nbd kernel side is changed to send out events
like loop, dm, md are doing it.
Comment 2 Marius Vollmer 2013-03-20 17:49:41 UTC
(In reply to comment #1)
> The nbd devices are set up loop devices, we first have dead device
> nodes, then later we attach stuff behind them. At the time of the udev
> creation event, nothing works at nbd devices.

That, unfortunately, makes a lot of sense.  Thanks a lot for the explanation!
Comment 3 Kay Sievers 2013-03-20 17:54:02 UTC
It should be possible though, to fix that in the kernel. It should be
just a couple of lines, with uevent sending hooks at the right place.

People familiar with nbd should be able to do that pretty quickly.

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