Re: [Qemu-devel] [PATCH v2 0/3] qcow2: Do not mark inactive images corrupt

[John Snow <jsnow@redhat.com>]

On 06/06/2018 03:36 PM, Max Reitz wrote:
> The non-public logs in
> https://bugzilla.redhat.com/show_bug.cgi?id=1583346 (sorry...) reveal
> this problem:
> 
> $ (Create a qcow2 file "foo.qcow2" with a corrupted first L1 entry)
> $ echo 'qemu-io none0 "read 0 512"' \
>     | x86_64-softmmu/qemu-system-x86_64 -drive if=none,file=foo.qcow2 \
>                                         -monitor stdio \
>                                         -incoming exec:'cat /dev/null'
> QEMU 2.12.50 monitor - type 'help' for more information
> (qemu) qemu-io none0 "read 0 512"
> qcow2: Marking image as corrupt: L2 table offset 0x44200 unaligned (L1 index: 0); further corruption events will be suppressed
> qemu-system-x86_64: block/io.c:1691: bdrv_co_pwritev: Assertion `!(bs->open_flags & BDRV_O_INACTIVE)' failed.
> [1]    18444 done                 echo 'qemu-io none0 "read 0 512"' |
>        18445 abort (core dumped)  x86_64-softmmu/qemu-system-x86_64 -drive if=none,file=foo.qcow2 -monitor stdi
> 
> Oops.
> 
> 
> The first patch in this series makes a function public that the second
> patch uses to fix the issue by treating all non-writable images like
> read-only images (yes, there is a difference...) in this regard (which
> most importantly means not trying to set the corrupt flag on them).
> Inactive images count as non-writable images, but not as read-only
> images, so that fixes it.
> 
> The third patch adds an iotest case.
> 
> 
> v2:
> - Use bdrv_is_writable() instead of copying its functionality [Jeff]
> 
> 
> git-backport-diff against v1:
> 
> Key:
> [----] : patches are identical
> [####] : number of functional differences between upstream/downstream patch
> [down] : patch is downstream-only
> The flags [FC] indicate (F)unctional and (C)ontextual differences, respectively
> 
> 001/3:[down] 'block: Make bdrv_is_writable() public'
> 002/3:[0004] [FC] 'qcow2: Do not mark inactive images corrupt'
> 003/3:[----] [--] 'iotests: Add case for a corrupted inactive image'
> 
> 
> Max Reitz (3):
>   block: Make bdrv_is_writable() public
>   qcow2: Do not mark inactive images corrupt
>   iotests: Add case for a corrupted inactive image
> 
>  include/block/block.h      |  1 +
>  block.c                    | 17 ++++++++++++++---
>  block/qcow2.c              |  2 +-
>  tests/qemu-iotests/060     | 30 ++++++++++++++++++++++++++++++
>  tests/qemu-iotests/060.out | 14 ++++++++++++++
>  5 files changed, 60 insertions(+), 4 deletions(-)
> 

Reviewed-by: John Snow <jsnow@redhat.com>