Re: [libvirt] [PATCH v3 5/5] blockcommit: turn on active commit

With this in place, I can (finally!) now do: virsh blockcommit $dom vda --shallow --wait --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 to regular files. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- src/qemu/qemu_driver.c | 43 ++++++++++++++++++++++++++++++++++++++----- 1 file changed, 38 insertions(+), 5 deletions(-) diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 728aa85..60dc9c6 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -15529,9 +15529,11 @@ 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))) @@ -15578,13 +15580,14 @@ 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) { /* We assume that no one will backport qemu 2.0 active commit * to an earlier qemu without also backporting the block job - * ready event; but this makes sure of that fact */ + * ready event; but this makes sure of that fact. + * + * XXX Also need to check other capability bit(s): qemu 1.7 + * supports async blockjob but not active commit; and qemu 2.0 + * active commit misbehaves on 0-byte file. */

if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKJOB_ASYNC)) { virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", _("active commit not supported with this QEMU binary"));

@@ -15667,6 +15678,21 @@ qemuDomainBlockCommit(virDomainPtr dom, } } + /* For an active commit, clone enough of the base to act as the mirror */ + if (mirror) { + /* XXX Support network commits */ + if (baseSource->type != VIR_STORAGE_TYPE_FILE && + baseSource->type != VIR_STORAGE_TYPE_BLOCK) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", + _("active commit to non-file not supported yet")); + goto endjob; + } + mirror->type = baseSource->type; + if (VIR_STRDUP(mirror->path, baseSource->path) < 0) + goto endjob; + mirror->format = baseSource->format; + } + /* Start the commit operation. Pass the user's original spelling, * if any, through to qemu, since qemu may behave differently * depending on whether the input was specified as relative or