[libvirt] [PATCH] Add directsync cache mode support for disk driver
Osier Yang
jyang at redhat.com
Fri Sep 2 13:43:47 UTC 2011
于 2011年09月02日 18:04, Daniel Veillard 写道:
> On Fri, Sep 02, 2011 at 03:38:38PM +0800, Osier Yang wrote:
>> Newer QEMU introduced cache=directsync for -drive, this patchset
>> is to expose it in libvirt layer.
>>
>> * Introduced a new QEMU capability flag ($prefix_CACHE_DIRECTSYNC),
>> As even $prefix_CACHE_V2 is set, we can't known if directsync
>> is supported.
>> ---
>> docs/formatdomain.html.in | 2 +-
>> docs/schemas/domain.rng | 1 +
>> src/conf/domain_conf.c | 3 ++-
>> src/conf/domain_conf.h | 1 +
>> src/qemu/qemu_capabilities.c | 6 +++++-
>> src/qemu/qemu_capabilities.h | 1 +
>> src/qemu/qemu_command.c | 29 ++++++++++++++++++++++-------
>> tests/qemuargv2xmltest.c | 1 +
>> tests/qemuxml2argvtest.c | 3 +++
>> tools/virsh.pod | 3 ++-
>> 10 files changed, 39 insertions(+), 11 deletions(-)
>>
>> diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
>> index f46771d..6cb36d3 100644
>> --- a/docs/formatdomain.html.in
>> +++ b/docs/formatdomain.html.in
>> @@ -976,7 +976,7 @@
>> <li>
>> The optional<code>cache</code> attribute controls the
>> cache mechanism, possible values are "default", "none",
>> - "writethrough" and "writeback".
>> + "writethrough", "writeback", and "directsync".
>> <span class="since">Since 0.6.0</span>
>> </li>
>> <li>
>> diff --git a/docs/schemas/domain.rng b/docs/schemas/domain.rng
>> index dd8c41a..e43b17d 100644
>> --- a/docs/schemas/domain.rng
>> +++ b/docs/schemas/domain.rng
>> @@ -829,6 +829,7 @@
>> <value>none</value>
>> <value>writeback</value>
>> <value>writethrough</value>
>> +<value>directsync</value>
>> </choice>
>> </attribute>
>> </define>
>> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
>> index 00212db..a2de8df 100644
>> --- a/src/conf/domain_conf.c
>> +++ b/src/conf/domain_conf.c
>> @@ -160,7 +160,8 @@ VIR_ENUM_IMPL(virDomainDiskCache, VIR_DOMAIN_DISK_CACHE_LAST,
>> "default",
>> "none",
>> "writethrough",
>> - "writeback")
>> + "writeback",
>> + "directsync")
>>
>> VIR_ENUM_IMPL(virDomainDiskErrorPolicy, VIR_DOMAIN_DISK_ERROR_POLICY_LAST,
>> "default",
>> diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
>> index 8382d28..0abb75e 100644
>> --- a/src/conf/domain_conf.h
>> +++ b/src/conf/domain_conf.h
>> @@ -165,6 +165,7 @@ enum virDomainDiskCache {
>> VIR_DOMAIN_DISK_CACHE_DISABLE,
>> VIR_DOMAIN_DISK_CACHE_WRITETHRU,
