[libvirt] [PATCH v2 7/7] qemu: Format 'write-cache' parameter for disk frontends

The disk cache mode translates to various frontend and backend attributes for the qemu block layer. For the frontend device the 'writeback' parameter is used and provided as 'write-cache'. Implement this so that we can later switch to using -blockdev where we will not pass the cachemode directly any more. Signed-off-by: Peter Krempa <pkrempa(a)redhat.com&gt; --- src/qemu/qemu_command.c | 27 ++++++++++++++++++++++ .../disk-drive-write-cache.new.args | 10 ++++---- 2 files changed, 33 insertions(+), 4 deletions(-) diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index a1a9e91e49..08c6e4faac 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -1822,6 +1822,30 @@ qemuCheckIOThreads(const virDomainDef *def, } +static int +qemuBuildDriveDevCacheStr(virDomainDiskDefPtr disk, + virBufferPtr buf, + virQEMUCapsPtr qemuCaps) +{ + bool wb; + + if (disk->cachemode == VIR_DOMAIN_DISK_CACHE_DEFAULT) + return 0; + + if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_DISK_WRITE_CACHE)) + return 0; + + if (qemuDomainDiskCachemodeFlags(disk->cachemode, &wb, NULL, NULL) < 0) + return -1; + + virBufferStrcat(buf, ",write-cache=", + virTristateSwitchTypeToString(virTristateSwitchFromBool(wb)), + NULL); + + return 0; +} + + char * qemuBuildDriveDevStr(const virDomainDef *def, virDomainDiskDefPtr disk, @@ -2134,6 +2158,9 @@ qemuBuildDriveDevStr(const virDomainDef *def, } } + if (qemuBuildDriveDevCacheStr(disk, &opt, qemuCaps) < 0) + goto error; + if (virBufferCheckError(&opt) < 0) goto error; diff --git a/tests/qemuxml2argvdata/disk-drive-write-cache.new.args b/tests/qemuxml2argvdata/disk-drive-write-cache.new.args index 90414a100f..3973249d18 100644 --- a/tests/qemuxml2argvdata/disk-drive-write-cache.new.args +++ b/tests/qemuxml2argvdata/disk-drive-write-cache.new.args @@ -28,16 +28,18 @@ server,nowait \ -device lsi,id=scsi0,bus=pci.0,addr=0x2 \ -drive file=/dev/HostVG/QEMUGuest1,format=qcow2,if=none,id=drive-ide0-0-0,\ cache=writeback \ --device ide-hd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0,bootindex=1 \ +-device ide-hd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0,bootindex=1,\ +write-cache=on \ -drive file=/dev/HostVG/QEMUGuest1,format=qcow2,if=none,id=drive-scsi0-0-0,\ cache=none \ --device scsi-hd,bus=scsi0.0,scsi-id=0,drive=drive-scsi0-0-0,id=scsi0-0-0 \ +-device scsi-hd,bus=scsi0.0,scsi-id=0,drive=drive-scsi0-0-0,id=scsi0-0-0,\ +write-cache=on \ -drive file=/dev/HostVG/QEMUGuest1,format=qcow2,if=none,id=drive-virtio-disk0,\ cache=writethrough \ -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x3,drive=drive-virtio-disk0,\ -id=virtio-disk0 \ +id=virtio-disk0,write-cache=off \ -drive file=/dev/HostVG/QEMUGuest1,format=qcow2,if=none,id=drive-usb-disk1,\ cache=directsync \ -device usb-storage,bus=usb.0,port=1,drive=drive-usb-disk1,id=usb-disk1,\ -removable=off \ +removable=off,write-cache=off \ -msg timestamp=on -- 2.16.2