[libvirt] [PATCH 11/11] qemu: Refactor qemuDomainBlockJobAbort()

[Michael Chapman]

On Wed, 1 Apr 2015, Peter Krempa wrote:
> Change few variable names and refactor the code flow. As an additional
> bonus the function now fails if the event state is not as expected.
> ---
> src/qemu/qemu_driver.c | 108 ++++++++++++++++++++++++-------------------------
> 1 file changed, 52 insertions(+), 56 deletions(-)
>
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index e9431ad..ee5bf8b 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -16279,13 +16279,13 @@ qemuDomainBlockJobAbort(virDomainPtr dom,
> {
>     virQEMUDriverPtr driver = dom->conn->privateData;
>     char *device = NULL;
> -    virObjectEventPtr event = NULL;
> -    virObjectEventPtr event2 = NULL;
>     virDomainDiskDefPtr disk;
>     virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
>     bool save = false;
>     int idx;
> -    bool async;
> +    bool modern;
> +    bool pivot = !!(flags & VIR_DOMAIN_BLOCK_JOB_ABORT_PIVOT);
> +    bool async = !!(flags & VIR_DOMAIN_BLOCK_JOB_ABORT_ASYNC);
>     virDomainObjPtr vm;
>     int ret = -1;
>
> @@ -16298,7 +16298,7 @@ qemuDomainBlockJobAbort(virDomainPtr dom,
>     if (virDomainBlockJobAbortEnsureACL(dom->conn, vm->def) < 0)
>         goto cleanup;
>
> -    if (qemuDomainSupportsBlockJobs(vm, &async) < 0)
> +    if (qemuDomainSupportsBlockJobs(vm, &modern) < 0)
>         goto cleanup;
>
>     if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
> @@ -16314,19 +16314,14 @@ qemuDomainBlockJobAbort(virDomainPtr dom,
>         goto endjob;
>     disk = vm->def->disks[idx];
>
> -    if (async && !(flags & VIR_DOMAIN_BLOCK_JOB_ABORT_ASYNC)) {
> -        /* prepare state for event delivery */
> +    if (modern && !async) {
> +        /* prepare state for event delivery. Since qemuDomainBlockPivot is
> +         * synchronous, but the event is delivered asynchronously we need to
> +         * wait too */
>         disk->blockJobStatus = -1;
>         disk->blockJobSync = true;
>     }
>
> -    if ((flags & VIR_DOMAIN_BLOCK_JOB_ABORT_PIVOT) &&
> -        !(async && disk->mirror)) {
> -        virReportError(VIR_ERR_OPERATION_INVALID,
> -                       _("pivot of disk '%s' requires an active copy job"),
> -                       disk->dst);
> -        goto endjob;
> -    }
>     if (disk->mirrorState != VIR_DOMAIN_DISK_MIRROR_STATE_NONE &&
>         disk->mirrorState != VIR_DOMAIN_DISK_MIRROR_STATE_READY) {
>         virReportError(VIR_ERR_OPERATION_INVALID,
> @@ -16335,29 +16330,29 @@ qemuDomainBlockJobAbort(virDomainPtr dom,
>         goto endjob;
>     }
>
> -    if (disk->mirror && (flags & VIR_DOMAIN_BLOCK_JOB_ABORT_PIVOT)) {
> -        ret = qemuDomainBlockPivot(driver, vm, device, disk);
> -        if (ret < 0 && async)
> +    if (pivot) {
> +        if (qemuDomainBlockPivot(driver, vm, device, disk) < 0)
>             goto endjob;
> -        goto waitjob;
> -    }

This still needs to assign to ret here, otherwise we won't return 0 on 
success.

