From d0fd04556c537b22355d8d6d3c834451dda0a441 Mon Sep 17 00:00:00 2001 From: Jonathon Jongsma Date: Fri, 5 Aug 2022 15:24:08 -0500 Subject: [PATCH] qemu: implement persistent file cache for nbdkit caps Implement the loadFile and saveFile virFileCacheHandlers callbacks so that nbdkit capabilities are cached perstistently across daemon restarts. The format and implementation is modeled on the qemu capabilities, but simplified slightly. Signed-off-by: Jonathon Jongsma Reviewed-by: Peter Krempa --- po/POTFILES | 1 + src/qemu/qemu_nbdkit.c | 226 ++++++++++++++++++++++++++++++++++++++++- 2 files changed, 225 insertions(+), 2 deletions(-) diff --git a/po/POTFILES b/po/POTFILES index 5d6ec195b4..6167f98ac5 100644 --- a/po/POTFILES +++ b/po/POTFILES @@ -181,6 +181,7 @@ src/qemu/qemu_monitor.c src/qemu/qemu_monitor_json.c src/qemu/qemu_monitor_text.c src/qemu/qemu_namespace.c +src/qemu/qemu_nbdkit.c src/qemu/qemu_passt.c src/qemu/qemu_process.c src/qemu/qemu_qapi.c diff --git a/src/qemu/qemu_nbdkit.c b/src/qemu/qemu_nbdkit.c index 9828f562f7..97612b637f 100644 --- a/src/qemu/qemu_nbdkit.c +++ b/src/qemu/qemu_nbdkit.c @@ -312,11 +312,233 @@ virNbdkitCapsNewData(const char *binary, } +static int +qemuNbdkitCapsValidateBinary(qemuNbdkitCaps *nbdkitCaps, + xmlXPathContextPtr ctxt) +{ + g_autofree char *str = NULL; + + if (!(str = virXPathString("string(./path)", ctxt))) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("missing path in nbdkit capabilities cache")); + return -1; + } + + if (STRNEQ(str, nbdkitCaps->path)) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("Expected caps for '%1$s' but saw '%2$s'"), + nbdkitCaps->path, str); + return -1; + } + + return 0; +} + + +static int +qemuNbdkitCapsParseFlags(qemuNbdkitCaps *nbdkitCaps, + xmlXPathContextPtr ctxt) +{ + g_autofree xmlNodePtr *nodes = NULL; + size_t i; + int n; + + if ((n = virXPathNodeSet("./flag", ctxt, &nodes)) < 0) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("failed to parse qemu capabilities flags")); + return -1; + } + + VIR_DEBUG("Got flags %d", n); + for (i = 0; i < n; i++) { + unsigned int flag; + + if (virXMLPropEnum(nodes[i], "name", qemuNbdkitCapsTypeFromString, + VIR_XML_PROP_REQUIRED, &flag) < 0) + return -1; + + qemuNbdkitCapsSet(nbdkitCaps, flag); + } + + return 0; +} + + +/* + * Parsing a doc that looks like + * + * + * /some/path + * 234235253 + * 234235253 + * 234235253 + * 234235253 + * 1002016 + * + * + * ... + * + * + * Returns 0 on success, 1 if outdated, -1 on error + */ +static int +qemuNbdkitCapsLoadCache(qemuNbdkitCaps *nbdkitCaps, + const char *filename) +{ + g_autoptr(xmlDoc) doc = NULL; + g_autoptr(xmlXPathContext) ctxt = NULL; + long long int l; + + if (!(doc = virXMLParse(filename, NULL, NULL, "nbdkitCaps", &ctxt, NULL, false))) + return -1; + + if (virXPathLongLong("string(./selfctime)", ctxt, &l) < 0) { + VIR_DEBUG("missing selfctime in nbdkit capabilities XML"); + return -1; + } + nbdkitCaps->libvirtCtime = (time_t)l; + + nbdkitCaps->libvirtVersion = 0; + virXPathUInt("string(./selfvers)", ctxt, &nbdkitCaps->libvirtVersion); + + if (nbdkitCaps->libvirtCtime != virGetSelfLastChanged() || + nbdkitCaps->libvirtVersion != LIBVIR_VERSION_NUMBER) { + VIR_DEBUG("Outdated capabilities in %s: libvirt changed (%lld vs %lld, %lu vs %lu), stopping load", + nbdkitCaps->path, + (long long)nbdkitCaps->libvirtCtime, + (long long)virGetSelfLastChanged(), + (unsigned long)nbdkitCaps->libvirtVersion, + (unsigned long)LIBVIR_VERSION_NUMBER); + return 1; + } + + if (qemuNbdkitCapsValidateBinary(nbdkitCaps, ctxt) < 0) + return -1; + + if (virXPathLongLong("string(./nbdkitctime)", ctxt, &l) < 0) { + VIR_DEBUG("missing nbdkitctime in nbdkit capabilities XML"); + return -1; + } + nbdkitCaps->ctime = (time_t)l; + + if (virXPathLongLong("string(./plugindirmtime)", ctxt, &l) < 0) { + VIR_DEBUG("missing plugindirmtime in nbdkit capabilities XML"); + return -1; + } + nbdkitCaps->pluginDirMtime = (time_t)l; + + if (virXPathLongLong("string(./filterdirmtime)", ctxt, &l) < 0) { + VIR_DEBUG("missing filterdirmtime in nbdkit capabilities XML"); + return -1; + } + nbdkitCaps->filterDirMtime = (time_t)l; + + if (qemuNbdkitCapsParseFlags(nbdkitCaps, ctxt) < 0) + return -1; + + if ((nbdkitCaps->version = virXPathString("string(./version)", ctxt)) == NULL) { + VIR_DEBUG("missing version in nbdkit capabilities cache"); + return -1; + } + + return 0; +} + + +static void* +virNbdkitCapsLoadFile(const char *filename, + const char *binary, + void *privData G_GNUC_UNUSED, + bool *outdated) +{ + g_autoptr(qemuNbdkitCaps) nbdkitCaps = qemuNbdkitCapsNew(binary); + int ret; + + if (!nbdkitCaps) + return NULL; + + ret = qemuNbdkitCapsLoadCache(nbdkitCaps, filename); + if (ret < 0) + return NULL; + if (ret == 1) { + *outdated = true; + return NULL; + } + + return g_steal_pointer(&nbdkitCaps); +} + + +static char* +qemuNbdkitCapsFormatCache(qemuNbdkitCaps *nbdkitCaps) +{ + g_auto(virBuffer) buf = VIR_BUFFER_INITIALIZER; + size_t i; + + virBufferAddLit(&buf, "\n"); + virBufferAdjustIndent(&buf, 2); + + virBufferEscapeString(&buf, "%s\n", + nbdkitCaps->path); + virBufferAsprintf(&buf, "%lu\n", + nbdkitCaps->ctime); + virBufferAsprintf(&buf, "%lu\n", + nbdkitCaps->pluginDirMtime); + virBufferAsprintf(&buf, "%lu\n", + nbdkitCaps->filterDirMtime); + virBufferAsprintf(&buf, "%lu\n", + nbdkitCaps->libvirtCtime); + virBufferAsprintf(&buf, "%u\n", + nbdkitCaps->libvirtVersion); + + for (i = 0; i < QEMU_NBDKIT_CAPS_LAST; i++) { + if (qemuNbdkitCapsGet(nbdkitCaps, i)) { + virBufferAsprintf(&buf, "\n", + qemuNbdkitCapsTypeToString(i)); + } + } + + virBufferAsprintf(&buf, "%s\n", + nbdkitCaps->version); + + virBufferAdjustIndent(&buf, -2); + virBufferAddLit(&buf, "\n"); + + return virBufferContentAndReset(&buf); +} + + +static int +virNbdkitCapsSaveFile(void *data, + const char *filename, + void *privData G_GNUC_UNUSED) +{ + qemuNbdkitCaps *nbdkitCaps = data; + g_autofree char *xml = NULL; + + xml = qemuNbdkitCapsFormatCache(nbdkitCaps); + + if (virFileWriteStr(filename, xml, 0600) < 0) { + virReportSystemError(errno, + _("Failed to save '%1$s' for '%2$s'"), + filename, nbdkitCaps->path); + return -1; + } + + VIR_DEBUG("Saved caps '%s' for '%s' with (%lu, %lu)", + filename, nbdkitCaps->path, + nbdkitCaps->ctime, + nbdkitCaps->libvirtCtime); + + return 0; +} + + virFileCacheHandlers nbdkitCapsCacheHandlers = { .isValid = virNbdkitCapsIsValid, .newData = virNbdkitCapsNewData, - .loadFile = NULL, - .saveFile = NULL, + .loadFile = virNbdkitCapsLoadFile, + .saveFile = virNbdkitCapsSaveFile, .privFree = NULL, };