Re: [Qemu-devel] [PATCH v6 09/20] parallels: Switch to .bdrv_co_block_status()

[Vladimir Sementsov-Ogievskiy]

07.12.2017 23:30, Eric Blake wrote:
> We are gradually moving away from sector-based interfaces, towards
> byte-based.  Update the parallels driver accordingly.  Note that
> the internal function block_status() is still sector-based, because
> it is still in use by other sector-based functions; but that's okay
> because request_alignment is 512 as a result of those functions.
> For now, no optimizations are added based on the mapping hint.
>
> Signed-off-by: Eric Blake <address@hidden>
>
> ---
> v5: fix pnum when return is 0
> v4: rebase to interface tweak, R-b dropped
> v3: no change
> v2: rebase to mapping parameter; it is ignored, so R-b kept
> ---
>   block/parallels.c | 22 +++++++++++++++-------
>   1 file changed, 15 insertions(+), 7 deletions(-)
>
> diff --git a/block/parallels.c b/block/parallels.c
> index 9545761f49..9a3d3748ae 100644
> --- a/block/parallels.c
> +++ b/block/parallels.c
> @@ -280,23 +280,31 @@ static coroutine_fn int 
> parallels_co_flush_to_os(BlockDriverState *bs)
>   }
>
>
> -static int64_t coroutine_fn parallels_co_get_block_status(BlockDriverState *bs,
> -        int64_t sector_num, int nb_sectors, int *pnum, BlockDriverState **file)
> +static int coroutine_fn parallels_co_block_status(BlockDriverState *bs,
> +                                                  bool want_zero,
> +                                                  int64_t offset,
> +                                                  int64_t bytes,
> +                                                  int64_t *pnum,
> +                                                  int64_t *map,
> +                                                  BlockDriverState **file)
>   {
>       BDRVParallelsState *s = bs->opaque;
> -    int64_t offset;
> +    int count;
>
> +    assert(QEMU_IS_ALIGNED(offset | bytes, BDRV_SECTOR_SIZE));
>       qemu_co_mutex_lock(&s->lock);
> -    offset = block_status(s, sector_num, nb_sectors, pnum);
> +    offset = block_status(s, offset >> BDRV_SECTOR_BITS,
> +                          bytes >> BDRV_SECTOR_BITS, &count);
>       qemu_co_mutex_unlock(&s->lock);
>
> +    *pnum = count * BDRV_SECTOR_SIZE;
>       if (offset < 0) {
>           return 0;
>       }
>
> +    *map = offset;

oh, didn't notice previous time :(, should be

*map = offset * BDRV_SECTOR_SIZE

(also, if you already use ">> BDRV_SECTOR_BITS" in this function,
would not it be more consistent to use "<< BDRV_SECTOR_BITS"
for sector-to-byte conversion?)

with that fixed (with "<<" or "*", up to you),
Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>

>       *file = bs->file->bs;
> -    return (offset << BDRV_SECTOR_BITS) |
> -        BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID;
> +    return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID;
>   }
>
>   static coroutine_fn int parallels_co_writev(BlockDriverState *bs,
> @@ -793,7 +801,7 @@ static BlockDriver bdrv_parallels = {
>       .bdrv_open                = parallels_open,
>       .bdrv_close               = parallels_close,
>       .bdrv_child_perm          = bdrv_format_default_perms,
> -    .bdrv_co_get_block_status = parallels_co_get_block_status,
> +    .bdrv_co_block_status     = parallels_co_block_status,
>       .bdrv_has_zero_init       = bdrv_has_zero_init_1,
>       .bdrv_co_flush_to_os      = parallels_co_flush_to_os,
>       .bdrv_co_readv  = parallels_co_readv,


--
Best regards,
Vladimir