Re: [Qemu-block] [PATCH v2 0/3] image fleecing

[John Snow]

On 06/29/2018 11:15 AM, Vladimir Sementsov-Ogievskiy wrote:
> Image fleecing, or external (or pull) backup scheme is near to complete.
> Here is forgotten test, written by Fam in far 2014, with two my necessary
> patches, previously sent separately, so the series are called "v2"
> 
> v2:
>  01: add transaction support
>  02: rebase on master, drop "'fleecing-filter': 'BlockdevCreateNotSupported'"
>      add empty .bdrv_close
>      add default .bdrv_child_perm
>  03: comparing to [PATCH v20 15/15] qemu-iotests: Image fleecing test case 08:
>      add -f iotests.imgfmt to qemu_io
>      fix target_img to be always qcow2
>      add -r to qemu_io for nbd
>      add fleecing-filter layer
>      wrap long lines
> 
> Fam Zheng (1):
>   qemu-iotests: Image fleecing test case 222
> 
> Vladimir Sementsov-Ogievskiy (2):
>   blockdev-backup: enable non-root nodes for backup source
>   block/fleecing-filter: new filter driver for fleecing
> 
>  qapi/block-core.json       |   6 ++-
>  block/fleecing-filter.c    |  80 ++++++++++++++++++++++++++++++++
>  blockdev.c                 |   4 +-
>  block/Makefile.objs        |   1 +
>  tests/qemu-iotests/222     | 112 
> +++++++++++++++++++++++++++++++++++++++++++++
>  tests/qemu-iotests/222.out |   5 ++
>  tests/qemu-iotests/group   |   1 +
>  7 files changed, 205 insertions(+), 4 deletions(-)
>  create mode 100644 block/fleecing-filter.c
>  create mode 100755 tests/qemu-iotests/222
>  create mode 100644 tests/qemu-iotests/222.out
> 

Have you been able to reproduce a race that proves the filter is
necessary, or can you explain how it might happen?

I think I mentioned it once as a possibility but I hadn't convinced myself.