[libvirt] [PATCH] Add new attribute writeout to <filesystem> element
Osier Yang
jyang at redhat.com
Thu Dec 22 07:25:08 UTC 2011
On 2011年12月22日 14:54, Deepak C Shetty wrote:
> This introduces new attribute writeout with only supported
> value as immediate. This will be an optional
> attribute with no defaults. This helps specify whether
> to skip the host page cache.
>
> When writeout is specified, meaning when writeout=immediate
> a writeback is explicitly initiated for the dirty pages in
> the host page cache as part of the guest file write operation.
>
> Usage:
> <filesystem type='mount' accessmode='passthrough' writeout='immediate'>
> <source dir='/export/to/guest'/>
> <target dir='mount_tag'/>
> </filesystem>
>
> Currently this only works with type='mount' for the QEMU/KVM driver.
>
> Signed-off-by: Deepak C Shetty<deepakcs at linux.vnet.ibm.com>
> ---
>
> docs/formatdomain.html.in | 8 +++++++-
> docs/schemas/domaincommon.rng | 5 +++++
> src/conf/domain_conf.c | 29 +++++++++++++++++++++++++++--
> src/conf/domain_conf.h | 10 ++++++++++
> src/qemu/qemu_command.c | 9 +++++++++
> 5 files changed, 58 insertions(+), 3 deletions(-)
>
> diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
> index c57b7b3..803db8e 100644
> --- a/docs/formatdomain.html.in
> +++ b/docs/formatdomain.html.in
> @@ -1303,7 +1303,7 @@
> <source name='my-vm-template'/>
> <target dir='/'/>
> </filesystem>
> -<filesystem type='mount' accessmode='passthrough'>
> +<filesystem type='mount' accessmode='passthrough' writeout='immediate'>
> <driver type='path'/>
> <source dir='/export/to/guest'/>
> <target dir='/import/from/host'/>
> @@ -1379,6 +1379,12 @@
> </dd>
> </dl>
>
> + The filesystem block has an optional attribute<code>writeout='immediate'</code>
<code>write</code>, and it's better to clarify it only supports
"immediate" currently.
> + to help specify whether to skip the host page cache. When writeout is specified, meaning when
> + writeout=immediate a writeback is explicitly initiated for the dirty pages in
> + the host page cache as part of the guest file write operation. When this attribute is not
> + specified, there are no defaults, meaning explicit writeback won't be initiated.
> +
> </dd>
>
> <dt><code>source</code></dt>
> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
> index 27ec1da..2298994 100644
> --- a/docs/schemas/domaincommon.rng
> +++ b/docs/schemas/domaincommon.rng
> @@ -1106,6 +1106,11 @@
> <value>squash</value>
> </choice>
> </attribute>
> +<attribute name="writeout">
> +<choice>
> +<value>immediate</value>
> +</choice>
> +</attribute>
> </optional>
> </element>
> </define>
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index 2c91f82..80b8eab 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -256,6 +256,9 @@ VIR_ENUM_IMPL(virDomainFSAccessMode, VIR_DOMAIN_FS_ACCESSMODE_LAST,
> "mapped",
> "squash")
>
> +VIR_ENUM_IMPL(virDomainFSWriteout, VIR_DOMAIN_FS_WRITEOUT_LAST,
> + "default",
> + "immediate")
>
> VIR_ENUM_IMPL(virDomainNet, VIR_DOMAIN_NET_TYPE_LAST,
> "user",
> @@ -3258,6 +3261,7 @@ virDomainFSDefParseXML(xmlNodePtr node,
> char *source = NULL;
> char *target = NULL;
> char *accessmode = NULL;
> + char *writeout = NULL;
>
> if (VIR_ALLOC(def)< 0) {
> virReportOOMError();
> @@ -3286,6 +3290,17 @@ virDomainFSDefParseXML(xmlNodePtr node,
> def->accessmode = VIR_DOMAIN_FS_ACCESSMODE_PASSTHROUGH;
> }
>
> + writeout = virXMLPropString(node, "writeout");
> + if (writeout) {
> + if ((def->writeout = virDomainFSWriteoutTypeFromString(writeout))< 0) {
> + virDomainReportError(VIR_ERR_INTERNAL_ERROR,
IMHO VIR_ERR_CONFIG_UNSUPPORTED is more proper here.
