Re: [libvirt] [PATCH v4 04/14] qemu: Generate alias and socket path for pr-helper
On 04/17/2018 01:49 PM, John Ferlan wrote:
>
>
> On 04/16/2018 10:56 AM, Michal Privoznik wrote:
>> On 04/13/2018 10:51 PM, John Ferlan wrote:
>>>
>>>
>>> On 04/10/2018 10:58 AM, Michal Privoznik wrote:
While we're not generating the command line just yet (look for
the next commits), we can generate the alias for pr-manager.
A domain can have up to one managed pr-manager (in which case
socket path is decided by libvirt and pr-helper is spawned by
libvirt too), but up to ndisks of unmanaged ones (one per disk
basically). In case of the former we can generate a simple alias
and be sure it'll not conflict. But in case of the latter to
>>>
>>> Well if it's only one, then it had better not conflict (IOW: after the
>>> and is unnecessary because there is check).
>>>
avoid any conflicts let's generate alias that's based on
something unique - like disk target.
>>>
>>> Make sure this commit message follows whatever happens in this patch...
>>>
Signed-off-by: Michal Privoznik
---
src/libvirt_private.syms | 2 ++
src/qemu/qemu_alias.c | 11 ++
src/qemu/qemu_alias.h | 2 ++
src/qemu/qemu_domain.c| 87
+--
src/qemu/qemu_domain.h| 10 ++
src/util/virstoragefile.c | 15
src/util/virstoragefile.h | 2 ++
7 files changed, 126 insertions(+), 3 deletions(-)
>>>
>>> This patch does two things - one is just the pure alias/path for the
>>> pr-helper for the active domain. The second is copy that same
>>> information to the private storage source, which I'm not sure (yet) why
>>> it's necessary since both can be regenerated as needed based on fairly
>>> static data as opposed to secinfo and encinfo which get filled in with
>>> information only available during Prepare (the interaction with the
>>> secret driver and the need for the @conn pointer) that wasn't available
>>> during launch/command line building. Although some of that has changed
>>> with more recent changes to be able to get a secret conn "on the fly".
>>> Anyway, I digress.
>>>
>>> The point being - please note why you're also saving something in the
>>> private storage source area... The 'path' is already present in the
>>> domain XML (both active and inactive) and the 'alias' could be saved in
>>> the active output if you tweaked virStoragePRDefFormat to match what
>>> virDomainDeviceInfoFormat does.
>>
>> Okay. I will put it in the commit message. I thought we've discussed
>> this earlier. I rather put and info into status XML even though it might
>> look useless right now than having to write some crazy backcompat code
>> later.
>>
>
> I don't think this is the same as @channelTargetDir (as you note in the
> next response). The problem there was a reliance on a name that ended up
> being too long and yes, it was a mess. I dunno - I think I've tried the
> future proofing things too and was told it was unnecessary.
Depends on problem you were trying to future proof from.
>
> Still in order to "provide insight" into my why... Here you have a @path
> that's essentially static outside of the commonly used priv->libDir and
> an @alias that is static when managed. When unmanaged, the @path is
> provided by a consumer and the @alias is essentially a static prefix
> followed by a commonly used source destination alias. So nothing so far
> that would need to be saved in two places.
Not true. If alias were a static string, then _qemuDomainDiskPRD would
need to reflect that. That means, alias must be 'const char *' because
storing a static string into 'char *' is a big NO NO. But at the same
time, alias is dynamically generated (for unmanaged disks), so it has to
be 'char *'. Sure, we can obfuscate it by inventing new struct member,
but
just look at how ugly it looks:
struct qemuDomainDiskPRD {
char *alias;
const char *constAlias;
char *path;
};
Also, think of all those special casing in the code that uses the
struct. This approach that I implemented here is used widely across our
code base: qemuAssignDeviceTPMAlias(), qemuAssignDeviceWatchdogAlias()
to name few.
Why we even need this struct you ask? Couple of reasons:
a) this approach implemented here is specific to QEMU and QEMU only. It
isn't hypervisor agnostic, thus it doesn't belong to _virStoragePRDef.
b) we should separate runtime and config data. That's why virStorage*()
functions live under src/util/ as they work with config and not runtime
(as in hypervisor specific). This merely mimics vm->privateData
abstraction.
