Upstream QEMU supports it since commit fb0490f69. --- docs/formatdomain.html.in | 9 +++++++++ docs/schemas/domaincommon.rng | 11 +++++++++++ src/conf/domain_conf.c | 24 +++++++++++++++++++++++- src/conf/domain_conf.h | 10 ++++++++++ src/libvirt_private.syms | 2 ++ src/qemu/qemu_capabilities.c | 3 +++ src/qemu/qemu_capabilities.h | 1 + src/qemu/qemu_command.c | 11 +++++++++++ 8 files changed, 70 insertions(+), 1 deletions(-) diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index 9cf0f12..779317f 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -1187,6 +1187,15 @@ <b>In general you should leave this option alone, unless you are very certain you know what you are doing.</b> </li> + <li> + The optional <code>copy_on_read</code> attribute controls + wether to copy read backing file into the image file. The + value can be either "on" or "off". + Copy-on-read avoids accessing the same backing file sectors + repeatedly and is useful when the backing file is over a slow + network. By default copy-on-read is off. + <span class='since'>Since 0.9.9 (QEMU and KVM only)</span> + </li> </ul> </dd> <dt><code>boot</code></dt> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng index 553a6f0..b511ec2 100644 --- a/docs/schemas/domaincommon.rng +++ b/docs/schemas/domaincommon.rng @@ -959,6 +959,14 @@ </choice> </attribute> </define> + <define name="copy_on_read"> + <attribute name='copy_on_read'> + <choice> + <value>on</value> + <value>off</value> + </choice> + </attribute> + </define> <define name="controller"> <element name="controller"> <choice> @@ -1308,6 +1316,9 @@ <optional> <ref name="event_idx"/> </optional> + <optional> + <ref name="copy_on_read"/> + </optional> <empty/> </element> </optional> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index 2897b4a..a51eb40 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -208,6 +208,11 @@ VIR_ENUM_IMPL(virDomainVirtioEventIdx, VIR_DOMAIN_VIRTIO_EVENT_IDX_LAST, "on", "off") +VIR_ENUM_IMPL(virDomainDiskCopyOnRead, VIR_DOMAIN_DISK_COPY_ON_READ_LAST, + "default", + "on", + "off") + VIR_ENUM_IMPL(virDomainDiskSnapshot, VIR_DOMAIN_DISK_SNAPSHOT_LAST, "default", "no", @@ -2621,6 +2626,7 @@ virDomainDiskDefParseXML(virCapsPtr caps, char *iotag = NULL; char *ioeventfd = NULL; char *event_idx = NULL; + char *copy_on_read = NULL; char *devaddr = NULL; virStorageEncryptionPtr encryption = NULL; char *serial = NULL; @@ -2749,6 +2755,7 @@ virDomainDiskDefParseXML(virCapsPtr caps, iotag = virXMLPropString(cur, "io"); ioeventfd = virXMLPropString(cur, "ioeventfd"); event_idx = virXMLPropString(cur, "event_idx"); + copy_on_read = virXMLPropString(cur, "copy_on_read"); } else if (xmlStrEqual(cur->name, BAD_CAST "auth")) { authUsername = virXMLPropString(cur, "username"); if (authUsername == NULL) { @@ -3053,6 +3060,17 @@ virDomainDiskDefParseXML(virCapsPtr caps, def->event_idx = idx; } + if (copy_on_read) { + int cor; + if ((cor = virDomainDiskCopyOnReadTypeFromString(copy_on_read)) <= 0) { + virDomainReportError(VIR_ERR_CONFIG_UNSUPPORTED, + _("unknown disk copy_on_read mode '%s'"), + copy_on_read); + goto error; + } + def->copy_on_read = cor; + } + if (devaddr) { if (virDomainParseLegacyDeviceAddress(devaddr, &def->info.addr.pci) < 0) { @@ -3146,6 +3164,7 @@ cleanup: VIR_FREE(iotag); VIR_FREE(ioeventfd); VIR_FREE(event_idx); + VIR_FREE(copy_on_read); VIR_FREE(devaddr); VIR_FREE(serial); virStorageEncryptionFree(encryption); @@ -9768,6 +9787,7 @@ virDomainDiskDefFormat(virBufferPtr buf, const char *iomode = virDomainDiskIoTypeToString(def->iomode); const char *ioeventfd = virDomainIoEventFdTypeToString(def->ioeventfd); const char *event_idx = virDomainVirtioEventIdxTypeToString(def->event_idx); + const char *copy_on_read = virDomainVirtioEventIdxTypeToString(def->copy_on_read); const char *startupPolicy = virDomainStartupPolicyTypeToString(def->startupPolicy); char uuidstr[VIR_UUID_STRING_BUFLEN]; @@ -9808,7 +9828,7 @@ virDomainDiskDefFormat(virBufferPtr buf, virBufferAddLit(buf, ">\n"); if (def->driverName || def->driverType || def->cachemode || - def->ioeventfd || def->event_idx) { + def->ioeventfd || def->event_idx || def->copy_on_read) { virBufferAddLit(buf, " <driver"); if (def->driverName) virBufferAsprintf(buf, " name='%s'", def->driverName); @@ -9826,6 +9846,8 @@ virDomainDiskDefFormat(virBufferPtr buf, virBufferAsprintf(buf, " ioeventfd='%s'", ioeventfd); if (def->event_idx) virBufferAsprintf(buf, " event_idx='%s'", event_idx); + if (def->copy_on_read) + virBufferAsprintf(buf, " copy_on_read='%s'", copy_on_read); virBufferAddLit(buf, "/>\n"); } diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h index 1f6e442..4575ab2 100644 --- a/src/conf/domain_conf.h +++ b/src/conf/domain_conf.h @@ -288,6 +288,14 @@ enum virDomainVirtioEventIdx { VIR_DOMAIN_VIRTIO_EVENT_IDX_LAST }; +enum virDomainDiskCopyOnRead { + VIR_DOMAIN_DISK_COPY_ON_READ_DEFAULT = 0, + VIR_DOMAIN_DISK_COPY_ON_READ_ON, + VIR_DOMAIN_DISK_COPY_ON_READ_OFF, + + VIR_DOMAIN_DISK_COPY_ON_READ_LAST +}; + enum virDomainDiskSnapshot { VIR_DOMAIN_DISK_SNAPSHOT_DEFAULT = 0, VIR_DOMAIN_DISK_SNAPSHOT_NO, @@ -363,6 +371,7 @@ struct _virDomainDiskDef { int iomode; int ioeventfd; int event_idx; + int copy_on_read; int snapshot; /* enum virDomainDiskSnapshot */ int startupPolicy; /* enum virDomainStartupPolicy */ unsigned int readonly : 1; @@ -1968,6 +1977,7 @@ VIR_ENUM_DECL(virDomainDiskSecretType) VIR_ENUM_DECL(virDomainDiskSnapshot) VIR_ENUM_DECL(virDomainIoEventFd) VIR_ENUM_DECL(virDomainVirtioEventIdx) +VIR_ENUM_DECL(virDomainDiskCopyOnRead) VIR_ENUM_DECL(virDomainController) VIR_ENUM_DECL(virDomainControllerModelSCSI) VIR_ENUM_DECL(virDomainControllerModelUSB) diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index 4a86bdc..63c2947 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -290,6 +290,8 @@ virDomainDeviceTypeToString; virDomainDiskBusTypeToString; virDomainDiskCacheTypeFromString; virDomainDiskCacheTypeToString; +virDomainDiskCopyOnReadTypeFromString; +virDomainDiskCopyOnReadTypeToString; virDomainDiskDefAssignAddress; virDomainDiskDefForeachPath; virDomainDiskDefFree; diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c index 43c7578..f32c792 100644 --- a/src/qemu/qemu_capabilities.c +++ b/src/qemu/qemu_capabilities.c @@ -144,6 +144,7 @@ VIR_ENUM_IMPL(qemuCaps, QEMU_CAPS_LAST, "ich9-ahci", "no-acpi", "fsdev-readonly", + "drive-copy-on-read", ); struct qemu_feature_flags { @@ -1023,6 +1024,8 @@ qemuCapsComputeCmdFlags(const char *help, qemuCapsSet(flags, QEMU_CAPS_DRIVE_READONLY); if (strstr(help, "aio=threads|native")) qemuCapsSet(flags, QEMU_CAPS_DRIVE_AIO); + if (strstr(help, "copy-on-read=on|off")) + qemuCapsSet(flags, QEMU_CAPS_DRIVE_COPY_ON_READ); } if ((p = strstr(help, "-vga")) && !strstr(help, "-std-vga")) { const char *nl = strstr(p, "\n"); diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h index c759baf..38106dd 100644 --- a/src/qemu/qemu_capabilities.h +++ b/src/qemu/qemu_capabilities.h @@ -117,6 +117,7 @@ enum qemuCapsFlags { QEMU_CAPS_ICH9_AHCI = 77, /* -device ich9-ahci */ QEMU_CAPS_NO_ACPI = 78, /* -no-acpi */ QEMU_CAPS_FSDEV_READONLY =79, /* -fsdev readonly supported */ + QEMU_CAPS_DRIVE_COPY_ON_READ = 80, /* -drive copy-on-read */ QEMU_CAPS_LAST, /* this must always be the last item */ }; diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index ea1b763..629f13d 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -1926,6 +1926,17 @@ qemuBuildDriveStr(virConnectPtr conn ATTRIBUTE_UNUSED, virBufferAddLit(&opt, ",cache=off"); } + if (disk->copy_on_read) { + if (qemuCapsGet(qemuCaps, QEMU_CAPS_DRIVE_COPY_ON_READ)) { + virBufferAsprintf(&opt, ",copy-on-read=%s", + virDomainDiskCopyOnReadTypeToString(disk->copy_on_read)); + } else { + qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", + _("copy_on_read is not supported by this QEMU binary")); + goto error; + } + } + if (qemuCapsGet(qemuCaps, QEMU_CAPS_MONITOR_JSON)) { const char *wpolicy = NULL, *rpolicy = NULL; -- 1.7.7.3