Re: [PATCH v7 0/5] fix & merge block_status_above and is_allocated_above

[Stefan Hajnoczi]

On Thu, Sep 24, 2020 at 10:39:58PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> Hi all!
> 
> These series are here to address the following problem:
> block-status-above functions may consider space after EOF of
> intermediate backing files as unallocated, which is wrong, as these
> backing files are the reason of producing zeroes, we never go further by
> backing chain after a short backing file. So, if such short-backing file
> is _inside_ requested sub-chain of the backing chain, we should never
> report space after its EOF as unallocated.
> 
> See patches 01,04,05 for details.
> 
> Note, that this series leaves for another day the general problem
> around block-status: misuse of BDRV_BLOCK_ALLOCATED as is-fs-allocated
> vs go-to-backing.
> Audit for this problem is done here:
> "backing chain & block status & filters"
> https://lists.gnu.org/archive/html/qemu-devel/2020-04/msg04706.html
> And I'm going to prepare series to address this problem.
> 
> Also, get_block_status func have same disease, but remains unfixed here:
> I want to make separate series for it.
> 
> v7:
> - add Alberto's r-bs in all patchs
> - rebase to new backing-chain handling, bdrv_filter_or_cow_bs is used instead 
> of backing_bs
> 
> 
> Based on series "[PATCH v9 0/7] coroutines: generate wrapper code" or
> in other words:
> Based-on: <20200924185414.28642-1-vsementsov@virtuozzo.com>
> 
> Vladimir Sementsov-Ogievskiy (5):
>   block/io: fix bdrv_co_block_status_above
>   block/io: bdrv_common_block_status_above: support include_base
>   block/io: bdrv_common_block_status_above: support bs == base
>   block/io: fix bdrv_is_allocated_above
>   iotests: add commit top->base cases to 274
> 
>  block/coroutines.h         |   2 +
>  block/io.c                 | 132 +++++++++++++++++++++----------------
>  block/qcow2.c              |  16 ++++-
>  tests/qemu-iotests/274     |  20 ++++++
>  tests/qemu-iotests/274.out |  68 +++++++++++++++++++
>  5 files changed, 179 insertions(+), 59 deletions(-)
> 
> -- 
> 2.21.3
> 

Thanks, applied to my block tree with Eric's spelling fixes:
https://github.com/stefanha/qemu/commits/block

Stefan

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