>
> Since @alias is an "internal" libvirt->qemu construct we wouldn't have
> the same problem as some "external" construct changing our definition.
> Unlike perhaps _qemuDomainVcpuPrivate where the alias perhaps changes
> based on ordering, insert, remove, etc. (I didn't look, but made the
> assumption). For PR there is one and it's not going to change. Even if
> it did, we would
Re: [libvirt] [PATCH v4 04/14] qemu: Generate alias and socket path for pr-helper
On 04/16/2018 10:56 AM, Michal Privoznik wrote: > On 04/13/2018 10:51 PM, John Ferlan wrote: >> >> >> On 04/10/2018 10:58 AM, Michal Privoznik wrote: >>> While we're not generating the command line just yet (look for >>> the next commits), we can generate the alias for pr-manager. >>> A domain can have up to one managed pr-manager (in which case >>> socket path is decided by libvirt and pr-helper is spawned by >>> libvirt too), but up to ndisks of unmanaged ones (one per disk >>> basically). In case of the former we can generate a simple alias >>> and be sure it'll not conflict. But in case of the latter to >> >> Well if it's only one, then it had better not conflict (IOW: after the >> and is unnecessary because there is check). >> >>> avoid any conflicts let's generate alias that's based on >>> something unique - like disk target. >>> >> >> Make sure this commit message follows whatever happens in this patch... >> >>> Signed-off-by: Michal Privoznik >>> --- >>> src/libvirt_private.syms | 2 ++ >>> src/qemu/qemu_alias.c | 11 ++ >>> src/qemu/qemu_alias.h | 2 ++ >>> src/qemu/qemu_domain.c| 87 >>> +-- >>> src/qemu/qemu_domain.h| 10 ++ >>> src/util/virstoragefile.c | 15 >>> src/util/virstoragefile.h | 2 ++ >>> 7 files changed, 126 insertions(+), 3 deletions(-) >>> >> >> This patch does two things - one is just the pure alias/path for the >> pr-helper for the active domain. The second is copy that same >> information to the private storage source, which I'm not sure (yet) why >> it's necessary since both can be regenerated as needed based on fairly >> static data as opposed to secinfo and encinfo which get filled in with >> information only available during Prepare (the interaction with the >> secret driver and the need for the @conn pointer) that wasn't available >> during launch/command line building. Although some of that has changed >> with more recent changes to be able to get a secret conn "on the fly". >> Anyway, I digress. >> >> The point being - please note why you're also saving something in the >> private storage source area... The 'path' is already present in the >> domain XML (both active and inactive) and the 'alias' could be saved in >> the active output if you tweaked virStoragePRDefFormat to match what >> virDomainDeviceInfoFormat does. > > Okay. I will put it in the commit message. I thought we've discussed > this earlier. I rather put and info into status XML even though it might > look useless right now than having to write some crazy backcompat code > later. > I don't think this is the same as @channelTargetDir (as you note in the next response). The problem there was a reliance on a name that ended up being too long and yes, it was a mess. I dunno - I think I've tried the future proofing things too and was told it was unnecessary. Still in order to "provide insight" into my why... Here you have a @path that's essentially static outside of the commonly used priv->libDir and an @alias that is static when managed. When unmanaged, the @path is provided by a consumer and the @alias is essentially a static prefix followed by a commonly used source destination alias. So nothing so far that would need to be saved in two places. Since @alias is an "internal" libvirt->qemu construct we wouldn't have the same problem as some "external" construct changing our definition. Unlike perhaps _qemuDomainVcpuPrivate where the alias perhaps changes based on ordering, insert, remove, etc. (I didn't look, but made the assumption). For PR there is one and it's not going to change. Even if it did, we would always know the former format to search on before using a newer format. In the long run, since there would be only one the PR alias belongs in the _qemuDomainObjPrivate further removing the need to have anything private. As noted somewhere during my review the existing need for a private structure for secrets could now be reworked/removed because the code now can generate the @conn on the fly rather than needing the @conn from the original connection in order to lookup the secret. Depends on if we want an error during command line generation or during the prepare phase. >> >> >>> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms >>> index a376e3bb0d..5b7b5514a2 100644 >>> --- a/src/libvirt_private.syms >>> +++ b/src/libvirt_private.syms >>> @@ -2799,7 +2799,9 @@ virStorageNetHostTransportTypeToString; >>> virStorageNetProtocolTypeToString; >>> virStoragePRDefFormat; >>> virStoragePRDefFree; >>> +virStoragePRDefIsEnabled; >>> virStoragePRDefIsEqual; >>> +virStoragePRDefIsManaged; >>> virStoragePRDefParseXML; >>> virStorageSourceBackingStoreClear; >>> virStorageSourceClear; >>> diff --git a/src/qemu/qemu_alias.c b/src/qemu/qemu_alias.c >>> index 95d1e0370a..6db3da27a8 100644 >>> --- a/src/qemu/qemu_alias.c >>> +++ b/src/qemu/qemu_alias.c >>> @@ -773,3 +773,14 @@ qemuAliasChardevFromDevAlias(co
Re: [libvirt] [PATCH v4 04/14] qemu: Generate alias and socket path for pr-helper
On 04/13/2018 10:51 PM, John Ferlan wrote:
>
>
> On 04/10/2018 10:58 AM, Michal Privoznik wrote:
>> While we're not generating the command line just yet (look for
>> the next commits), we can generate the alias for pr-manager.
