[libvirt PATCH v2] qemu: implement QEMU NBD source reconnect delay attribute
Christian Nautze
christian.nautze at exoscale.ch
Wed Feb 22 09:29:48 UTC 2023
I had a first version on gitlab
https://gitlab.com/libvirt/libvirt/-/merge_requests/216
where I added the attribute to the source. Peter Krempa noted that
this most likely has to be moved to the reconnect element.
I actually prefer adding it to reconnect (with choice in the schema).
If there are no objections I will make the necessary change...
On Tue, 21 Feb 2023 at 23:10, Jonathon Jongsma <jjongsma at redhat.com> wrote:
> On 2/17/23 10:50 AM, Christian Nautze wrote:
> > Currently it's only possible to set this parameter during domain
> > creation via QEMU commandline passthrough feature.
> > With the new delay attribute it's also possible to set this
> > parameter if you want to attach a new NBD disk
> > using "virsh attach-device domain device.xml" e.g.:
> >
> > <disk type='network' device='disk'>
> > <driver name='qemu' type='raw'/>
> > <source protocol='nbd' name='foo'>
> > <host name='example.org' port='6000'/>
> > <reconnect delay='10'/>
> > </source>
> > <target dev='vdb' bus='virtio'/>
> > </disk>
> >
> > Signed-off-by: Christian Nautze <christian.nautze at exoscale.ch>
> >
>
>
> I wonder about the choice between using an attribute vs a child element
> for this value. Most of the things that use child elements for are more
> complex values. For example, 'host' is an address and a port, 'cookies'
> is a collection of cookie elements, even the existing 'reconnect'
> element has two sub-values. On the other hand, things that are a simple
> value tend to be specified as attributes instead. NBD sources in
> particular have attributes 'name', 'tls', and 'tlsHostname'. Since this
> is a single integer value, I wonder if it would make more sense to use
> another nbd-specific attribute such as 'reconnectDelay'. For example:
>
> <source protocol='nbd' name='foo' reconnectDelay='10'>
>
> This might also reduce potential confusion about how to specify the
> 'reconnect' element, but has the downside of having two different
> reconnect-related elements. To be honest, I'm not sure whether there is
> an overal philosophy on attributes vs. elements, so I will happily defer
> to more veteran libvirt developers.
>
> If we do use the <reconnect> sub-element, I think the schema would need
> to use <choice> to indicate that it's either ('enabled'+'timeout') OR
> 'delay', not an arbitrary subset of these attributes.
>
> Jonathon
>
>
> > ---
> > Change: reconnect element: drop mandatory 'enabled' attribute when using
> 'delay'
> > ---
> > docs/formatdomain.rst | 11 +++++++--
> > src/conf/domain_conf.c | 12 ++++++++++
> > src/conf/schemas/domaincommon.rng | 3 +++
> > src/conf/schemas/storagecommon.rng | 13 ++++++++---
> > src/conf/storage_source_conf.c | 1 +
> > src/conf/storage_source_conf.h | 4 ++++
> > src/qemu/qemu_block.c | 4 +++-
> > src/qemu/qemu_domain.c | 9 ++++++++
> > .../disk-network-nbd.x86_64-latest.args | 23 +++++++++++--------
> > tests/qemuxml2argvdata/disk-network-nbd.xml | 8 +++++++
> > tests/qemuxml2xmloutdata/disk-network-nbd.xml | 9 ++++++++
> > 11 files changed, 81 insertions(+), 16 deletions(-)
> >
> > diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
> > index 36c6d87907..ee30c51cea 100644
> > --- a/docs/formatdomain.rst
> > +++ b/docs/formatdomain.rst
> > @@ -2946,13 +2946,20 @@ paravirtualized driver is specified via the
> ``disk`` element.
> > are intended to be default, then the entire element may be
> omitted.
> > ``reconnect``
> > For disk type ``vhostuser`` configures reconnect timeout if the
> connection
> > - is lost. It has two mandatory attributes:
> > + is lost. This is set with the two mandatory attributes
> ``enabled`` and
> > + ``timeout``.
