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Re: [Qemu-block] [PATCH v5 05/42] block: Add chain helper functions
From: |
Max Reitz |
Subject: |
Re: [Qemu-block] [PATCH v5 05/42] block: Add chain helper functions |
Date: |
Thu, 13 Jun 2019 14:33:52 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 |
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.
>
>> + */
>> +
>> + 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>
>
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- [Qemu-block] [PATCH v5 01/42] block: Mark commit and mirror as filter drivers, (continued)
- [Qemu-block] [PATCH v5 01/42] block: Mark commit and mirror as filter drivers, Max Reitz, 2019/06/12
- [Qemu-block] [PATCH v5 02/42] copy-on-read: Support compressed writes, Max Reitz, 2019/06/12
- [Qemu-block] [PATCH v5 03/42] throttle: Support compressed writes, Max Reitz, 2019/06/12
- [Qemu-block] [PATCH v5 04/42] block: Add child access functions, Max Reitz, 2019/06/12
- [Qemu-block] [PATCH v5 05/42] block: Add chain helper functions, Max Reitz, 2019/06/12
- [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