Currently, when we are doing (managed) save, we insert the
iohelper between the qemu and OS. The pipe is created, the
writing end is passed to qemu and the reading end to the
iohelper. It reads data and write them into given file. However,
with write() being asynchronous data may still be in OS
caches and hence in some (corner) cases, all migration data
may have been read and written (not physically though). So
qemu will report success, as well as iohelper. However, with
some non local filesystems, where ENOSPACE is polled every X
time units, we may get into situation where all operations
succeeded but data hasn't reached the disk. And in fact will
never do. Therefore we ought sync caches to make sure data
has reached the block device on remote host.
(cherry picked from commit f32e3a2dd6)
https://bugzilla.redhat.com/show_bug.cgi?id=871312
Recent fixes made almost all the right steps to make emulator pinned
to the cpuset of the whole domain in case <emulatorpin> isn't
specified, but qemudDomainGetEmulatorPinInfo still reports all the
CPUs even when cpuset is specified. This patch fixes that.
(cherry picked from commit 10c5212b10)
Three FORWARD chain rules are added and two INPUT chain rules
are added when a network is started but only the FORWARD chain
rules are removed when the network is destroyed.
(cherry picked from commit adaa7ab653)
This patch resolves: https://bugzilla.redhat.com/show_bug.cgi?id=871201
If libvirt is restarted after updating the dnsmasq or radvd packages,
a subsequent "virsh net-destroy" will fail to kill the dnsmasq/radvd
process.
The problem is that when libvirtd restarts, it re-reads the dnsmasq
and radvd pidfiles, then does a sanity check on each pid it finds,
including checking that the symbolic link in /proc/$pid/exe actually
points to the same file as the path used by libvirt to execute the
binary in the first place. If this fails, libvirt assumes that the
process is no longer alive.
But if the original binary has been replaced, the link in /proc is set
to "$binarypath (deleted)" (it literally has the string " (deleted)"
appended to the link text stored in the filesystem), so even if a new
binary exists in the same location, attempts to resolve the link will
fail.
In the end, not only is the old dnsmasq/radvd not terminated when the
network is stopped, but a new dnsmasq can't be started when the
network is later restarted (because the original process is still
listening on the ports that the new process wants).
The solution is, when the initial "use stat to check for identical
inodes" check for identity between /proc/$pid/exe and $binpath fails,
to check /proc/$pid/exe for a link ending with " (deleted)" and if so,
truncate that part of the link and compare what's left with the
original binarypath.
A twist to this problem is that on systems with "merged" /sbin and
/usr/sbin (i.e. /sbin is really just a symlink to /usr/sbin; Fedora
17+ is an example of this), libvirt may have started the process using
one path, but /proc/$pid/exe lists a different path (indeed, on F17
this is the case - libvirtd uses /sbin/dnsmasq, but /proc/$pid/exe
shows "/usr/sbin/dnsmasq"). The further bit of code to resolve this is
to call virFileResolveAllLinks() on both the original binarypath and
on the truncated link we read from /proc/$pid/exe, and compare the
results.
The resulting code still succeeds in all the same cases it did before,
but also succeeds if the binary was deleted or replaced after it was
started.
(cherry picked from commit 7bafe009d9)
After separating 5.x and 5.1 versions of ESX, we forgot to add 5.1
into the list of allowed connections, so connections to 5.1 fail since
v1.0.0-rc1-5-g1e7cd39
(cherry picked from commit bab7752c0c)
This resolves:
https://bugzilla.redhat.com/show_bug.cgi?id=881480
These three functions:
virDomainNetGetActualBridgeName
virDomainNetGetActualDirectDev
virDomainNetGetActualDirectMode
return attributes that are in a union whose contents are interpreted
differently depending on the actual->type and so they should only
return non-0 when actual->type is 'bridge' (in the first case) or
'direct' (in the other two cases, but I had neglected to do that, so
...DirectDev() was returning bridge.brname (which happens to share the
same spot in the union with direct.linkdev) if actual->type was
'bridge', and ...BridgeName was returning direct.linkdev when
actual->type was 'direct'.
How does this involve Bug 881480 (which was about the inability to
switch between two networks that both have "<forward mode='bridge'/>
<bridge name='xxx'/>"? Whenever the return value of
virDomainNetGetActualDirectDev() for the new and old network
definitions doesn't match, qemuDomainChangeNet() requires a "complete
reconnect" of the device, which qemu currently doesn't
support. ...DirectDev() *should* have been returning NULL for old and
new, but was instead returning the old and new bridge names, which
differ.
