[libvirt] [PATCH 5/6] 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 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index bbd3cd0a7d..83e263e9f9 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -1882,6 +1882,30 @@ 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, @@ -2194,6 +2218,9 @@ qemuBuildDriveDevStr(const virDomainDef *def, } } + if (qemuBuildDriveDevCacheStr(disk, &opt, qemuCaps) < 0) + goto error; + if (virBufferCheckError(&opt) < 0) goto error; -- 2.16.2