[libvirt PATCH v5 18/32] qemu: include nbdkit state in private xml
Jonathon Jongsma
jjongsma at redhat.com
Tue Feb 14 17:08:05 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 | 52 +++++++++++++++++
src/qemu/qemu_nbdkit.c | 71 +++++++++++++++++++++++
src/qemu/qemu_nbdkit.h | 8 +++
src/qemu/qemu_process.c | 6 ++
tests/qemustatusxml2xmldata/modern-in.xml | 4 ++
5 files changed, 141 insertions(+)
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 099ce2ab9a..781b80b46d 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -1936,6 +1936,33 @@ 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))) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("missing nbdkit pidfile"));
+ return -1;
+ }
+
+ if (!(socketfile = virXPathString("string(./socketfile)", ctxt))) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("missing nbdkit socketfile"));
+ return -1;
+ }
+
+ qemuNbdkitReconnectStorageSource(src, pidfile, socketfile);
+
+ return 0;
+}
+
+
static int
qemuStorageSourcePrivateDataParse(xmlXPathContextPtr ctxt,
virStorageSource *src)
@@ -1948,6 +1975,7 @@ qemuStorageSourcePrivateDataParse(xmlXPathContextPtr ctxt,
g_autofree char *thresholdEventWithIndex = NULL;
bool fdsetPresent = false;
unsigned int fdSetID;
+ xmlNodePtr nbdkitnode = NULL;
src->nodestorage = virXPathString("string(./nodenames/nodename[@type='storage']/@name)", ctxt);
src->nodeformat = virXPathString("string(./nodenames/nodename[@type='format']/@name)", ctxt);
@@ -1996,6 +2024,10 @@ 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;
}
@@ -2013,6 +2045,23 @@ 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)
@@ -2059,6 +2108,9 @@ 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 c79c9ec6cd..5f0c0c23b5 100644
--- a/src/qemu/qemu_nbdkit.c
+++ b/src/qemu/qemu_nbdkit.c
@@ -628,6 +628,77 @@ 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 void
+qemuNbdkitStorageSourceManageProcessOne(virStorageSource *source)
+{
+ qemuDomainStorageSourcePrivate *srcpriv = QEMU_DOMAIN_STORAGE_SOURCE_PRIVATE(source);
+ qemuNbdkitProcess *proc;
+
+ if (!srcpriv)
+ return;
+
+ proc = srcpriv->nbdkitProcess;
+
+ if (!proc)
+ return;
+
+ if (proc->pid <= 0) {
+ if (virPidFileReadPath(proc->pidfile, &proc->pid) < 0) {
+ VIR_WARN("Unable to read pidfile '%s'", proc->pidfile);
+ return;
+ }
+ }
+
+ if (virProcessKill(proc->pid, 0) < 0)
+ VIR_WARN("nbdkit process %i is not alive", proc->pid);
+}
+
+/**
+ * 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.
+ */
+void
+qemuNbdkitStorageSourceManageProcess(virStorageSource *source)
+{
+ virStorageSource *backing;
+ for (backing = source; backing != NULL; backing = backing->backingStore)
+ qemuNbdkitStorageSourceManageProcessOne(backing);
+}
+
bool
qemuNbdkitInitStorageSource(qemuNbdkitCaps *caps,
diff --git a/src/qemu/qemu_nbdkit.h b/src/qemu/qemu_nbdkit.h
index ccd418b7d3..7e2aeed4eb 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);
+
+void
+qemuNbdkitStorageSourceManageProcess(virStorageSource *src);
+
bool
qemuNbdkitCapsGet(qemuNbdkitCaps *nbdkitCaps,
qemuNbdkitCapsFlags flag);
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index a61c3192fd..d0b797575d 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -9035,6 +9035,12 @@ qemuProcessReconnect(void *opaque)
}
}
+ for (i = 0; i < obj->def->ndisks; i++)
+ qemuNbdkitStorageSourceManageProcess(obj->def->disks[i]->src);
+
+ if (obj->def->os.loader && obj->def->os.loader->nvram)
+ qemuNbdkitStorageSourceManageProcess(obj->def->os.loader->nvram);
+
/* 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 cdab1d7178..6efb52fb14 100644
--- a/tests/qemustatusxml2xmldata/modern-in.xml
+++ b/tests/qemustatusxml2xmldata/modern-in.xml
@@ -345,6 +345,10 @@
<fdset type='storage' id='1337'/>
</fdsets>
<thresholdEvent indexUsed='yes'/>
+ <nbdkit>
+ <pidfile>/path/to/nbdkit.pid</pidfile>
+ <socketfile>/path/to/nbdkit.socket</socketfile>
+ </nbdkit>
</privateData>
</source>
<backingStore/>
--
2.39.1
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