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Re: [Qemu-block] [PATCH v5 05/42] block: Add chain helper functions
From: |
Vladimir Sementsov-Ogievskiy |
Subject: |
Re: [Qemu-block] [PATCH v5 05/42] block: Add chain helper functions |
Date: |
Thu, 13 Jun 2019 12:39:29 +0000 |
13.06.2019 15:33, Max Reitz wrote:
> On 13.06.19 14:26, Vladimir Sementsov-Ogievskiy wrote:
>> 13.06.2019 1:09, Max Reitz wrote:
>>> Add some helper functions for skipping filters in a chain of block
>>> nodes.
>>>
>>> Signed-off-by: Max Reitz <address@hidden>
>>> ---
>>> include/block/block_int.h | 3 +++
>>> block.c | 55 +++++++++++++++++++++++++++++++++++++++
>>> 2 files changed, 58 insertions(+)
>>>
>>> diff --git a/include/block/block_int.h b/include/block/block_int.h
>>> index 7ce71623f8..875a33f255 100644
>>> --- a/include/block/block_int.h
>>> +++ b/include/block/block_int.h
>>> @@ -1264,6 +1264,9 @@ BdrvChild *bdrv_filtered_child(BlockDriverState *bs);
>>> BdrvChild *bdrv_metadata_child(BlockDriverState *bs);
>>> BdrvChild *bdrv_storage_child(BlockDriverState *bs);
>>> BdrvChild *bdrv_primary_child(BlockDriverState *bs);
>>> +BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs);
>>> +BlockDriverState *bdrv_skip_rw_filters(BlockDriverState *bs);
>>> +BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs);
>>>
>>> static inline BlockDriverState *child_bs(BdrvChild *child)
>>> {
>>> diff --git a/block.c b/block.c
>>> index 724d8889a6..be18130944 100644
>>> --- a/block.c
>>> +++ b/block.c
>>> @@ -6494,3 +6494,58 @@ BdrvChild *bdrv_primary_child(BlockDriverState *bs)
>>> {
>>> return bdrv_filtered_rw_child(bs) ?: bs->file;
>>> }
>>> +
>>> +static BlockDriverState *bdrv_skip_filters(BlockDriverState *bs,
>>> + bool stop_on_explicit_filter)
>>> +{
>>> + BdrvChild *filtered;
>>> +
>>> + if (!bs) {
>>> + return NULL;
>>> + }
>>> +
>>> + while (!(stop_on_explicit_filter && !bs->implicit)) {
>>> + filtered = bdrv_filtered_rw_child(bs);
>>> + if (!filtered) {
>>> + break;
>>> + }
>>> + bs = filtered->bs;
>>> + }
>>> + /*
>>> + * Note that this treats nodes with bs->drv == NULL
>>
>> as well as filters without filtered_rw child
>
> A filter always must have a filtered_rw child, though. So I don’t quite
> understand what you mean here...
>
> Max
>
>> as not being
>>> + * R/W filters (bs->drv == NULL should be replaced by something
>>> + * else anyway).
>>> + * The advantage of this behavior is that this function will thus
>>> + * always return a non-NULL value (given a non-NULL @bs).
>>
>> and this is the advantage of what I've written, not about bs->drv.
I mean, that advantage seems unrelated to the reason about bs->drv == NULL,
as even with bs->drv == NULL we can go to bs->backing or bs->file..
But I don't really care, my r-b stays here anyway
>>
>>> + */
>>> +
>>> + return bs;
>>> +}
>>> +
>>> +/*
>>> + * Return the first BDS that has not been added implicitly or that
>>> + * does not have an RW-filtered child down the chain starting from @bs
>>> + * (including @bs itself).
>>> + */
>>> +BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs)
>>> +{
>>> + return bdrv_skip_filters(bs, true);
>>> +}
>>> +
>>> +/*
>>> + * Return the first BDS that does not have an RW-filtered child down
>>> + * the chain starting from @bs (including @bs itself).
>>> + */
>>> +BlockDriverState *bdrv_skip_rw_filters(BlockDriverState *bs)
>>> +{
>>> + return bdrv_skip_filters(bs, false);
>>> +}
>>> +
>>> +/*
>>> + * For a backing chain, return the first non-filter backing image of
>>> + * the first non-filter image.
>>> + */
>>> +BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs)
>>> +{
>>> + return
>>> bdrv_skip_rw_filters(bdrv_filtered_cow_bs(bdrv_skip_rw_filters(bs)));
>>> +}
>>>
>>
>>
>> Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>
>>
>
>
--
Best regards,
Vladimir
- Re: [Qemu-block] [PATCH v5 01/42] block: Mark commit and mirror as filter drivers, (continued)
- [Qemu-block] [PATCH v5 06/42] qcow2: Implement .bdrv_storage_child(), Max Reitz, 2019/06/12
- [Qemu-block] [PATCH v5 08/42] block: bdrv_set_backing_hd() is about bs->backing, Max Reitz, 2019/06/12
- [Qemu-block] [PATCH v5 07/42] block: *filtered_cow_child() for *has_zero_init(), Max Reitz, 2019/06/12
- [Qemu-block] [PATCH v5 10/42] block: Use CAF in bdrv_is_encrypted(), Max Reitz, 2019/06/12
- [Qemu-block] [PATCH v5 11/42] block: Add bdrv_supports_compressed_writes(), Max Reitz, 2019/06/12