1. Do not detach device forcefully when it's removed. This breaks
libvirt (which thinks the device is still there). After this change, it
is possible to detach device using libvirt, even if it was already
removed physically from backend domain (unless it is dom0 - in which
case it is still broken). So, this is partial fix for
QubesOS/qubes-issues#1082.
2. Do not trigger "change" udev event when only QubesDB state needs to
be updated - this leads to massive udev events queue, and heavy I/O
usage - for example scanning all LVM many times. In some cases it even
caused infinite event queue.
3. Do not use QUBES_EXPOSED udev property - it was needed a while back
before QubesDB, because concurrent xenstore accesses are expensive
(because of transactions). It isn't the problem on QubesDB.
4. Cache information about device-mapper, so it is possible to
reconstruct it at device remove - when the actual device cannot be
queried anymore. This is specifically about list of lower layer devices
used.
5. Allow excluding loop devices pointing at a file in directory marked
with ".qubes-exclude-block-devices" file. This is more generic than
hardcoding /var/lib/qubes.
QubesOS/qubes-issues#3084FixesQubesOS/qubes-issues#3073QubesOS/qubes-issues#1082
For example, attaching a device-mapper device to another VM increases
its "dmsetup info" open count in is_used(), which triggered its removal
from qvm-block.
The canonical device name is not necessarily used in /proc/mounts or
/proc/self/mountinfo, see /dev/dm-0 vs. /dev/mapper/dmroot. (And only
checking by major:minor is not possible in the case of btrfs.)
Also fixes another bug where e.g. dm-10 would match when really only
dm-1 was mounted, or when the mountpoint path included the device name,
etc.
Also catches enabled swap.
During early dom0 boot, before xenstored is started any access to it
through /proc/xen/xenbus (or /dev/xen/xenbus) will wait until xenstored
is started. If that happens in script ordered to start before xenstored,
we have a deadlock. Prevent this by using `xenstore-ls -s` in dom0,
which will fail immediately when xenstored isn't running yet. This fail
isn't a problem, because when xenstored isn't running yet, surely device
isn't attached anywhere.
QubesOS/qubes-issues#1081
This prevents simultaneous attachment of the same device (in practice)
to multiple VMs.
This change to be effective requires udev action being called when such
device is attached/detached to some domain. Script
/etc/xen/scripts/block will take care of it.
FixesQubesOS/qubes-issues#1081
Exclude exclude device if mounted/part of other device, or any of its
partition is used (same definition). Update this state whenever device
or it's partition receives udev event.
FixesQubesOS/qubes-issues#1600
When device becomes non-attachable (for example because it gets mounted,
or used as part of LVM/RAID/whatever), it should be removed from
advertised available devices. The code for removing QubesDB entry was
buggy - the device is actually a directory in QubesDB, not a single
entry.
QubesOS/qubes-issues#1600
