On Fri, Sep 30, 2016 at 06:00:41PM -0400, John Snow wrote:
> BlockJobs will begin hiding their state in preparation for some
> refactorings anyway, so let's internalize the user_pause mechanism
> instead of leaving it to callers to correctly manage.
>
> Signed-off-by: John Snow <js...@redhat.com>
> ---
> block/io.c | 2 +-
> blockdev.c | 10 ++++------
> blockjob.c | 16 ++++++++++++----
> include/block/blockjob.h | 11 ++++++++++-
> 4 files changed, 27 insertions(+), 12 deletions(-)
>
> diff --git a/block/io.c b/block/io.c
> index fdf7080..868b065 100644
> --- a/block/io.c
> +++ b/block/io.c
> @@ -291,7 +291,7 @@ void bdrv_drain_all(void)
> AioContext *aio_context = blk_get_aio_context(job->blk);
>
> aio_context_acquire(aio_context);
> - block_job_pause(job);
> + block_job_pause(job, false);
Hmm. Maybe semantically, an enum might work better here than a bool. When
I see "block_job_pause(job, false)", it reads like you just un-paused the
job, rather than paused it with some contextual info. Perhaps
JOB_USER_PAUSE and JOB_SYS_PAUSE (or just JOB_USER and JOB_SYS)?
> aio_context_release(aio_context);
> }
>
> diff --git a/blockdev.c b/blockdev.c
> index 03200e7..268452f 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -3629,7 +3629,7 @@ void qmp_block_job_cancel(const char *device,
> force = false;
> }
>
> - if (job->user_paused && !force) {
> + if (block_job_paused(job) && !force) {
> error_setg(errp, "The block job for device '%s' is currently paused",
> device);
> goto out;
> @@ -3646,13 +3646,12 @@ void qmp_block_job_pause(const char *device, Error
> **errp)
> AioContext *aio_context;
> BlockJob *job = find_block_job(device, &aio_context, errp);
>
> - if (!job || job->user_paused) {
> + if (!job || block_job_paused(job)) {
> return;
> }
>
> - job->user_paused = true;
> trace_qmp_block_job_pause(job);
> - block_job_pause(job);
> + block_job_pause(job, true);
> aio_context_release(aio_context);
> }
>
> @@ -3661,11 +3660,10 @@ void qmp_block_job_resume(const char *device, Error
> **errp)
> AioContext *aio_context;
> BlockJob *job = find_block_job(device, &aio_context, errp);
>
> - if (!job || !job->user_paused) {
> + if (!job || !block_job_paused(job)) {
> return;
> }
>
> - job->user_paused = false;
> trace_qmp_block_job_resume(job);
> block_job_iostatus_reset(job);
> block_job_resume(job);
> diff --git a/blockjob.c b/blockjob.c
> index 6a300ba..2a35f50 100644
> --- a/blockjob.c
> +++ b/blockjob.c
> @@ -104,7 +104,7 @@ static void block_job_detach_aio_context(void *opaque)
> /* In case the job terminates during aio_poll()... */
> block_job_ref(job);
>
> - block_job_pause(job);
> + block_job_pause(job, false);
>
> if (!job->paused) {
> /* If job is !job->busy this kicks it into the next pause point. */
> @@ -343,9 +343,12 @@ void block_job_complete(BlockJob *job, Error **errp)
> job->driver->complete(job, errp);
> }
>
> -void block_job_pause(BlockJob *job)
> +void block_job_pause(BlockJob *job, bool user)
> {
> job->pause_count++;
> + if (user) {
> + job->user_paused = true;
> + }
> }
>
> static bool block_job_should_pause(BlockJob *job)
> @@ -353,6 +356,11 @@ static bool block_job_should_pause(BlockJob *job)
> return job->pause_count > 0;
> }
>
> +bool block_job_paused(BlockJob *job)
I think a more apt name for this would be "block_job_user_paused()", because
it doesn't tell if the job is paused per se, but only if it is paused by a
user.
> +{
> + return job ? job->user_paused : 0;
> +}
> +
> void coroutine_fn block_job_pause_point(BlockJob *job)
> {
> if (!block_job_should_pause(job)) {
> @@ -386,6 +394,7 @@ void block_job_resume(BlockJob *job)
> if (job->pause_count) {
> return;
> }
> + job->user_paused = false;
At first I was thinking block_job_resume() would need a way of knowing if it
was a user resume, similar to block_job_pause(). But I guess not... if the
user paused it, then job->pause_count should always be > 0, I think.
But wait...could we ever get into a state where something like this happens:
block_job_pause(job, true); /* user paused */
[...]
block_job_pause(job, false); /* system paused */
[...]
block_job_resume(job); /* user resumes */
[...] /* job->user_paused is still true, although it shouldn't be */
block_job_resume(job); /* system resumes */
/* now job->user_paused is false */
> block_job_enter(job);
> }
>
> @@ -592,8 +601,7 @@ BlockErrorAction block_job_error_action(BlockJob *job,
> BlockdevOnError on_err,
> 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_pause(job, true);
> block_job_iostatus_set_err(job, error);
> }
> return action;
> diff --git a/include/block/blockjob.h b/include/block/blockjob.h
> index 4ddb4ae..081f6c2 100644
> --- a/include/block/blockjob.h
> +++ b/include/block/blockjob.h
> @@ -347,10 +347,19 @@ void coroutine_fn block_job_pause_point(BlockJob *job);
> /**
> * block_job_pause:
> * @job: The job to be paused.
> + * @user: Requested explicitly via user?
> *
> * Asynchronously pause the specified job.
> */
> -void block_job_pause(BlockJob *job);
> +void block_job_pause(BlockJob *job, bool user);
> +
> +/**
> + * block_job_paused:
> + * @job: The job to query.
> + *
> + * Returns true if the job is user-paused.
> + */
> +bool block_job_paused(BlockJob *job);
>
> /**
> * block_job_resume:
> --
> 2.7.4
>