(The other two functions weren't causing any behavioral problems in
virDomainChangeNet(), but their problem and fix was identical, so I
included them in this same patch).
(cherry picked from commit 3738cf41f1)
This bug resolves CVE-2012-3411, which is described in the following
bugzilla report:
https://bugzilla.redhat.com/show_bug.cgi?id=833033
The following report is specifically for libvirt on Fedora:
https://bugzilla.redhat.com/show_bug.cgi?id=874702
In short, a dnsmasq instance run with the intention of listening for
DHCP/DNS requests only on a libvirt virtual network (which is
constructed using a Linux host bridge) would also answer queries sent
from outside the virtualization host.
This patch takes advantage of a new dnsmasq option "--bind-dynamic",
which will cause the listening socket to be setup such that it will
only receive those requests that actually come in via the bridge
interface. In order for this behavior to actually occur, not only must
"--bind-interfaces" be replaced with "--bind-dynamic", but also all
"--listen-address" options must be replaced with a single
"--interface" option. Fully:
--bind-interfaces --except-interface lo --listen-address x.x.x.x ...
(with --listen-address possibly repeated) is replaced with:
--bind-dynamic --interface virbrX
Of course libvirt can't use this new option if the host's dnsmasq
doesn't have it, but we still want libvirt to function (because the
great majority of libvirt installations, which only have mode='nat'
networks using RFC1918 private address ranges (e.g. 192.168.122.0/24),
are immune to this vulnerability from anywhere beyond the local subnet
of the host), so we use the new dnsmasqCaps API to check if dnsmasq
supports the new option and, if not, we use the "old" option style
instead. In order to assure that this permissiveness doesn't lead to a
vulnerable system, we do check for non-private addresses in this case,
and refuse to start the network if both a) we are using the old-style
options, and b) the network has a publicly routable IP
address. Hopefully this will provide the proper balance of not being
disruptive to those not practically affected, and making sure that
those who *are* affected get their dnsmasq upgraded.
(--bind-dynamic was added to dnsmasq in upstream commit
54dd393f3938fc0c19088fbd319b95e37d81a2b0, which was included in
dnsmasq-2.63)
This new function returns true if the given address is in the range of
any "private" or "local" networks as defined in RFC1918 (IPv4) or
RFC3484/RFC4193 (IPv6), otherwise they return false.
These ranges are:
192.168.0.0/16
172.16.0.0/16
10.0.0.0/24
FC00::/7
FEC0::/10
In order to optionally take advantage of new features in dnsmasq when
the host's version of dnsmasq supports them, but still be able to run
on hosts that don't support the new features, we need to be able to
detect the version of dnsmasq running on the host, and possibly
determine from the help output what options are in this dnsmasq.
This patch implements a greatly simplified version of the capabilities
code we already have for qemu. A dnsmasqCaps device can be created and
populated either from running a program on disk, reading a file with
the concatenated output of "dnsmasq --version; dnsmasq --help", or
examining a buffer in memory that contains the concatenated output of
those two commands. Simple functions to retrieve capabilities flags,
the version number, and the path of the binary are also included.
bridge_driver.c creates a single dnsmasqCaps object at driver startup,
and disposes of it at driver shutdown. Any time it must be used, the
dnsmasqCapsRefresh method is called - it checks the mtime of the
binary, and re-runs the checks if the binary has changed.
networkxml2argvtest.c creates 2 "artificial" dnsmasqCaps objects at
startup - one "restricted" (doesn't support --bind-dynamic) and one
"full" (does support --bind-dynamic). Some of the test cases use one
and some the other, to make sure both code pathes are tested.
When libvirt cannot find a suitable CPU model for host CPU (easily
reproducible by running libvirt in a guest), it would not provide CPU
topology in capabilities XML either. Even though CPU topology is known
and can be queried by virNodeGetInfo. With this patch, CPU topology will
always be provided in capabilities XML regardless on the presence of CPU
model.
(cherry picked from commit f1c7010040)
Conflicts:
src/qemu/qemu_capabilities.c
src/qemu/qemu_command.c
The new code uses capabilities caching.
