The new API is named as "virDomainBlockResize", intending to add
support for qemu monitor command "block_resize" (both HMP and QMP).
Similar with APIs like "virDomainSetMemoryFlags", the units for
argument "size" is kilobytes.
Add the core functions that implement the functionality of the API.
Suspend is done by using an asynchronous mechanism so that we can return
the status to the caller before the host gets suspended. This asynchronous
operation is achieved by suspending the host in a separate thread of
execution. However, returning the status to the caller is only best-effort,
but not guaranteed.
To resume the host, an RTC alarm is set up (based on how long we want to
suspend) before suspending the host. When this alarm fires, the host
gets woken up.
Suspend-to-RAM operation on a host running Linux can take upto more than 20
seconds, depending on the load of the system. (Freezing of tasks, an operation
preceding any suspend operation, is given up after a 20 second timeout).
And Suspend-to-Disk can take even more time, considering the time required
for compaction, creating the memory image and writing it to disk etc.
So, we do not allow the user to specify a suspend duration of less than 60
seconds, to be on the safer side, since we don't want to prematurely declare
failure when we only had to wait for some more time.
This API can be used to check if the socket associated with
virConnectPtr is still open or it was closed (probably because keepalive
protocol timed out). If there the connection is local (i.e., no socket
is associated with the connection, it is trivially always alive.
virConnectSetKeepAlive public API can be used by a client connecting to
remote server to start using keepalive protocol. The API is handled
directly by remote driver and not transmitted over the wire to the
server.
Given that we can now handle the target's disk shorthand, in addition
to an absolute path to the file or block device used on the host,
the term 'disk' fits a bit better as the parameter name than 'path'.
* include/libvirt/libvirt.h.in: Update some parameter names.
* src/libvirt.c (virDomainBlockStats, virDomainBlockStatsFlags)
(virDomainBlockPeek, virDomainGetBlockInfo, virDomainBlockJobAbort)
(virDomainGetBlockJobInfo, virDomainBlockJobSetSpeed)
(virDomainBlockPull): Likewise.
Commit 89b6284f made it possible to pass either a source name or
the target device to most API demanding a disk designation, but
forgot to update the documentation. It also failed to update
virDomainBlockStats to take both forms. This patch fixes both the
documentation and the remaining function.
Xen continues to use just device shorthand (that is, I did not
implement path lookup there, since xen does not track a domain_conf
to quickly tie a path back to the device shorthand).
* src/libvirt.c (virDomainBlockStats, virDomainBlockStatsFlags)
(virDomainGetBlockInfo, virDomainBlockPeek)
(virDomainBlockJobAbort, virDomainGetBlockJobInfo)
(virDomainBlockJobSetSpeed, virDomainBlockPull): Document
acceptable disk naming conventions.
* src/qemu/qemu_driver.c (qemuDomainBlockStats)
(qemuDomainBlockStatsFlags): Allow lookup by source name.
* src/test/test_driver.c (testDomainBlockStats): Likewise.
Signed-off-by: Eli Qiao <taget@linux.vnet.ibm.com>
When configuring a URI alias like this in 'libvirt.conf':
uri_aliases = [
"jj#j=qemu+ssh://root@127.0.0.1/system",
"sleet=qemu+ssh://root@sleet.cloud.example.com/system",
]
virsh -c jj#j
It will show this error message:
'no connection driver available for No connection for URI jj#j'
Actually，we expect this message below：
Malformed 'uri_aliases' config entry 'jj#j=qemu+ssh://root@127.0.0.1/system', aliases may only contain 'a-Z, 0-9, _, -'
Give this patch to fix this error.
This allows strings to be transported between client and server
in the context of name-type-value virTypedParameter functions.
For compatibility,
o new clients will not send strings to old servers, based on
a feature check
o new servers will not send strings to old clients without the
flag VIR_TYPED_PARAM_STRING_OKAY; this will be enforced at
the RPC layer in the next patch, so that drivers need not
worry about it in general. The one exception is that
virDomainGetSchedulerParameters lacks a flags argument, so
it must not return a string; drivers that forward that
function on to virDomainGetSchedulerParametersFlags will
have to pay attention to the flag.
o the flag VIR_TYPED_PARAM_STRING_OKAY is set automatically,
based on a feature check (so far, no driver implements it),
so clients do not have to worry about it
Future patches can then enable the feature on a per-driver basis.
