On Thu, Jul 17, 2025 at 03:14:36PM +0200, Martin Kletzander wrote:
From: Martin Kletzander <mklet...@redhat.com>That allows for disabling discard in a way that some guest OSes (e.g. Windows) understand and do not try to trim the disk. Resolves: https://issues.redhat.com/browse/RHEL-72006 Signed-off-by: Martin Kletzander <mklet...@redhat.com> --- Out of all the approaches for allowing previously default value 100% of them are ugly. This one is maybe slightly more error-prone.
And then I forgot to add the tests, I have the following already applied
locally:
diff --git c/tests/qemuxmlconfdata/disk-blockio-no-discard.x86_64-latest.args
w/tests/qemuxmlconfdata/disk-blockio-no-discard.x86_64-latest.args
new file mode 100644
index 000000000000..0e477c6e40de
--- /dev/null
+++ w/tests/qemuxmlconfdata/disk-blockio-no-discard.x86_64-latest.args
@@ -0,0 +1,37 @@
+LC_ALL=C \
+PATH=/bin \
+HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1 \
+USER=test \
+LOGNAME=test \
+XDG_DATA_HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1/.local/share \
+XDG_CACHE_HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1/.cache \
+XDG_CONFIG_HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1/.config \
+/usr/bin/qemu-system-x86_64 \
+-name guest=QEMUGuest1,debug-threads=on \
+-S \
+-object
'{"qom-type":"secret","id":"masterKey0","format":"raw","file":"/var/lib/libvirt/qemu/domain--1-QEMUGuest1/master-key.aes"}'
\
+-machine pc,usb=off,dump-guest-core=off,memory-backend=pc.ram,acpi=off \
+-accel tcg \
+-cpu qemu64 \
+-m size=219136k \
+-object '{"qom-type":"memory-backend-ram","id":"pc.ram","size":224395264}' \
+-overcommit mem-lock=off \
+-smp 1,sockets=1,cores=1,threads=1 \
+-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \
+-display none \
+-no-user-config \
+-nodefaults \
+-chardev socket,id=charmonitor,fd=1729,server=on,wait=off \
+-mon chardev=charmonitor,id=monitor,mode=control \
+-rtc base=utc \
+-no-shutdown \
+-boot strict=on \
+-device
'{"driver":"piix3-usb-uhci","id":"usb","bus":"pci.0","addr":"0x1.0x2"}' \
+-blockdev
'{"driver":"host_device","filename":"/dev/HostVG/QEMUGuest1","node-name":"libvirt-2-storage","read-only":true}'
\
+-device
'{"driver":"ide-cd","bus":"ide.0","unit":1,"drive":"libvirt-2-storage","id":"ide0-0-1"}'
\
+-blockdev
'{"driver":"file","filename":"/tmp/idedisk.img","node-name":"libvirt-1-storage","read-only":false}'
\
+-device
'{"driver":"ide-hd","bus":"ide.0","unit":2,"drive":"libvirt-1-storage","id":"ide0-0-2","bootindex":1,"logical_block_size":512,"physical_block_size":512,"discard_granularity":0}'
\
+-audiodev '{"id":"audio1","driver":"none"}' \
+-device
'{"driver":"virtio-balloon-pci","id":"balloon0","bus":"pci.0","addr":"0x2"}' \
+-sandbox
on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
+-msg timestamp=on
diff --git c/tests/qemuxmlconfdata/disk-blockio-no-discard.x86_64-latest.xml
w/tests/qemuxmlconfdata/disk-blockio-no-discard.x86_64-latest.xml
new file mode 100644
index 000000000000..94cff1ce6a18
--- /dev/null
+++ w/tests/qemuxmlconfdata/disk-blockio-no-discard.x86_64-latest.xml
@@ -0,0 +1,48 @@
+<domain type='qemu'>
+ <name>QEMUGuest1</name>
+ <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+ <memory unit='KiB'>219136</memory>
+ <currentMemory unit='KiB'>219136</currentMemory>
+ <vcpu placement='static'>1</vcpu>
+ <os>
+ <type arch='x86_64' machine='pc'>hvm</type>
+ <boot dev='hd'/>
