Re: [PATCH v4 2/5] block: reject a reopen of an unusable node instead of crashing

[Kevin Wolf <kwolf@redhat.com>]

Am 24.08.2026 um 15:37 hat Denis V. Lunev geschrieben:
> From: Denis V. Lunev <den@openvz.org>
> 
> qcow2_signal_corruption() drops bs->drv, so a node can lose its driver
> at any time and a reopen has to expect that. Both ends of the path
> assume otherwise:
> 
>   $ qemu-io -c "read 0 64k" -c "reopen -r" corrupt.qcow2
>   qcow2: Marking image as corrupt: Cluster allocation offset 0x1200
>   unaligned (L2 offset: 0x40000, L2 index: 0); ...
>   Segmentation fault
> 
> bdrv_reopen_queue_child() dereferences bs->drv while descending into
> the children the node opened itself, and bdrv_reopen_prepare() asserts
> on it. commit_clean() reopens the base of a commit job back to
> read-only, so a base which goes corrupt under the job arrives here too.
> 
> There is nothing to reopen for such a node, so stop descending into its
> children and let bdrv_reopen_prepare() report what every caller of
> bdrv_reopen() already handles. bdrv_reopen_commit() and
> bdrv_reopen_abort() keep their assertion, only a prepared entry reaches
> them.
> 
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> Reviewed-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
> CC: Kevin Wolf <kwolf@redhat.com>
> CC: Hanna Reitz <hreitz@redhat.com>
> CC: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
> Cc: qemu-stable@nongnu.org

Reviewed-by: Kevin Wolf <kwolf@redhat.com>