This patch also ensures that drivers can blindly strdup() field
names (previously, a malicious client could stuff 80 non-NUL bytes
into field and cause a read overrun).
* src/libvirt_internal.h (VIR_DRV_FEATURE_TYPED_PARAM_STRING): New
driver feature.
* src/libvirt.c (virTypedParameterValidateSet)
(virTypedParameterSanitizeGet): New helper functions.
(virDomainSetMemoryParameters, virDomainSetBlkioParameters)
(virDomainSetSchedulerParameters)
(virDomainSetSchedulerParametersFlags)
(virDomainGetMemoryParameters, virDomainGetBlkioParameters)
(virDomainGetSchedulerParameters)
(virDomainGetSchedulerParametersFlags, virDomainBlockStatsFlags):
Use them.
* src/util/util.h (virTypedParameterArrayClear): New helper
function.
* src/util/util.c (virTypedParameterArrayClear): Implement it.
* src/libvirt_private.syms (util.h): Export it.
Based on an initial patch by Hu Tao, with feedback from
Daniel P. Berrange.
Signed-off-by: Eric Blake <eblake@redhat.com>
virDomainBlockStatsFlags was missing a check that was present in
virDomainGetMemoryParameters. Additionally, I found that the
existing descriptions were a bit hard to read. A later patch
will fix qemu to return fewer than max parameters if @nparams
was too small on input.
* src/libvirt.c (virDomainGetMemoryParameters)
(virDomainGetBlkioParameters, virDomainGetSchedulerParameters)
(virDomainGetSchedulerParametersFlags):
Tweak documentation wording.
(virDomainBlockStatsFlags): Likewise, and add sanity check.
with /etc/libvirt/libvirt.conf below:
uri_aliases = [
"hail=qemu:///system",
"sleet=qemu+ssh://root 9 115 122 57/system",
"sam=qemu+unix:///system?socket=/var/run/libvirt/libvirt-sock",
]
Neither "virsh -c hailly" nor "hai" should result in matching "hail=qemu:///system"
Fix URI alias prefix matching when connecting
Signed-off-by: Wen Ruo Lv <lvroyce@linux.vnet.ibm.com>
The virDomainOpenGraphics API allows a libvirt client to pass in
a file descriptor for an open socket pair, and get it connected
to the graphics display of the guest. This is limited to working
with local libvirt hypervisors connected over a UNIX domain
socket, since it will use UNIX FD passing
* include/libvirt/libvirt.h.in: Define virDomainOpenGraphics
* src/driver.h: Define driver for virDomainOpenGraphics
* src/libvirt_public.syms, src/libvirt.c: Entry point for
virDomainOpenGraphics
* src/libvirt_internal.h: VIR_DRV_FEATURE_FD_PASSING
Based on a report by Coverity. waitpid() can leak resources if it
fails with EINTR, so it should never be used without checking return
status. But we already have a helper function that does that, so
use it in more places.
* src/lxc/lxc_container.c (lxcContainerAvailable): Use safer
virWaitPid.
* daemon/libvirtd.c (daemonForkIntoBackground): Likewise.
* tests/testutils.c (virtTestCaptureProgramOutput, virtTestMain):
Likewise.
* src/libvirt.c (virConnectAuthGainPolkit): Simplify with virCommand.
This adds support for a libvirt client configuration file
either /etc/libvirt/libvirt.conf for privileged clients,
or $HOME/.libvirt/libvirt.conf for unprivileged clients.
It allows one parameter
uri_aliases = [
"hail=qemu+ssh://root@hail.cloud.example.com/system",
"sleet=qemu+ssh://root@sleet.cloud.example.com/system",
]
Any call to virConnectOpen with a non-NULL URI will first
attempt to match against the uri_aliases list. An application
can disable this by using VIR_CONNECT_NO_ALIASES
* docs/uri.html.in: Document URI aliases
* include/libvirt/libvirt.h.in: Add VIR_CONNECT_NO_ALIASES
* libvirt.spec.in, mingw32-libvirt.spec.in: Add /etc/libvirt/libvirt.conf
* src/Makefile.am: Install default config file
* src/libvirt.c: Add support for URI aliases
* src/remote/remote_driver.c: Don't try to handle URIs
with no scheme and which clearly are not paths
* src/util/conf.c: Don't raise error on virConfFree(NULL)
* src/xen/xen_driver.c: Don't raise error on URIs
with no scheme
The previous API addition allowed traversal up the hierarchy;
this one makes it easier to traverse down the hierarchy.