> > + For disk type ``network`` and protocol ``nbd`` the QEMU NBD
> reconnect delay
> > + can be set via attribute ``delay``:
> >
> > ``enabled``
> > If the reconnect feature is enabled, accepts ``yes`` and
> ``no``
> > ``timeout``
> > The amount of seconds after which hypervisor tries to
> reconnect.
> > -
> > + ``delay``
> > + Only for NBD hosts. The amount of seconds during which all
> requests are
> > + paused and will be rerun after a successful reconnect. After
> that time, any
> > + delayed requests and all future requests before a successful
> reconnect
> > + will immediately fail. If not set the default QEMU value is 0.
> >
> > For a "file" or "volume" disk type which represents a cdrom or
> floppy (the
> > ``device`` attribute), it is possible to define policy what to do
> with the
> > diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> > index a5578324b9..3f2ba2aab8 100644
> > --- a/src/conf/domain_conf.c
> > +++ b/src/conf/domain_conf.c
> > @@ -7146,6 +7146,15 @@ virDomainDiskSourceNetworkParse(xmlNodePtr node,
> > src->tlsFromConfig = !!value;
> > }
> >
> > + if (src->protocol == VIR_STORAGE_NET_PROTOCOL_NBD) {
> > + xmlNodePtr cur;
> > + if ((cur = virXPathNode("./reconnect", ctxt))) {
> > + if (virXMLPropUInt(cur, "delay", 10, VIR_XML_PROP_NONE,
> > + &src->reconnectDelay) < 0)
> > + return -1;
> > + }
> > + }
> > +
> > /* for historical reasons we store the volume and image name in
> one XML
> > * element although it complicates thing when attempting to access
> them. */
> > if (src->path &&
> > @@ -22073,6 +22082,9 @@ virDomainDiskSourceFormatNetwork(virBuffer
> *attrBuf,
> > virBufferAddLit(childBuf, "/>\n");
> > }
> >
> > + if (src->reconnectDelay) {
> > + virBufferAsprintf(childBuf, "<reconnect delay='%u'/>\n",
> src->reconnectDelay);
> > + }
> >
> > virBufferEscapeString(childBuf, "<snapshot name='%s'/>\n",
> src->snapshot);
> > virBufferEscapeString(childBuf, "<config file='%s'/>\n",
> src->configFile);
> > diff --git a/src/conf/schemas/domaincommon.rng
> b/src/conf/schemas/domaincommon.rng
> > index a57dd212ab..dd5fbeac09 100644
> > --- a/src/conf/schemas/domaincommon.rng
> > +++ b/src/conf/schemas/domaincommon.rng
> > @@ -2199,6 +2199,9 @@
> > </optional>
> > <ref name="diskSourceCommon"/>
> > <ref name="diskSourceNetworkHost"/>
> > + <optional>
> > + <ref name="reconnect"/>
> > + </optional>
> > <optional>
> > <ref name="encryption"/>
> > </optional>
> > diff --git a/src/conf/schemas/storagecommon.rng
> b/src/conf/schemas/storagecommon.rng
> > index 4d6e646c9a..582375358c 100644
> > --- a/src/conf/schemas/storagecommon.rng
> > +++ b/src/conf/schemas/storagecommon.rng
> > @@ -55,14 +55,21 @@
> >
> > <define name="reconnect">
> > <element name="reconnect">
> > - <attribute name="enabled">
> > - <ref name="virYesNo"/>
> > - </attribute>
> > + <optional>
> > + <attribute name="enabled">
> > + <ref name="virYesNo"/>
> > + </attribute>
> > + </optional>
> > <optional>
> > <attribute name="timeout">
> > <ref name="unsignedInt"/>
> > </attribute>
> > </optional>
> > + <optional>
