From 751ebd76e654bd1e65da08ecf694325282b4cfcc Mon Sep 17 00:00:00 2001 From: Fam Zheng Date: Fri, 3 Apr 2015 22:05:18 +0800 Subject: blockjob: Allow nested pause 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. [Extended doc comments as suggested by Paolo Bonzini . --Stefan] Signed-off-by: Fam Zheng Reviewed-by: Stefan Hajnoczi Reviewed-by: Paolo Bonzini Reviewed-by: Alberto Garcia Message-id: 1428069921-2957-2-git-send-email-famz@redhat.com Signed-off-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- include/block/blockjob.h | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) (limited to 'include/block') diff --git a/include/block/blockjob.h b/include/block/blockjob.h index b6d4ebbe03..57d8ef13e2 100644 --- a/include/block/blockjob.h +++ b/include/block/blockjob.h @@ -79,10 +79,16 @@ struct BlockJob { bool cancelled; /** - * Set to true if the job is either paused, or will pause itself - * as soon as possible (if busy == true). + * Counter for pause request. If non-zero, the block job is either paused, + * or if busy == true will pause itself as soon as possible. */ - bool paused; + int pause_count; + + /** + * Set to true if the job is paused by user. Can be unpaused with the + * block-job-resume QMP command. + */ + bool user_paused; /** * Set to false by the job while it is in a quiescent state, where @@ -225,10 +231,18 @@ void block_job_pause(BlockJob *job); * block_job_resume: * @job: The job to be resumed. * - * Resume the specified job. + * Resume the specified job. Must be paired with a preceding block_job_pause. */ void block_job_resume(BlockJob *job); +/** + * block_job_enter: + * @job: The job to enter. + * + * Continue the specified job by entering the coroutine. + */ +void block_job_enter(BlockJob *job); + /** * block_job_event_cancelled: * @job: The job whose information is requested. -- cgit v1.2.3-55-g7522