In the python bindings, virDomainSnapshotNumChildren can be
generated, but virDomainSnapshotListChildrenNames had to copy
from the hand-written example of virDomainSnapshotListNames.
* include/libvirt/libvirt.h.in (virDomainSnapshotNumChildren)
(virDomainSnapshotListChildrenNames): New prototypes.
(VIR_DOMAIN_SNAPSHOT_LIST_DESCENDANTS): New flag alias.
* src/libvirt.c (virDomainSnapshotNumChildren)
(virDomainSnapshotListChildrenNames): New functions.
* src/libvirt_public.syms: Export them.
* src/driver.h (virDrvDomainSnapshotNumChildren)
(virDrvDomainSnapshotListChildrenNames): New callbacks.
* python/generator.py (skip_impl, nameFixup): Update lists.
* python/libvirt-override-api.xml: Likewise.
* python/libvirt-override.c
(libvirt_virDomainSnapshotListChildrenNames): New wrapper function.
Although reverting to a snapshot is a form of data loss, this is
normally expected. However, there are two cases where additional
surprises (failure to run the reverted state, or a break in
connectivity to the domain) can come into play. Requiring extra
acknowledgment in these cases will make it less likely that
someone can get into an unrecoverable state due to a default revert.
Also create a new error code, so users can distinguish when forcing
would make a difference, rather than having to blindly request force.
* include/libvirt/libvirt.h.in (VIR_DOMAIN_SNAPSHOT_REVERT_FORCE):
New flag.
* src/libvirt.c (virDomainRevertToSnapshot): Document it.
* include/libvirt/virterror.h (VIR_ERR_SNAPSHOT_REVERT_RISKY): New
error value.
* src/util/virterror.c (virErrorMsg): Implement it.
* tools/virsh.c (cmdDomainSnapshotRevert): Add --force to virsh.
* tools/virsh.pod (snapshot-revert): Document it.
Although a client can already obtain a snapshot's parent by
dumping and parsing the xml, then doing a snapshot lookup by
name, it is more efficient to get the parent in one step, which
in turn will make operations that must traverse a snapshot
hierarchy easier to perform.
* include/libvirt/libvirt.h.in (virDomainSnapshotGetParent):
Declare.
* src/libvirt.c (virDomainSnapshotGetParent): New function.
* src/libvirt_public.syms: Export it.
* src/driver.h (virDrvDomainSnapshotGetParent): New callback.
Documentation did not specify, that some permissions are required on
target path for coredump for the user running the hypervisor.
Diff to v1:
- reword statements
These functions access internals of the opaque object, and do
not need any rpc counterpart. It could be argued that we should
have provided these when snapshot objects were first introduced,
since all the other vir*Ptr objects have at least a GetName accessor.
* include/libvirt/libvirt.h.in (virDomainSnapshotGetName)
(virDomainSnapshotGetDomain, virDomainSnapshotGetConnect): Declare.
* src/libvirt.c (virDomainSnapshotGetName)
(virDomainSnapshotGetDomain, virDomainSnapshotGetConnect): New
functions.
* src/libvirt_public.syms: Export them.
Prior to this patch, <domainsnapshot>/<disks> was ignored. This
changes it to be an error unless an explicit disk snapshot is
requested (a future patch may relax things if it turns out to
be useful to have a <disks> specification alongside a system
checkpoint).
* include/libvirt/libvirt.h.in
(VIR_DOMAIN_SNAPSHOT_CREATE_DISK_ONLY): New flag.
* src/libvirt.c (virDomainSnapshotCreateXML): Document it.
* src/esx/esx_driver.c (esxDomainSnapshotCreateXML): Disk
snapshots not supported yet.
* src/vbox/vbox_tmpl.c (vboxDomainSnapshotCreateXML): Likewise.
* src/qemu/qemu_driver.c (qemuDomainSnapshotCreateXML): Likewise.
Since a snapshot is fully recoverable, it is useful to have a
snapshot as a means of hibernating a guest, then reverting to
the snapshot to wake the guest up. This mode of usage is
similar to 'virsh save/virsh restore', except that virsh
save uses an external file while virsh snapshot keeps the
vm state internal to a qcow2 file. However, it only works on
persistent domains.