> -    if (disk->mirror) {
> -        disk->mirrorState = VIR_DOMAIN_DISK_MIRROR_STATE_ABORT;
> -        save = true;
> -    }
> +    } else {
> +        if (disk->mirror) {
> +            disk->mirrorState = VIR_DOMAIN_DISK_MIRROR_STATE_ABORT;
> +            save = true;
> +        }
>
> -    qemuDomainObjEnterMonitor(driver, vm);
> -    ret = qemuMonitorBlockJobCancel(qemuDomainGetMonitor(vm), device, async);
> -    if (qemuDomainObjExitMonitor(driver, vm) < 0)
> -        ret = -1;
> +        qemuDomainObjEnterMonitor(driver, vm);
> +        ret = qemuMonitorBlockJobCancel(qemuDomainGetMonitor(vm), device, modern);
> +        if (qemuDomainObjExitMonitor(driver, vm) < 0) {
> +            ret = -1;
> +            goto endjob;
> +        }
>
> -    if (ret < 0) {
> -        if (disk->mirror)
> -            disk->mirrorState = VIR_DOMAIN_DISK_MIRROR_STATE_NONE;
> -        goto endjob;
> +        if (ret < 0) {
> +            if (disk->mirror)
> +                disk->mirrorState = VIR_DOMAIN_DISK_MIRROR_STATE_NONE;
> +            goto endjob;
> +        }
>     }
>
> - waitjob:
>     /* If we have made changes to XML due to a copy job, make a best
>      * effort to save it now.  But we can ignore failure, since there
>      * will be further changes when the event marks completion.  */
> @@ -16372,33 +16367,38 @@ qemuDomainBlockJobAbort(virDomainPtr dom,
>      * while still holding the VM job, to prevent newly scheduled
>      * block jobs from confusing us.  */
>     if (!async) {
> -        /* Older qemu that lacked async reporting also lacked
> -         * blockcopy and active commit, so we can hardcode the
> -         * event to pull, and we know the XML doesn't need
> -         * updating.  We have to generate two event variants.  */
> -        int type = VIR_DOMAIN_BLOCK_JOB_TYPE_PULL;
> -        int status = VIR_DOMAIN_BLOCK_JOB_CANCELED;
> -        event = virDomainEventBlockJobNewFromObj(vm, disk->src->path, type,
> -                                                 status);
> -        event2 = virDomainEventBlockJob2NewFromObj(vm, disk->dst, type,
> -                                                   status);
> -    } else if (disk->blockJobSync) {
> -        /* XXX If the event reports failure, we should reflect
> -         * that back into the return status of this API call.  */
> -
> -        while (disk->blockJobStatus == -1 && disk->blockJobSync) {
> -            if (virCondWait(&disk->blockJobSyncCond, &vm->parent.lock) < 0) {
> -                virReportSystemError(errno, "%s",
> -                                     _("Unable to wait on block job sync "
> -                                       "condition"));
> -                disk->blockJobSync = false;
> -                goto endjob;
> +        if (!modern) {
> +            /* Older qemu that lacked async reporting also lacked
> +             * blockcopy and active commit, so we can hardcode the
> +             * event to pull and let qemuBlockJobEventProcess() handle
> +             * the rest as usual */
> +            disk->blockJobType = VIR_DOMAIN_BLOCK_JOB_TYPE_PULL;
> +            disk->blockJobStatus = VIR_DOMAIN_BLOCK_JOB_CANCELED;
> +        } else {
> +            while (disk->blockJobStatus == -1 && disk->blockJobSync) {
> +                if (virCondWait(&disk->blockJobSyncCond, &vm->parent.lock) < 0) {
> +                    virReportSystemError(errno, "%s",
> +                                         _("Unable to wait on block job sync "
> +                                           "condition"));
> +                    disk->blockJobSync = false;
> +                    goto endjob;
> +                }
>             }
>         }
>
>         qemuBlockJobEventProcess(driver, vm, disk,
>                                  disk->blockJobType,
>                                  disk->blockJobStatus);
> +
> +        /* adjust the return code */
> +        if ((pivot && disk->blockJobStatus != VIR_DOMAIN_BLOCK_JOB_COMPLETED) ||
> +            (!pivot && disk->blockJobStatus != VIR_DOMAIN_BLOCK_JOB_CANCELED)) {

I'm wondering whether it is simpler to examine disk->mirrorState here 
rather than disk->blockJobStatus. The second test doesn't look right: QEMU 
signals COMPLETED if a drive mirror is canceled after it's fully synced.

> +            virReportError(VIR_ERR_OPERATION_FAILED,
> +                           _("failed to terminate block job on disk '%s'"),
> +                           disk->dst);
> +           ret = -1;
> +        }
> +
>         disk->blockJobSync = false;
>     }
>
> @@ -16409,10 +16409,6 @@ qemuDomainBlockJobAbort(virDomainPtr dom,
>     virObjectUnref(cfg);
>     VIR_FREE(device);
>     qemuDomObjEndAPI(&vm);
> -    if (event)
> -        qemuDomainEventQueue(driver, event);
> -    if (event2)
> -        qemuDomainEventQueue(driver, event2);
>     return ret;
> }
>
>

- Michael