Am 12.02.2018 um 11:02 hat Daniel P. Berrangé geschrieben: > On Mon, Feb 12, 2018 at 10:58:31AM +0100, Paolo Bonzini wrote: > > On 10/02/2018 00:07, John Snow wrote: > > >> + /* Early check to avoid creating target */ > > >> + if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_MIRROR_SOURCE, errp)) { > > >> + return; > > >> + } > > >> + > > >> aio_context = bdrv_get_aio_context(bs); > > >> aio_context_acquire(aio_context); > > >> > > >> > > > What's the implication of the temporarily-extant target node that it > > > needs to be avoided so strictly? > > > > > > > Creating a file on disk, that no one will ever remvoe. :) > > Fortunately libvirt's SELinux policy will probably prevent QEMU creating > it in the first place :-)
Well, calling drive-mirror without allowing QEMU to create the target image would be a bit pointless, so I think we can assume that libvirt did set up the file permission so that QEMU can create it. (Unless mode=existing is used, but I understand that libvirt doesn't want to create images with qemu-img, so that doesn't seem to be the case...) I don't know if libvirt takes care to remove a potentially already created file if the command then fails, but hopefully it does and the patch is not actually needed with libvirt. Kevin