In the usage pattern of snapshot/revert for hibernating a guest,
there is no need to keep the guest running between the two points
in time, especially since that would generate runtime state that
would just be discarded. Add a flag to make it possible to
stop the domain after the snapshot has completed.
* include/libvirt/libvirt.h.in (VIR_DOMAIN_SNAPSHOT_CREATE_HALT):
New flag.
* src/libvirt.c (virDomainSnapshotCreateXML): Document it.
* src/qemu/qemu_driver.c (qemuDomainSnapshotCreateXML)
(qemuDomainSnapshotCreateActive): Implement it.
Reverting to a state prior to an external snapshot risks
corrupting any other branches in the snapshot hierarchy that
were using the snapshot as a read-only backing file. So
disk snapshot code will default to preventing reverting to
a snapshot that has any children, meaning that deleting just
the children of a snapshot becomes a useful operation in
preparing that snapshot for being a future reversion target.
The code for the new flag is simple - it's one less deletion,
plus a tweak to keep the current snapshot correct.
* include/libvirt/libvirt.h.in
(VIR_DOMAIN_SNAPSHOT_DELETE_CHILDREN_ONLY): New flag.
* src/libvirt.c (virDomainSnapshotDelete): Document it, and
enforce mutual exclusion.
* src/qemu/qemu_driver.c (qemuDomainSnapshotDelete): Implement
it.
Just like VM saved state images (virsh save), snapshots MUST
track the inactive domain xml to detect any ABI incompatibilities.
The indentation is not perfect, but functionality comes before form.
Later patches will actually supply a full domain; for now, this
wires up the storage to support one, but doesn't ever generate one
in dumpxml output.
Happily, libvirt.c was already rejecting use of VIR_DOMAIN_XML_SECURE
from read-only connections, even though before this patch, there was
no information to be secured by the use of that flag.
And while we're at it, mark the libvirt snapshot metadata files
as internal-use only.
* src/libvirt.c (virDomainSnapshotGetXMLDesc): Document flag.
* src/conf/domain_conf.h (_virDomainSnapshotDef): Add member.
(virDomainSnapshotDefParseString, virDomainSnapshotDefFormat):
Update signature.
* src/conf/domain_conf.c (virDomainSnapshotDefFree): Clean up.
(virDomainSnapshotDefParseString): Optionally parse domain.
(virDomainSnapshotDefFormat): Output full domain.
* src/esx/esx_driver.c (esxDomainSnapshotCreateXML)
(esxDomainSnapshotGetXMLDesc): Update callers.
* src/vbox/vbox_tmpl.c (vboxDomainSnapshotCreateXML)
(vboxDomainSnapshotGetXMLDesc): Likewise.
* src/qemu/qemu_driver.c (qemuDomainSnapshotCreateXML)
(qemuDomainSnapshotLoad, qemuDomainSnapshotGetXMLDesc)
(qemuDomainSnapshotWriteMetadata): Likewise.
* docs/formatsnapshot.html.in: Rework doc example.
Based on a patch by Philipp Hahn.
Just as leaving managed save metadata behind can cause problems
when creating a new domain that happens to collide with the name
of the just-deleted domain, the same is true of leaving any
snapshot metadata behind. For safety sake, extend the semantic
change of commit b26a9fa9 to also cover snapshot metadata as a
reason to reject undefining an inactive domain. A future patch
will make sure that shutdown of a transient domain automatically
deletes snapshot metadata (whether by destroy, shutdown, or
guest-initiated action). Management apps of transient domains
should take care to capture xml of snapshots, if it is necessary
to recreate the snapshot metadata on a later transient domain
with the same name and uuid.
This also documents a new flag that hypervisors can choose to
support as a shortcut for taking care of the metadata as part of
the undefine process; however, nontrivial driver support for these
flags will be deferred to future patches.
Note that ESX and VBox can never be transient; therefore, they
do not have to worry about automatic cleanup after shutdown
(the persistent domain still remains); likewise they never
store snapshot metadata, so the undefine flag is trivial.
The nontrivial work remaining is thus in the qemu driver.
* include/libvirt/libvirt.h.in
(VIR_DOMAIN_UNDEFINE_SNAPSHOTS_METADATA): New flag.
* src/libvirt.c (virDomainUndefine, virDomainUndefineFlags):
Document new limitations and flag.
* src/esx/esx_driver.c (esxDomainUndefineFlags): Trivial
implementation.
* src/vbox/vbox_tmpl.c (vboxDomainUndefineFlags): Likewise.
