On Mon, 27 Feb 2023 at 12:15, Christian Nautze <christian.nautze@exoscale.ch> 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@exoscale.ch>

---
Changes: schema reconnect element: drop mandatory 'enabled' attribute when using 'delay'
reconnect element: use choice for attributes
---
docs/formatdomain.rst | 11 +++++++--
src/conf/domain_conf.c | 12 ++++++++++
src/conf/schemas/domaincommon.rng | 3 +++
src/conf/schemas/storagecommon.rng | 19 ++++++++++-----
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, 84 insertions(+), 19 deletions(-)

diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
index 638768c18d..e4ea330a0d 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 84ffd93b7f..1e5c88e45d 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 &&
@@ -22087,6 +22096,9 @@ 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 ab4886b783..03aab6f7e5 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..23eff9ecb1 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="timeout">
+ <choice>
+ <group>
+ <attribute name="enabled">
+ <ref name="virYesNo"/>
+ </attribute>
+ <optional>
+ <attribute name="timeout">
+ <ref name="unsignedInt"/>
+ </attribute>
+ </optional>
+ </group>
+ <attribute name="delay">
<ref name="unsignedInt"/>
</attribute>
- </optional>
+ </choice>
</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 4cf9a259ea..1206d59f4a 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>
--
2.34.1