Some of the error messages in this function should have been
virReportSystemError (since they have an errno they want to log), but
were mistakenly written as netlinkError, which expects a libvirt error
code instead. The result was that when one of the errors was
encountered, "No error message provided" would be printed instead of
something meaningful (see
https://bugzilla.redhat.com/show_bug.cgi?id=816465 for an example).

Once qemu monitor reports migration has completed, we just closed our
end of the pipe and let migration tunnel die. This generated bogus error
in case we did so before the thread saw EOF on the pipe and migration
was aborted even though it was in fact successful.

With this patch we first wake up the tunnel thread and once it has read
all data from the pipe and finished the stream we close the
filedescriptor.

A small additional bonus of this patch is that real errors reported
inside qemuMigrationIOFunc are not overwritten by virStreamAbort any
more.

When QEMU reported failed or canceled migration, we correctly detected
it but didn't really consider it as an error condition and migration
protocol just went on. Luckily, some of the subsequent steps eventually
failed end we reported an (unrelated and mostly random) error back to
the caller.

Currently, non-blocking calls are either sent immediately or discarded
in case sending would block. This was implemented based on the
assumption that the non-blocking keepalive call is not needed as there
are other calls in the queue which would keep the connection alive.
However, if those calls are no-reply calls (such as those carrying
stream data), the remote party knows the connection is alive but since
we don't get any reply from it, we think the connection is dead.

This is most visible in tunnelled migration. If it happens to be longer
than keepalive timeout (30s by default), it may be unexpectedly aborted
because the connection is considered to be dead.

With this patch, we only discard non-blocking calls when the last call
with a thread is completed and thus there is no thread left to keep
sending the remaining non-blocking calls.

In some cases (spotted with broken connection during tunneled migration)
we were overwriting the original error with worse or even misleading
errors generated when we were cleaning up after failed migration.

The docs for virConnectSetKeepAlive() advertise that this function
should be able to disable keepalives on negative or zero interval time.

This patch removes the check that prohibited this and adds code to
disable keepalives on negative/zero interval.

* src/libvirt.c: virConnectSetKeepAlive(): - remove check for negative
                                             values
* src/rpc/virnetclient.c
* src/rpc/virnetclient.h: - add virNetClientKeepAliveStop() to disable
                            keepalive messages
* src/remote/remote_driver.c: remoteSetKeepAlive(): -add ability to
                                                     disable keepalives

This patch resolves https://bugzilla.redhat.com/show_bug.cgi?id=815270

The function virNetDevMacVLanVPortProfileRegisterCallback() takes an
arg "virtPortProfile", and was checking it for non-NULL before using
it. However, the prototype for
virNetDevMacVLanPortProfileRegisterCallback had marked that arg with
ATTRIBUTE_NONNULL(). Contrary to what one may think,
ATTRIBUTE_NONNULL() does not provide any guarantee that an arg marked
as such really is always non-null; the only effect to the code
generated by gcc, is that gcc *assumes* it is non-NULL; this results
in, for example, the check for a non-NULL value being optimized out.

(Unfortunately, this code removal only occurs when optimization is
enabled, and I am in the habit of doing local builds with optimization
off to ease debugging, so the bug didn't show up in my earlier local
testing).

In general, virPortProfile might always be NULL, so it shouldn't be
marked as ATTRIBUTE_NONNULL. One other function prototype made this
same error, so this patch fixes it as well.

Commit 8fe455fd tried to work around
a regression introduced in upstream gnulib that requires gettext 0.18
or newer on all projects using bootstrap, by making libvirt require
gettext 0.18.  But this fails on RHEL 6.2, which still ships gettext
0.17.  Revert that change, and instead, import the latest round of
gnulib updates that fix that problem properly.

If you have already built in the window where libvirt required 0.18,
be aware that incremental updates may run into problems: this is
because 'autopoint --force' will not downgrade m4/po.m4 back to an
older version, but it must be downgraded back to 0.17 levels to work
with this patch.  You may either manually remove that file then rerun
bootstrap, or it may prove easier to just clean up all non-git files
to start from a clean slate.

* bootstrap.conf: Revert minimum gettext back to 0.17.
* configure.ac: Likewise.
* .gnulib: Update to latest, for bootstrap fixes.
* bootstrap: Resync from gnulib.

