Commit 2c78051a introduced build breaker with type in Makefile.am by
specifying wrong header file.
Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

Add tests to testing HVM default features (pae, acpi, apic)
conversion from xm config to libvirt xml. If no pae|acpi|apic
specified in xm config, after conversion, libvirt xml should
by default include:
 <features>
   <pae/>
   <apic/>
   <acpi/>
 </features>
Signed-off-by: NChunyan Liu <cyliu@suse.com>

According to xm.config manual, HVM pae|apic|acpi feature default
is 1 (enabled). But in conversion from xm config to libvirt xml,
if xm config doesn't contain pae|apic|acpi, it sets default value
to 0, this causes some problems in HVM guest.

Update parser codes to set HVM pae|apic|acpi default value to 1
to match xm config convension.
Signed-off-by: NChunyan Liu <cyliu@suse.com>

Now that xenconfig supports parsing and formatting Xen's
XL config format, integrate it into the libxl driver's
connectDomainXML{From,To}Native functions.
Signed-off-by: NKiarie Kahurani <davidkiarie4@gmail.com>
Signed-off-by: NJim Fehlig <jfehlig@suse.com>

add tests for the xen_xl config parser
Signed-off-by: NKiarie Kahurani <davidkiarie4@gmail.com>
Signed-off-by: NJim Fehlig <jfehlig@suse.com>

Introduce a Xen xl parser

This parser allows for users to convert the new xl disk format and
spice graphics config to libvirt xml format and vice versa. Regarding
the spice graphics config, the code is pretty much straight forward.
For the disk {formating, parsing}, this parser takes care of the new
xl format which include positional parameters and key/value parameters.
In xl format disk config a <diskspec> consists of parameters separated by
commas. If the parameters do not contain an '=' they are automatically
assigned to certain options following the order below

   target, format, vdev, access

The above are the only mandatory parameters in the <diskspec> but there
are many more disk config options. These options can be specified as
key=value pairs. This takes care of the rest of the options such as

  devtype, backend, backendtype, script, direct-io-safe,

The positional paramters can also be specified in key/value form
for example

    /dev/vg/guest-volume,,hda
    /dev/vg/guest-volume,raw,hda,rw
    format=raw, vdev=hda, access=rw, target=/dev/vg/guest-volume

are interpleted to one config.

In xm format, the above diskspec would be written as

phy:/dev/vg/guest-volume,hda,w

The disk parser is based on the same parser used successfully by
the Xen project for several years now.  Ian Jackson authored the
scanner, which is used by this commit with mimimal changes.  Only
the PREFIX option is changed, to produce function and file names
more consistent with libvirt's convention.
Signed-off-by: NKiarie Kahurani <davidkiarie4@gmail.com>
Signed-off-by: NJim Fehlig <jfehlig@suse.com>

Export helper functions for reuse in getting values
from a virConfPtr object
Signed-off-by: NKiarie Kahurani <davidkiarie4@gmail.com>
Signed-off-by: NJim Fehlig <jfehlig@suse.com>

The <domain/> element under /capabilities/guest/arch/ can have no
child elements. If that's the case we format:

        <domain type='xen'>
        </domain>

instead of simpler:

        <domain type='xen'/>

This commit fixes that.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

VIR_STORAGE_FILE_AUTO should be used only in xml provided to
libvirt by user, if I understood correctly. Driver should
set storage source format to specific disk format in
*DomainGetXMLDesc.

CDROMs in PCS use raw image format.
Signed-off-by: NDmitry Guryanov <dguryanov@parallels.com>

There are two more places after commit 3865941b that need to be adapted
in order to get rid of some test failures when building as root.
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

Some of the nwfilter tests are now failing since --concurrent shows
up in the ebtables command. To avoid this, implement a function
preventing the probing for lock support in the eb/iptables tools
and use it in the tests.
Signed-off-by: NStefan Berger <stefanb@linux.vnet.ibm.com>

There is one problem that causes various errors in the daemon.  When
domain is waiting for a job, it is unlocked while waiting on the
condition.  However, if that domain is for example transient and being
removed in another API (e.g. cancelling incoming migration), it get's
unref'd.  If the first call, that was waiting, fails to get the job, it
unref's the domain object, and because it was the last reference, it
causes clearing of the whole domain object.  However, when finishing the
call, the domain must be unlocked, but there is no way for the API to
know whether it was cleaned or not (unless there is some ugly temporary
variable, but let's scratch that).

