Re: [PATCH v4 1/9] block: Add flags to BlockDriver.bdrv_co_truncate()

[Vladimir Sementsov-Ogievskiy]

20.04.2020 16:32, Kevin Wolf wrote:
> This adds a new BdrvRequestFlags parameter to the .bdrv_co_truncate()
> driver callbacks, and a supported_truncate_flags field in
> BlockDriverState that allows drivers to advertise support for request
> flags in the context of truncate.
>
> For now, we always pass 0 and no drivers declare support for any flag.
>
> Signed-off-by: Kevin Wolf<address@hidden>
> ---

[..]

> --- a/block/io.c
> +++ b/block/io.c
> @@ -3344,6 +3344,7 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child, 
> int64_t offset, bool exact,
>       BlockDriverState *bs = child->bs;
>       BlockDriver *drv = bs->drv;
>       BdrvTrackedRequest req;
> +    BdrvRequestFlags flags = 0;
>       int64_t old_size, new_bytes;
>       int ret;
>   
> @@ -3394,7 +3395,12 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child, int64_t offset, bool exact,
>       }
>   
>       if (drv->bdrv_co_truncate) {
> -        ret = drv->bdrv_co_truncate(bs, offset, exact, prealloc, errp);
> +        if (flags & ~bs->supported_truncate_flags) {
> +            error_setg(errp, "Block driver does not support requested flags");
> +            ret = -ENOTSUP;
> +            goto out;
> +        }
> +        ret = drv->bdrv_co_truncate(bs, offset, exact, prealloc, flags, errp);
>       } else if (bs->file && drv->is_filter) {
>           ret = bdrv_co_truncate(bs->file, offset, exact, prealloc, errp);

Hmm, I think it's incorrect to silently omit flags here.. But in current patch 
flags are always 0, and you update this place in the following patch. OK

With updated block/file-win32.c:

Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>

--
Best regards,
Vladimir