Add 2 new functions to the virSocketAddr 'class':

- virSocketAddrEqual: tests whether two IP addresses and their ports are equal
- virSocketaddSetIPv4Addr: set a virSocketAddr given a 32 bit int

Use embedded buffers for the MAC addresses and the VM's UUID.

This patch improves the previously added virAtomicInt implementation
by using gcc-builtins if possible. The needed builtins are available
since GCC >= 4.1. At least the 4.0 docs don't mention them.

Commit c9cd419c added copying of the
makefile for translation files from gnulib. The makefile from gnulib is
of version 0.18 but the build configuration cretes macros from version
0.17 which breaks the build with message:

*** error: gettext infrastructure mismatch: using a Makefile.in.in from
gettext version 0.18 but the autoconf macros are from gettext version
0.17

vboxArray is not castable to a COM item type. vboxArray is a
wrapper around the XPCOM and MSCOM specific array handling.

In this case we can avoid passing NULL as an empty array to
IMachine::Delete by passing a dummy IMedium* array with a single
NULL item.

This will only work for veth devices since venet devices don't have
a target element.

In order to track a block copy job across libvirtd restarts, we
need to save internal XML that tracks the name of the file
holding the mirror.  Displaying this name in dumpxml might also
be useful to the user, even if we don't yet have a way to (re-)
start a domain with mirroring enabled up front.  This is done
with a new <mirror> sub-element to <disk>, as in:

    <disk type='file' device='disk'>
      <driver name='qemu' type='raw'/>
      <source file='/var/lib/libvirt/images/original.img'/>
      <mirror file='/var/lib/libvirt/images/copy.img' format='qcow2' ready='yes'/>
      ...
    </disk>

For now, the element is output-only, in live domains; it is ignored
when defining a domain or hot-plugging a disk (since those contexts
use VIR_DOMAIN_XML_INACTIVE in parsing).  The 'ready' attribute appears
when libvirt knows that the job has changed from the initial pulling
phase over to the mirroring phase, although absence of the attribute
is not a sure indicator of the current phase.  If we come up with a way
to make qemu start with mirroring enabled, we can relax the xml
restriction, and allow <mirror> (but not attribute 'ready') on input.
Testing active-only XML meant tweaking the testsuite slightly, but it
was worth it.

* docs/schemas/domaincommon.rng (diskspec): Add diskMirror.
* docs/formatdomain.html.in (elementsDisks): Document it.
* src/conf/domain_conf.h (_virDomainDiskDef): New members.
* src/conf/domain_conf.c (virDomainDiskDefFree): Clean them.
(virDomainDiskDefParseXML): Parse them, but only internally.
(virDomainDiskDefFormat): Output them.
* tests/qemuxml2argvdata/qemuxml2argv-disk-mirror.xml: New test file.
* tests/qemuxml2xmloutdata/qemuxml2xmlout-disk-mirror.xml: Likewise.
* tests/qemuxml2xmltest.c (testInfo): Alter members.
(testCompareXMLToXMLHelper): Allow more test control.
(mymain): Run new test.

Rather than further overloading 'blockpull', I decided to create a
new virsh command to expose the new flags of virDomainBlockRebase.

Blocking until the command completes naturally is pointless, since
the block copy job is intended to run indefinitely.  Instead, I
made the command support three --wait modes: by default, it runs until
mirroring is started; with --pivot, it pivots as soon as mirroring
is started; and with --finish, it aborts (for a clean copy) as
soon as mirroring is started.

* tools/virsh.c (VSH_CMD_BLOCK_JOB_COPY): New mode.
(blockJobImpl): Support new flags.
(cmdBlockCopy): New command.
(cmdBlockJob): Support new job info, new abort flag.
* tools/virsh.pod (blockcopy, blockjob): Document the new command
and flags.

This patch introduces a new block job, useful for live storage
migration using pre-copy streaming.  Justification for including
this under virDomainBlockRebase rather than adding a new command
includes: 1) there are now two possible block jobs in qemu, with
virDomainBlockRebase starting either type of command, and
virDomainBlockJobInfo and virDomainBlockJobAbort working to end
either type; 2) reusing this command allows distros to backport
this feature to the libvirt 0.9.10 API without a .so bump.