+ </os>
+ <cpu mode='custom' match='exact' check='none'>
+ <model fallback='forbid'>qemu64</model>
+ </cpu>
+ <clock offset='utc'/>
+ <on_poweroff>destroy</on_poweroff>
+ <on_reboot>restart</on_reboot>
+ <on_crash>destroy</on_crash>
+ <devices>
+ <emulator>/usr/bin/qemu-system-x86_64</emulator>
+ <disk type='block' device='cdrom'>
+ <driver name='qemu' type='raw'/>
+ <source dev='/dev/HostVG/QEMUGuest1'/>
+ <target dev='hda' bus='ide'/>
+ <readonly/>
+ <address type='drive' controller='0' bus='0' target='0' unit='1'/>
+ </disk>
+ <disk type='file' device='disk'>
+ <driver name='qemu' type='raw'/>
+ <source file='/tmp/idedisk.img'/>
+ <blockio logical_block_size='512' physical_block_size='512'
discard_granularity='0'/>
+ <target dev='hdc' bus='ide'/>
+ <address type='drive' controller='0' bus='0' target='0' unit='2'/>
+ </disk>
+ <controller type='usb' index='0' model='piix3-uhci'>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x01'
function='0x2'/>
+ </controller>
+ <controller type='ide' index='0'>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x01'
function='0x1'/>
+ </controller>
+ <controller type='pci' index='0' model='pci-root'/>
+ <input type='mouse' bus='ps2'/>
+ <input type='keyboard' bus='ps2'/>
+ <audio id='1' type='none'/>
+ <memballoon model='virtio'>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x02'
function='0x0'/>
+ </memballoon>
+ </devices>
+</domain>
diff --git c/tests/qemuxmlconfdata/disk-blockio-no-discard.xml
w/tests/qemuxmlconfdata/disk-blockio-no-discard.xml
new file mode 100644
index 000000000000..600022391512
--- /dev/null
+++ w/tests/qemuxmlconfdata/disk-blockio-no-discard.xml
@@ -0,0 +1,32 @@
+<domain type='qemu'>
+ <name>QEMUGuest1</name>
+ <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+ <memory unit='KiB'>219136</memory>
+ <currentMemory unit='KiB'>219136</currentMemory>
+ <vcpu placement='static'>1</vcpu>
+ <os>
+ <type arch='x86_64' machine='pc'>hvm</type>
+ <boot dev='hd'/>
+ </os>
+ <clock offset='utc'/>
+ <on_poweroff>destroy</on_poweroff>
+ <on_reboot>restart</on_reboot>
+ <on_crash>destroy</on_crash>
+ <devices>
+ <emulator>/usr/bin/qemu-system-x86_64</emulator>
+ <disk type='block' device='cdrom'>
+ <source dev='/dev/HostVG/QEMUGuest1'/>
+ <target dev='hda' bus='ide'/>
+ <address type='drive' controller='0' bus='0' target='0' unit='1'/>
+ </disk>
+ <disk type='file' device='disk'>
+ <source file='/tmp/idedisk.img'/>
+ <target dev='hdc' bus='ide'/>
+ <address type='drive' controller='0' bus='0' target='0' unit='2'/>
+ <blockio logical_block_size='512' physical_block_size='512'
discard_granularity='0'/>
+ </disk>
+ <controller type='usb' index='0'/>
+ <controller type='ide' index='0'/>
+ <memballoon model='virtio'/>
+ </devices>
+</domain>
src/conf/domain_conf.c | 12 ++++++++----
src/conf/domain_conf.h | 1 +
src/conf/domain_validate.c | 2 +-
src/qemu/qemu_command.c | 7 ++++++-
tests/qemuxmlconftest.c | 1 +
5 files changed, 17 insertions(+), 6 deletions(-)
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index bfc62b62705f..ba0d4a7b128c 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -8554,6 +8554,8 @@ virDomainDiskDefParseXML(virDomainXMLOption *xmlopt,
}
if ((blockioNode = virXPathNode("./blockio", ctxt))) {
+ int tmp = 0;
+
if (virXMLPropUInt(blockioNode, "logical_block_size", 10,
VIR_XML_PROP_NONE,
&def->blockio.logical_block_size) < 0)
return NULL;
