Re: [libvirt] [PATCH] libxl: fix disk detach when <driver> not specified

On 02/07/2017 03:26 AM, Michal Privoznik wrote: > On 02/06/2017 11:08 PM, Jim Fehlig wrote: >> When a user does not explicitly set a <driver> in the disk config, >> libvirt defers selection of a default to libxl. This approach works >> fine when starting a domain with such configuration or attaching a >> disk to a running domain. But when detaching such a disk, libxl >> will fail with "unrecognized disk backend type: 0". libxl makes no >> attempt to recalculate a default backend (driver) on detach and >> simply fails when uninitialized. >> >> This patch updates the libvirt disk config with the backend selected >> by libxl when starting a domain or attaching a disk to a running >> domain. Another benefit of this approach is that the live XML is >> also updated with the backend driver selected by libxl. >> >> Signed-off-by: Jim Fehlig <jfehlig(a)suse.com&gt; >> --- >> src/libxl/libxl_conf.c | 33 +++++++++++++++++++++++++++++++++ >> src/libxl/libxl_conf.h | 4 ++++ >> src/libxl/libxl_domain.c | 25 +++++++++++++++++++++++++ >> src/libxl/libxl_driver.c | 2 +- >> 4 files changed, 63 insertions(+), 1 deletion(-) >> >> diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c >> index b5186f2..6ef7570 100644 >> --- a/src/libxl/libxl_conf.c >> +++ b/src/libxl/libxl_conf.c >> @@ -851,6 +851,7 @@ libxlMakeDisk(virDomainDiskDefPtr l_disk, >> libxl_device_disk *x_disk) >> * xl-disk-configuration.txt in the xen documentation and let >> * libxl pick a suitable backend. >> */ >> + virDomainDiskSetFormat(l_disk, VIR_STORAGE_FILE_RAW); >> x_disk->format = LIBXL_DISK_FORMAT_RAW; >> x_disk->backend = LIBXL_DISK_BACKEND_UNKNOWN; > > This doesn't feel right. I know what do you want it here for, but this > function is meant to take 'const' disk definition and translate it to > libxl definition. Although, I don't have a better suggestion where to > put it. How about in the UpdateDisk function introduced in this patch? E.g. update it to raw if current format is VIR_STORAGE_FILE_NONE?