>> A domain can have up to one managed pr-manager (in which case
>> socket path is decided by libvirt and pr-helper is spawned by
>> libvirt too), but up to ndisks of unmanaged ones (one per disk
>> basically). In case of the former we can generate a simple alias
>> and be sure it'll not conflict. But in case of the latter to
>
> Well if it's only one, then it had better not conflict (IOW: after the
> and is unnecessary because there is check).
>
>> avoid any conflicts let's generate alias that's based on
>> something unique - like disk target.
>>
>
> Make sure this commit message follows whatever happens in this patch...
>
>> Signed-off-by: Michal Privoznik
>> ---
>> src/libvirt_private.syms | 2 ++
>> src/qemu/qemu_alias.c | 11 ++
>> src/qemu/qemu_alias.h | 2 ++
>> src/qemu/qemu_domain.c| 87
>> +--
>> src/qemu/qemu_domain.h| 10 ++
>> src/util/virstoragefile.c | 15
>> src/util/virstoragefile.h | 2 ++
>> 7 files changed, 126 insertions(+), 3 deletions(-)
>>
>
> This patch does two things - one is just the pure alias/path for the
> pr-helper for the active domain. The second is copy that same
> information to the private storage source, which I'm not sure (yet) why
> it's necessary since both can be regenerated as needed based on fairly
> static data as opposed to secinfo and encinfo which get filled in with
> information only available during Prepare (the interaction with the
> secret driver and the need for the @conn pointer) that wasn't available
> during launch/command line building. Although some of that has changed
> with more recent changes to be able to get a secret conn "on the fly".
> Anyway, I digress.
>
> The point being - please note why you're also saving something in the
> private storage source area... The 'path' is already present in the
> domain XML (both active and inactive) and the 'alias' could be saved in
> the active output if you tweaked virStoragePRDefFormat to match what
> virDomainDeviceInfoFormat does.
Okay. I will put it in the commit message. I thought we've discussed
this earlier. I rather put and info into status XML even though it might
look useless right now than having to write some crazy backcompat code
later.
>
>
>> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
>> index a376e3bb0d..5b7b5514a2 100644
>> --- a/src/libvirt_private.syms
>> +++ b/src/libvirt_private.syms
>> @@ -2799,7 +2799,9 @@ virStorageNetHostTransportTypeToString;
>> virStorageNetProtocolTypeToString;
>> virStoragePRDefFormat;
>> virStoragePRDefFree;
>> +virStoragePRDefIsEnabled;
>> virStoragePRDefIsEqual;
>> +virStoragePRDefIsManaged;
>> virStoragePRDefParseXML;
>> virStorageSourceBackingStoreClear;
>> virStorageSourceClear;
>> diff --git a/src/qemu/qemu_alias.c b/src/qemu/qemu_alias.c
>> index 95d1e0370a..6db3da27a8 100644
>> --- a/src/qemu/qemu_alias.c
>> +++ b/src/qemu/qemu_alias.c
>> @@ -773,3 +773,14 @@ qemuAliasChardevFromDevAlias(const char *devAlias)
>>
>> return ret;
>> }
>> +
>> +
>> +char *
>> +qemuDomainGetManagedPRAlias(void)
>> +{
>> +char *alias;
>> +
>> +ignore_value(VIR_STRDUP(alias, "pr-helper0"));
>> +
>> +return alias;
>> +}
>
> I don't really see a purpose for this function. If it were to survive,
> then it could take a parameter "const char *srcalias" and create/return
> the alias from that based on what's in qemuDomainPrepareDiskPRD.
