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Re: [Qemu-block] [Qemu-devel] [PATCH] blockdev: no need to drain in qmp_
From: |
Fam Zheng |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH] blockdev: no need to drain in qmp_block_commit |
Date: |
Thu, 28 May 2015 21:44:41 -0400 (EDT) |
----- Original Message -----
> Draining is not necessary, I/O can happen as soon as the
> commit coroutine yields. Draining can be necessary before
> reopening the file for read/write, or while modifying the
> backing file chain, but that is done separately in
> bdrv_reopen_multiple or bdrv_close; this particular
> bdrv_drain_all does nothing for that.
>
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
> blockdev.c | 3 ---
> 1 file changed, 3 deletions(-)
>
> diff --git a/blockdev.c b/blockdev.c
> index d506a70..aee0395 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -2355,9 +2355,6 @@ void qmp_block_commit(const char *device,
> aio_context = bdrv_get_aio_context(bs);
> aio_context_acquire(aio_context);
>
> - /* drain all i/o before commits */
> - bdrv_drain_all();
> -
Reviewed-by: Fam Zheng <address@hidden>
> if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_COMMIT_SOURCE, errp)) {
> goto out;
> }
> --
> 2.4.1
>
>
>