In Fedora 16, we quit enabling cgconfig because systemd set up
default cgroups that were good enough for our use. But in F17,
when we switched to systemd, we reverted and started up cgconfig
again. See also the tail of this thread:
https://www.redhat.com/archives/libvir-list/2012-October/msg01657.html
* libvirt.spec.in (with_systemd): Rely on systemd for cgroups.
(cherry picked from commit b61eadf3c6)
The string comparison logic was inverted and matched the first drive
that does *not* have the name we search for.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit 23d47b33a2)
The QEMU -drive id= begins with libvirt's QEMU host drive prefix
("drive-"), which is stripped off in several places two convert between
host ("-drive") and guest ("-device") device names.
In the case of BlkIoTune it is unnecessary to strip the QEMU host drive
prefix because we operate on "info block"/"query-block" output that uses
host drive names.
Stripping the prefix incorrectly caused string comparisons to fail since
we were comparing the guest device name against the host device name.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit 04ee70bfda)
Found this when building on RHEL5:
parallels/parallels_storage.c: In function 'parallelsStorageOpen':
parallels/parallels_storage.c:180: error: 'for' loop initial declaration used outside C99 mode
(and similar error in parallels_driver.c). This was in spite of
configuring with "-Wno-error".
(cherry picked from commit 73ebd86d73)
Replace '%' by '&' for correct escaping of '>' in Domain specification.
Signed-off-by: Philipp Hahn <hahn@univention.de>
(cherry picked from commit 7083cdc7bd)
This was found during testing of the fix for:
https://bugzilla.redhat.com/show_bug.cgi?id=868483
networkValidate was supposed to check for the existence of multiple
portgroups and report an error if this was encountered. It did, but
there were two problems:
1) even though it logged an error, it still returned success, allowing
the operation to continue.
2) It could exit the portgroup checking loop early (or possibly not
even do it once) if a vlan tag was supplied in the base network config
or one of the portgroups.
This patch fixes networkValidate to return failure in addition to
logging the error, and also changes it to not exit the portgroup
checking loop early. The logic was a bit off in the checking for vlan
anyway, and it's intertwined with fixing the early loop exit, so I
fixed that as well. Now it correctly checks for combinations where a
<virtualport> is specified in the base network def and <vlan> is given
in a portgroup, as well as the opposite (<vlan> in base network def
and <virtualport> in portgroup), and ignores the case of a disallowed
vlan when using *no* portgroup if there is a default portgroup (since
in that case there is no way to not use any portgroup).
(cherry picked from commit d8aae15aa1)
Also remove warnings for upcoming versions. There hadn't been any
compatibility problems with new ESX version over the whole lifetime
of the ESX driver, so I don't expect any in the future.
Update documentation to mention vSphere 5.x support.
(cherry picked from commit 1e7cd39511)
In commit 371ddc98, I mistakenly added the check for sysctl
version 9 after setting the hypercall version to 1, which will
fail with
error : xenHypervisorDoV1Op:967 : Unable to issue hypervisor
ioctl 3166208: Function not implemented
This check should be included along with the others that use
hypercall version 2.
(cherry picked from commit 9785f2b6f2)
When restoring selinux labels after a VM is stopped, any non-standard
path that doesn't have a default selinux label causes the process
to stop and exit early. This isn't really an error condition IMO.
Of course the selinux API could be erroring for some other reason
but hopefully that's rare enough to not need explicit handling.
Common example here is storing disk images in a non-standard location
like under /mnt.
(cherry picked from commit 767be8be72)
Rename the 'wait' parameter to 'loop'.
This silences the warning:
storage/storage_backend.c:1348:34: error: declaration of 'wait' shadows
a global declaration [-Werror=shadow]
and fixes the build with -Werror.
--
Note: loop is pool backwards.
(cherry picked from commit b326765c80)
virStorageVolLookupByPath is an API call that virt-manager uses
quite a bit when dealing with storage. This call use BackendStablePath
which has several usleep() heuristics that can be tripped up
and hang virt-manager for a while.
Current example: an empty mpath pool pointing to /dev/mapper makes
_any_ calls to virStorageVolLookupByPath take 5 seconds.
The sleep heuristics are actually only needed in certain cases
when we are waiting for new storage to appear, so let's skip the
timeout steps when calling from LookupByPath.