The purpose is to generate alias at only one place instead of several
virAsprintf-s scattered all around the code.
>
> Eventually when the qemuProcessKillPRDaemon is created, it doesn't
> necessarily distinguish between managed and unmanaged...
Well, unmanaged helper should not have its socket in libvirt private
path. Under any circumstances. And what qemuProcessKillPRDaemon does is:
1) it constructs PID file path
2) and kills any pr-helper that might had been left behind.
I find this approach more robust than plain "check if there is a disk
with pr-helper and if so kill it" because if libvirt is ever split brained
> Still having it
> fail because it couldn't strdup what amounts to be a static string
> doesn't make much sense.
Well, there are couple of reasons for stdup()-ing a static string:
a) it simplifies the code, e.g. qemuDomainDiskPRDFree() doesn't have to
care if alias is a static string or dynamically allocated one,
b) higher memory consumption (by 11 bytes btw) is only for a short
period of time (when constructing PID file path). Although, the alias is
kept around for entire time domain is running.
And if libvirt is unable to allocate 11 bytes then you're in much bigger
trouble anyways.
>
> diff --git a/src/qemu/qemu_alias.h b/src/qemu/qemu_alias.h
>> index 8c74
Re: [libvirt] [PATCH v4 04/14] qemu: Generate alias and socket path for pr-helper
On 04/10/2018 10:58 AM, Michal Privoznik wrote:
> While we're not generating the command line just yet (look for
> the next commits), we can generate the alias for pr-manager.
> A domain can have up to one managed pr-manager (in which case
> socket path is decided by libvirt and pr-helper is spawned by
> libvirt too), but up to ndisks of unmanaged ones (one per disk
> basically). In case of the former we can generate a simple alias
> and be sure it'll not conflict. But in case of the latter to
Well if it's only one, then it had better not conflict (IOW: after the
and is unnecessary because there is check).
> avoid any conflicts let's generate alias that's based on
> something unique - like disk target.
>
Make sure this commit message follows whatever happens in this patch...
> Signed-off-by: Michal Privoznik
> ---
> src/libvirt_private.syms | 2 ++
> src/qemu/qemu_alias.c | 11 ++
> src/qemu/qemu_alias.h | 2 ++
> src/qemu/qemu_domain.c| 87
> +--
> src/qemu/qemu_domain.h| 10 ++
> src/util/virstoragefile.c | 15
> src/util/virstoragefile.h | 2 ++
> 7 files changed, 126 insertions(+), 3 deletions(-)
>
This patch does two things - one is just the pure alias/path for the
pr-helper for the active domain. The second is copy that same
information to the private storage source, which I'm not sure (yet) why
it's necessary since both can be regenerated as needed based on fairly
static data as opposed to secinfo and encinfo which get filled in with
information only available during Prepare (the interaction with the
secret driver and the need for the @conn pointer) that wasn't available
during launch/command line building. Although some of that has changed
with more recent changes to be able to get a secret conn "on the fly".
Anyway, I digress.
The point being - please note why you're also saving something in the
private storage source area... The 'path' is already present in the
domain XML (both active and inactive) and the 'alias' could be saved in
the active output if you tweaked virStoragePRDefFormat to match what
virDomainDeviceInfoFormat does.
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index a376e3bb0d..5b7b5514a2 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -2799,7 +2799,9 @@ virStorageNetHostTransportTypeToString;
> virStorageNetProtocolTypeToString;
> virStoragePRDefFormat;
> virStoragePRDefFree;
> +virStoragePRDefIsEnabled;
> virStoragePRDefIsEqual;
> +virStoragePRDefIsManaged;
> virStoragePRDefParseXML;
> virStorageSourceBackingStoreClear;
> virStorageSourceClear;
> diff --git a/src/qemu/qemu_alias.c b/src/qemu/qemu_alias.c
> index 95d1e0370a..6db3da27a8 100644
> --- a/src/qemu/qemu_alias.c
> +++ b/src/qemu/qemu_alias.c
> @@ -773,3 +773,14 @@ qemuAliasChardevFromDevAlias(const char *devAlias)
>
> return ret;
> }
> +
> +
> +char *
> +qemuDomainGetManagedPRAlias(void)
> +{
> +char *alias;
> +
> +ignore_value(VIR_STRDUP(alias, "pr-helper0"));
> +
> +return alias;
> +}
I don't really see a purpose for this function. If it were to survive,
then it could take a parameter "const char *srcalias" and create/return
the alias from that based on what's in qemuDomainPrepareDiskPRD.
