[libvirt PATCH v4 18/31] qemu: include nbdkit state in private xml
Jonathon Jongsma
jjongsma at redhat.com
Fri Jan 20 22:03:12 UTC 2023
Add xml to the private data for a disk source to represent the nbdkit
process so that the state can be re-created if the libvirt daemon is
restarted. Format:
<nbdkit>
<pidfile>/path/to/nbdkit.pid</pidfile>
<socketfile>/path/to/nbdkit.socket</socketfile>
</nbdkit>
Signed-off-by: Jonathon Jongsma <jjongsma at redhat.com>
---
src/qemu/qemu_domain.c | 48 ++++++++++++++
src/qemu/qemu_nbdkit.c | 77 +++++++++++++++++++++++
src/qemu/qemu_nbdkit.h | 8 +++
src/qemu/qemu_process.c | 11 ++++
tests/qemustatusxml2xmldata/modern-in.xml | 4 ++
5 files changed, 148 insertions(+)
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 0e3eaf49f8..28d4bddf14 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -1911,6 +1911,29 @@ qemuStorageSourcePrivateDataAssignSecinfo(qemuDomainSecretInfo **secinfo,
}
+static int
+qemuStorageSourcePrivateDataParseNbdkit(xmlNodePtr node,
+ xmlXPathContextPtr ctxt,
+ virStorageSource *src)
+{
+ g_autofree char *pidfile = NULL;
+ g_autofree char *socketfile = NULL;
+ VIR_XPATH_NODE_AUTORESTORE(ctxt);
+
+ ctxt->node = node;
+
+ if (!(pidfile = virXPathString("string(./pidfile)", ctxt)))
+ return -1;
+
+ if (!(socketfile = virXPathString("string(./socketfile)", ctxt)))
+ return -1;
+
+ qemuNbdkitReconnectStorageSource(src, pidfile, socketfile);
+
+ return 0;
+}
+
+
static int
qemuStorageSourcePrivateDataParse(xmlXPathContextPtr ctxt,
virStorageSource *src)
@@ -1921,6 +1944,7 @@ qemuStorageSourcePrivateDataParse(xmlXPathContextPtr ctxt,
g_autofree char *httpcookiealias = NULL;
g_autofree char *tlskeyalias = NULL;
g_autofree char *thresholdEventWithIndex = NULL;
+ xmlNodePtr nbdkitnode = NULL;
src->nodestorage = virXPathString("string(./nodenames/nodename[@type='storage']/@name)", ctxt);
src->nodeformat = virXPathString("string(./nodenames/nodename[@type='format']/@name)", ctxt);
@@ -1964,6 +1988,10 @@ qemuStorageSourcePrivateDataParse(xmlXPathContextPtr ctxt,
virTristateBoolTypeFromString(thresholdEventWithIndex) == VIR_TRISTATE_BOOL_YES)
src->thresholdEventWithIndex = true;
+ if ((nbdkitnode = virXPathNode("nbdkit", ctxt))) {
+ if (qemuStorageSourcePrivateDataParseNbdkit(nbdkitnode, ctxt, src) < 0)
+ return -1;
+ }
return 0;
}
@@ -1981,6 +2009,23 @@ qemuStorageSourcePrivateDataFormatSecinfo(virBuffer *buf,
}
+static void
+qemuStorageSourcePrivateDataFormatNbdkit(qemuNbdkitProcess *nbdkit,
+ virBuffer *buf)
+{
+ g_auto(virBuffer) childBuf = VIR_BUFFER_INIT_CHILD(buf);
+
+ if (!nbdkit)
+ return;
+
+ virBufferEscapeString(&childBuf, "<pidfile>%s</pidfile>\n",
+ nbdkit->pidfile);
+ virBufferEscapeString(&childBuf, "<socketfile>%s</socketfile>\n",
+ nbdkit->socketfile);
+ virXMLFormatElement(buf, "nbdkit", NULL, &childBuf);
+}
+
+
static int
qemuStorageSourcePrivateDataFormat(virStorageSource *src,
virBuffer *buf)
@@ -2019,6 +2064,9 @@ qemuStorageSourcePrivateDataFormat(virStorageSource *src,
if (src->thresholdEventWithIndex)
virBufferAddLit(buf, "<thresholdEvent indexUsed='yes'/>\n");
+ if (srcPriv)
+ qemuStorageSourcePrivateDataFormatNbdkit(srcPriv->nbdkitProcess, buf);
+
return 0;
}
diff --git a/src/qemu/qemu_nbdkit.c b/src/qemu/qemu_nbdkit.c
index 00ca945904..2b26e9bc08 100644
--- a/src/qemu/qemu_nbdkit.c
+++ b/src/qemu/qemu_nbdkit.c
@@ -627,6 +627,83 @@ qemuNbdkitProcessNew(virStorageSource *source,
return nbdkit;
}
+/**
+ * qemuNbdkitReconnectStorageSource:
+ * @source: a storage source
+ * @pidfile: a pidfile for an nbdkit process
+ * @socketfile: the socket file associated with the nbdkit process
+ *
+ * This function constructs a new qemuNbdkitProcess object with the given values for @pidfile and
+ * @socketfile and stores it in @source. This is intended to be called when the libvirt daemon is
+ * restarted and tries to reconnect to all currently-running domains. Since this function is called
+ * from the code that parses the current daemon state, it should not perform any filesystem
+ * operations, or anything else that might fail. Additional initialization will be done later by
+ * calling qemuNbdkitStorageSourceManageProcess().