(cherry picked from commit 77eff5eeb2)
It might need some time till the LUN's stable path shows up on
initiator host, and although the time window is not foreseeable,
as a better than nothing fix, this patch adds timeout for the
stable path discovery process.
(cherry picked from commit de7f0774c3)
On F17 at least, every time libvirtd starts we get this in syslog:
libvirtd: Could not find keytab file: /etc/libvirt/krb5.tab: No such file or directory
This comes from cyrus-sasl, and happens regardless of whether the
gssapi plugin is requested, which is what actually uses
/etc/libvirt/krb5.tab.
While cyrus-sasl shouldn't complain, we can easily make it shut up by
commenting out the keytab value by default.
Also update the keytab comment to the more modern one from qemu's
sasl config file.
(cherry picked from commit fe772f24a6)
This resolves: https://bugzilla.redhat.com/show_bug.cgi?id=868483
virNetworkUpdate, virNetworkDefine, and virNetworkCreate all three
allow network definitions to contain multiple <portgroup> elements
with default='yes'. Only a single default portgroup should be allowed
for each network.
This patch updates networkValidate() (called by both
virNetworkCreate() and virNetworkDefine()) and
virNetworkDefUpdatePortGroup (called by virNetworkUpdate() to not
allow multiple default portgroups.
(cherry picked from commit 6f8a8b30c9)
This fixes the problem reported in:
https://bugzilla.redhat.com/show_bug.cgi?id=868389
Previously, the dnsmasq hosts file (used for static dhcp entries, and
addnhosts file (used for additional dns host entries) were only
created/referenced on the dnsmasq commandline if there was something
to put in them at the time the network was started. Once we can update
a network definition while it's active (which is now possible with
virNetworkUpdate), this is no longer a valid strategy - if there were
0 dhcp static hosts (resulting in no reference to the hosts file on the
commandline), then one was later added, the commandline wouldn't have
linked dnsmasq up to the file, so even though we create it, dnsmasq
doesn't pay any attention.
The solution is to just always create these files and reference them
on the dnsmasq commandline (almost always, anyway). That way dnsmasq
can notice when a new entry is added at runtime (a SIGHUP is sent to
dnsmasq by virNetworkUdpate whenever a host entry is added or removed)
The exception to this is that the dhcp static hosts file isn't created
if there are no lease ranges *and* no static hosts. This is because in
this case dnsmasq won't be setup to listen for dhcp requests anyway -
in that case, if the count of dhcp hosts goes from 0 to 1, dnsmasq
will need to be restarted anyway (to get it listening on the dhcp
port). Likewise, if the dhcp hosts count goes from 1 to 0 (and there
are no dhcp ranges) we need to restart dnsmasq so that it will stop
listening on port 67. These special situations are handled in the
bridge driver's networkUpdate() by checking for ((bool)
nranges||nhosts) both before and after the update, and triggering a
dnsmasq restart if the before and after don't match.
(cherry picked from commit 1cb1f9dabf)
https://bugzilla.redhat.com/show_bug.cgi?id=866364
pointed out a crash due to virNetworkObjAssignDef free'ing
network->newDef without NULLing it afterward. A fix for this is in
upstream commit b7e9202401. While the
NULLing of newDef was a legitimate fix, newDef should have already
been empty (NULL) anyway (as indicated in the comment that was deleted
by that commit).
The reason that newDef had a non-NULL value (i.e. the root cause) was
that networkStartNetwork() had failed after populating
network->newDef, but then neglected to free/NULL newDef in the
cleanup.
(A bit of background here: network->newDef should contain the
persistent config of a network when a network is active (and of course
only when it is persisten), and NULL at all other times. There is also
a network->def which should contain the persistent definition of the
network when it is inactive, and the current live state at all other
times. The idea is that you can make changes to network->newDef which
will take effect the next time the network is restarted, but won't
mess with the current state of the network (virDomainObj has a similar
pair of virDomainDefs that behave in the same fashion). Personally I
think there should be a network->live and network->config, and the
location of the persistent config should *always* be in
network->config, but that's for a later cleanup).
Since I love things to be symmetric, I created a new function called
virNetworkObjUnsetDefTransient(), which reverses the effects of
virNetworkObjSetDefTransient(). I don't really like the name of the
new function, but then I also didn't really like the name of the old
one either (it's just named that way to match a similar function in
the domain conf code).