The root cause is that our APIs don't ref the objects they are using and
all use the implicit reference that the object has when it is in the
domain list.  That reference can be removed when the API is waiting for
a job.  And because each domain doesn't do its ref'ing, it results in
the ugly checking of the return value of virObjectUnref() that we have
everywhere.

This patch changes qemuDomObjFromDomain() to ref the domain (using
virDomainObjListFindByUUIDRef()) and adds qemuDomObjEndAPI() which
should be the only function in which the return value of
virObjectUnref() is checked.  This makes all reference counting
deterministic and makes the code a bit clearer.
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

Commit 1a80b97d, which added the virCgroupHasEmptyTasks() function
forgot that the parameter @cgroup may be NULL and did not check that.
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

Add an email alias after updating my email address in commit 738a2aec.

Fix the typo in struct virSecurityModel's comment for its doi field.

The members of struct virSecurityLabel and struct virSecurityModel
were not shown in the libvirt API docs because the corresponding
<field> elements were missing from the libvirt-api.xml.

The reason is that apibuild.py does not cope well with typedef's
using inline struct definitions. It fails to associate the comment
with the typedef and because of this refuses to write out the
field of the struct.

Although QMP returns info about vCPU threads in TCG mode, the
data it returns is mostly lies. Only the first vCPU has a valid
thread_id returned. The thread_id given for the other vCPUs is
in fact the main emulator thread. All vCPUs actually run under
the same thread in TCG mode.

Our vCPU pinning code is not at all able to cope with this
so if you try to set CPU affinity per-vCPU you end up with
wierd errors

error: Failed to start domain instance-00000007
error: cannot set CPU affinity on process 24365: Invalid argument

Since few people will care about the performance of TCG with
strict CPU pinning, lets just disable that for now, so we get
a clear error message

error: Failed to start domain instance-00000007
error: Requested operation is not valid: cpu affinity is not supported

The code assumes that def->vcpus == nvcpupids, so when we setup
fake CPU pids for old QEMU with nvcpupids == 1, we cause the
later code to read off the end of the array. This has fun results
like sche_setaffinity(0, ...) which changes libvirtd's own CPU
affinity, or even better sched_setaffinity($RANDOM, ...) which
changes the affinity of a random OS process.

Libvirt BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1175397
QEMU BZ:    https://bugzilla.redhat.com/show_bug.cgi?id=1170093

In qemu there are two interesting arguments:

1) -numa to create a guest NUMA node
2) -object memory-backend-{ram,file} to tell qemu which memory
region on which host's NUMA node it should allocate the guest
memory from.

Combining these two together we can instruct qemu to create a
guest NUMA node that is tied to a host NUMA node. And it works
just fine. However, depending on machine type used, there might
be some issued during migration when OVMF is enabled (see QEMU
BZ). While this truly is a QEMU bug, we can help avoiding it. The
problem lies within the memory backend objects somewhere. Having
said that, fix on our side consists on putting those objects on
the command line if and only if needed. For instance, while
previously we would construct this (in all ways correct) command
line:

    -object memory-backend-ram,size=256M,id=ram-node0 \
    -numa node,nodeid=0,cpus=0,memdev=ram-node0

now we create just:

    -numa node,nodeid=0,cpus=0,mem=256

because the backend object is obviously not tied to any specific
host NUMA node.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

Commit ca91ba78 moved these into the qemuDomainPrepareDisk helper,
but forgot to remove them from here as well.

Commit ca91ba78 moved qemuSetupDiskCgroup into the qemuDomainPrepareDisk
helper, but failed to call it for usb disks.

https://bugzilla.redhat.com/show_bug.cgi?id=1175668`

On a system with 160 CPUs the /proc/cpuinfo size grows beyond
the currently set limit of 10KB causing an internal error.

This patch increases the buffer size to 1MB.
Signed-off-by: NBoris Fiuczynski <fiuczy@linux.vnet.ibm.com>

Coverity flagged commit 0282ca45 as introducing a memory leak;
in all my refactoring to make capacity probing conditional on
whether the image is non-raw, I missed deleting the unconditional
probe.