* src/qemu/qemu_driver.c (qemuDomainUndefineFlags): Enforce
the limitations.
The first two flags are essential for being able to replicate
snapshot hierarchies across multiple hosts, which will come in
handy for supervised migrations. It also allows a management app
to take a snapshot of a transient domain, save the metadata, stop
the domain, recreate a new transient domain by the same name,
redefine the snapshot, then revert to it.
This is not quite as convenient as leaving the metadata behind
after a domain is no longer around, but doing that has a few
problems: 1. the libvirt API can only delete snapshot metadata
if there is a valid domain handle to use to get to that snapshot
object - if stale data is left behind without a domain, there is
no way to request that the data be cleaned up. 2. creating a new
domain with the same name but different uuid than the older
domain where a snapshot existed cannot use the older snapshot
data; this risks confusing libvirt, and forbidding the stale
data is similar to the recent patch to forbid stale managed save.
The first two flags might be useful on hypervisors with no metadata,
but only for modifying the notion of the current snapshot;
however, I don't know how to do that for ESX or VBox.
The third flag is a convenience option, to combine a creation with
a delete metadata into one step. It is trivial for hypervisors
with no metadata.
The qemu changes will be involved enough to warrant a separate patch.
* include/libvirt/libvirt.h.in
(VIR_DOMAIN_SNAPSHOT_CREATE_REDEFINE)
(VIR_DOMAIN_SNAPSHOT_CREATE_CURRENT)
(VIR_DOMAIN_SNAPSHOT_CREATE_NO_METADATA): New flags.
* src/libvirt.c (virDomainSnapshotCreateXML): Document them, and
enforce mutual exclusion.
* src/esx/esx_driver.c (esxDomainSnapshotCreateXML): Trivial
implementation.
* src/vbox/vbox_tmpl.c (vboxDomainSnapshotCreateXML): Likewise.
* docs/formatsnapshot.html.in: Document re-creation.
To make it easier to know when undefine will fail because of existing
snapshot metadata, we need to know how many snapshots have metadata.
Also, it is handy to filter the list of snapshots to just those that
have no parents; document that flag now, but implement it in later patches.
* include/libvirt/libvirt.h.in (VIR_DOMAIN_SNAPSHOT_LIST_ROOTS)
(VIR_DOMAIN_SNAPSHOT_LIST_METADATA): New flags.
* src/libvirt.c (virDomainSnapshotNum)
(virDomainSnapshotListNames): Document them.
* src/esx/esx_driver.c (esxDomainSnapshotNum)
(esxDomainSnapshotListNames): Implement trivial flag.
* src/vbox/vbox_tmpl.c (vboxDomainSnapshotNum)
(vboxDomainSnapshotListNames): Likewise.
* src/qemu/qemu_driver.c (qemuDomainSnapshotNum)
(qemuDomainSnapshotListNames): Likewise.
A future patch will make it impossible to remove a domain if it
would leave behind any libvirt-tracked metadata about snapshots,
since stale metadata interferes with a new domain by the same name.
But requiring snaphot contents to be deleted before removing a
domain is harsh; with qemu, qemu-img can still make use of the
contents after the libvirt domain is gone. Therefore, we need
an option to get rid of libvirt tracking information, but not
the actual contents. For hypervisors that do not track any
metadata in libvirt, the implementation is trivial; all remaining
hypervisors (really, just qemu) will be dealt with separately.
* include/libvirt/libvirt.h.in
(VIR_DOMAIN_SNAPSHOT_DELETE_METADATA_ONLY): New flag.
* src/libvirt.c (virDomainSnapshotDelete): Document it.
* src/esx/esx_driver.c (esxDomainSnapshotDelete): Trivially
supported when there is no libvirt metadata.
* src/vbox/vbox_tmpl.c (vboxDomainSnapshotDelete): Likewise.
While it is nice that snapshots and saved images remember whether
the domain was running or paused, sometimes the restoration phase
wants to guarantee a particular state (paused to allow hot-plugging,
or running without needing to call resume). This introduces new
flags to allow the control, and a later patch will implement the
flags for qemu.
* include/libvirt/libvirt.h.in (VIR_DOMAIN_SAVE_RUNNING)
(VIR_DOMAIN_SAVE_PAUSED, VIR_DOMAIN_SNAPSHOT_REVERT_RUNNING)
(VIR_DOMAIN_SNAPSHOT_REVERT_PAUSED): New flags.