Note that a future patch may add a more powerful interface named
virDomainBlockJobCopy, dedicated to just the block copy job, in
order to expose even more options (such as setting an arbitrary
format type for the destination without having to probe it from a
pre-existing destination file); adding a new command for targetting
just block copy would be similar to how we already have
virDomainBlockPull for targetting just the block pull job.

Using a live VM with the backing chain:
  base <- snap1 <- snap2
as the starting point, we have:

- virDomainBlockRebase(dom, disk, "/path/to/copy", 0,
    VIR_DOMAIN_BLOCK_REBASE_COPY)
creates /path/to/copy with the same format as snap2, with no backing
file, so entire chain is copied and flattened

- virDomainBlockRebase(dom, disk, "/path/to/copy", 0,
    VIR_DOMAIN_BLOCK_REBASE_COPY|VIR_DOMAIN_BLOCK_REBASE_COPY_RAW)
creates /path/to/copy as a raw file, so entire chain is copied and
flattened

- virDomainBlockRebase(dom, disk, "/path/to/copy", 0,
    VIR_DOMAIN_BLOCK_REBASE_COPY|VIR_DOMAIN_BLOCK_REBASE_SHALLOW)
creates /path/to/copy with the same format as snap2, but with snap1 as
a backing file, so only snap2 is copied.

- virDomainBlockRebase(dom, disk, "/path/to/copy", 0,
    VIR_DOMAIN_BLOCK_REBASE_COPY|VIR_DOMAIN_BLOCK_REBASE_REUSE_EXT)
reuse existing /path/to/copy (must have empty contents, and format is
probed[*] from the metadata), and copy the full chain

- virDomainBlockRebase(dom, disk, "/path/to/copy", 0,
    VIR_DOMAIN_BLOCK_REBASE_COPY|VIR_DOMAIN_BLOCK_REBASE_REUSE_EXT|
    VIR_DOMAIN_BLOCK_REBASE_SHALLOW)
reuse existing /path/to/copy (contents must be identical to snap1,
and format is probed[*] from the metadata), and copy only the contents
of snap2

- virDomainBlockRebase(dom, disk, "/path/to/copy", 0,
    VIR_DOMAIN_BLOCK_REBASE_COPY|VIR_DOMAIN_BLOCK_REBASE_REUSE_EXT|
    VIR_DOMAIN_BLOCK_REBASE_SHALLOW|VIR_DOMAIN_BLOCK_REBASE_COPY_RAW)
reuse existing /path/to/copy (must be raw volume with contents
identical to snap1), and copy only the contents of snap2

Less useful combinations:

- virDomainBlockRebase(dom, disk, "/path/to/copy", 0,
    VIR_DOMAIN_BLOCK_REBASE_COPY|VIR_DOMAIN_BLOCK_REBASE_SHALLOW|
    VIR_DOMAIN_BLOCK_REBASE_COPY_RAW)
fail if source is not raw, otherwise create /path/to/copy as raw and
the single file is copied (no chain involved)

- virDomainBlockRebase(dom, disk, "/path/to/copy", 0,
    VIR_DOMAIN_BLOCK_REBASE_COPY|VIR_DOMAIN_BLOCK_REBASE_REUSE_EXT|
    VIR_DOMAIN_BLOCK_REBASE_COPY_RAW)
makes little sense: the destination must be raw but have no contents,
meaning that it is an empty file, so there is nothing to reuse

The other three flags are rejected without VIR_DOMAIN_BLOCK_COPY.

[*] Note that probing an existing file for its format can be a security
risk _if_ there is a possibility that the existing file is 'raw', in
which case the guest can manipulate the file to appear like some other
format.  But, by virtue of the VIR_DOMAIN_BLOCK_REBASE_COPY_RAW flag,
it is possible to avoid probing of raw files, at which point, probing
of any remaining file type is no longer a security risk.

It would be nice if we could issue an event when pivoting from phase 1
to phase 2, but qemu hasn't implemented that, and we would have to poll
in order to synthesize it ourselves.  Meanwhile, qemu will give us a
distinct job info and completion event when we either cancel or pivot
to end the job.  Pivoting is accomplished via the new:

virDomainBlockJobAbort(dom, disk, VIR_DOMAIN_BLOCK_JOB_ABORT_PIVOT)

Management applications can pre-create the copy with a relative
backing file name, and use the VIR_DOMAIN_BLOCK_REBASE_REUSE_EXT
flag to have qemu reuse the metadata; if the management application
also copies the backing files to a new location, this can be used
to perform live storage migration of an entire backing chain.

