Re: [PATCH 8/9] qemu: Add -blockdev support for block pull job

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On Wed, Jul 24, 2019 at 11:07:35PM +0200, Peter Krempa wrote:
Introduce the handler for finalizing a block pull job which will allow
to use it with blockdev.

This patch also contains some additional machinery which is required to
store all the relevant job data in the status XML which will also be
reused with other block job types.

Signed-off-by: Peter Krempa <pkrempa@xxxxxxxxxx>
---
src/qemu/qemu_blockjob.c                      | 191 +++++++++++++++++-
src/qemu/qemu_blockjob.h                      |  18 ++
src/qemu/qemu_domain.c                        |  77 +++++++
src/qemu/qemu_driver.c                        |  33 ++-
.../blockjob-blockdev-in.xml                  |   4 +
5 files changed, 313 insertions(+), 10 deletions(-)

diff --git a/src/qemu/qemu_blockjob.c b/src/qemu/qemu_blockjob.c
index 0c0ae89f10..a29af7ec48 100644
--- a/src/qemu/qemu_blockjob.c
+++ b/src/qemu/qemu_blockjob.c
+/**
+ * qemuBlockJobProcessEventCompletedPull:
+ * @driver: qemu driver object
+ * @vm: domain object
+ * @job: job data
+ * @asyncJob: qemu asynchronous job type (for monitor interaction)
+ *
+ * This function executes the finalizing steps after a successful block pull job
+ * (block-stream in qemu terminology. The pull job copies all the data from the
+ * images in the backing chain up to the 'base' image. The 'base' image becomes
+ * the backing store of the active top level image. If 'base' was not used
+ * everything is pulled into the top level image and the top level image will
+ * cease to have backing store. All intermediate images between the active image
+ * and base image are no longer required and can be unplugged.
+ */
+static void
+qemuBlockJobProcessEventCompletedPull(virQEMUDriverPtr driver,
+                                      virDomainObjPtr vm,
+                                      qemuBlockJobDataPtr job,
+                                      qemuDomainAsyncJob asyncJob)
+{
+    virStorageSourcePtr baseparent = NULL;
+    virDomainDiskDefPtr cfgdisk = NULL;
+    virStorageSourcePtr cfgbase = NULL;
+    virStorageSourcePtr cfgbaseparent = NULL;
+    virStorageSourcePtr n;
+    virStorageSourcePtr tmp;
+
+    VIR_DEBUG("pull job '%s' on VM '%s' completed", job->name, vm->def->name);
+
+    /* if the job isn't associated with a disk there's nothing to do */
+    if (!job->disk)
+        return;
+
+    if ((cfgdisk = qemuBlockJobGetConfigDisk(vm, job->disk, job->data.pull.base)))
+        cfgbase = cfgdisk->src->backingStore;
+

Consider:
     cfgdisk = ...();
     if (cfgdisk)
         cfgbase = ...;
     else
         ...();

+    if (!cfgdisk)
+        qemuBlockJobClearConfigChain(vm, job->disk);
+
+    /* when pulling if 'base' is right below the top image we don't have to modify it */
+    if (job->disk->src->backingStore == job->data.pull.base)
+        return;
+
+    if (job->data.pull.base) {
+        for (n = job->disk->src->backingStore; n && n != job->data.pull.base; n = n->backingStore) {
+            /* find the image on top of 'base' */
+
+            if (cfgbase) {
+                cfgbaseparent = cfgbase;
+                cfgbase = cfgbase->backingStore;
+            }
+
+            baseparent = n;
+        }
+    }
+
+    tmp = job->disk->src->backingStore;
+    job->disk->src->backingStore = job->data.pull.base;
+    if (baseparent)
+        baseparent->backingStore = NULL;
+    qemuBlockJobEventProcessConcludedRemoveChain(driver, vm, asyncJob, tmp);
+    virObjectUnref(tmp);
+
+    if (cfgdisk) {
+        tmp = cfgdisk->src->backingStore;

You can unref tmp directly here

+        cfgdisk->src->backingStore = cfgbase;
+        if (cfgbaseparent)
+            cfgbaseparent->backingStore = NULL;
+        virObjectUnref(tmp);
+    }
+}
+
+
static void
qemuBlockJobEventProcessConcludedTransition(qemuBlockJobDataPtr job,
                                            virQEMUDriverPtr driver,
                                            virDomainObjPtr vm,
-                                            qemuDomainAsyncJob asyncJob ATTRIBUTE_UNUSED)
+                                            qemuDomainAsyncJob asyncJob)
{
    switch ((qemuBlockjobState) job->newstate) {
    case QEMU_BLOCKJOB_STATE_COMPLETED:
        switch ((qemuBlockJobType) job->type) {
        case QEMU_BLOCKJOB_TYPE_PULL:
+            qemuBlockJobProcessEventCompletedPull(driver, vm, job, asyncJob);
+            break;
+
        case QEMU_BLOCKJOB_TYPE_COMMIT:
        case QEMU_BLOCKJOB_TYPE_ACTIVE_COMMIT:
        case QEMU_BLOCKJOB_TYPE_COPY:
diff --git a/src/qemu/qemu_blockjob.h b/src/qemu/qemu_blockjob.h
index 3299207610..d5848fb72c 100644
--- a/src/qemu/qemu_blockjob.h
+++ b/src/qemu/qemu_blockjob.h
@@ -68,6 +68,15 @@ verify((int)QEMU_BLOCKJOB_TYPE_INTERNAL == VIR_DOMAIN_BLOCK_JOB_TYPE_LAST);