> + _("unknown filesystem writeout '%s'"), writeout);
> + goto error;
> + }
> + } else {
> + def->writeout = VIR_DOMAIN_FS_WRITEOUT_DEFAULT;
> + }
> +
> cur = node->children;
> while (cur != NULL) {
> if (cur->type == XML_ELEMENT_NODE) {
> @@ -3348,6 +3363,7 @@ cleanup:
> VIR_FREE(target);
> VIR_FREE(source);
> VIR_FREE(accessmode);
> + VIR_FREE(writeout);
>
> return def;
>
> @@ -10006,6 +10022,7 @@ virDomainFSDefFormat(virBufferPtr buf,
> const char *type = virDomainFSTypeToString(def->type);
> const char *accessmode = virDomainFSAccessModeTypeToString(def->accessmode);
> const char *fsdriver = virDomainFSDriverTypeTypeToString(def->fsdriver);
> + const char *writeout = virDomainFSWriteoutTypeToString(def->writeout);
>
> if (!type) {
> virDomainReportError(VIR_ERR_INTERNAL_ERROR,
> @@ -10022,12 +10039,20 @@ virDomainFSDefFormat(virBufferPtr buf,
> if (def->fsdriver == VIR_DOMAIN_FS_DRIVER_TYPE_PATH ||
> def->fsdriver == VIR_DOMAIN_FS_DRIVER_TYPE_DEFAULT) {
> virBufferAsprintf(buf,
> - "<filesystem type='%s' accessmode='%s'>\n",
> + "<filesystem type='%s' accessmode='%s'",
> type, accessmode);
> } else {
> virBufferAsprintf(buf,
> - "<filesystem type='%s'>\n", type);
> + "<filesystem type='%s'", type);
> }
> +
> + /* Dont generate anything if writeout is set to default */
Dont -> Don't
> + if (def->writeout) {
> + virBufferAsprintf(buf, " writeout='%s'", writeout);
> + }
> +
> + /* close the filesystem element */
> + virBufferAddLit(buf,">\n");
>
> if (def->fsdriver) {
> virBufferAsprintf(buf, "<driver type='%s'/>\n", fsdriver);
> diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
> index 3229a6f..bf4d79b 100644
> --- a/src/conf/domain_conf.h
> +++ b/src/conf/domain_conf.h
> @@ -450,12 +450,21 @@ enum virDomainFSAccessMode {
> VIR_DOMAIN_FS_ACCESSMODE_LAST
> };
>
> +/* Filesystem Writeout */
> +enum virDomainFSWriteout {
> + VIR_DOMAIN_FS_WRITEOUT_DEFAULT = 0,
> + VIR_DOMAIN_FS_WRITEOUT_IMMEDIATE,
> +
> + VIR_DOMAIN_FS_WRITEOUT_LAST
> +};
> +
> typedef struct _virDomainFSDef virDomainFSDef;
> typedef virDomainFSDef *virDomainFSDefPtr;
> struct _virDomainFSDef {
> int type;
> int fsdriver;
> int accessmode;
> + int writeout;
> char *src;
> char *dst;
> unsigned int readonly : 1;
> @@ -1973,6 +1982,7 @@ VIR_ENUM_DECL(virDomainControllerModelUSB)
> VIR_ENUM_DECL(virDomainFS)
> VIR_ENUM_DECL(virDomainFSDriverType)
> VIR_ENUM_DECL(virDomainFSAccessMode)
> +VIR_ENUM_DECL(virDomainFSWriteout)
> VIR_ENUM_DECL(virDomainNet)
> VIR_ENUM_DECL(virDomainNetBackend)
> VIR_ENUM_DECL(virDomainNetVirtioTxMode)
> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index 1f70eb1..ccfd092 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
> @@ -108,6 +108,10 @@ VIR_ENUM_IMPL(qemuDomainFSDriver, VIR_DOMAIN_FS_DRIVER_TYPE_LAST,
> "local",
> "handle");
>
> +VIR_ENUM_DECL(qemuDomainFSWriteout)
> +VIR_ENUM_IMPL(qemuDomainFSWriteout, VIR_DOMAIN_FS_WRITEOUT_LAST,
> + "default",
> + "immediate");
>
> static void
> uname_normalize (struct utsname *ut)
> @@ -1990,6 +1994,7 @@ char *qemuBuildFSStr(virDomainFSDefPtr fs,
> {
> virBuffer opt = VIR_BUFFER_INITIALIZER;
> const char *driver = qemuDomainFSDriverTypeToString(fs->fsdriver);
> + const char *writeout = qemuDomainFSWriteoutTypeToString(fs->writeout);
>
> if (fs->type != VIR_DOMAIN_FS_TYPE_MOUNT) {
> qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> @@ -2014,6 +2019,10 @@ char *qemuBuildFSStr(virDomainFSDefPtr fs,
> virBufferAddLit(&opt, ",security_model=none");
> }
> }
> +
> + if (fs->writeout != VIR_DOMAIN_FS_WRITEOUT_DEFAULT) {
Since the "writeout" option is introduced far later than the the
"-fsdev". i.e. "writeout" can be not supported by qemu even if
"-fsdev" is supported. So we might want to detect the capability
first and report error earlier than starting the qemu process.
Like QEMU_CAPS_FSDEV_READONLY in commit a1a83c5.
Others looks good, (I just planned to add this support, you step
one more than me. :-)
Regards,
Osier
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