* include/libvirt/libvirt.h.in (VIR_DOMAIN_BLOCK_JOB_TYPE_COPY):
New block job type.
(virDomainBlockJobAbortFlags, virDomainBlockRebaseFlags): New enums.
* src/libvirt.c (virDomainBlockRebase): Document the new flags,
and implement general restrictions on flag combinations.
(virDomainBlockJobAbort): Document the new flag.
(virDomainSaveFlags, virDomainSnapshotCreateXML)
(virDomainRevertToSnapshot, virDomainDetachDeviceFlags): Document
restrictions.
* include/libvirt/virterror.h (VIR_ERR_BLOCK_COPY_ACTIVE): New
error.
* src/util/virterror.c (virErrorMsg): Define it.

This patch modifies the CPU comparrison function to report the
incompatibilities in more detail to ease identification of problems.

* src/cpu/cpu.h:
    cpuGuestData(): Add argument to return detailed error message.
* src/cpu/cpu.c:
    cpuGuestData(): Add passthrough for error argument.
* src/cpu/cpu_x86.c
    x86FeatureNames(): Add function to convert a CPU definition to flag
                       names.
    x86Compute(): - Add error message parameter
                  - Add macro for reporting detailed error messages.
                  - Improve error reporting.
                  - Simplify calculation of forbidden flags.
    x86DataIteratorInit():
    x86cpuidMatchAny(): Remove functions that are no longer needed.
* src/qemu/qemu_command.c:
    qemuBuildCpuArgStr(): - Modify for new function prototype
                          - Add detailed error reports
                          - Change error code on incompatible processors
                            to VIR_ERR_CONFIG_UNSUPPORTED instead of
                            internal error
* tests/cputest.c:
    cpuTestGuestData(): Modify for new function prototype

commit 2223ea98 removes src/libvirt_dbus.syms, but it forgets
to remove it from EXTRA_DIST. It will cause 'make dist' failed.

virThreadSelf tries to access the virThreadPtr stored in TLS for the
current thread via TlsGetValue. When virThreadSelf is called on a thread
that was not created via virThreadCreate (e.g. the main thread) then
TlsGetValue returns NULL as TlsAlloc initializes TLS slots to NULL.

virThreadSelf can be called on the main thread via this call chain from
virsh

vshDeinit
virEventAddTimeout
virEventPollAddTimeout
virEventPollInterruptLocked
virThreadIsSelf

triggering a segfault as virThreadSelf unconditionally dereferences the
return value of TlsGetValue.

Fix this by making virThreadSelf check the TLS slot value for NULL and
setting the given virThreadPtr accordingly.

Reported by Marcel Müller.

Caused by commit 4445e16b that
made the code used the connection private data pointer before
it was initialized.

POSIX says that sa_sigaction is only safe to use if sa_flags
includes SA_SIGINFO; conversely, sa_handler is only safe to
use when flags excludes that bit.  Gnulib doesn't guarantee
an implementation of SA_SIGINFO, but does guarantee that
if SA_SIGINFO is undefined, we can safely define it to 0 as
long as we don't dereference the 2nd or 3rd argument of
any handler otherwise registered via sa_sigaction.

Based on a report by Wen Congyang.

* src/rpc/virnetserver.c (SA_SIGINFO): Stub for mingw.
(virNetServerSignalHandler): Avoid bogus dereference.
(virNetServerFatalSignal, virNetServerNew): Set flags properly.
(virNetServerAddSignalHandler): Drop unneeded #ifdef.

I almost copied-and-pasted some redundant () into my new code,
and figured a general cleanup prereq patch would be better instead.

No semantic change.

* src/conf/domain_conf.c (virDomainLeaseDefParseXML)
(virDomainDiskDefParseXML, virDomainFSDefParseXML)
(virDomainActualNetDefParseXML, virDomainNetDefParseXML)
(virDomainGraphicsDefParseXML, virDomainVideoAccelDefParseXML)
(virDomainVideoDefParseXML, virDomainHostdevFind)
(virDomainControllerInsertPreAlloced, virDomainDefParseXML)
(virDomainObjParseXML, virDomainCpuSetFormat)
(virDomainCpuSetParse, virDomainDiskDefFormat)
(virDomainActualNetDefFormat, virDomainNetDefFormat)
(virDomainTimerDefFormat, virDomainGraphicsListenDefFormat)
(virDomainDefFormatInternal, virDomainNetGetActualHostdev)
(virDomainNetGetActualBandwidth, virDomainGraphicsGetListen):
Reduce extra ().