> > + <attribute name="delay">
> > + <ref name="unsignedInt"/>
> > + </attribute>
> > + </optional>
> > </element>
> > </define>
> >
> > diff --git a/src/conf/storage_source_conf.c
> b/src/conf/storage_source_conf.c
> > index cecd7e811e..58009fd06e 100644
> > --- a/src/conf/storage_source_conf.c
> > +++ b/src/conf/storage_source_conf.c
> > @@ -811,6 +811,7 @@ virStorageSourceCopy(const virStorageSource *src,
> > def->sslverify = src->sslverify;
> > def->readahead = src->readahead;
> > def->timeout = src->timeout;
> > + def->reconnectDelay = src->reconnectDelay;
> > def->metadataCacheMaxSize = src->metadataCacheMaxSize;
> >
> > /* storage driver metadata are not copied */
> > diff --git a/src/conf/storage_source_conf.h
> b/src/conf/storage_source_conf.h
> > index 14a6825d54..c6187dda59 100644
> > --- a/src/conf/storage_source_conf.h
> > +++ b/src/conf/storage_source_conf.h
> > @@ -312,6 +312,10 @@ struct _virStorageSource {
> > unsigned long long readahead; /* size of the readahead buffer in
> bytes */
> > unsigned long long timeout; /* connection timeout in seconds */
> >
> > + /* NBD QEMU reconnect-delay option,
> > + * 0 as default value */
> > + unsigned int reconnectDelay;
> > +
> > virStorageSourceNVMeDef *nvme; /* type == VIR_STORAGE_TYPE_NVME */
> >
> > virDomainChrSourceDef *vhostuser; /* type ==
> VIR_STORAGE_TYPE_VHOST_USER */
> > diff --git a/src/qemu/qemu_block.c b/src/qemu/qemu_block.c
> > index 5e700eff99..8fcebd8992 100644
> > --- a/src/qemu/qemu_block.c
> > +++ b/src/qemu/qemu_block.c
> > @@ -529,6 +529,7 @@ qemuBlockStorageSourceGetNBDProps(virStorageSource
> *src,
> > "S:export", src->path,
> > "S:tls-creds", tlsAlias,
> > "S:tls-hostname", tlsHostname,
> > + "p:reconnect-delay", src->reconnectDelay,
> > NULL) < 0)
> > return NULL;
> >
> > @@ -1848,7 +1849,8 @@ qemuBlockGetBackingStoreString(virStorageSource
> *src,
> > src->ncookies == 0 &&
> > src->sslverify == VIR_TRISTATE_BOOL_ABSENT &&
> > src->timeout == 0 &&
> > - src->readahead == 0) {
> > + src->readahead == 0 &&
> > + src->reconnectDelay == 0) {
> >
> > switch ((virStorageNetProtocol) src->protocol) {
> > case VIR_STORAGE_NET_PROTOCOL_NBD:
> > diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
> > index e9bc0f375d..02ae3823fb 100644
> > --- a/src/qemu/qemu_domain.c
> > +++ b/src/qemu/qemu_domain.c
> > @@ -5020,6 +5020,15 @@ qemuDomainValidateStorageSource(virStorageSource
> *src,
> > }
> > }
> >
> > + if (src->reconnectDelay > 0) {
> > + if (actualType != VIR_STORAGE_TYPE_NETWORK ||
> > + src->protocol != VIR_STORAGE_NET_PROTOCOL_NBD) {
> > + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> > + _("reconnect delay is supported only with
> NBD protocol"));
> > + return -1;
> > + }
> > + }
> > +
> > if (src->query &&
> > (actualType != VIR_STORAGE_TYPE_NETWORK ||
> > (src->protocol != VIR_STORAGE_NET_PROTOCOL_HTTPS &&
> > diff --git a/tests/qemuxml2argvdata/disk-network-nbd.x86_64-latest.args
> b/tests/qemuxml2argvdata/disk-network-nbd.x86_64-latest.args
> > index 21e619af3e..e8d13b0bd4 100644
> > --- a/tests/qemuxml2argvdata/disk-network-nbd.x86_64-latest.args