* src/libvirt.c (virDomainSaveFlags, virDomainRestoreFlags)
(virDomainManagedSave, virDomainSaveImageDefineXML)
(virDomainRevertToSnapshot): Document their use, and enforce
mutual exclusion.
This patch adds the ability to make the filesystem for a filesystem
pool during a pool build.
The patch adds two new flags, no overwrite and overwrite, to control
when mkfs gets executed. By default, the patch preserves the
current behavior, i.e., if no flags are specified, pool build on a
filesystem pool only makes the directory on which the filesystem
will be mounted.
If the no overwrite flag is specified, the target device is checked
to determine if a filesystem of the type specified in the pool is
present. If a filesystem of that type is already present, mkfs is
not executed and the build call returns an error. Otherwise, mkfs
is executed and any data present on the device is overwritten.
If the overwrite flag is specified, mkfs is always executed, and any
existing data on the target device is overwritten unconditionally.
There is no reason to forbid pausing an autodestroy domain
(not to mention that 'virsh start --paused --autodestroy'
succeeds in creating a paused autodestroy domain).
Meanwhile, qemu was failing to enforce the API documentation that
autodestroy domains cannot be saved. And while the original
documentation only mentioned save/restore, snapshots are another
form of saving that are close enough in semantics as to make no
sense on one-shot domains.
* src/qemu/qemu_driver.c (qemudDomainSuspend): Drop bogus check.
(qemuDomainSaveInternal, qemuDomainSnapshotCreateXML): Forbid
saves of autodestroy domains.
* src/libvirt.c (virDomainCreateWithFlags, virDomainCreateXML):
Document snapshot interaction.
There have been several instances of people having problems with
a broken managed save file, and not aware that they could use
'virsh managedsave-remove dom' to fix things. Making it possible
to do this as part of starting a domain makes the same functionality
easier to find, and one less API call.
* include/libvirt/libvirt.h.in (VIR_DOMAIN_START_FORCE_BOOT): New
flag.
* src/libvirt.c (virDomainCreateWithFlags): Document it.
* src/qemu/qemu_driver.c (qemuDomainObjStart): Alter signature.
(qemuAutostartDomain, qemuDomainStartWithFlags): Update callers.
* tools/virsh.c (cmdStart): Expose it in virsh.
* tools/virsh.pod (start): Document it.
When virStreamAbort is called on a stream that has not been used yet,
quite confusing error is returned: "this function is not supported by
the connection driver". Let's just ignore such streams as there's
nothing to abort anyway.
If migration failed on source daemon, the migration is automatically
canceled by the daemon itself. Thus we don't need to call
virDomainMigrateConfirm3(cancelled=1). Calling it doesn't cause any harm
but the resulting error message printed in logs may confuse people.
* src/qemu/qemu_migration.c: avoid dead 'ret' assignment and silence
clang warning.
Detected by ccc-analyzer:
libvirt.c:4277:5: warning: Value stored to 'ret' is never read
ret = domain->conn->driver->domainMigrateConfirm3
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I was testing a virsh patch, and wanted to see if I had passed the
flags I thought. But with LIBVIRT_DEBUG in the environment, I just
saw:
14:24:52.359: 15022: debug : virDomainSnapshotNum:15586 : dom=0xc9c180, (VM: name=rhel_6-64, uuid=48f8e8e7-e14f-0e14-02f0-ce71997bdcab),
including a trailing space. This fixes the issues.
* src/libvirt.c: Log flag parameters, even if currently unused.
(VIR_DOMAIN_DEBUG_0): Drop trailing comma in log.
(VIR_DOMAIN_DEBUG_1): Split guts into...
(VIR_DOMAIN_DEBUG_2): ...new macro.
Transient domains reject attempts to set autostart, and using
virDomainCreate to restart a domain only works on persistent
domains. Therefore, managed save makes no sense on transient
domains, and should be rejected up front rather than creating
an otherwise unrecoverable managed save file.
Besides, transient domains imply that a lot more management is
being done by the upper layer; this includes the assumption
that the upper layer is okay managing the saved state file
created by virDomainSave, and does not need to use managed save.
* src/libvirt.c: Document that transient domains are incompatible
with managed save.
* src/qemu/qemu_driver.c (qemuDomainManagedSave): Enforce it.
* src/libxl/libxl_driver.c (libxlDomainManagedSave): Likewise.