* src/qemu/qemu_driver.c (qemuStorageLimitsRefresh): Drop
redundant assignment.
Signed-off-by: NEric Blake <eblake@redhat.com>

A recent lvm change has resulted in a change for the "default" type of
logical volume created when the "--virtualsize" or "--V" is supplied on
the command line (e.g. when the allocation and capacity values of a to
be created volume differ). It seems that at the very least the following
change adjusts the default type:

https://git.fedorahosted.org/cgit/lvm2.git/commit/?id=e0164f21

and the following may also have some impact.

https://git.fedorahosted.org/cgit/lvm2.git/commit/?id=87fc3b71

When using the virsh vol-create-as or vol-create xmlfile commands, the
result is that libvirt will now create a "thin logical volume" and a
"thin logical volume pool" rather than just a "thin snapshot logical
volume". For example the following sequence:

  # lvcreate --name test -L 2M -V 5M lvm_test
    Rounding up size to full physical extent 4.00 MiB
    Rounding up size to full physical extent 8.00 MiB
    Logical volume "test" created.
  # lvs lvm_test
    LV    VG       Attr       LSize Pool  Origin Data%  Meta%  Move Log Cpy%Sync Convert
    lvol1 lvm_test twi-a-tz-- 4.00m              0.00   0.98
    test  lvm_test Vwi-a-tz-- 8.00m lvol1        0.00

compared to the former code which had the following:

    LV   VG       Attr       LSize  Pool Origin         Data%  Move Log Cpy%Sync Convert
    test LVM_Test swi-a-s---  4.00m      [test_vorigin]   0.00

Since libvirt doesn't know how to parse the thin logical volume
and pool, it will fail to find the newly created volume and pool
even though it exists in the volume group.

It cannot find since the command used to find/parse returns a thin volume
'test' with no associated device, for example the output is:

  lvol1##UgUwkp-fTFP-C0rc-ufue-xrYh-dkPr-FGPFPx#lvol1_tdata(0)#thin-pool#1#4194304#4194304#4194304#twi-a-tz--
  test##NcaIoH-4YWJ-QKu3-sJc3-EOcS-goff-cThLIL##thin#0#8388608#4194304#8388608#Vwi-a-tz--

as compared to the former which had the following:

      test#[test_vorigin]#Dt5Of3-4WE6-buvw-CWJ4-XOiz-ywOU-YULYw6#/dev/sda3(1300)#linear#1#4194304#4194304#4194304#swi-a-s---

While it's possible to generate code to handle the new thin lv and pool, this
patch will add a "--type snapshot" onto the lvcreate command libvirt uses
in order to "for now" be able to continue to utilize the thin snapshots

https://bugzilla.redhat.com/show_bug.cgi?id=1174569

There's nothing we need to do for shared iSCSI devices in
qemuAddSharedHostdev and qemuRemoveSharedHostdev. The iSCSI layer
takes care about that for us.
Signed-off-by: NLuyao Huang <lhuang@redhat.com>
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

Wire up backing chain recursion.  For the first time, it is now
possible to get libvirt to expose that qemu tracks read statistics
on backing files, as well as report maximum extent written on a
backing file during a block-commit operation.

For a running domain, where one of the two images has a backing
file, I see the traditional output:

$ virsh domstats --block testvm2
Domain: 'testvm2'
  block.count=2
  block.0.name=vda
  block.0.path=/tmp/wrapper.qcow2
  block.0.rd.reqs=1
  block.0.rd.bytes=512
  block.0.rd.times=28858
  block.0.wr.reqs=0
  block.0.wr.bytes=0
  block.0.wr.times=0
  block.0.fl.reqs=0
  block.0.fl.times=0
  block.0.allocation=0
  block.0.capacity=1310720000
  block.0.physical=200704
  block.1.name=vdb
  block.1.path=/dev/sda7
  block.1.rd.reqs=0
  block.1.rd.bytes=0
  block.1.rd.times=0
  block.1.wr.reqs=0
  block.1.wr.bytes=0
  block.1.wr.times=0
  block.1.fl.reqs=0
  block.1.fl.times=0
  block.1.allocation=0
  block.1.capacity=1310720000

vs. the new output:

