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: Eric Blake <eblake@redhat.com>
I'm about to make block stats optionally more complex to cover
backing chains, where block.count will no longer equal the number
of <disks> for a domain. For these reasons, it is nicer if the
statistics output includes the source path (for local files).
This patch doesn't add anything for network disks, although we
may decide to add that later.
With this patch, I now see the following for the same domain as
in the previous patch (one qcow2 file, 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.1.name=hdc
* src/libvirt-domain.c (virConnectGetAllDomainStats): Document
new field.
* tools/virsh.pod (domstats): Document new field.
* src/qemu/qemu_driver.c (qemuDomainGetStatsBlock): Return the new
stat for local files/block devices.
(QEMU_ADD_NAME_PARAM): Add parameter.
(qemuDomainGetStatsInterface): Update caller.
Signed-off-by: Eric Blake <eblake@redhat.com>
At least with 'virsh domstats --block' on an offline domain, we
currently output no stats even though we recognize the stat
category. Although a later patch will improve this situation,
it is better to document that this is expected behavior.
Also, while the current implementation rejects filtering flags
for virDomainListGetStats, this limitation may be lifted in the
future and we do not enforce it at the API level.
* src/libvirt-domain.c (virConnectGetAllDomainStats): Document
that recognized stats might not be reported.
(virDomainListGetStats): Likewise, and tweak filtering documentation.
Signed-off-by: Eric Blake <eblake@redhat.com>
Based on previous commit, we can now precreate missing volumes. While
digging out the functionality from storage driver would be nicer, if
you've seen the code it's nearly impossible. So I'm going from the
other end:
1) For given disk target, disk path is looked up.
2) For the disk path, storage pool is looked up, a volume XML is
constructed and then passed to virStorageVolCreateXML() which has all
the knowledge how to create raw images, (encrypted) qcow(2) images,
etc.
One of the advantages of this approach is, we don't have to care about
image conversion - qemu does that for us. So for instance, users can
transform qcow2 into raw on migration (if the correct XML is passed to
the migration API).
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Since our big split of libvirt.c there are only a few functions
living there. The majority was moved to corresponding subfile,
e.g. domain functions were moved to libvirt-domain.c. However,
the patches for virDomainGetFSInfo() and virDomainFSInfoFree()
introduction were posted prior the big split and merged after.
This resulted in two domain functions landing in wrong file.
Move them to the correct one.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Commit 28f8dfd (v1.0.0) introduced a security hole: in at least
the qemu implementation of virDomainGetXMLDesc, the use of the
flag VIR_DOMAIN_XML_MIGRATABLE (which is usable from a read-only
connection) triggers the implicit use of VIR_DOMAIN_XML_SECURE
prior to calling qemuDomainFormatXML. However, the use of
VIR_DOMAIN_XML_SECURE is supposed to be restricted to read-write
clients only. This patch treats the migratable flag as requiring
the same permissions, rather than analyzing what might break if
migratable xml no longer includes secret information.
Fortunately, the information leak is low-risk: all that is gated
by the VIR_DOMAIN_XML_SECURE flag is the VNC connection password;
but VNC passwords are already weak (FIPS forbids their use, and
on a non-FIPS machine, anyone stupid enough to trust a max-8-byte
password sent in plaintext over the network deserves what they
get). SPICE offers better security than VNC, and all other
secrets are properly protected by use of virSecret associations
rather than direct output in domain XML.
* src/remote/remote_protocol.x (REMOTE_PROC_DOMAIN_GET_XML_DESC):
Tighten rules on use of migratable flag.
* src/libvirt-domain.c (virDomainGetXMLDesc): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
