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 --- blockjob.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) (limited to 'blockjob.c') diff --git a/blockjob.c b/blockjob.c index ba2255d91f..2755465259 100644 --- a/blockjob.c +++ b/blockjob.c @@ -107,7 +107,7 @@ void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp) void block_job_complete(BlockJob *job, Error **errp) { - if (job->paused || job->cancelled || !job->driver->complete) { + if (job->pause_count || job->cancelled || !job->driver->complete) { error_set(errp, QERR_BLOCK_JOB_NOT_READY, bdrv_get_device_name(job->bs)); return; @@ -118,17 +118,26 @@ void block_job_complete(BlockJob *job, Error **errp) void block_job_pause(BlockJob *job) { - job->paused = true; + job->pause_count++; } bool block_job_is_paused(BlockJob *job) { - return job->paused; + return job->pause_count > 0; } void block_job_resume(BlockJob *job) { - job->paused = false; + assert(job->pause_count > 0); + job->pause_count--; + if (job->pause_count) { + return; + } + block_job_enter(job); +} + +void block_job_enter(BlockJob *job) +{ block_job_iostatus_reset(job); if (job->co && !job->busy) { qemu_coroutine_enter(job->co, NULL); @@ -138,7 +147,7 @@ void block_job_resume(BlockJob *job) void block_job_cancel(BlockJob *job) { job->cancelled = true; - block_job_resume(job); + block_job_enter(job); } bool block_job_is_cancelled(BlockJob *job) @@ -258,7 +267,7 @@ BlockJobInfo *block_job_query(BlockJob *job) info->device = g_strdup(bdrv_get_device_name(job->bs)); info->len = job->len; info->busy = job->busy; - info->paused = job->paused; + info->paused = job->pause_count > 0; info->offset = job->offset; info->speed = job->speed; info->io_status = job->iostatus; @@ -335,6 +344,8 @@ BlockErrorAction block_job_error_action(BlockJob *job, BlockDriverState *bs, IO_OPERATION_TYPE_WRITE, action, &error_abort); if (action == BLOCK_ERROR_ACTION_STOP) { + /* make the pause user visible, which will be resumed from QMP. */ + job->user_paused = true; block_job_pause(job); block_job_iostatus_set_err(job, error); if (bs != job->bs) { -- cgit v1.2.3