Eventually when the qemuProcessKillPRDaemon is created, it doesn't
necessarily distinguish between managed and unmanaged... Still having it
fail because it couldn't strdup what amounts to be a static string
doesn't make much sense.
diff --git a/src/qemu/qemu_alias.h b/src/qemu/qemu_alias.h
> index 8c744138ce..91e0a9c893 100644
> --- a/src/qemu/qemu_alias.h
> +++ b/src/qemu/qemu_alias.h
> @@ -92,4 +92,6 @@ char *qemuAliasTLSObjFromSrcAlias(const char *srcAlias)
> char *qemuAliasChardevFromDevAlias(const char *devAlias)
> ATTRIBUTE_NONNULL(1);
>
> +char * qemuDomainGetManagedPRAlias(void);
> +
> #endif /* __QEMU_ALIAS_H__*/
> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
> index 5a7b5f8417..361a80be84 100644
> --- a/src/qemu/qemu_domain.c
> +++ b/src/qemu/qemu_domain.c
> @@ -982,6 +982,18 @@ qemuDomainSecretInfoFree(qemuDomainSecretInfoPtr
> *secinfo)
> }
>
>
> +static void
> +qemuDomainDiskPRDFree(qemuDomainDiskPRDPtr prd)
> +{
> +if (!prd)
> +return;
> +
> +VIR_FREE(prd->alias);
> +VIR_FREE(prd->path);
> +VIR_FREE(prd);
> +}
> +
> +
> static virClassPtr qemuDomainDiskPrivateClass;
> static void qemuDomainDiskPrivateDispose(void *obj);
>
> @@ -1062,6 +1074,7 @@ qemuDomainStorageSourcePrivateDispose(void *obj)
>
> qemuDomainSecretInfoFree(&priv->secinfo);
> qemuDomainSecretInfoFree(&priv->encinfo);
> +qemuDomainDiskPRDFree(priv->prd);
> }
>
>
> @@ -1473,9 +1486,6 @@
> qemuDomainSecretStorageSourcePrepare(qemuDomainObjPrivatePtr priv,
> if (!hasAuth && !hasEnc)
> return 0;
>
> -if (!(src->privateData = qemuDomainStorageSourcePrivateNew()))
> -return -1
[libvirt] [PATCH v4 04/14] qemu: Generate alias and socket path for pr-helper
While we're not generating the command line just yet (look for
the next commits), we can generate the alias for pr-manager.
A domain can have up to one managed pr-manager (in which case
socket path is decided by libvirt and pr-helper is spawned by
libvirt too), but up to ndisks of unmanaged ones (one per disk
basically). In case of the former we can generate a simple alias
and be sure it'll not conflict. But in case of the latter to
avoid any conflicts let's generate alias that's based on
something unique - like disk target.
