[linux-lvm] Identifying useable block devices

[Marius Vollmer]

Peter Rajnoha <prajnoha at redhat.com> writes:

> On 01/22/2014 10:23 AM, Marius Vollmer wrote:
>
>> Is it guaranteed (modulo bugs) that the DM_UDEV_DISABLE_*_RULES flags
>> are only ever removed from a node, and are never added to it over it's
>> lifetime between add/remove events?
>
> No, we don't have this restriction generally

Ok.

>> This isn't true right now, and UDisks fails to handle it correctly
>> when a flag is added in a "change" event.  I am asking to figure out
>> where the fix should go.
>
> Well, udisks should always check the DM_UDEV_DISABLE_OTHER_RULES_FLAG
> and if it's set, skip its processing. It already has:
>
> # honor the flag that device-mapper sets if the device should be ignored
> ENV{DM_UDEV_DISABLE_OTHER_RULES_FLAG}=="1", GOTO="udisks_end"
>
> ..in 80-udisks.rules. So it should be already following this.

That's from UDisks 1, I am concerned with UDisks2, which is a quite
different beast, I think.  Sorry for not making this clear.

The problem with UDisks2, as I see it, is that it ignores a "change" or
"add" event that has DM_UDEV_DISABLE_OTHER_RULES_FLAG set, while I think
it should treat it as a "remove" event.

I have proposed this patch:

    https://bugs.freedesktop.org/attachment.cgi?id=92577&action=edit

> Hmm, could you please send the whole log.

Sure, attached.

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> This is what I see on my machine:

I think you also this, for dm-2:

> UDEV  [170.743992] add      /devices/virtual/block/dm-2 (block)
> DM_UDEV_DISABLE_DISK_RULES_FLAG=1
> DM_UDEV_DISABLE_OTHER_RULES_FLAG=1
> DM_UDEV_DISABLE_SUBSYSTEM_RULES_FLAG=1
>
> UDEV  [170.771393] change   /devices/virtual/block/dm-2 (block)
> DM_NAME=vg-pool
> DM_UDEV_DISABLE_LIBRARY_FALLBACK_FLAG=1
[...]
> UDEV  [170.809403] change   /devices/virtual/block/dm-2 (block)
> DM_NAME=vg-pool
> DM_UDEV_DISABLE_LIBRARY_FALLBACK_FLAG=1
> DM_UDEV_PRIMARY_SOURCE_FLAG=1
[...]
> UDEV  [170.871863] change   /devices/virtual/block/dm-2 (block)
> DM_NAME=vg-pool
> DM_UDEV_DISABLE_DISK_RULES_FLAG=1
> DM_UDEV_DISABLE_LIBRARY_FALLBACK_FLAG=1
> DM_UDEV_DISABLE_OTHER_RULES_FLAG=1
> DM_UDEV_DISABLE_SUBSYSTEM_RULES_FLAG=1
> DM_UDEV_PRIMARY_SOURCE_FLAG=1
[...]