$ virsh domstats --block --backing testvm2
Domain: 'testvm2'
  block.count=3
  block.0.name=vda
  block.0.path=/tmp/wrapper.qcow2
  block.0.rd.reqs=1
  block.0.rd.bytes=512
  block.0.rd.times=28858
  block.0.wr.reqs=0
  block.0.wr.bytes=0
  block.0.wr.times=0
  block.0.fl.reqs=0
  block.0.fl.times=0
  block.0.allocation=0
  block.0.capacity=1310720000
  block.0.physical=200704
  block.1.name=vda
  block.1.path=/dev/sda6
  block.1.backingIndex=1
  block.1.rd.reqs=0
  block.1.rd.bytes=0
  block.1.rd.times=0
  block.1.wr.reqs=0
  block.1.wr.bytes=0
  block.1.wr.times=0
  block.1.fl.reqs=0
  block.1.fl.times=0
  block.1.allocation=327680
  block.1.capacity=786432000
  block.2.name=vdb
  block.2.path=/dev/sda7
  block.2.rd.reqs=0
  block.2.rd.bytes=0
  block.2.rd.times=0
  block.2.wr.reqs=0
  block.2.wr.bytes=0
  block.2.wr.times=0
  block.2.fl.reqs=0
  block.2.fl.times=0
  block.2.allocation=0
  block.2.capacity=1310720000

I may later do a patch that trims the output to avoid 0 stats,
particularly for backing files (which are more likely to have
0 stats, at least for write statistics when no block-commit
is performed).  Also, I still plan to expose physical size
information (qemu doesn't expose it yet, so it requires a stat,
and for block devices, a further open/seek operation).  But
this patch is good enough without worrying about that yet.

* src/qemu/qemu_driver.c (QEMU_DOMAIN_STATS_BACKING): New internal
enum bit.
(qemuConnectGetAllDomainStats): Recognize new user flag, and pass
details to...
(qemuDomainGetStatsBlock): ...here, where we can do longer recursion.
(qemuDomainGetStatsOneBlock): Output new field.
Signed-off-by: NEric Blake <eblake@redhat.com>

In order to report stats on backing chains, we need to separate
the output of stats for one block from how we traverse blocks.

* src/qemu/qemu_driver.c (qemuDomainGetStatsBlock): Split...
(qemuDomainGetStatsOneBlock): ...into new helper.
Signed-off-by: NEric Blake <eblake@redhat.com>

This patch introduces access to allocation information about
a backing chain of a live domain.  While querying storage
volumes for read-only disks could provide some of the details,
we do NOT want to read() a file while qemu is writing it.
Also, there is one case where we have to rely on qemu: when
doing a block commit into a backing file, where that file is
stored in qcow2 format on a host block device, we want to know
the current highest write offset into that image, in order to
know if the disk must be resized larger.  qemu-img does not
(currently) show this information, and none of the earlier
block APIs were extensible enough to expose it.  But
virDomainListGetStats is perfect for the job!

We don't need a new group of statistics, as the existing block
group is sufficient.  On the other hand, as existing libvirt
releases already report 1:1 mapping of block.count to <disk>
devices, changing the array size could confuse older clients;
and even with newer clients, the time and memory taken to
report additional statistics is not always necessary (backing
files are generally read-only except for block-commit, so while
read statistics may change, sizing statistics will not).  So
the choice here is to add a new flag that only newer callers
will pass, when they are prepared for the additional information.

This patch introduces the new API, but it will take more
patches to get it implemented for qemu.

* include/libvirt/libvirt-domain.h
(VIR_CONNECT_GET_ALL_DOMAINS_STATS_BACKING): New flag.
* src/libvirt-domain.c (virConnectGetAllDomainStats): Document it,
and add a new field when it is in use.
* tools/virsh-domain-monitor.c (cmdDomstats): Use new flag.
* tools/virsh.pod (domstats): Document it.
Signed-off-by: NEric Blake <eblake@redhat.com>

A coming patch will make it optionally possible to list backing
chain block stats; in this mode of operation, block.counts is no
longer the number of <disks> in the domain, but the number of
blocks in the array being reported.  We still want block.count
listed first, but rather than iterate the tree twice (once to
count, and once to list stats), it's easier to just touch things
up after the fact.

