Re: [libvirt] [PATCH 3/5] libvirt/qemu - support persistent modification of devices.

15 Mar 2011

On Mon, 14 Mar 2011 13:29:13 +0800
Wen Congyang <wency@cn.fujitsu.com> wrote:
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At 03/03/2011 09:11 AM, KAMEZAWA Hiroyuki Write:
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From f7a997e3cd58cfac81e131afdd20c3691267831d Mon Sep 17 00:00:00 2001
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Date: Thu, 3 Mar 2011 09:43:07 +0900
Subject: [PATCH 3/5] libivrt/qemu - support persistent modification of devices.
Now, virsh attach-***/detach-*** has --persistent option and
it can update XML definition of inactive domains.
Now, disk and nic are supported in Xen, but none in qemu.
This patch adds a function for permanent modification for qemu.
Following patches will add disk/network suport.
TODO:
  - finally, need to do hotplug + XML modification for active domain.
Changelog v3->v4
  - fixed trailing white spaces.
  - splitted into 2 part and this patch only contains wrappers.
Changelog v2->v3:
  - clean ups.
  - handle all VIR_DOMAIN_DEVICE_MODIFY_XXX flags.
---
 src/qemu/qemu_driver.c |  143 ++++++++++++++++++++++++++++++++++++++++++++----
 1 files changed, 131 insertions(+), 12 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index c9095bb..3248cdc 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -4099,16 +4099,131 @@ cleanup:
     return ret;
 }
-static int qemudDomainAttachDeviceFlags(virDomainPtr dom,
+/*
+ * Attach a device given by XML, the change will be persistent
+ * and domain XML definition file is updated.
+ */
+static int qemuDomainAttachDevicePersistent(virDomainDefPtr vmdef,
+                                            virDomainDeviceDefPtr newdev)
+{
+
+    /* At first, check device confliction */
+    switch(newdev->type) {
+    default:
+        qemuReportError(VIR_ERR_INVALID_ARG, "%s",
When the device is not supported, we should use VIR_ERR_CONFIG_UNSUPPORTED
instead of VIR_ERR_INVALID_ARG.
will change.
...
...
+                        _("Sorry, the device is not suppored for now"));
+        return -1;
+    }
+
+    return 0;
+}
+
+static int qemuDomainDetachDevicePersistent(virDomainDefPtr vmdef,
+                                       virDomainDeviceDefPtr device)
The coding style is wrong: virDomainDeviceDefPtr shoulde be left justified
with virDomainDefPtr.
Hmm, okay.
...
...
+{
+    switch(device->type) {
+    default:
+        qemuReportError(VIR_ERR_INVALID_ARG, "%s",
+                        _("Sorry, the device is not suppored for now"));
+        return -1;
+    }
+    return 0;
+}
+
+static int qemuDomainModifyDevicePersistent(virDomainPtr dom,
                                         const char *xml,
-                                        unsigned int flags) {
-    if (flags & VIR_DOMAIN_DEVICE_MODIFY_CONFIG) {
-        qemuReportError(VIR_ERR_OPERATION_INVALID,
-                        "%s", _("cannot modify the persistent configuration of a domain"));
+                                        unsigned int attach, int flags)
Why do you modify the type of flag?
my bug.
...
...
+{
+    struct qemud_driver *driver;
+    virDomainDeviceDefPtr device;
+    virDomainDefPtr vmdef;
+    virDomainObjPtr vm;
+    int ret = -1;
+
+    if (!dom || !dom->conn || !dom->name || !xml) {
dom and dom->conn does not need check, they are always not null.
Ok, so, Xen code should be fixed. (This is just a copy-n-paste.)
...
...
+        qemuReportError(VIR_ERR_INTERNAL_ERROR,
+                        _("internal error : %s"),  __FUNCTION__);
Do not use __FUNCTION__ here, the macro qemuReportError will do it.
...
+        return -1;
+    }
+    /*
+     * When both of MODIFY_CONFIG and MODIFY_LIVE is specified at the same time,
