On 04/10/2018 10:58 AM, Michal Privoznik wrote:
> When plugging a disk into domain we need to start qemu-pr-helper
> process iff this is the first disk with PR enabled for the
> domain. Otherwise the helper is already running (or not needed).
>
> Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
> ---
> src/qemu/qemu_hotplug.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++
> src/qemu/qemu_process.c | 4 ++--
> src/qemu/qemu_process.h | 5 +++++
> 3 files changed, 58 insertions(+), 2 deletions(-)
>
Personally not a fan of splitting up the hotplug need for PR daemon from
need for adding the object to the disk and the separate unplug patch,
but I understand why it's done this way.
> diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
> index f0d549de38..468153c79c 100644
> --- a/src/qemu/qemu_hotplug.c
> +++ b/src/qemu/qemu_hotplug.c
> @@ -348,6 +348,49 @@ qemuDomainChangeEjectableMedia(virQEMUDriverPtr driver,
> }
>
>
> +/**
> + * qemuDomainMaybeStartPRDaemon:
> + * @vm: domain object
> + * @disk: disk to hotplug
> + *
> + * Checks if it's needed to start qemu-pr-helper and starts it.
> + *
> + * Returns: 0 if qemu-pr-helper is not needed
> + * 1 if it is needed and was started
> + * -1 otherwise.
> + */
> +static int
> +qemuDomainMaybeStartPRDaemon(virDomainObjPtr vm,
> + virDomainDiskDefPtr disk)
> +{
> + size_t i;
> + qemuDomainStorageSourcePrivatePtr srcPriv;
> +
> + if (!virStoragePRDefIsManaged(disk->src->pr)) {
> + /* @disk itself does not require qemu-pr-helper. */
> + return 0;
> + }
> +
If we used the fact that the thing was already started for the domain in
some sort of domain private data (which could even store the PID-file
path), then we wouldn't need the following...
> + for (i = 0; i < vm->def->ndisks; i++) {
> + const virDomainDiskDef *domainDisk = vm->def->disks[i];
> +
> + if (virStoragePRDefIsManaged(domainDisk->src->pr)) {
> + /* qemu-pr-helper should be already started because
> + * another disk in domain requires it. */
> + return 0;
> + }
> + }
> +
> + /* @disk requires qemu-pr-helper but none is running.
> + * Start it now. */
> + srcPriv = QEMU_DOMAIN_STORAGE_SOURCE_PRIVATE(disk->src);
> + if (qemuProcessStartPRDaemon(vm, srcPriv->prd) < 0)
> + return -1;
and the above would set things for us (conceivably)
John
> +
> + return 1;
> +}
> +
> +
> /**
> * qemuDomainAttachDiskGeneric:
> *
> @@ -368,6 +411,7 @@ qemuDomainAttachDiskGeneric(virQEMUDriverPtr driver,
> bool driveAdded = false;
> bool secobjAdded = false;
> bool encobjAdded = false;
> + bool prdStarted = false;
> virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
> virJSONValuePtr secobjProps = NULL;
> virJSONValuePtr encobjProps = NULL;
> @@ -384,6 +428,11 @@ qemuDomainAttachDiskGeneric(virQEMUDriverPtr driver,
> if (qemuDomainPrepareDiskSource(disk, priv, cfg) < 0)
> goto error;
>
> + if ((rv = qemuDomainMaybeStartPRDaemon(vm, disk)) < 0)
> + goto cleanup;
> + else if (rv > 0)
> + prdStarted = true;
> +
> srcPriv = QEMU_DOMAIN_STORAGE_SOURCE_PRIVATE(disk->src);
> if (srcPriv) {
> secinfo = srcPriv->secinfo;
> @@ -481,6 +530,8 @@ qemuDomainAttachDiskGeneric(virQEMUDriverPtr driver,
> error:
> qemuDomainDelDiskSrcTLSObject(driver, vm, disk->src);
> ignore_value(qemuHotplugPrepareDiskAccess(driver, vm, disk, NULL, true));
> + if (prdStarted)
> + qemuProcessKillPRDaemon(vm);
> goto cleanup;
> }
>
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index 982c989a0a..11aaeabb38 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -2571,7 +2571,7 @@ qemuProcessBuildPRHelperPidfilePath(virDomainObjPtr vm,
> }
>
>
> -static void
> +void
> qemuProcessKillPRDaemon(virDomainObjPtr vm)
> {
> virErrorPtr orig_err;
> @@ -2629,7 +2629,7 @@ qemuProcessStartPRDaemonHook(void *opaque)
> }
>
>
> -static int
> +int
> qemuProcessStartPRDaemon(virDomainObjPtr vm,
> qemuDomainDiskPRDPtr prd)
> {
> diff --git a/src/qemu/qemu_process.h b/src/qemu/qemu_process.h
> index 2741115673..8df5832e23 100644
> --- a/src/qemu/qemu_process.h
> +++ b/src/qemu/qemu_process.h
> @@ -203,4 +203,9 @@ int qemuProcessRefreshDisks(virQEMUDriverPtr driver,
> virDomainObjPtr vm,
> qemuDomainAsyncJob asyncJob);
>
> +int qemuProcessStartPRDaemon(virDomainObjPtr vm,
> + qemuDomainDiskPRDPtr prd);
> +
> +void qemuProcessKillPRDaemon(virDomainObjPtr vm);
> +
> #endif /* __QEMU_PROCESS_H__ */
>
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