* src/qemu/qemu_driver.c (qemuDomainGetStatsBlock): Compute count
after the fact.
Signed-off-by: NEric Blake <eblake@redhat.com>

The prior refactoring can now be put to use. With the same domain
as the earlier commit 7b499262 (one qcow2 disk and an empty
cdrom drive):
$ virsh domstats --block foo
Domain: 'foo'
  block.count=2
  block.0.name=hda
  block.0.path=/var/lib/libvirt/images/foo.qcow2
  block.0.allocation=1309614080
  block.0.capacity=42949672960
  block.0.physical=1309671424
  block.1.name=hdc

* src/qemu/qemu_driver.c (qemuDomainGetStatsBlock): Use
qemuStorageLimitsRefresh to report offline statistics.
Signed-off-by: NEric Blake <eblake@redhat.com>

Create a helper function that can be reused for gathering block
info from virDomainListGetStats.

* src/qemu/qemu_driver.c (qemuDomainGetBlockInfo): Split guts...
(qemuStorageLimitsRefresh): ...into new helper function.
Signed-off-by: NEric Blake <eblake@redhat.com>

The documentation for virDomainBlockInfo was confusing: it stated
that 'physical' was the size of the container, then gave an example
of it being the amount of storage used by a sparse file (that is,
for a sparse raw image on a regular file, the wording implied
capacity==physical, while allocation was smaller; but the example
instead claimed physical==allocation).  Since we use 'physical' for
the last offset of a block device, we should do likewise for
regular files.

Furthermore, the example claimed that for a qcow2 regular file,
allocation==physical.  At the time the code was first written,
this was true (qcow2 files were allocated sequentially, and were
never sparse, so the last sector written happened to also match
the disk space occupied); but modern qemu does much better and
can punch holes for a qcow2 with allocation < physical.

Basically, after this patch, the three fields are now reliably
mapped as:
 'capacity' - how much storage the guest can see (equal to
physical for raw images, determined by image metadata otherwise)
 'allocation' - how much storage the image occupies (similar to
what 'du' would report)
 'physical' - the last offset of the image (similar to what 'ls'
would report)

'capacity' can be larger than 'physical' (such as for a qcow2
image that does not vary much from a backing file) or smaller
(such as for a qcow2 file with lots of internal snapshots).
Likewise, 'allocation' can be (slightly) larger than 'physical'
(such as counting the tail of cluster allocations required to
round a file size up to filesystem granularity) or smaller
(for a sparse file).  A block-resize operation changes capacity
(which, for raw images, also changes physical); many non-raw
images automatically grow physical and allocation as necessary
when starting with an allocation smaller than capacity; and even
when capacity and physical stay unchanged, allocation can change
when converting sectors from holes to data or back.

Note that this does not change semantics for qcow2 images stored
on block devices; there, we still rely on qemu to report the
highest written extent for allocation.  So using this API to
track when to extend a block device because a qcow2 image is
about to exceed a threshold will not see any changes.

Also, note that virStorageVolInfo is unfortunately limited to
just 'capacity' and 'allocation' (we can't expand it to add
'physical', although we can expand the XML to add it there);
historically, that struct's 'allocation' value has reported
file size for qcow2 files (what this patch terms 'physical'
for a domain block device), but disk usage for raw files (what
this patch terms 'allocation').  So follow-up patches will be
needed to make storage volumes report the same allocation
values and get at physical values, where those differ.

* include/libvirt/libvirt-domain.h (_virDomainBlockInfo): Tweak
documentation to match saner definition.
* src/qemu/qemu_driver.c (qemuDomainGetBlockInfo): For regular
files, physical size is capacity, not allocation.
Signed-off-by: NEric Blake <eblake@redhat.com>

Ultimately, we want to avoid read()ing a file while qemu is running.
We still have to open() block devices to determine their physical
size, but that is safer.  This patch rearranges code to group
together all code that reads the image, to make it easier for later
patches to skip the metadata collection when possible.

* src/qemu/qemu_driver.c (qemuDomainGetBlockInfo): Check for empty
disk up front.  Place metadata reading next to use.
Signed-off-by: NEric Blake <eblake@redhat.com>

When requested in a later patch, the QMP command results are now
examined recursively.  As qemu_driver will eventually have to
read items out of the hash table as stored by this patch, the
computation of backing alias string is done in a shared location.

