From dfa657aa2746abdd0110eb4ce172f14a4a9c660f Mon Sep 17 00:00:00 2001 From: Jonathon Jongsma Date: Fri, 8 Jul 2022 10:40:06 -0500 Subject: [PATCH] qemu: include nbdkit state in private xml 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: /path/to/nbdkit.pid /path/to/nbdkit.socket Signed-off-by: Jonathon Jongsma Reviewed-by: Peter Krempa --- 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 0192673794..f9e901a186 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -1958,6 +1958,33 @@ 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) @@ -1971,6 +1998,7 @@ qemuStorageSourcePrivateDataParse(xmlXPathContextPtr ctxt, bool fdsetPresent = false; unsigned int fdSetID; int enccount; + xmlNodePtr nbdkitnode = NULL; src->nodestorage = virXPathString("string(./nodenames/nodename[@type='storage']/@name)", ctxt); src->nodeformat = virXPathString("string(./nodenames/nodename[@type='format']/@name)", ctxt); @@ -2036,6 +2064,10 @@ 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; } @@ -2053,6 +2085,23 @@ qemuStorageSourcePrivateDataFormatSecinfo(virBuffer *buf, } +static void +qemuStorageSourcePrivateDataFormatNbdkit(qemuNbdkitProcess *nbdkit, + virBuffer *buf) +{ + g_auto(virBuffer) childBuf = VIR_BUFFER_INIT_CHILD(buf); + + if (!nbdkit) + return; + + virBufferEscapeString(&childBuf, "%s\n", + nbdkit->pidfile); + virBufferEscapeString(&childBuf, "%s\n", + nbdkit->socketfile); + virXMLFormatElement(buf, "nbdkit", NULL, &childBuf); +} + + static int qemuStorageSourcePrivateDataFormat(virStorageSource *src, virBuffer *buf) @@ -2102,6 +2151,9 @@ qemuStorageSourcePrivateDataFormat(virStorageSource *src, if (src->thresholdEventWithIndex) virBufferAddLit(buf, "\n"); + if (srcPriv) + qemuStorageSourcePrivateDataFormatNbdkit(srcPriv->nbdkitProcess, buf); + return 0; } diff --git a/src/qemu/qemu_nbdkit.c b/src/qemu/qemu_nbdkit.c index 81861bae4a..e3923ab4f2 100644 --- a/src/qemu/qemu_nbdkit.c +++ b/src/qemu/qemu_nbdkit.c @@ -627,6 +627,77 @@ 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 d2ae82d42f..a181df2123 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -9054,6 +9054,12 @@ 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 95fc569029..e139c8d38c 100644 --- a/tests/qemustatusxml2xmldata/modern-in.xml +++ b/tests/qemustatusxml2xmldata/modern-in.xml @@ -345,6 +345,10 @@ + + /path/to/nbdkit.pid + /path/to/nbdkit.socket +