Am 27.09.2016 um 04:20 hat Fam Zheng geschrieben: > We already specified BDRV_O_UNMAP when opening images in 'qemu-img > commit', but didn't turn on the "unmap" in the active commit job. This > patch fixes that so that zeroed clusters in top image can be discarded > which is desired in the virt-sparsify use case, where a temporary > overlay is created and fstrim'ed before commiting back, to free space in > the original image. > > The block-commit keeps the existing behavior. > > Signed-off-by: Fam Zheng <f...@redhat.com>
Is there a good reason for not using discard in an active commit if the image was opened with BDRV_O_UNMAP? That is, wouldn't it make sense to just set the unmap option for the mirror unconditionally and also for block-commit? If there is a reason, we should probably add an option to block-commit, but I still feels that enabling it should be the default then. Kevin
