Re: [Qemu-devel] [RFC patch 2/3] block-backend: add drained_begin / drained_end ops

[Paolo Bonzini]

On 16/03/2017 01:46, John Snow wrote:
> 
> - Does the presence of blk->quiesce_counter relieve the burden of needing
>   blk->public.io_limits_disabled? I could probably eliminate this counter
>   entirely and just spy on the root node's quiescent state at key moments
>   instead. I am confident I'm traipsing on delicate drain semantics.

Tricky question.  I believe io_limits_disabled is a bit of a hack.

Certainly you could get rid of disable_external now that we have
drained_begin/drained_end, but it would be a separate patch.

> - Should I treat the separation of a quisced BDS/BB as a drained_end request
>   as an analogue to how blk_insert_bs (in this patch) handles this?

I think so.

Paolo