On 05/26/2015 09:01 AM, Michal Privoznik wrote: > When playing with disk migration lately, I've noticed this warning in > domain logs: > > WARNING: Image format was not specified for 'nbd://masina:49153/drive-virtio-disk0' and probing guessed raw. > Automatically detecting the format is dangerous for raw images, write operations on block 0 will be restricted. > Specify the 'raw' format explicitly to remove the restrictions. > > So I started digging into qemu source code to see what has triggered > the warning. I'd expect qemu to know formats of guest's disks since we > tell them on command line. This lead me to qmp_drive_mirror() where > the following can be found: > > if (!has_format) { > format = mode == NEW_IMAGE_MODE_EXISTING ? NULL : bs->drv->format_name; > } > > So, format is automatically initialized from the disk iff mode != > "existing". Unfortunately, in migration we are tied to use this mode > (NBD doesn't support creating new images). Therefore the only way to > avoid this warning is to pass format. The format that libvirt thinks > should be in sync with qemu anyway. > > Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx> > --- > src/qemu/qemu_migration.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c > index 32c43f3..279b43f 100644 > --- a/src/qemu/qemu_migration.c > +++ b/src/qemu/qemu_migration.c > @@ -1943,6 +1943,7 @@ qemuMigrationDriveMirror(virQEMUDriverPtr driver, > for (i = 0; i < vm->def->ndisks; i++) { > virDomainDiskDefPtr disk = vm->def->disks[i]; > qemuDomainDiskPrivatePtr diskPriv = QEMU_DOMAIN_DISK_PRIVATE(disk); > + const char *format; format is not initialized here... > int mon_ret; > > /* skip shared, RO and source-less disks */ > @@ -1950,6 +1951,9 @@ qemuMigrationDriveMirror(virQEMUDriverPtr driver, > !virDomainDiskGetSource(disk)) > continue; > > + if (disk->src->format > 0) > + format = virStorageFileFormatTypeToString(disk->src->format); then only initialized if src->format > 0 Also this should be VIR_STORAGE_FILE_NONE instead of 0 > + > VIR_FREE(diskAlias); > VIR_FREE(nbd_dest); > if ((virAsprintf(&diskAlias, "%s%s", > @@ -1967,7 +1971,7 @@ qemuMigrationDriveMirror(virQEMUDriverPtr driver, > } > > mon_ret = qemuMonitorDriveMirror(priv->mon, diskAlias, nbd_dest, > - NULL, speed, 0, 0, mirror_flags); > + format, speed, 0, 0, mirror_flags); Then used here... My compiler balked... Initializing to NULL worked... ACK with that change. John > > if (qemuDomainObjExitMonitor(driver, vm) < 0 || mon_ret < 0) { > qemuBlockJobSyncEnd(driver, vm, disk, NULL); > -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list