Re: [PATCH v3 5/5] block/block-copy: use aio-task-pool API

[Max Reitz <mreitz@redhat.com>]

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On 29.04.20 08:10, Vladimir Sementsov-Ogievskiy wrote:
> Run block_copy iterations in parallel in aio tasks.
> 
> Changes:
>   - BlockCopyTask becomes aio task structure. Add zeroes field to pass
>     it to block_copy_do_copy
>   - add call state - it's a state of one call of block_copy(), shared
>     between parallel tasks. For now used only to keep information about
>     first error: is it read or not.
>   - convert block_copy_dirty_clusters to aio-task loop.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  block/block-copy.c | 104 +++++++++++++++++++++++++++++++++++++++------
>  1 file changed, 91 insertions(+), 13 deletions(-)
> 
> diff --git a/block/block-copy.c b/block/block-copy.c
> index 5cf032c4d8..f5ef91f292 100644
> --- a/block/block-copy.c
> +++ b/block/block-copy.c

[...]

> @@ -261,6 +278,30 @@ void block_copy_set_progress_meter(BlockCopyState *s, ProgressMeter *pm)
>      s->progress = pm;
>  }
>  
> +/* Takes ownership on @task */

Still *of

> +static coroutine_fn int block_copy_task_run(AioTaskPool *pool,
> +                                            BlockCopyTask *task)
> +{
> +    if (!pool) {
> +        int ret = task->task.func(&task->task);
> +
> +        g_free(task);
> +        return ret;
> +    }
> +
> +    aio_task_pool_wait_slot(pool);
> +    if (aio_task_pool_status(pool) < 0) {
> +        co_put_to_shres(task->s->mem, task->bytes);
> +        block_copy_task_end(task, -EAGAIN);

It looks like you may have missed my nit picks on v2 regarding this
patch, so I’m going to ask again whether -ECANCELED might be better here
(even though it still doesn’t really matter).

> +        g_free(task);
> +        return aio_task_pool_status(pool);

And whether it may be better to return a constant like -ECANCELED here,
because how a previous task failed shouldn’t really concern this task
(or its error code).

> +    }
> +
> +    aio_task_pool_start_task(pool, &task->task);
> +
> +    return 0;
> +}
> +
>  /*
>   * block_copy_do_copy
>   *

[...]

> @@ -525,25 +590,38 @@ static int coroutine_fn block_copy_dirty_clusters(BlockCopyState *s,

[...]

> +out:
> +    if (aio) {
> +        aio_task_pool_wait_all(aio);
> +        if (ret == 0) {
> +            ret = aio_task_pool_status(aio);
> +        }
> +        g_free(aio);

I’d still prefer aio_task_pool_free().

Max


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