VIR_ENUM_DECL(qemuBlockjob);

+
+typedef struct _qemuBlockJobPullData qemuBlockJobPullData;
+typedef qemuBlockJobPullData *qemuBlockJobDataPullPtr;
+
+struct _qemuBlockJobPullData {
+    virStorageSourcePtr base;
+};
+
+
typedef struct _qemuBlockJobData qemuBlockJobData;
typedef qemuBlockJobData *qemuBlockJobDataPtr;

@@ -80,6 +89,10 @@ struct _qemuBlockJobData {
    virStorageSourcePtr chain; /* Reference to the chain the job operates on. */
    virStorageSourcePtr mirrorChain; /* reference to 'mirror' part of the job */

+    union {
+        qemuBlockJobPullData pull;
+    } data;
+
    int type; /* qemuBlockJobType */
    int state; /* qemuBlockjobState */
    char *errmsg;
@@ -114,6 +127,11 @@ void
qemuBlockJobDiskRegisterMirror(qemuBlockJobDataPtr job)
    ATTRIBUTE_NONNULL(1);

+qemuBlockJobDataPtr
+qemuBlockJobDiskNewPull(virDomainObjPtr vm,
+                        virDomainDiskDefPtr disk,
+                        virStorageSourcePtr base);
+
qemuBlockJobDataPtr
qemuBlockJobDiskGetJob(virDomainDiskDefPtr disk)
    ATTRIBUTE_NONNULL(1);
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index c508f55287..ec1dda4870 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -2390,6 +2390,21 @@ qemuDomainObjPrivateXMLFormatBlockjobIterator(void *payload,
            return -1;
    }

+    switch ((qemuBlockJobType) job->type) {
+        case QEMU_BLOCKJOB_TYPE_PULL:
+            if (job->data.pull.base)
+                virBufferAsprintf(&childBuf, "<base node='%s'/>\n", job->data.pull.base->nodeformat);
+            break;
+
+        case QEMU_BLOCKJOB_TYPE_COMMIT:
+        case QEMU_BLOCKJOB_TYPE_ACTIVE_COMMIT:
+        case QEMU_BLOCKJOB_TYPE_COPY:
+        case QEMU_BLOCKJOB_TYPE_NONE:
+        case QEMU_BLOCKJOB_TYPE_INTERNAL:
+        case QEMU_BLOCKJOB_TYPE_LAST:
+            break;
+    }
+
    return virXMLFormatElement(data->buf, "blockjob", &attrBuf, &childBuf);
}

@@ -2793,6 +2808,64 @@ qemuDomainObjPrivateXMLParseBlockjobChain(xmlNodePtr node,
}


+static void
+qemuDomainObjPrivateXMLParseBlockjobNodename(qemuBlockJobDataPtr job,
+                                             const char *xpath,
+                                             virStorageSourcePtr *src,
+                                             xmlXPathContextPtr ctxt)
+{
+    VIR_AUTOFREE(char *) nodename = NULL;
+
+    *src = NULL;
+
+    if (!(nodename = virXPathString(xpath, ctxt)))
+        return;
+
+    if (job->disk &&
+        (*src = virStorageSourceFindByNodeName(job->disk->src, nodename, NULL)))
+        return;
+
+    if (job->chain &&
+        (*src = virStorageSourceFindByNodeName(job->chain, nodename, NULL)))
+        return;
+
+    if (job->mirrorChain &&
+        (*src = virStorageSourceFindByNodeName(job->mirrorChain, nodename, NULL)))
+        return;
+
+    /* the node was in the XML but was not found in the job definitions */
+    VIR_DEBUG("marking block job '%s' as invalid: node name '%s' missing",
+              job->name, nodename);
+    job->invalidData = true;
+}
+
+
+static void
+qemuDomainObjPrivateXMLParseBlockjobDataSpecific(qemuBlockJobDataPtr job,
+                                                 xmlXPathContextPtr ctxt)
+{
+    switch ((qemuBlockJobType) job->type) {
+        case QEMU_BLOCKJOB_TYPE_PULL:
+            qemuDomainObjPrivateXMLParseBlockjobNodename(job,
+                                                         "string(./base/@node)",
+                                                         &job->data.pull.base,
+                                                         ctxt);
+            /* base is not present if pulling everything */
+            break;
+
+        case QEMU_BLOCKJOB_TYPE_COMMIT:
+        case QEMU_BLOCKJOB_TYPE_ACTIVE_COMMIT:
+        case QEMU_BLOCKJOB_TYPE_COPY:
+        case QEMU_BLOCKJOB_TYPE_NONE:
+        case QEMU_BLOCKJOB_TYPE_INTERNAL:

+        case QEMU_BLOCKJOB_TYPE_LAST:

virReportEnumRangeError

+            break;
+    }
+
+    return;
+}
+
+
static int
qemuDomainObjPrivateXMLParseBlockjobData(virDomainObjPtr vm,
                                         xmlNodePtr node,
@@ -2863,10 +2936,14 @@ qemuDomainObjPrivateXMLParseBlockjobData(virDomainObjPtr vm,
    job->errmsg = virXPathString("string(./errmsg)", ctxt);
    job->invalidData = invalidData;
    job->disk = disk;
+    if (invalidData)
+        VIR_DEBUG("marking block job '%s' as invalid: basic data broken", job->name);


This hunk belongs to a separate patch.

    if (mirror)
        qemuBlockJobDiskRegisterMirror(job);

+    qemuDomainObjPrivateXMLParseBlockjobDataSpecific(job, ctxt);
+

Possibly this one too.

    if (qemuBlockJobRegister(job, vm, disk, false) < 0)
        return -1;

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index b6d705b679..705c1a06c0 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -17040,7 +17040,8 @@ qemuDomainBlockPullCommon(virQEMUDriverPtr driver,
                          unsigned int flags)
{
    qemuDomainObjPrivatePtr priv = vm->privateData;
-    VIR_AUTOFREE(char *) device = NULL;
+    const char *device = NULL;
+    const char *jobname = NULL;
    virDomainDiskDefPtr disk;
    virStorageSourcePtr baseSource = NULL;
    unsigned int baseIndex = 0;
@@ -17048,6 +17049,8 @@ qemuDomainBlockPullCommon(virQEMUDriverPtr driver,
    VIR_AUTOFREE(char *) backingPath = NULL;
    unsigned long long speed = bandwidth;
    qemuBlockJobDataPtr job = NULL;
+    bool persistjob = false;
+    const char *nodebase = NULL;
    int ret = -1;

    if (flags & VIR_DOMAIN_BLOCK_REBASE_RELATIVE && !base) {
@@ -17066,9 +17069,6 @@ qemuDomainBlockPullCommon(virQEMUDriverPtr driver,
    if (!(disk = qemuDomainDiskByName(vm->def, path)))
        goto endjob;

-    if (!(device = qemuAliasDiskDriveFromDisk(disk)))
-        goto endjob;
-
    if (qemuDomainDiskBlockJobIsActive(disk))
        goto endjob;

@@ -17111,16 +17111,31 @@ qemuDomainBlockPullCommon(virQEMUDriverPtr driver,
        speed <<= 20;
    }

-    if (!(job = qemuBlockJobDiskNew(vm, disk, QEMU_BLOCKJOB_TYPE_PULL, device)))
+    if (!(job = qemuBlockJobDiskNewPull(vm, disk, baseSource)))
        goto endjob;

+    if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKDEV)) {

Please put this capability in a 'blockdev' bool and use it instead of
jobname below:

+        jobname = job->name;
+        persistjob = true;
+        if (baseSource) {
+            nodebase = baseSource->nodeformat;
+            if (!backingPath &&
+                !(backingPath = qemuBlockGetBackingStoreString(baseSource)))
+                goto endjob;
+        }
+        device = disk->src->nodeformat;
+    } else {
+        device = job->name;
+    }
+
    qemuDomainObjEnterMonitor(driver, vm);
-    if (baseSource)
+    if (baseSource && !jobname)

if (!blockdev && baseSource)

        basePath = qemuMonitorDiskNameLookup(priv->mon, device, disk->src,
                                             baseSource);
-    if (!baseSource || basePath)

Oh, this is a clever way to avoiding a 'exit_monitor' label and jump to
it when the above command fails.

-        ret = qemuMonitorBlockStream(priv->mon, device, NULL, false, basePath,
-                                     NULL, backingPath, speed);
+
+    if (!baseSource || basePath || jobname)

Please either:
 * separate the conditions:
   if (blockdev ||
       (the old one || ))
   grab a pint and hide in Winchester until we can get rid of the
   cleverness
 * introduce the exit_monitor label and avoid the need to extend the
   condition at all

+        ret = qemuMonitorBlockStream(priv->mon, device, jobname, persistjob, basePath,
+                                     nodebase, backingPath, speed);
    if (qemuDomainObjExitMonitor(driver, vm) < 0)
        ret = -1;


Reviewed-by: Ján Tomko <jtomko@xxxxxxxxxx>

Jano

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