Signed-off-by: Michal Privoznik
---
src/libvirt_private.syms | 2 ++
src/qemu/qemu_alias.c | 11 ++
src/qemu/qemu_alias.h | 2 ++
src/qemu/qemu_domain.c| 87 +--
src/qemu/qemu_domain.h| 10 ++
src/util/virstoragefile.c | 15
src/util/virstoragefile.h | 2 ++
7 files changed, 126 insertions(+), 3 deletions(-)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index a376e3bb0d..5b7b5514a2 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -2799,7 +2799,9 @@ virStorageNetHostTransportTypeToString;
virStorageNetProtocolTypeToString;
virStoragePRDefFormat;
virStoragePRDefFree;
+virStoragePRDefIsEnabled;
virStoragePRDefIsEqual;
+virStoragePRDefIsManaged;
virStoragePRDefParseXML;
virStorageSourceBackingStoreClear;
virStorageSourceClear;
diff --git a/src/qemu/qemu_alias.c b/src/qemu/qemu_alias.c
index 95d1e0370a..6db3da27a8 100644
--- a/src/qemu/qemu_alias.c
+++ b/src/qemu/qemu_alias.c
@@ -773,3 +773,14 @@ qemuAliasChardevFromDevAlias(const char *devAlias)
return ret;
}
+
+
+char *
+qemuDomainGetManagedPRAlias(void)
+{
+char *alias;
+
+ignore_value(VIR_STRDUP(alias, "pr-helper0"));
+
+return alias;
+}
diff --git a/src/qemu/qemu_alias.h b/src/qemu/qemu_alias.h
index 8c744138ce..91e0a9c893 100644
--- a/src/qemu/qemu_alias.h
+++ b/src/qemu/qemu_alias.h
@@ -92,4 +92,6 @@ char *qemuAliasTLSObjFromSrcAlias(const char *srcAlias)
char *qemuAliasChardevFromDevAlias(const char *devAlias)
ATTRIBUTE_NONNULL(1);
+char * qemuDomainGetManagedPRAlias(void);
+
#endif /* __QEMU_ALIAS_H__*/
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 5a7b5f8417..361a80be84 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -982,6 +982,18 @@ qemuDomainSecretInfoFree(qemuDomainSecretInfoPtr *secinfo)
}
+static void
+qemuDomainDiskPRDFree(qemuDomainDiskPRDPtr prd)
+{
+if (!prd)
+return;
+
+VIR_FREE(prd->alias);
+VIR_FREE(prd->path);
+VIR_FREE(prd);
+}
+
+
static virClassPtr qemuDomainDiskPrivateClass;
static void qemuDomainDiskPrivateDispose(void *obj);
@@ -1062,6 +1074,7 @@ qemuDomainStorageSourcePrivateDispose(void *obj)
qemuDomainSecretInfoFree(&priv->secinfo);
qemuDomainSecretInfoFree(&priv->encinfo);
+qemuDomainDiskPRDFree(priv->prd);
}
@@ -1473,9 +1486,6 @@
qemuDomainSecretStorageSourcePrepare(qemuDomainObjPrivatePtr priv,
if (!hasAuth && !hasEnc)
return 0;
-if (!(src->privateData = qemuDomainStorageSourcePrivateNew()))
-return -1;
-
srcPriv = QEMU_DOMAIN_STORAGE_SOURCE_PRIVATE(src);
if (hasAuth) {
@@ -11925,11 +11935,79 @@ qemuDomainPrepareDiskCachemode(virDomainDiskDefPtr
disk)
}
+static int
+qemuDomainPrepareDiskPRD(qemuDomainObjPrivatePtr priv,
+ virDomainDiskDefPtr disk)
+{
+qemuDomainStorageSourcePrivatePtr srcPriv;
+virStoragePRDefPtr prd = disk->src->pr;
+char *prAlias = NULL;
+char *prPath = NULL;
+int ret = -1;
+
+if (!virStoragePRDefIsEnabled(prd))
+return 0;
+
+if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_PR_MANAGER_HELPER)) {
+virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+ _("reservations not supported with this QEMU binary"));
+return ret;
+}
+
+if (!virStorageSourceIsLocalStorage(disk->src)) {
+virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+ _("reservations supported only for local storage"));
+return ret;
+}
+
+srcPriv = QEMU_DOMAIN_STORAGE_SOURCE_PRIVATE(disk->src);
+
+/* Managed PR means there's one pr-manager object per domain
+ * and the pr-helper process is spawned and managed by
+ * libvirt.
+ * If PR is unmanaged there's one pr-manager object per disk
+ * (in general each disk can have its own pr-manager) and
+ * it's user's responsibility to start the pr-helper process.
+ */
+if (virStoragePRDefIsManaged(prd)) {
+/* Generate PR helper socket path & alias that are same
+ * for each disk in the domain. */
+
+if (!(prAlias = qemuDomainGetManagedPRAlias()))
+return ret;
+
+if (virAsprintf(&prPath, "%s/pr-helper0.sock", priv->libDir) < 0)
+goto cleanup;
+
+} else {
+if (virAsprintf(&prAlias, "pr-helper-%s", disk->info.alias) < 0)
+return ret;
+
+