(cherry picked from commit 78fab2770b)
AUTHORS.in tracks the maintainers, as well as some folks who were
previously in AUTHORS but don't have a git commit with proper
attribution.
Generated output is sorted alphabetically and lacks pretty spacing, so
tweak AUTHORS.in to follow the same format.
Additionally, drop the syntax-check rule that previously validated
AUTHORS against git log.
(cherry picked from commit 7b21981cdb)
Conflicts:
.mailmap
AUTHORS
Several people have reported that if the .gnulib submodule is dirty,
then 'make' will go into an infinite loop attempting to rerun bootstrap,
because that never cleans up the dirty submodule. By default, we
should halt and make the user investigate, but if the user doesn't
know why or care that the submodule is dirty, I also added the ability
to 'make CLEAN_SUBMODULE=1' to get things going again.
Also, while testing this, I noticed that when a submodule update was
needed, 'make' would first run autoreconf, then bootstrap (which
reruns autoreconf); adding a strategic dependency allows for less work.
* .gnulib: Update to latest, for maint.mk improvements.
* cfg.mk (_autogen): Also hook maint.mk, to run before autoreconf.
* autogen.sh (bootstrap): Refuse to run if gnulib is dirty, unless
user requests discarding gnulib changes.
(cherry picked from commit c5f162200c)
Relabeling tapfd right after the tap device is created.
qemuPhysIfaceConnect is common function called both for static
netdevs and for hotplug netdevs.
(cherry picked from commit 4492ef7f48)
which frees all allocated memory but doesn't set the passed pointer to
NULL. Therefore, we must do it ourselves. This is causing actual
libvirtd crash: Basically, when doing 'virsh net-edit' the newDef should
be dropped. And the memory is freed, indeed. However, the pointer is
not set to NULL but kept instead. And the next duo of calls 'virsh
net-start' and 'virsh net-destroy' starts the disaster. The latter one
does the same as 'virsh destroy'; it sees that newDef is nonNULL so it
replaces def with newDef (which has been freed already as said a few
lines above). Therefore any subsequent call accessing def will hit the ground.
(cherry picked from commit b7e9202401)
It should relabel tapfd of virtual network of type VIR_DOMAIN_NET_TYPE_DIRECT
rather than VIR_DOMAIN_NET_TYPE_NETWORK and VIR_DOMAIN_NET_TYPE_BRIDGE
(commit ae368ebfcc introduced this bug)
Caution: The context of the two hunks is identical other than indentation.
Please be extremely cautious of where the patch gets applied.
(cherry picked from commit 89b63f0ad4)
In commit 9674f2c637, I forgot to change
selabel_lookup with the other functions, so this one-liner does exactly
that.
(cherry picked from commit 6676c1fc8f)
BZ:https://bugzilla.redhat.com/show_bug.cgi?id=851981
When using macvtap, a character device gets first created by
kernel with name /dev/tapN, its selinux context is:
system_u:object_r:device_t:s0
Shortly, when udev gets notification when new file is created
in /dev, it will then jump in and relabel this file back to the
expected default context:
system_u:object_r:tun_tap_device_t:s0
There is a time gap happened.
Sometimes, it will have migration failed, AVC error message:
type=AVC msg=audit(1349858424.233:42507): avc: denied { read write } for
pid=19926 comm="qemu-kvm" path="/dev/tap33" dev=devtmpfs ino=131524
scontext=unconfined_u:system_r:svirt_t:s0:c598,c908
tcontext=system_u:object_r:device_t:s0 tclass=chr_file
This patch will label the tapfd device before qemu process starts:
system_u:object_r:tun_tap_device_t:MCS(MCS from seclabel->label)
(cherry picked from commit ae368ebfcc)
We are currently able to work only with non-translated SELinux
contexts, but we are using functions that work with translated
contexts throughout the code. This patch swaps all SELinux context
translation relative calls with their raw sisters to avoid parsing
problems.
The problems can be experienced with mcstrans for example. The
difference is that if you have translations enabled (yum install
mcstrans; service mcstrans start), fgetfilecon_raw() will get you
something like 'system_u:object_r:virt_image_t:s0', whereas
fgetfilecon() will return 'system_u:object_r:virt_image_t:SystemLow'
that we cannot parse.
I was trying to confirm that the _raw variants were here since the dawn of
time, but the only thing I see now is that it was imported together in
the upstream repo [1] from svn, so before 2008.