>> VIR_DOMAIN_DISK_CACHE_WRITEBACK,
>> + VIR_DOMAIN_DISK_CACHE_DIRECTSYNC,
>>
>> VIR_DOMAIN_DISK_CACHE_LAST
>> };
>> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
>> index f665de4..631d683 100644
>> --- a/src/qemu/qemu_capabilities.c
>> +++ b/src/qemu/qemu_capabilities.c
>> @@ -125,6 +125,7 @@ VIR_ENUM_IMPL(qemuCaps, QEMU_CAPS_LAST,
>> "sga",
>> "virtio-blk-pci.event_idx",
>> "virtio-net-pci.event_idx",
>> + "cache-directsync",
>> );
>>
>> struct qemu_feature_flags {
>> @@ -902,8 +903,11 @@ qemuCapsComputeCmdFlags(const char *help,
>> if (strstr(help, "-drive")) {
>> qemuCapsSet(flags, QEMU_CAPS_DRIVE);
>> if (strstr(help, "cache=")&&
>> - !strstr(help, "cache=on|off"))
>> + !strstr(help, "cache=on|off")) {
>> qemuCapsSet(flags, QEMU_CAPS_DRIVE_CACHE_V2);
>> + if (strstr(help, "directsync"))
>> + qemuCapsSet(flags, QEMU_CAPS_DRIVE_CACHE_DIRECTSYNC);
>> + }
>> if (strstr(help, "format="))
>> qemuCapsSet(flags, QEMU_CAPS_DRIVE_FORMAT);
>> if (strstr(help, "readonly="))
>> diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h
>> index 13af0b9..c01d438 100644
>> --- a/src/qemu/qemu_capabilities.h
>> +++ b/src/qemu/qemu_capabilities.h
>> @@ -100,6 +100,7 @@ enum qemuCapsFlags {
>> QEMU_CAPS_SGA = 62, /* Serial Graphics Adapter */
>> QEMU_CAPS_VIRTIO_BLK_EVENT_IDX = 63, /* virtio-blk-pci.event_idx */
>> QEMU_CAPS_VIRTIO_NET_EVENT_IDX = 64, /* virtio-net-pci.event_idx */
>> + QEMU_CAPS_DRIVE_CACHE_DIRECTSYNC = 65, /* Is cache=directsync supported? */
>>
>> 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 44a553b..fa52dc0 100644
>> --- a/src/qemu/qemu_command.c
>> +++ b/src/qemu/qemu_command.c
>> @@ -64,14 +64,16 @@ VIR_ENUM_DECL(qemuDiskCacheV2)
>> VIR_ENUM_IMPL(qemuDiskCacheV1, VIR_DOMAIN_DISK_CACHE_LAST,
>> "default",
>> "off",
>> - "off", /* writethrough not supported, so for safety, disable */
>> - "on"); /* Old 'on' was equivalent to 'writeback' */
>> + "off", /* writethrough not supported, so for safety, disable */
>> + "on", /* Old 'on' was equivalent to 'writeback' */
>> + "off"); /* directsync not supported, for safety, disable */
>>
>> VIR_ENUM_IMPL(qemuDiskCacheV2, VIR_DOMAIN_DISK_CACHE_LAST,
>> "default",
>> "none",
>> "writethrough",
>> - "writeback");
>> + "writeback",
>> + "directsync");
>>
>> VIR_ENUM_DECL(qemuVideo)
>>
>> @@ -1516,10 +1518,21 @@ qemuBuildDriveStr(virDomainDiskDefPtr disk,
>> }
>>
>> if (disk->cachemode) {
>> - const char *mode =
>> - qemuCapsGet(qemuCaps, QEMU_CAPS_DRIVE_CACHE_V2) ?
