Re: [PATCH v2 3/4] block: remember the writability a reopen starts from

On 8/11/26 6:42 PM, Denis V. Lunev wrote:
> bdrv_reopen_commit() updates bs->open_flags, so by the time
> .bdrv_reopen_commit_post() runs a driver can no longer tell whether
> the node has just become writable or was writable all along. Only the
> transition is worth reacting to.
> 
> Record the value while the queue is built, next to the other
> pre-reopen state BDRVReopenState already keeps.
> 
> Signed-off-by: Denis V. Lunev <[email protected]>
> CC: Kevin Wolf <[email protected]>
> CC: Hanna Reitz <[email protected]>
> CC: Andrey Drobyshev <[email protected]>
> Cc: [email protected]
> ---
>  block.c                      | 1 +
>  include/block/block-common.h | 1 +
>  2 files changed, 2 insertions(+)
> 
> diff --git a/block.c b/block.c
> index 99ed06f8ca..c50d9474fc 100644
> --- a/block.c
> +++ b/block.c
> @@ -4473,6 +4473,7 @@ bdrv_reopen_queue_child(BlockReopenQueue *bs_queue, BlockDriverState *bs,
>      bs_entry->state.options = options;
>      bs_entry->state.explicit_options = explicit_options;
>      bs_entry->state.flags = flags;
> +    bs_entry->state.was_writable = bdrv_is_writable(bs);
>  
>      /*
>       * If keep_old_opts is false then it means that unspecified
> diff --git a/include/block/block-common.h b/include/block/block-common.h
> index 895ea17541..f64b2d6f35 100644
> --- a/include/block/block-common.h
> +++ b/include/block/block-common.h
> @@ -360,6 +360,7 @@ typedef struct BDRVReopenState {
>      int flags;
>      BlockdevDetectZeroesOptions detect_zeroes;
>      bool backing_missing;
> +    bool was_writable; /* bs->open_flags is updated on commit */
>      BlockDriverState *old_backing_bs; /* keep pointer for permissions update */
>      BlockDriverState *old_file_bs; /* keep pointer for permissions update */
>      QDict *options;

If we start tracking pre-reopen flags state, wouldn't it be better to
just save 'int old_flags'?  Otherwise, once we have an urge to track
smth else besides writeability - we'll need to waste another struct field.

Andrey