Re: [Qemu-devel] [PATCH v5 24/42] block: Use child access functions for QAPI queries

[Vladimir Sementsov-Ogievskiy]

13.06.2019 1:09, Max Reitz wrote:
> query-block and query-named-block-nodes now return any filtered child
> under "backing", not just bs->backing or COW children.  This is so that
> filters do not interrupt the reported backing chain.  This changes the
> output for iotest 184, as the throttled node now appears as a backing
> child.
> 
> Signed-off-by: Max Reitz <address@hidden>
> ---
>   block/qapi.c               | 35 ++++++++++++++++++++---------------
>   tests/qemu-iotests/184.out |  7 ++++++-
>   2 files changed, 26 insertions(+), 16 deletions(-)
> 
> diff --git a/block/qapi.c b/block/qapi.c
> index 0c13c86f4e..1fd2937abc 100644
> --- a/block/qapi.c
> +++ b/block/qapi.c
> @@ -150,9 +150,13 @@ BlockDeviceInfo *bdrv_block_device_info(BlockBackend 
> *blk,
>               return NULL;
>           }
>   
> -        if (bs0->drv && bs0->backing) {
> +        if (bs0->drv && bdrv_filtered_child(bs0)) {
> +            /*
> +             * Put any filtered child here (for backwards compatibility to 
> when
> +             * we put bs0->backing here, which might be any filtered child).
> +             */
>               info->backing_file_depth++;
> -            bs0 = bs0->backing->bs;
> +            bs0 = bdrv_filtered_bs(bs0);


so, here we report all filtered filter children as backing ...

>               (*p_image_info)->has_backing_image = true;
>               p_image_info = &((*p_image_info)->backing_image);
>           } else {
> @@ -161,9 +165,8 @@ BlockDeviceInfo *bdrv_block_device_info(BlockBackend *blk,
>   
>           /* Skip automatically inserted nodes that the user isn't aware of 
> for
>            * query-block (blk != NULL), but not for query-named-block-nodes */
> -        while (blk && bs0->drv && bs0->implicit) {
> -            bs0 = backing_bs(bs0);
> -            assert(bs0);
> +        if (blk) {
> +            bs0 = bdrv_skip_implicit_filters(bs0);
>           }
>       }
>   
> @@ -348,9 +351,9 @@ static void bdrv_query_info(BlockBackend *blk, BlockInfo 
> **p_info,
>       BlockDriverState *bs = blk_bs(blk);
>       char *qdev;
>   
> -    /* Skip automatically inserted nodes that the user isn't aware of */
> -    while (bs && bs->drv && bs->implicit) {
> -        bs = backing_bs(bs);
> +    if (bs) {
> +        /* Skip automatically inserted nodes that the user isn't aware of */
> +        bs = bdrv_skip_implicit_filters(bs);
>       }
>   
>       info->device = g_strdup(blk_name(blk));
> @@ -507,6 +510,7 @@ static void bdrv_query_blk_stats(BlockDeviceStats *ds, 
> BlockBackend *blk)
>   static BlockStats *bdrv_query_bds_stats(BlockDriverState *bs,
>                                           bool blk_level)
>   {
> +    BlockDriverState *storage_bs, *cow_bs;
>       BlockStats *s = NULL;
>   
>       s = g_malloc0(sizeof(*s));
> @@ -519,9 +523,8 @@ static BlockStats *bdrv_query_bds_stats(BlockDriverState 
> *bs,
>       /* Skip automatically inserted nodes that the user isn't aware of in
>        * a BlockBackend-level command. Stay at the exact node for a node-level
>        * command. */
> -    while (blk_level && bs->drv && bs->implicit) {
> -        bs = backing_bs(bs);
> -        assert(bs);
> +    if (blk_level) {
> +        bs = bdrv_skip_implicit_filters(bs);
>       }
>   
>       if (bdrv_get_node_name(bs)[0]) {
> @@ -531,14 +534,16 @@ static BlockStats 
> *bdrv_query_bds_stats(BlockDriverState *bs,
>   
>       s->stats->wr_highest_offset = stat64_get(&bs->wr_highest_offset);
>   
> -    if (bs->file) {
> +    storage_bs = bdrv_storage_bs(bs);
> +    if (storage_bs) {
>           s->has_parent = true;
> -        s->parent = bdrv_query_bds_stats(bs->file->bs, blk_level);
> +        s->parent = bdrv_query_bds_stats(storage_bs, blk_level);

... and here not as "backing" but as "parent"

Shouldn't we report filter-child as backing here too, for consistency?

anyway:

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

>       }
>   
> -    if (blk_level && bs->backing) {
> +    cow_bs = bdrv_filtered_cow_bs(bs);
> +    if (blk_level && cow_bs) {
>           s->has_backing = true;
> -        s->backing = bdrv_query_bds_stats(bs->backing->bs, blk_level);
> +        s->backing = bdrv_query_bds_stats(cow_bs, blk_level);
>       }
>   
>       return s;
> diff --git a/tests/qemu-iotests/184.out b/tests/qemu-iotests/184.out
> index 3deb3cfb94..1d61f7e224 100644
> --- a/tests/qemu-iotests/184.out
> +++ b/tests/qemu-iotests/184.out
> @@ -27,6 +27,11 @@ Testing:
>               "iops_rd": 0,
>               "detect_zeroes": "off",
>               "image": {
> +                "backing-image": {
> +                    "virtual-size": 1073741824,
> +                    "filename": "null-co://",
> +                    "format": "null-co"
> +                },
>                   "virtual-size": 1073741824,
>                   "filename": "json:{\"throttle-group\": \"group0\", 
> \"driver\": \"throttle\", \"file\": {\"driver\": \"null-co\"}}",
>                   "format": "throttle"
> @@ -34,7 +39,7 @@ Testing:
>               "iops_wr": 0,
>               "ro": false,
>               "node-name": "throttle0",
> -            "backing_file_depth": 0,
> +            "backing_file_depth": 1,
>               "drv": "throttle",
>               "iops": 0,
>               "bps_wr": 0,
> 


-- 
Best regards,
Vladimir