[libvirt] [PATCH v2] qemu: Support copy on read for disk
Osier Yang
jyang at redhat.com
Thu Jan 12 10:13:27 UTC 2012
The new introduced optional attribute "copy_on_read</code> 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.
---
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 ++++
tests/qemuhelptest.c | 3 +-
.../qemuxml2argv-disk-copy_on_read.args | 11 ++++
.../qemuxml2argv-disk-copy_on_read.xml | 50 ++++++++++++++++++++
tests/qemuxml2argvtest.c | 4 ++
12 files changed, 137 insertions(+), 2 deletions(-)
create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-disk-copy_on_read.args
create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-disk-copy_on_read.xml
diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index 42e23a1..3a42ebb 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -1202,6 +1202,15 @@
<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 e93ae77..fdcbc28 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -958,6 +958,9 @@
<optional>
<ref name="event_idx"/>
</optional>
+ <optional>
+ <ref name="copy_on_read"/>
+ </optional>
<empty/>
</element>
</define>
@@ -1025,6 +1028,14 @@
</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>
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 180dd2b..c70faee 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -209,6 +209,11 @@ 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",
@@ -2783,6 +2788,7 @@ 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;
@@ -2911,6 +2917,7 @@ 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) {
@@ -3226,6 +3233,17 @@ 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) {
@@ -3319,6 +3337,7 @@ cleanup:
VIR_FREE(iotag);
VIR_FREE(ioeventfd);
VIR_FREE(event_idx);
+ VIR_FREE(copy_on_read);
VIR_FREE(devaddr);
VIR_FREE(serial);
virStorageEncryptionFree(encryption);
@@ -9870,6 +9889,7 @@ 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];
@@ -9910,7 +9930,7 @@ 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);
@@ -9928,6 +9948,8 @@ 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 3d5d4f8..bac5a87 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -308,6 +308,14 @@ 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,
@@ -384,6 +392,7 @@ 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;
@@ -1969,6 +1978,7 @@ 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 ca4beb1..27a093c 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 6842cfe..530bbb1 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -147,6 +147,7 @@ VIR_ENUM_IMPL(qemuCaps, QEMU_CAPS_LAST,
"virtio-blk-pci.scsi",
"blk-sg-io",
+ "drive-copy-on-read",
);
struct qemu_feature_flags {
@@ -1026,6 +1027,8 @@ 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 d47177c..ee9d5ab 100644
--- a/src/qemu/qemu_capabilities.h
+++ b/src/qemu/qemu_capabilities.h
@@ -120,6 +120,7 @@ enum qemuCapsFlags {
QEMU_CAPS_VIRTIO_BLK_SCSI = 80, /* virtio-blk-pci.scsi */
QEMU_CAPS_VIRTIO_BLK_SG_IO = 81, /* support for SG_IO commands, reportedly added in 0.11 */
+ QEMU_CAPS_DRIVE_COPY_ON_READ = 82, /* -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 16ffb4c..ee51965 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -1929,6 +1929,17 @@ 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;
diff --git a/tests/qemuhelptest.c b/tests/qemuhelptest.c
index 1ef0d9b..2b08af9 100644
--- a/tests/qemuhelptest.c
+++ b/tests/qemuhelptest.c
@@ -592,7 +592,8 @@ mymain(void)
QEMU_CAPS_PCI_ROMBAR,
QEMU_CAPS_NO_ACPI,
QEMU_CAPS_VIRTIO_BLK_SCSI,
- QEMU_CAPS_VIRTIO_BLK_SG_IO);
+ QEMU_CAPS_VIRTIO_BLK_SG_IO,
+ QEMU_CAPS_DRIVE_COPY_ON_READ);