>> - qemuDiskCacheV2TypeToString(disk->cachemode) :
>> - qemuDiskCacheV1TypeToString(disk->cachemode);
>> + const char *mode = NULL;
>> +
>> + if (qemuCapsGet(qemuCaps, QEMU_CAPS_DRIVE_CACHE_V2)) {
>> + mode = qemuDiskCacheV2TypeToString(disk->cachemode);
>> +
>> + if (disk->cachemode == VIR_DOMAIN_DISK_CACHE_DIRECTSYNC&&
>> + !qemuCapsGet(qemuCaps, QEMU_CAPS_DRIVE_CACHE_DIRECTSYNC)) {
>> + qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
>> + _("disk cache mode 'directsync' is not "
>> + "supported by this QEMU"));
>> + goto error;
>> + }
>> + } else {
>> + mode = qemuDiskCacheV1TypeToString(disk->cachemode);
>> + }
>>
>> virBufferAsprintf(&opt, ",cache=%s", mode);
>> } else if (disk->shared&& !disk->readonly) {
>> @@ -5211,6 +5224,8 @@ qemuParseCommandLineDisk(virCapsPtr caps,
>> def->cachemode = VIR_DOMAIN_DISK_CACHE_WRITEBACK;
>> else if (STREQ(values[i], "writethrough"))
>> def->cachemode = VIR_DOMAIN_DISK_CACHE_WRITETHRU;
>> + else if (STREQ(values[i], "directsync"))
>> + def->cachemode = VIR_DOMAIN_DISK_CACHE_DIRECTSYNC;
>> } else if (STREQ(keywords[i], "werror") ||
>> STREQ(keywords[i], "rerror")) {
>> if (STREQ(values[i], "stop"))
>> diff --git a/tests/qemuargv2xmltest.c b/tests/qemuargv2xmltest.c
>> index c2b6cf2..91f15af 100644
>> --- a/tests/qemuargv2xmltest.c
>> +++ b/tests/qemuargv2xmltest.c
>> @@ -168,6 +168,7 @@ mymain(void)
>> DO_TEST("disk-drive-cache-v2-wt");
>> DO_TEST("disk-drive-cache-v2-wb");
>> DO_TEST("disk-drive-cache-v2-none");
>> + DO_TEST("disk-drive-cache-directsync");
>> DO_TEST("disk-drive-network-nbd");
>> DO_TEST("disk-drive-network-rbd");
>> DO_TEST("disk-drive-network-sheepdog");
>> diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c
>> index 6e8da5e..b009bf3 100644
>> --- a/tests/qemuxml2argvtest.c
>> +++ b/tests/qemuxml2argvtest.c
>> @@ -338,6 +338,9 @@ mymain(void)
>> QEMU_CAPS_DRIVE, QEMU_CAPS_DRIVE_CACHE_V2, QEMU_CAPS_DRIVE_FORMAT);
>> DO_TEST("disk-drive-cache-v2-none", false,
>> QEMU_CAPS_DRIVE, QEMU_CAPS_DRIVE_CACHE_V2, QEMU_CAPS_DRIVE_FORMAT);
>> + DO_TEST("disk-drive-cache-directsync", false,
>> + QEMU_CAPS_DRIVE, QEMU_CAPS_DRIVE_CACHE_V2,
>> + QEMU_CAPS_DRIVE_CACHE_DIRECTSYNC, QEMU_CAPS_DRIVE_FORMAT);
>> DO_TEST("disk-drive-network-nbd", false,
>> QEMU_CAPS_DRIVE, QEMU_CAPS_DRIVE_FORMAT);
>> DO_TEST("disk-drive-network-rbd", false,
>> diff --git a/tools/virsh.pod b/tools/virsh.pod
>> index b90c26e..5ac2c5c 100644
>> --- a/tools/virsh.pod
>> +++ b/tools/virsh.pod
>> @@ -1099,7 +1099,8 @@ floppy device; consider using B<update-device> for this usage instead.
>> I<mode> can specify the two specific mode I<readonly> or I<shareable>.
>> I<persistent> indicates the changes will affect the next boot of the domain.
>> I<sourcetype> can indicate the type of source (block|file)
>> -I<cache> can be one of "default", "none", "writethrough" or "writeback".
>> +I<cache> can be one of "default", "none", "writethrough", "writeback", or
>> +"directsync".
>> I<serial> is the serial of disk device. I<shareable> indicates the disk device
>> is shareable between domains.
>> I<address> is the address of disk device in the form of pci:domain.bus.slot.function,
> ACK, though I would prefer if docs/formatdomain.html.in was expanded
> to explain the semantic of that new flag !
>
> Daniel
>
I pushed with document:
"directsync" is like "writethrough", but it bypasses the host page
cache.
Regards,
Osier
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