@@ -8562,9 +8564,11 @@ virDomainDiskDefParseXML(virDomainXMLOption *xmlopt,
&def->blockio.physical_block_size) < 0)
return NULL;
- if (virXMLPropUInt(blockioNode, "discard_granularity", 10,
VIR_XML_PROP_NONE,
- &def->blockio.discard_granularity) < 0)
+ if ((tmp = virXMLPropUInt(blockioNode, "discard_granularity", 10,
VIR_XML_PROP_NONE,
+ &def->blockio.discard_granularity)) < 0)
return NULL;
+ if (tmp > 0)
+ def->blockio.discard_granularity_specified = true;
}
if ((driverNode = virXPathNode("./driver", ctxt))) {
@@ -23102,7 +23106,7 @@ virDomainDiskBlockIoDefFormat(virBuffer *buf,
{
if (def->blockio.logical_block_size > 0 ||
def->blockio.physical_block_size > 0 ||
- def->blockio.discard_granularity > 0) {
+ def->blockio.discard_granularity_specified) {
virBufferAddLit(buf, "<blockio");
if (def->blockio.logical_block_size > 0) {
virBufferAsprintf(buf,
@@ -23114,7 +23118,7 @@ virDomainDiskBlockIoDefFormat(virBuffer *buf,
" physical_block_size='%u'",
def->blockio.physical_block_size);
}
- if (def->blockio.discard_granularity > 0) {
+ if (def->blockio.discard_granularity_specified) {
virBufferAsprintf(buf,
" discard_granularity='%u'",
def->blockio.discard_granularity);
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 6997cf7c09be..6008ec66d3fe 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -560,6 +560,7 @@ struct _virDomainDiskDef {
unsigned int logical_block_size;
unsigned int physical_block_size;
unsigned int discard_granularity;
+ bool discard_granularity_specified;
} blockio;
virDomainBlockIoTuneInfo blkdeviotune;
diff --git a/src/conf/domain_validate.c b/src/conf/domain_validate.c
index b28af7fa5618..8f7259a0e1ed 100644
--- a/src/conf/domain_validate.c
+++ b/src/conf/domain_validate.c
@@ -462,7 +462,7 @@ virDomainDiskVhostUserValidate(const virDomainDiskDef *disk)
if (disk->blockio.logical_block_size > 0 ||
disk->blockio.physical_block_size > 0 ||
- disk->blockio.discard_granularity > 0) {
+ disk->blockio.discard_granularity_specified) {
virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
_("blockio is not supported with vhostuser disk"));
return -1;
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 7658cc4d395a..fc6ce4dd9143 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -1899,7 +1899,6 @@ qemuBuildDiskDeviceProps(const virDomainDef *def,
"S:loadparm", bootLoadparm,
"p:logical_block_size", logical_block_size,
"p:physical_block_size", physical_block_size,
- "p:discard_granularity", discard_granularity,
"A:wwn", &wwn,
"p:rotation_rate", disk->rotation_rate,
"S:vendor", disk->vendor,
@@ -1917,6 +1916,12 @@ qemuBuildDiskDeviceProps(const virDomainDef *def,
NULL) < 0)
return NULL;
+ if (disk->blockio.discard_granularity_specified &&
+ virJSONValueObjectAdd(&props,
+ "u:discard_granularity", discard_granularity,
+ NULL) < 0)
+ return NULL;
+
return g_steal_pointer(&props);
}
diff --git a/tests/qemuxmlconftest.c b/tests/qemuxmlconftest.c
index 9fba98429019..ae8efd58f8ac 100644
--- a/tests/qemuxmlconftest.c
+++ b/tests/qemuxmlconftest.c
@@ -1694,6 +1694,7 @@ mymain(void)
DO_TEST_CAPS_LATEST("disk-ide-wwn");
DO_TEST_CAPS_LATEST("disk-geometry");
DO_TEST_CAPS_LATEST("disk-blockio");
+ DO_TEST_CAPS_LATEST("disk-blockio-no-discard");
driver.config->storageUseNbdkit = 1;
DO_TEST_CAPS_LATEST_NBDKIT("disk-cdrom-network-nbdkit",
QEMU_NBDKIT_CAPS_PLUGIN_CURL);
--
2.50.1
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