[PATCH 1/2] conf: add disk cache tuning parameters after qemu

[Nikolay Shirokovskiy <nshirokovskiy@xxxxxxxxxxxxx>]

xml example:

<disk ...>
  <cachetune writeback='on' direct='off' no_flush='on'/>
</disk>

Parameters semantics match corresponding qemu 'cache.*' parameters.

--

I wonder should we use flush or sync name instead of qemu no_flush?
---
 docs/schemas/domaincommon.rng | 22 +++++++++++
 src/conf/domain_conf.c        | 90 +++++++++++++++++++++++++++++++++++++++++++
 src/conf/domain_conf.h        |  7 ++++
 3 files changed, 119 insertions(+)

diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
index 95c7882..17e4ac9 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -1208,6 +1208,9 @@
         <ref name="geometry"/>
       </optional>
       <optional>
+        <ref name="cachetune"/>
+      </optional>
+      <optional>
         <ref name="diskBlockIo"/>
       </optional>
       <optional>
@@ -1597,6 +1600,25 @@
       </optional>
     </element>
   </define>
+  <define name="cachetune">
+    <element name="cachetune">
+      <optional>
+        <attribute name="writeback">
+          <ref name="virOnOff"/>
+        </attribute>
+      </optional>
+      <optional>
+        <attribute name="direct">
+          <ref name="virOnOff"/>
+        </attribute>
+      </optional>
+      <optional>
+        <attribute name="no_flush">
+          <ref name="virOnOff"/>
+        </attribute>
+      </optional>
+    </element>
+  </define>
   <define name="geometry">
     <element name="geometry">
       <attribute name="cyls">
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index dd34cec..092696c 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -7405,6 +7405,52 @@ virDomainDiskDefParseValidate(const virDomainDiskDef *def)
     return 0;
 }
 
+static int
+virDomainDiskCachetuneDefFormat(virBufferPtr buf,
+                                virDomainDiskDefPtr def)
+{
+    const char *writeback = virTristateSwitchTypeToString(def->cachetune.writeback);
+    const char *direct = virTristateSwitchTypeToString(def->cachetune.direct);
+    const char *no_flush = virTristateSwitchTypeToString(def->cachetune.no_flush);
+
+    if (!writeback) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("unexpected disk cachetune writeback mode %d"),
+                       def->cachetune.writeback);
+        return -1;
+    }
+
+    if (!direct) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("unexpected disk cachetune direct mode %d"),
+                       def->cachetune.direct);
+        return -1;
+    }
+
+    if (!no_flush) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("unexpected disk cachetune no_flush mode %d"),
+                       def->cachetune.no_flush);
+        return -1;
+    }
+
+    if (def->cachetune.writeback ||
+        def->cachetune.direct ||
+        def->cachetune.no_flush) {
+        virBufferAddLit(buf, "<cachetune");
+
+        if (def->cachetune.writeback)
+            virBufferAsprintf(buf, " writeback='%s'", writeback);
+        if (def->cachetune.direct)
+            virBufferAsprintf(buf, " direct='%s'", direct);
+        if (def->cachetune.no_flush)
+            virBufferAsprintf(buf, " no_flush='%s'", no_flush);
+
+        virBufferAddLit(buf, "/>\n");
+    }
+
+    return 0;
+}
 
 static int
 virDomainDiskDefDriverParseXML(virDomainDiskDefPtr def,
@@ -7521,6 +7567,45 @@ virDomainDiskDefDriverParseXML(virDomainDiskDefPtr def,
     return ret;
 }
 
+static int
+virDomainDiskDefCachetuneParse(virDomainDiskDefPtr def,
+                               xmlNodePtr cur,
+                               xmlXPathContextPtr ctxt ATTRIBUTE_UNUSED)
+{
+    char *tmp = NULL;
+    int ret = -1;
+
+    if ((tmp = virXMLPropString(cur, "writeback")) &&
+        (def->cachetune.writeback = virTristateSwitchTypeFromString(tmp)) < 0) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("unknown disk cache writeback setting '%s'"), tmp);
+        goto cleanup;
+    }
+    VIR_FREE(tmp);
+
+    if ((tmp = virXMLPropString(cur, "direct")) &&
+        (def->cachetune.direct = virTristateSwitchTypeFromString(tmp)) < 0) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("unknown disk cache direct setting '%s'"), tmp);
+        goto cleanup;
+    }
+    VIR_FREE(tmp);
+
+    if ((tmp = virXMLPropString(cur, "no_flush")) &&
+        (def->cachetune.no_flush = virTristateSwitchTypeFromString(tmp)) < 0) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("unknown disk cache no_flush setting '%s'"), tmp);
+        goto cleanup;
+    }
+    VIR_FREE(tmp);
+
+    ret = 0;
+
+ cleanup:
+    VIR_FREE(tmp);
+
+    return ret;
+}
 
 #define VENDOR_LEN  8
 #define PRODUCT_LEN 16
@@ -7738,6 +7823,9 @@ virDomainDiskDefParseXML(virDomainXMLOptionPtr xmlopt,
             }
         } else if (xmlStrEqual(cur->name, BAD_CAST "boot")) {
             /* boot is parsed as part of virDomainDeviceInfoParseXML */
+        } else if (xmlStrEqual(cur->name, BAD_CAST "cachetune")) {
+            if (virDomainDiskDefCachetuneParse(def, cur, ctxt) < 0)
+                goto error;
         }
     }
 
@@ -20182,6 +20270,8 @@ virDomainDiskDefFormat(virBufferPtr buf,
 
     virDomainDiskGeometryDefFormat(buf, def);
     virDomainDiskBlockIoDefFormat(buf, def);
+    if (virDomainDiskCachetuneDefFormat(buf, def) < 0)
+        return -1;
 
     /* For now, mirroring is currently output-only: we only output it
      * for live domains, therefore we ignore it on input except for
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index ce90c27..2cc85e6 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -597,6 +597,13 @@ struct _virDomainDiskDef {
     char *vendor;
     char *product;
     int cachemode; /* enum virDomainDiskCache */
+
+    struct {
+        int writeback; /* enum virTristateSwitch */
+        int direct; /* enum virTristateSwitch */
+        int no_flush; /* enum virTristateSwitch */
+    } cachetune;
+
     int error_policy;  /* enum virDomainDiskErrorPolicy */
     int rerror_policy; /* enum virDomainDiskErrorPolicy */
     int iomode; /* enum virDomainDiskIo */
-- 
1.8.3.1

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