DO_TEST("qemu-1.0", 1000000, 0, 0,
QEMU_CAPS_VNC_COLON,
QEMU_CAPS_NO_REBOOT,
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-disk-copy_on_read.args b/tests/qemuxml2argvdata/qemuxml2argv-disk-copy_on_read.args
new file mode 100644
index 0000000..2ca586d
--- /dev/null
+++ b/tests/qemuxml2argvdata/qemuxml2argv-disk-copy_on_read.args
@@ -0,0 +1,11 @@
+LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \
+/usr/bin/qemu -S -M pc-0.13 -m 1024 -smp 1 -nodefaults \
+-monitor unix:/tmp/test-monitor,server,nowait -no-acpi \
+-boot dc -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x6 \
+-drive file=/var/lib/libvirt/images/f14.img,if=none,id=drive-virtio-disk0,copy-on-read=on \
+-device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0 \
+-drive file=/var/lib/libvirt/Fedora-14-x86_64-Live-KDE.iso,if=none,media=cdrom,id=drive-ide0-1-0 \
+-device ide-drive,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 \
+-device virtio-net-pci,tx=bh,vlan=0,id=net0,mac=52:54:00:e5:48:58,bus=pci.0,addr=0x3 \
+-net user,vlan=0,name=hostnet0 -serial pty -usb -vnc 127.0.0.1:-809 -std-vga \
+-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-disk-copy_on_read.xml b/tests/qemuxml2argvdata/qemuxml2argv-disk-copy_on_read.xml
new file mode 100644
index 0000000..433c641
--- /dev/null
+++ b/tests/qemuxml2argvdata/qemuxml2argv-disk-copy_on_read.xml
@@ -0,0 +1,50 @@
+<domain type='qemu'>
+ <name>test</name>
+ <memory>1048576</memory>
+ <vcpu>1</vcpu>
+ <os>
+ <type arch='x86_64' machine='pc-0.13'>hvm</type>
+ <boot dev='cdrom'/>
+ <boot dev='hd'/>
+ <bootmenu enable='yes'/>
+ </os>
+ <clock offset='utc'/>
+ <on_poweroff>destroy</on_poweroff>
+ <on_reboot>restart</on_reboot>
+ <on_crash>restart</on_crash>
+ <devices>
+ <emulator>/usr/bin/qemu</emulator>
+ <disk type='file' device='disk'>
+ <driver name='qemu' type='qcow2' copy_on_read='on'/>
+ <source file='/var/lib/libvirt/images/f14.img'/>
+ <target dev='vda' bus='virtio'/>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
+ </disk>
+ <disk type='file' device='cdrom'>
+ <driver name='qemu' type='raw'/>
+ <source file='/var/lib/libvirt/Fedora-14-x86_64-Live-KDE.iso'/>
+ <target dev='hdc' bus='ide'/>
+ <readonly/>
+ <address type='drive' controller='0' bus='1' unit='0'/>
+ </disk>
+ <interface type='user'>
+ <mac address='52:54:00:e5:48:58'/>
+ <model type='virtio'/>
+ <driver name='vhost' txmode='iothread'/>
+ </interface>
+ <controller type='virtio-serial' index='0'>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
+ </controller>
+ <serial type='pty'>
+ <target port='0'/>
+ </serial>
+ <console type='pty'>
+ <target type='serial' port='0'/>
+ </console>
+ <graphics type='vnc' port='5091' autoport='no' listen='127.0.0.1'/>
+ <video>
+ <model type='vga' vram='9216' heads='1'/>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
+ </video>
+ </devices>
+</domain>
diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c
index d87654c..30bea37 100644
--- a/tests/qemuxml2argvtest.c
+++ b/tests/qemuxml2argvtest.c
@@ -439,6 +439,10 @@ mymain(void)
QEMU_CAPS_DRIVE, QEMU_CAPS_VIRTIO_IOEVENTFD,
QEMU_CAPS_VIRTIO_TX_ALG, QEMU_CAPS_DEVICE,
QEMU_CAPS_VIRTIO_BLK_SCSI, QEMU_CAPS_VIRTIO_BLK_SG_IO);
+ DO_TEST("disk-copy_on_read", false,
+ QEMU_CAPS_DRIVE, QEMU_CAPS_DRIVE_COPY_ON_READ,
+ QEMU_CAPS_VIRTIO_TX_ALG, QEMU_CAPS_DEVICE,
+ QEMU_CAPS_VIRTIO_BLK_SCSI, QEMU_CAPS_VIRTIO_BLK_SG_IO);
DO_TEST("disk-snapshot", false,
QEMU_CAPS_DRIVE, QEMU_CAPS_DRIVE_CACHE_V2, QEMU_CAPS_DRIVE_FORMAT);
DO_TEST("event_idx", false,
--
1.7.7.3
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