+     * return error for now. We should support this later.
+     */
+    if (flags & VIR_DOMAIN_DEVICE_MODIFY_LIVE) {
+        qemuReportError(VIR_ERR_INVALID_ARG, "%s",
Please use VIR_ERR_OPERATION_INVALID instead of VIR_ERR_INVALID_ARG.
ok.
...
...
+                        _("Now, cannot modify alive domain and its definition "
+                          "at the same time."));
         return -1;
     }
-    return qemudDomainAttachDevice(dom, xml);
+    driver = dom->conn->privateData;
+    qemuDriverLock(driver);
+    vm = virDomainFindByUUID(&driver->domains, dom->uuid);
+    if (!vm) {
+        qemuReportError(VIR_ERR_NO_DOMAIN, _("cannot find domain '%s'"),
+                        dom->name);
You use UUID to search the domain, so the error message should be:
no domain with matching uuid '%s'
ok.
...
...
+        goto unlock_out;
+    }
+
+    if (qemuDomainObjBeginJobWithDriver(driver, vm) < 0)
+        goto unlock_out;
+
+    if (virDomainObjIsActive(vm)) {
+        /*
+         * For now, just allow updating inactive domains. Further development
+         * will allow updating both active domain and its config file at
+         * the same time.
+         */
+        qemuReportError(VIR_ERR_OPERATION_INVALID, "%s",
+              _("Now, it's unsupported to update active domain's definition."));
+        goto endjob;
+    }
+
+    vmdef = virDomainObjGetPersistentDef(driver->caps, vm);
+
+    if (!vmdef)
+        goto endjob;
+
+    device = virDomainDeviceDefParse(driver->caps,
+                 vmdef, xml, VIR_DOMAIN_XML_INACTIVE);
+    if (!device)
+        goto endjob;
+
+    if (attach)
+        ret = qemuDomainAttachDevicePersistent(vmdef, device);
+    else
+        ret = qemuDomainDetachDevicePersistent(vmdef, device);
+
+    if (!ret) /* save the result */
+        ret = virDomainSaveConfig(driver->configDir, vmdef);
+
+    virDomainDeviceDefFree(device);
+
+endjob:
+    if (qemuDomainObjEndJob(vm) == 0)
+        vm = NULL;
+    if (vm)
+        virDomainObjUnlock(vm);
When qemuDomainObjBeginJobWithDriver() failed, we should unlock the domain.
So we should do it when we goto unlock_out.
ok.
...
...
+unlock_out:
+    qemuDriverUnlock(driver);
+    return ret;
+}
+
+static int qemudDomainAttachDeviceFlags(virDomainPtr dom,
+                                        const char *xml,
+                                        unsigned int flags)
+{
+    if (flags & VIR_DOMAIN_DEVICE_MODIFY_CONFIG)
+        return qemuDomainModifyDevicePersistent(dom, xml, 1, flags);
+
+    if (flags & VIR_DOMAIN_DEVICE_MODIFY_LIVE)
+        return qemudDomainAttachDevice(dom, xml);
+
+    qemuReportError(VIR_ERR_INVALID_ARG,
+        _("bad flag: %x only MODIFY_LIVE, MODIFY_CONFIG are supported now"),
+       flags);
+
+    return -1;
 }
@@ -4322,13 +4437,17 @@ cleanup:
 static int qemudDomainDetachDeviceFlags(virDomainPtr dom,
                                         const char *xml,
                                         unsigned int flags) {
-    if (flags & VIR_DOMAIN_DEVICE_MODIFY_CONFIG) {
-        qemuReportError(VIR_ERR_OPERATION_INVALID,
-                        "%s", _("cannot modify the persistent configuration of a domain"));
-        return -1;
-    }
-    return qemudDomainDetachDevice(dom, xml);
+    if (flags & VIR_DOMAIN_DEVICE_MODIFY_CONFIG)
+        return qemuDomainModifyDevicePersistent(dom, xml, 0, flags);
+
+    if (flags & VIR_DOMAIN_DEVICE_MODIFY_LIVE)
+        return qemudDomainDetachDevice(dom, xml);
+
+    qemuReportError(VIR_ERR_INVALID_ARG,
+        _("bad flag: %x only MODIFY_LIVE, MODIFY_CONFIG are supported now"),
+        flags);
+    return -1;
 }
static int qemudDomainGetAutostart(virDomainPtr dom,
Thank you.
-Kame

    