> > +++ b/tests/qemuxml2argvdata/disk-network-nbd.x86_64-latest.args
> > @@ -28,21 +28,24 @@
> XDG_CONFIG_HOME=/tmp/lib/domain--1-QEMUGuest1/.config \
> > -no-acpi \
> > -boot strict=on \
> > -device
> '{"driver":"piix3-usb-uhci","id":"usb","bus":"pci.0","addr":"0x1.0x2"}' \
> > --blockdev '{"driver":"nbd","server":{"type":"inet","host":"example.org","port":"6000"},"node-name":"libvirt-5-storage","auto-read-only":true,"discard":"unmap"}'
> \
> > +-blockdev '{"driver":"nbd","server":{"type":"inet","host":"example.org","port":"6000"},"node-name":"libvirt-6-storage","auto-read-only":true,"discard":"unmap"}'
> \
> > +-blockdev
> '{"node-name":"libvirt-6-format","read-only":false,"driver":"raw","file":"libvirt-6-storage"}'
> \
> > +-device
> '{"driver":"virtio-blk-pci","bus":"pci.0","addr":"0x2","drive":"libvirt-6-format","id":"virtio-disk0","bootindex":1}'
> \
> > +-blockdev '{"driver":"nbd","server":{"type":"inet","host":"example.org","port":"6000"},"export":"bar","node-name":"libvirt-5-storage","auto-read-only":true,"discard":"unmap"}'
> \
> > -blockdev
> '{"node-name":"libvirt-5-format","read-only":false,"driver":"raw","file":"libvirt-5-storage"}'
> \
> > --device
> '{"driver":"virtio-blk-pci","bus":"pci.0","addr":"0x2","drive":"libvirt-5-format","id":"virtio-disk0","bootindex":1}'
> \
> > --blockdev '{"driver":"nbd","server":{"type":"inet","host":"example.org","port":"6000"},"export":"bar","node-name":"libvirt-4-storage","auto-read-only":true,"discard":"unmap"}'
> \
> > +-device
> '{"driver":"virtio-blk-pci","bus":"pci.0","addr":"0x3","drive":"libvirt-5-format","id":"virtio-disk1"}'
> \
> > +-blockdev
> '{"driver":"nbd","server":{"type":"inet","host":"::1","port":"6000"},"node-name":"libvirt-4-storage","auto-read-only":true,"discard":"unmap"}'
> \
> > -blockdev
> '{"node-name":"libvirt-4-format","read-only":false,"driver":"raw","file":"libvirt-4-storage"}'
> \
> > --device
> '{"driver":"virtio-blk-pci","bus":"pci.0","addr":"0x3","drive":"libvirt-4-format","id":"virtio-disk1"}'
> \
> > --blockdev
> '{"driver":"nbd","server":{"type":"inet","host":"::1","port":"6000"},"node-name":"libvirt-3-storage","auto-read-only":true,"discard":"unmap"}'
> \
> > +-device
> '{"driver":"virtio-blk-pci","bus":"pci.0","addr":"0x4","drive":"libvirt-4-format","id":"virtio-disk2"}'
> \
> > +-blockdev
> '{"driver":"nbd","server":{"type":"inet","host":"::1","port":"6000"},"export":"bar","node-name":"libvirt-3-storage","auto-read-only":true,"discard":"unmap"}'
> \
> > -blockdev
> '{"node-name":"libvirt-3-format","read-only":false,"driver":"raw","file":"libvirt-3-storage"}'
> \
> > --device
> '{"driver":"virtio-blk-pci","bus":"pci.0","addr":"0x4","drive":"libvirt-3-format","id":"virtio-disk2"}'
> \
> > --blockdev
> '{"driver":"nbd","server":{"type":"inet","host":"::1","port":"6000"},"export":"bar","node-name":"libvirt-2-storage","auto-read-only":true,"discard":"unmap"}'
> \
> > +-device
> '{"driver":"virtio-blk-pci","bus":"pci.0","addr":"0x5","drive":"libvirt-3-format","id":"virtio-disk3"}'
> \
> > +-blockdev
