Am 08.05.2019 um 16:01 hat Max Reitz geschrieben: > This series allows using qemu-img rebase (without -u) on images that do > not have a backing file. Right now, this fails with the rather cryptic > error message: > > $ qemu-img rebase -b base.qcow2 foo.qcow2 > qemu-img: Could not open old backing file '': The 'file' block driver > requires a file name > > Yeah, well, OK. > > With how rebase currently works, this would lead to the overlay being > filled with zeroes, however. This is where patch 2 comes in and instead > makes rebase use blk_pwrite_zeroes() whenever it handles an area past > the input’s backing file’s EOF. > > (Note that additionally we could try to punch holes in the overlay > whenever it matches the new backing file, but that’s something I’ll put > off for later. (We don’t even have a reliable method for punching holes > into an overlay yet, although I would like to have such because it could > make active commit more efficient.)) > > And patch 3 adds the usual test.
Thanks, applied to the block branch. Kevin
