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@redhat.com>

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 238c6ed6207659d472d40ecfe4ddac1a416dbd77..b666f3715f5561fb4aff158bf6be2589d158b48e 100644 (file)
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -1824,6 +1824,30 @@ 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,
@@ -2140,6 +2164,9 @@ 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.x86_64-2.7.0.args b/tests/qemuxml2argvdata/disk-drive-write-cache.x86_64-2.7.0.args
index 9af27dbbaf730b86d7dba2a98c2b60eeed1a2002..7b67f4369c3ab18a60acfaa8cc8ddbc7c9411343 100644 (file)
--- a/tests/qemuxml2argvdata/disk-drive-write-cache.x86_64-2.7.0.args
+++ b/tests/qemuxml2argvdata/disk-drive-write-cache.x86_64-2.7.0.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

diff --git a/tests/qemuxml2argvdata/disk-drive-write-cache.x86_64-latest.args b/tests/qemuxml2argvdata/disk-drive-write-cache.x86_64-latest.args
index b4bef8752922693363b2bd695ad809c8cb651905..a63c5b7477a6abf0cf78a4c4a9c2cc88ac2806d3 100644 (file)
--- a/tests/qemuxml2argvdata/disk-drive-write-cache.x86_64-latest.args
+++ b/tests/qemuxml2argvdata/disk-drive-write-cache.x86_64-latest.args
@@ -28,18 +28,20 @@ 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 \
 -sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,\
 resourcecontrol=deny \
 -msg timestamp=on