Re: [Qemu-devel] [PATCH v2 1/4] blockjob: Allow nested pause

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Fri, Apr 03, 2015 at 10:05:18PM +0800, Fam Zheng wrote:
> This patch changes block_job_pause to increase the pause counter and
> block_job_resume to decrease it.
> 
> The counter will allow calling block_job_pause/block_job_resume
> unconditionally on a job when we need to suspend the IO temporarily.
> 
> From now on, each block_job_resume must be paired with a block_job_pause
> to keep the counter balanced.
> 
> The user pause from QMP or HMP will only trigger block_job_pause once
> until it's resumed, this is achieved by adding a user_paused flag in
> BlockJob.
> 
> One occurrence of block_job_resume in mirror_complete is replaced with
> block_job_enter which does what is necessary.
> 
> In block_job_cancel, the cancel flag is good enough to instruct
> coroutines to quit loop, so use block_job_enter to replace the unpaired
> block_job_resume.
> 
> Upon block job IO error, user is notified about the entering to the
> pause state, so this pause belongs to user pause, set the flag
> accordingly and expect a matching QMP resume.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  block/mirror.c           |  2 +-
>  blockdev.c               |  8 +++++---
>  blockjob.c               | 23 +++++++++++++++++------
>  include/block/blockjob.h | 20 ++++++++++++++++----
>  4 files changed, 39 insertions(+), 14 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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