+ */
+void
+qemuNbdkitReconnectStorageSource(virStorageSource *source,
+ const char *pidfile,
+ const char *socketfile)
+{
+ qemuDomainStorageSourcePrivate *srcpriv = qemuDomainStorageSourcePrivateFetch(source);
+
+ if (srcpriv->nbdkitProcess) {
+ VIR_WARN("source already has an nbdkit process");
+ return;
+ }
+
+ srcpriv->nbdkitProcess = qemuNbdkitProcessNew(source, pidfile, socketfile);
+}
+
+
+static int
+qemuNbdkitStorageSourceManageProcessOne(virStorageSource *source)
+{
+ qemuDomainStorageSourcePrivate *srcpriv = QEMU_DOMAIN_STORAGE_SOURCE_PRIVATE(source);
+ qemuNbdkitProcess *proc;
+
+ if (!srcpriv)
+ return 0;
+
+ proc = srcpriv->nbdkitProcess;
+
+ if (proc) {
+ if (proc->pid <= 0) {
+ if (virPidFileReadPath(proc->pidfile, &proc->pid) < 0)
+ return -1;
+ }
+
+ if (virProcessKill(proc->pid, 0) < 0) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("nbdkit process %i is not alive"), proc->pid);
+ return -1;
+ }
+ }
+
+ return 0;
+}
+
+/**
+ * qemuNbdkitStorageSourceManageProcess:
+ * @source: a storage source
+ * @vm: the vm that owns this storage source
+ *
+ * This function re-enables monitoring of any nbdkit processes associated with the backing chain of
+ * @source. It is intended to be called after libvirt restarts and has loaded its current state from
+ * disk and is attempting to re-connect to active domains.
+ */
+int
+qemuNbdkitStorageSourceManageProcess(virStorageSource *source)
+{
+ virStorageSource *backing;
+ for (backing = source->backingStore; backing != NULL; backing = backing->backingStore) {
+ if (qemuNbdkitStorageSourceManageProcessOne(backing) < 0)
+ return -1;
+ }
+
+ return qemuNbdkitStorageSourceManageProcessOne(source);
+}
+
bool
qemuNbdkitInitStorageSource(qemuNbdkitCaps *caps,
diff --git a/src/qemu/qemu_nbdkit.h b/src/qemu/qemu_nbdkit.h
index ccd418b7d3..2be46b6002 100644
--- a/src/qemu/qemu_nbdkit.h
+++ b/src/qemu/qemu_nbdkit.h
@@ -54,6 +54,14 @@ qemuNbdkitInitStorageSource(qemuNbdkitCaps *nbdkitCaps,
uid_t user,
gid_t group);
+void
+qemuNbdkitReconnectStorageSource(virStorageSource *source,
+ const char *pidfile,
+ const char *socketfile);
+
+int
+qemuNbdkitStorageSourceManageProcess(virStorageSource *src);
+
bool
qemuNbdkitCapsGet(qemuNbdkitCaps *nbdkitCaps,
qemuNbdkitCapsFlags flag);
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 6d1751b5d7..7ec31ef6ac 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -9047,6 +9047,17 @@ qemuProcessReconnect(void *opaque)
}
}
+ for (i = 0; i < obj->def->ndisks; i++) {
+ virDomainDiskDef *disk = obj->def->disks[i];
+ if (qemuNbdkitStorageSourceManageProcess(disk->src) < 0)
+ goto error;
+ }
+
+ if (obj->def->os.loader && obj->def->os.loader->nvram) {
+ if (qemuNbdkitStorageSourceManageProcess(obj->def->os.loader->nvram) < 0)
+ goto error;
+ }
+
/* update domain state XML with possibly updated state in virDomainObj */
if (virDomainObjSave(obj, driver->xmlopt, cfg->stateDir) < 0)
goto error;
diff --git a/tests/qemustatusxml2xmldata/modern-in.xml b/tests/qemustatusxml2xmldata/modern-in.xml
index 7759034f7a..71b3eb4736 100644
--- a/tests/qemustatusxml2xmldata/modern-in.xml
+++ b/tests/qemustatusxml2xmldata/modern-in.xml
@@ -342,6 +342,10 @@
<TLSx509 alias='transport-alias'/>
</objects>
<thresholdEvent indexUsed='yes'/>
+ <nbdkit>
+ <pidfile>/path/to/nbdkit.pid</pidfile>
+ <socketfile>/path/to/nbdkit.socket</socketfile>
+ </nbdkit>
</privateData>
</source>
<backingStore/>
--
2.39.0
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