Ensure we don't introduce any more lousy integer parsing in new
code, while avoiding a scrub-down of existing legacy code.

Note that we also need to enable sc_prohibit_atoi_atof (see cfg.mk
local-checks-to-skip) before we are bulletproof, but that also
entails scrubbing I'm not ready to do at the moment.

* src/util/util.c (virStrToLong_i, virStrToLong_ui)
(virStrToLong_l, virStrToLong_ul, virStrToLong_ll)
(virStrToLong_ull, virStrToDouble): Mark exemptions.
* src/util/virmacaddr.c (virMacAddrParse): Likewise.
* cfg.mk (sc_prohibit_strtol): New syntax check.
(exclude_file_name_regexp--sc_prohibit_strtol): Ignore files that
I'm not willing to fix yet.
(local-checks-to-skip): Re-enable sc_prohibit_atoi_atof.

https://bugzilla.redhat.com/show_bug.cgi?id=617711 reported that
even with my recent patched to allow <memory unit='G'>1</memory>,
people can still get away with trying <memory>1G</memory> and
silently get <memory unit='KiB'>1</memory> instead.  While
virt-xml-validate catches the error, our C parser did not.

Not to mention that it's always fun to fix bugs while reducing
lines of code.  :)

* src/conf/domain_conf.c (virDomainParseMemory): Check for parse error.
(virDomainDefParseXML): Avoid strtoll.
* src/conf/storage_conf.c (virStorageDefParsePerms): Likewise.
* src/util/xml.c (virXPathLongBase, virXPathULongBase)
(virXPathULongLong, virXPathLongLong): Likewise.

We were forgetting to check errno for overflow.

* tools/virsh.c (get_integer_keycode, vshCommandOptInt)
(vshCommandOptUInt, vshCommandOptUL, vshCommandOptLongLong)
(vshCommandOptULongLong): Rewrite to be safer.

Commit 78345c68 makes at least gcc 4.1.2 on RHEL 5 complain:

cc1: warnings being treated as errors
In file included from vbox/vbox_V4_0.c:13:
vbox/vbox_tmpl.c: In function 'vboxDomainUndefineFlags':
vbox/vbox_tmpl.c:5298: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]

* src/vbox/vbox_tmpl.c (vboxDomainUndefineFlags): Use union to
avoid compiler warning.

Building a fresh checkout on RHEL 5 has been broken since commit
29db7a00, due to a gnulib regression in the bootstrap script
(incremental builds from a checkout earlier than that point were
okay, though).

* .gnulib: Update to latest, for bootstrap fixes.
* bootstrap: Resync from gnulib.
* gnulib/local/top/maint.mk.diff: Drop patch that was added
upstream in the meantime.

Detected by valgrind, via Alex Jia.  Caused by imcomplete
copy-and-paste from vshWatchJob in commit 3b96a892.

* tools/virsh.c (cmdBlockPull): fix uninitialized memory usage.

* How to reproduce?
$ qemu-img create /var/lib/libvirt/images/test 1M
$ cat > /tmp/test.xml <<EOF
<domain type='qemu'>
  <name>test</name>
  <memory>219200</memory>
  <vcpu>1</vcpu>
  <os>
    <type arch='x86_64'>hvm</type>
    <boot dev='hd'/>
  </os>
  <devices>
    <disk type='file' device='disk'>
      <driver name='qemu' type='raw'/>
      <source file='/var/lib/libvirt/images/test'/>
      <target dev='vda' bus='virtio'/>
    </disk>
    <input type='mouse' bus='ps2'/>
    <graphics type='spice' autoport='yes' listen='0.0.0.0'/>
  </devices>
</domain>
EOF
$ virsh define /tmp/test.xml
$ valgrind -v virsh blockpull test /var/lib/libvirt/images/test --wait

actual result:

==10906== 1 errors in context 1 of 1:
==10906== Syscall param rt_sigaction(act->sa_flags) points to uninitialised byte(s)
==10906==    at 0x39CF80F5BE: __libc_sigaction (sigaction.c:67)
==10906==    by 0x43016C: cmdBlockPull (virsh.c:7638)
==10906==    by 0x4150D4: vshCommandRun (virsh.c:18574)
==10906==    by 0x425E73: main (virsh.c:20178)
==10906==  Address 0x7fefffae8 is on thread 1's stack

DBus connection. The HAL device code further requires that
the DBus connection is integrated with the event loop and
provides such glue logic itself.