> '{"driver":"nbd","server":{"type":"unix","path":"/var/run/nbdsock"},"export":"bar","node-name":"libvirt-2-storage","auto-read-only":true,"discard":"unmap"}'
> \
> > -blockdev
> '{"node-name":"libvirt-2-format","read-only":false,"driver":"raw","file":"libvirt-2-storage"}'
> \
> > --device
> '{"driver":"virtio-blk-pci","bus":"pci.0","addr":"0x5","drive":"libvirt-2-format","id":"virtio-disk3"}'
> \
> > --blockdev
> '{"driver":"nbd","server":{"type":"unix","path":"/var/run/nbdsock"},"export":"bar","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}'
> \
> > +-device
> '{"driver":"virtio-blk-pci","bus":"pci.0","addr":"0x6","drive":"libvirt-2-format","id":"virtio-disk4"}'
> \
> > +-blockdev '{"driver":"nbd","server":{"type":"inet","host":"example.org","port":"6000"},"export":"foo","reconnect-delay":10,"node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}'
> \
> > -blockdev
> '{"node-name":"libvirt-1-format","read-only":false,"driver":"raw","file":"libvirt-1-storage"}'
> \
> > --device
> '{"driver":"virtio-blk-pci","bus":"pci.0","addr":"0x6","drive":"libvirt-1-format","id":"virtio-disk4"}'
> \
> > +-device
> '{"driver":"virtio-blk-pci","bus":"pci.0","addr":"0x7","drive":"libvirt-1-format","id":"virtio-disk5"}'
> \
> > -audiodev '{"id":"audio1","driver":"none"}' \
> > -sandbox
> on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
> > -msg timestamp=on
> > diff --git a/tests/qemuxml2argvdata/disk-network-nbd.xml
> b/tests/qemuxml2argvdata/disk-network-nbd.xml
> > index 8ac6cc3b7b..4e8b1e5b03 100644
> > --- a/tests/qemuxml2argvdata/disk-network-nbd.xml
> > +++ b/tests/qemuxml2argvdata/disk-network-nbd.xml
> > @@ -49,6 +49,14 @@
> > </source>
> > <target dev='vde' bus='virtio'/>
> > </disk>
> > + <disk type='network' device='disk'>
> > + <driver name='qemu' type='raw'/>
> > + <source protocol='nbd' name='foo'>
> > + <host name='example.org' port='6000'/>
> > + <reconnect delay='10'/>
> > + </source>
> > + <target dev='vdf' bus='virtio'/>
> > + </disk>
> > <controller type='usb' index='0'/>
> > <controller type='ide' index='0'/>
> > <controller type='pci' index='0' model='pci-root'/>
> > diff --git a/tests/qemuxml2xmloutdata/disk-network-nbd.xml
> b/tests/qemuxml2xmloutdata/disk-network-nbd.xml
> > index f8dcca4bab..38d1f290c8 100644
> > --- a/tests/qemuxml2xmloutdata/disk-network-nbd.xml
> > +++ b/tests/qemuxml2xmloutdata/disk-network-nbd.xml
> > @@ -54,6 +54,15 @@
> > <target dev='vde' bus='virtio'/>
> > <address type='pci' domain='0x0000' bus='0x00' slot='0x06'
> function='0x0'/>
> > </disk>
> > + <disk type='network' device='disk'>
> > + <driver name='qemu' type='raw'/>
> > + <source protocol='nbd' name='foo'>
> > + <host name='example.org' port='6000'/>
> > + <reconnect delay='10'/>
> > + </source>
> > + <target dev='vdf' bus='virtio'/>
> > + <address type='pci' domain='0x0000' bus='0x00' slot='0x07'
> function='0x0'/>
> > + </disk>
> > <controller type='usb' index='0'>
> > <address type='pci' domain='0x0000' bus='0x00' slot='0x01'
> function='0x2'/>
> > </controller>
>
>
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