Re: [Qemu-devel] [PATCH v5 1/4] block/io: fix copy_range

[Fam Zheng]

On Mon, 07/09 19:37, Vladimir Sementsov-Ogievskiy wrote:
> Here two things are fixed:
> 
> 1. Architecture
> 
> On each recursion step, we go to the child of src or dst, only for one
> of them. So, it's wrong to create tracked requests for both on each
> step. It leads to tracked requests duplication.
> 
> 2. Wait for serializing requests on write path independently of
>    BDRV_REQ_NO_SERIALISING
> 
> Before commit 9ded4a01149 "backup: Use copy offloading",
> BDRV_REQ_NO_SERIALISING was used for only one case: read in
> copy-on-write operation during backup. Also, the flag was handled only
> on read path (in bdrv_co_preadv and bdrv_aligned_preadv).
> 
> After 9ded4a01149, flag is used for not waiting serializing operations
> on backup target (in same case of copy-on-write operation). This
> behavior change is unsubstantiated and potentially dangerous, let's
> drop it and add additional asserts and documentation.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>

Reviewed-by: Fam Zheng <address@hidden>