Bug#403687: lvm2: several issues with devmapper devices
elendil at planet.nl
Wed Jan 10 13:18:04 CET 2007
Steve asked today:
<vorlon> fjp: I'm confused why bug #403687 is marked as RC, instead of bug
I've decided to answer by mail instead of on IRC because this issue
probably needs some coordination between maintainers of several packages.
It looks certain that #402511, and probably also #401393 were introduced
by this change in udev (0.103-1):
* udev.rules, devfs.rules: stop suppressing creation of dm-* devices,
because they are needed by HAL. (Closes: #392623)
The second line in this snippet from /etc/udev/udev.rules was dropped:
# device mapper creates its own device nodes, so ignore these
The reason I filed #402511 as important is because, although it is a clear
regression and IMHO rather ugly, it is still mostly a cosmetic issue.
It looks like vgchange just loops over all /dev/dm-* devices and checks if
any of them are LVM volumes, and prints an error if a device does not
My conclusion is that udev now creates /dev/dm-* device nodes for cryto
devices (and possibly other dm devices too), but nothing yet takes
responsibility for _deleting_ them when the corresponding crypto devices
are brought down . This looks like a structural issue, but I have no
idea if that should be the responsibility of the device mapper, udev or
I also wonder what the risk is of other, not yet reported, issues
introduced by the change in udev.
The reason I filed #403687 as RC is because IMO it is the _combination_ of
several issues introduced by the change in udev that needs to be looked
at before the release. I have no idea how important the HAL-support is,
but the regressions it introduced seem serious enough to consider
IMO the management of /dev/dm-* devices is something that needs to be
looked into structurally by maintainers of _all_ involved packages
(probably also dmraid), I'll leave it to others whether that needs to be
done before or after the release.
 The crypto devices in /dev/mapper/ *are* correctly removed after
S48cryptdisks has run, but the corresponding /dev/dm-* devices are not.
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