[libvirt] [PATCH v5 4/4] blockcommit: turn on active commit
With this in place, I can (finally!) now do:
virsh blockcommit $dom vda --shallow --verbose --pivot
and watch qemu shorten the backing chain by one, followed by
libvirt automatically updating the dumpxml output, effectively
undoing the work of virsh snapshot-commit --no-metadata --disk-only.
Commit is SOOOO much faster than blockpull, when I'm still fairly
close in time to when the temporary qcow2 wrapper file was created
via a snapshot operation!
* src/qemu/qemu_driver.c (qemuDomainBlockCommit): Implement live
commit.
Signed-off-by: Eric Blake <eblake(a)redhat.com>
---
src/qemu/qemu_driver.c | 36 ++++++++++++++++++++++++++++++++----
1 file changed, 32 insertions(+), 4 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 683eaf3..9cf8fe8 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -15517,9 +15517,11 @@ qemuDomainBlockCommit(virDomainPtr dom,
char *topPath = NULL;
char *basePath = NULL;
char *backingPath = NULL;
+ virStorageSourcePtr mirror = NULL;
- /* XXX Add support for COMMIT_ACTIVE, COMMIT_DELETE */
+ /* XXX Add support for COMMIT_DELETE */
virCheckFlags(VIR_DOMAIN_BLOCK_COMMIT_SHALLOW |
+ VIR_DOMAIN_BLOCK_COMMIT_ACTIVE |
VIR_DOMAIN_BLOCK_COMMIT_RELATIVE, -1);
if (!(vm = qemuDomObjFromDomain(dom)))
@@ -15568,9 +15570,6 @@ qemuDomainBlockCommit(virDomainPtr dom,
&top_parent)))
goto endjob;
- /* FIXME: qemu 2.0 supports active commit, but as a two-stage
- * process; qemu 2.1 is further improving active commit. We need
- * to start supporting it in libvirt. */
if (topSource == disk->src) {
if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_ACTIVE_COMMIT)) {
virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
@@ -15584,6 +15583,12 @@ qemuDomainBlockCommit(virDomainPtr dom,
disk->dst);
goto endjob;
}
+ if (disk->mirror) {
+ virReportError(VIR_ERR_BLOCK_COPY_ACTIVE,
+ _("disk '%s' already in active block job"),
+ disk->dst);
+ goto endjob;
+ }
} else if (flags & VIR_DOMAIN_BLOCK_COMMIT_ACTIVE) {
virReportError(VIR_ERR_INVALID_ARG,
_("active commit requested but '%s' is not
active"),
@@ -15614,6 +15619,16 @@ qemuDomainBlockCommit(virDomainPtr dom,
goto endjob;
}
+ /* For an active commit, clone enough of the base to act as the mirror */
+ if (topSource == disk->src) {
+ if (!(mirror = virStorageSourceCopy(baseSource, false)))
+ goto endjob;
+ if (virStorageSourceInitChainElement(mirror,
+ disk->src,
+ false) < 0)
+ goto endjob;
+ }
+
/* For the commit to succeed, we must allow qemu to open both the
* 'base' image and the parent of 'top' as read/write; 'top'
might
* not have a parent, or might already be read-write. XXX It
@@ -15665,6 +15680,18 @@ qemuDomainBlockCommit(virDomainPtr dom,
bandwidth);
qemuDomainObjExitMonitor(driver, vm);
+ if (ret == 0 && mirror) {
+ virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
+
+ disk->mirror = mirror;
+ mirror = NULL;
+ disk->mirrorJob = VIR_DOMAIN_BLOCK_JOB_TYPE_ACTIVE_COMMIT;
+ if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm) < 0)
+ VIR_WARN("Unable to save status on vm %s after block job",
+ vm->def->name);
+ virObjectUnref(cfg);
+ }
+
endjob:
if (ret < 0 && clean_access) {
/* Revert access to read-only, if possible. */
@@ -15674,6 +15701,7 @@ qemuDomainBlockCommit(virDomainPtr dom,
qemuDomainPrepareDiskChainElement(driver, vm, top_parent,
VIR_DISK_CHAIN_READ_ONLY);
}
+ virStorageSourceFree(mirror);
if (!qemuDomainObjEndJob(driver, vm))
vm = NULL;
--
1.9.3