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Re: [PATCH v2 2/7] block/block-copy: use block_status
From: |
Max Reitz |
Subject: |
Re: [PATCH v2 2/7] block/block-copy: use block_status |
Date: |
Fri, 7 Feb 2020 18:46:45 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 |
On 27.11.19 19:08, Vladimir Sementsov-Ogievskiy wrote:
> Use bdrv_block_status_above to chose effective chunk size and to handle
> zeroes effectively.
>
> This substitutes checking for just being allocated or not, and drops
> old code path for it. Assistance by backup job is dropped too, as
> caching block-status information is more difficult than just caching
> is-allocated information in our dirty bitmap, and backup job is not
> good place for this caching anyway.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> ---
> block/block-copy.c | 67 +++++++++++++++++++++++++++++++++++++---------
> block/trace-events | 1 +
> 2 files changed, 55 insertions(+), 13 deletions(-)
>
> diff --git a/block/block-copy.c b/block/block-copy.c
> index 8602e2cae7..74295d93d5 100644
> --- a/block/block-copy.c
> +++ b/block/block-copy.c
[...]
> @@ -336,23 +375,25 @@ int coroutine_fn block_copy(BlockCopyState *s,
> chunk_end = next_zero;
> }
>
> - if (s->skip_unallocated) {
> - ret = block_copy_reset_unallocated(s, start, &status_bytes);
> - if (ret == 0) {
> - trace_block_copy_skip_range(s, start, status_bytes);
> - start += status_bytes;
> - continue;
> - }
> - /* Clamp to known allocated region */
> - chunk_end = MIN(chunk_end, start + status_bytes);
> + ret = block_copy_block_status(s, start, chunk_end - start,
> + &status_bytes);
> + if (s->skip_unallocated && !(ret & BDRV_BLOCK_ALLOCATED)) {
> + bdrv_reset_dirty_bitmap(s->copy_bitmap, start, status_bytes);
> + s->progress_reset_callback(s->progress_opaque);
> + trace_block_copy_skip_range(s, start, status_bytes);
> + start += status_bytes;
> + continue;
> }
>
> + chunk_end = MIN(chunk_end, start + status_bytes);
I’m not sure how much the old “Clamp to known allocated region” actually
helps, but I wouldn’t drop it anyway.
Apart from this nit, the patch looks good to me.
Max
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- Re: [PATCH v2 2/7] block/block-copy: use block_status,
Max Reitz <=