Re: [Qemu-block] [PATCH 0/3] qemu-img: Allow rebase with no input base

[Max Reitz]

Ping again

(I feel like I just need to start merging unreviewed patches until I
break something (can't take that long) so you get so scared of my
patches that you at least refuse them outright)

On 13.07.18 13:14, Max Reitz wrote:
> This series allows using qemu-img rebase 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.
> 
> 
> Max Reitz (3):
>   qemu-img: Allow rebase with no input base
>   qemu-img: Use zero writes after source backing EOF
>   iotests: Add test for rebase without input base
> 
>  qemu-img.c                 | 72 +++++++++++++++++++++++---------------
>  tests/qemu-iotests/024     | 70 ++++++++++++++++++++++++++++++++++++
>  tests/qemu-iotests/024.out | 37 ++++++++++++++++++++
>  3 files changed, 150 insertions(+), 29 deletions(-)
>

signature.asc
Description: OpenPGP digital signature