From: Michal Privoznik <mprivozn@redhat.com>
Date: Mon, 28 May 2018 14:28:09 +0000 (+0200)
Subject: qemu: Don't build cache= cmd line for scsi-block
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=16782dc329f63d41b6e9cc5717f132b769945cec;p=libvirt.git

qemu: Don't build cache= cmd line for scsi-block

Trying to set any cache for <disk device='lun'/> makes no sense.
Such disk translates into -device scsi-block on the command line
and the device lacks any cache setting because it's merely a
middle man between qemu and real SCSI device.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 7408f6bc70..c7ff074e29 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -1824,6 +1824,11 @@ qemuBuildDriveDevCacheStr(virDomainDiskDefPtr disk,
     if (disk->cachemode == VIR_DOMAIN_DISK_CACHE_DEFAULT)
         return 0;
 
+    /* VIR_DOMAIN_DISK_DEVICE_LUN translates into 'scsi-block'
+     * where any caching setting makes no sense. */
+    if (disk->device == VIR_DOMAIN_DISK_DEVICE_LUN)
+        return 0;
+
     if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_DISK_WRITE_CACHE))
         return 0;