* src/qemu/qemu_domain.h (qemuDomainStorageAlias): New prototype.
* src/qemu/qemu_domain.c (qemuDomainStorageAlias): Implement it.
* src/qemu/qemu_monitor_json.c
(qemuMonitorJSONGetOneBlockStatsInfo)
(qemuMonitorJSONBlockStatsUpdateCapacityOne): Perform recursion.
(qemuMonitorJSONGetAllBlockStatsInfo)
(qemuMonitorJSONBlockStatsUpdateCapacity): Update callers.
Signed-off-by: NEric Blake <eblake@redhat.com>

A future patch will allow recursion into backing chains when
collecting block stats.  This patch should not change behavior,
but merely moves out the common code that will be reused once
recursion is enabled, and adds the parameter that will turn on
recursion.

* src/qemu/qemu_monitor.h (qemuMonitorGetAllBlockStatsInfo)
(qemuMonitorBlockStatsUpdateCapacity): Add recursion parameter,
although it is ignored for now.
* src/qemu/qemu_monitor.h (qemuMonitorGetAllBlockStatsInfo)
(qemuMonitorBlockStatsUpdateCapacity): Likewise.
* src/qemu/qemu_monitor_json.h
(qemuMonitorJSONGetAllBlockStatsInfo)
(qemuMonitorJSONBlockStatsUpdateCapacity): Likewise.
* src/qemu/qemu_monitor_json.c
(qemuMonitorJSONGetAllBlockStatsInfo)
(qemuMonitorJSONBlockStatsUpdateCapacity): Add parameter, and
split...
(qemuMonitorJSONGetOneBlockStatsInfo)
(qemuMonitorJSONBlockStatsUpdateCapacityOne): ...into helpers.
(qemuMonitorJSONGetBlockStatsInfo): Update caller.
* src/qemu/qemu_driver.c (qemuDomainGetStatsBlock): Update caller.
* src/qemu/qemu_migration.c (qemuMigrationCookieAddNBD): Likewise.
Signed-off-by: NEric Blake <eblake@redhat.com>

Right now, grabbing blockinfo always calls stat on the disk, then
opens the image to determine the capacity, using a throw-away
virStorageSourcePtr.  This has a couple of drawbacks:

1. We are calling stat and opening a file on every invocation of
the API.  However, there are cases where the stats should NOT be
changing between successive calls (if a domain is running, no
one should be changing the physical size of a block device or raw
image behind our backs; capacity of read-only files should not
be changing; and we are the gateway to the block-resize command
to know when the capacity of read-write files should be changing).
True, we still have to use stat in some cases (a sparse raw file
changes allocation if it is read-write and the amount of holes is
changing, and a read-write qcow2 image stored in a file changes
physical size if it was not fully pre-allocated).  But for
read-only images, even this should be something we can remember
from the previous time, rather than repeating every call.

2. We want to enhance the power of virDomainListGetStats, by
sharing code.  But we already have a virStorageSourcePtr for
each disk, and it would be easier to reuse the common structure
than to have to worry about the one-off virDomainBlockInfoPtr.

While this patch does not optimize reuse of information in point
1, it does get us closer to being able to do so; by updating a
structure that survives between consecutive calls.

* src/util/virstoragefile.h (_virStorageSource): Add physical, to
mirror virDomainBlockInfo; rearrange fields to match public struct.
(virStorageSourceCopy): Copy the new field.
* src/qemu/qemu_driver.c (qemuDomainGetBlockInfo): Store into
storage source, then copy to block info.
Signed-off-by: NEric Blake <eblake@redhat.com>

In order for a future patch to virDomainListGetStats to reuse
some code for determining disk usage of offline domains, we
need to make it easier to pull out part of the guts of grabbing
blockinfo.  The current implementation grabs a job fairly late
in the game, while getstats will already own a job; reordering
things so that the job is always grabbed up front in both
functions will make it easier to pull out the common code.
This patch results in grabbing a job in cases where one was not
previously needed, but as it is a query job, it should not be
noticeably slower.

This patch touches the same code as the fix for CVE-2014-6458
(commit b7992595); in that patch, we avoided hotplug changing
a disk reference during the time of obtaining a monitor lock
by copying all data we needed and no longer referencing disk;
this patch goes the other way and ensures that by holding the
job, the disk cannot be changed so we no longer need to worry
about the disk being invalidated across the monitor lock.

* src/qemu/qemu_driver.c (qemuDomainGetBlockInfo): Rearrange job
control to be outside of disk information.
Signed-off-by: NEric Blake <eblake@redhat.com>