The forthcoming FirewallD integration also requires a
dbus connection with event loop integration. Thus we need
to pull the current event loop glue out of the HAL driver.

Thus we create src/util/virdbus.{c,h} files. This contains
just one method virDBusGetSystemBus() which obtains a handle
to the single shared system bus instance, with event glue
automagically setup.

Fix the support for trusted DHCP server in the ebtables code's
hard-coded function applying DHCP only filtering rules:
Rather than using a char * use the more flexible
virNWFilterVarValuePtr that contains the trusted DHCP server(s)
IP address. Process all entries.

Since all callers so far provided NULL as parameter, no changes
are necessary in any other code.

For threading support, add atomic add and sub operations working on
integers. Base this on locking support provided by virMutex.

Implement function to remove all entries of a hash table.

The sequence:
  long long val;
  if ((long long) val != val)
is dead code.

* src/util/util.c (virStrToLong_ll, virStrToLong_ull): Remove
useless cast.

Currently upon a migration a callback is created when a 802.1qbg link
is set to PREASSOCIATE, this should not happen because this is a no-op
on most switches, and does not lead to an ASSOCIATE state.  This patch
only creates callbacks when CREATE or RESTORE is requested.  Migration
and libvirtd restart scenarios are already handled elsewhere.
Signed-off-by: ND. Herrendoerfer <d.herrendoerfer@herrendoerfer.name>

The below patch fixes the following memory leak.

==20624== 24 bytes in 2 blocks are definitely lost in loss record 532 of 1,867
==20624==    at 0x4A05E46: malloc (vg_replace_malloc.c:195)
==20624==    by 0x38EC27FC01: strdup (strdup.c:43)
==20624==    by 0x4EB6BA3: virDomainChrSourceDefCopy (domain_conf.c:1122)
==20624==    by 0x495D76: qemuProcessFindCharDevicePTYs (qemu_process.c:1497)
==20624==    by 0x498321: qemuProcessWaitForMonitor (qemu_process.c:1258)
==20624==    by 0x49B5F9: qemuProcessStart (qemu_process.c:3652)
==20624==    by 0x468B5C: qemuDomainObjStart (qemu_driver.c:4753)
==20624==    by 0x469171: qemuDomainStartWithFlags (qemu_driver.c:4810)
==20624==    by 0x4F21735: virDomainCreate (libvirt.c:8153)
==20624==    by 0x4302BF: remoteDispatchDomainCreateHelper (remote_dispatch.h:852)
==20624==    by 0x4F72C14: virNetServerProgramDispatch (virnetserverprogram.c:416)
==20624==    by 0x4F6D690: virNetServerHandleJob (virnetserver.c:164)
==20624==    by 0x4E8F43D: virThreadPoolWorker (threadpool.c:144)
==20624==    by 0x4E8EAB5: virThreadHelper (threads-pthread.c:161)
==20624==    by 0x38EC606CCA: start_thread (pthread_create.c:301)
==20624==    by 0x38EC2E0C2C: clone (clone.S:115) 

I'm tired of shell-scripting to wait for completion of a block pull,
when virsh can be taught to do the same.  I couldn't quite reuse
vshWatchJob, as this is not a case of a long-running command where
a second thread must be used to probe job status (at least, not unless
I make virsh start doing blocking waits for an event to fire), but it
served as inspiration for my simpler single-threaded loop.  There is
up to a half-second delay between sending SIGINT and the job being
aborted, but I didn't think it worth the complexity of a second thread
and use of poll() just to minimize that delay.

* tools/virsh.c (cmdBlockPull): Add new options to wait for
completion.
(blockJobImpl): Add argument.
(cmdBlockJob): Adjust caller.
* tools/virsh.pod (blockjob): Document new mode.