Thanks Laurent Bigonville for finding this out.
[1] http://oss.tresys.com/git/selinux.git
(cherry picked from commit 9674f2c637)
I hit this problem recently when trying to create a bridge with an IPv6
address on a 3.2 kernel: dnsmasq (and, further, radvd) would not bind to
the given address, waiting 20s and then giving up with -EADDRNOTAVAIL
(resp. exiting immediately with "error parsing or activating the config
file", without libvirt noticing it, BTW). This can be reproduced with (I
think) any kernel >= 2.6.39 and the following XML (to be used with
"virsh net-create"):
<network>
<name>test-bridge</name>
<bridge name='testbr0' />
<ip family='ipv6' address='fd00::1' prefix='64'>
</ip>
</network>
(it happens even when you have an IPv4, too)
The problem is that since commit [1] (which, ironically, was made to
“help IPv6 autoconfiguration”) the linux bridge code makes bridges
behave like “real” devices regarding carrier detection. This makes the
bridges created by libvirt, which are started without any up devices,
stay with the NO-CARRIER flag set, and thus prevents DAD (Duplicate
address detection) from happening, thus letting the IPv6 address flagged
as “tentative”. Such addresses cannot be bound to (see RFC 2462), so
dnsmasq fails binding to it (for radvd, it detects that "interface XXX
is not RUNNING", thus that "interface XXX does not exist, ignoring the
interface" (sic)). It seems that this behavior was enhanced somehow with
commit [2] by avoiding setting NO-CARRIER on empty bridges, but I
couldn't reproduce this behavior on my kernel. Anyway, with the “dummy
tap to set MAC address” trick, this wouldn't work.
To fix this, the idea is to get the bridge's attached device to be up so
that DAD can happen (deactivating DAD altogether is not a good idea, I
think). Currently, libvirt creates a dummy TAP device to set the MAC
address of the bridge, keeping it down. But even if we set this device
up, it is not RUNNING as soon as the tap file descriptor attached to it
is closed, thus still preventing DAD. So, we must modify the API a bit,
so that we can get the fd, keep the tap device persistent, run the
daemons, and close it after DAD has taken place. After that, the bridge
will be flagged NO-CARRIER again, but the daemons will be running, even
if not happy about the device's state (but we don't really care about
the bridge's daemons doing anything when no up interface is connected to
it).
Other solutions that I envisioned were:
* Keeping the *-nic interface up: this would waste an fd for each
bridge during all its life. May be acceptable, I don't really
know.
* Stop using the dummy tap trick, and set the MAC address directly
on the bridge: it is possible since quite some time it seems,
even if then there is the problem of the bridge not being
RUNNING when empty, contrary to what [2] says, so this will need
fixing (and this fix only happened in 3.1, so it wouldn't work
for 2.6.39)
* Using the --interface option of dnsmasq, but I saw somewhere
that it's not used by libvirt for backward compatibility. I am
not sure this would solve this problem, though, as I don't know
how dnsmasq binds itself to it with this option.
This is why this patch does what's described earlier.
This patch also makes radvd start even if the interface is
“missing” (i.e. it is not RUNNING), as it daemonizes before binding to
it, and thus sometimes does it after the interface has been brought down
by us (by closing the tap fd), and then originally stops. This also
makes it stop yelling about it in the logs when the interface is down at
a later time.
[1]
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=1faa4356a3bd89ea11fb92752d897cff3a20ec0e
[2]
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=b64b73d7d0c480f75684519c6134e79d50c1b341
(cherry picked from commit db488c7917)
When p2p migration fails early because qemuMigrationIsAllowed or
qemuMigrationIsSafe say migration should be cancelled, we fail to clear
the migration-out async job. As a result of that, further APIs called
for the same domain may fail with Timed out during operation: cannot
acquire state change lock.
Reported by Guido Winkelmann.
(cherry picked from commit 837993d845)
On F17 at least, this command fails:
$ sudo /usr/sbin/lvcreate --name sparsetest -L 0K --virtualsize 16384K vgvirt
Unable to create new logical volume with no extents
Which is unfortunate since allocation=0 is what virt-manager tries to use
by default.
Rather than telling the user 'don't do that', let's just give them the
smallest allocation possible if alloc=0 is requested.
https://bugzilla.redhat.com/show_bug.cgi?id=866481
(cherry picked from commit 9f0e9cba27)
