On 04/19/2017 10:42 AM, Paolo Bonzini wrote:
> The new functions helps respecting the invariant that the coroutine
> is entered with false user_resume, zero pause count and no error
> recorded in the iostatus.
>
> Resetting the iostatus is now common to all of block_job_cancel_async,
> block_job_user_resume and block_job_iostatus_reset, albeit with slight
> differences:
>
> - block_job_cancel_async resets the iostatus, and resumes the job if
> there was an error, but the coroutine is not restarted immediately.
> For example the caller may continue with a call to block_job_finish_sync.
>
> - block_job_user_resume resets the iostatus. It wants to resume the job
> unconditionally, even if there was no error.
>
> - block_job_iostatus_reset doesn't resume the job at all. Maybe that's
> a bug but it should be fixed separately.
>
> block_job_iostatus_reset does the least common denominator, so add some
> checking but otherwise leave it as the entry point for resetting the
> iostatus.
>
> Signed-off-by: Paolo Bonzini <[email protected]>
> ---
> v1->v2: rewritten
>
> blockjob.c | 24 ++++++++++++++++++++----
> 1 file changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/blockjob.c b/blockjob.c
> index 5906266..1756153 100644
> --- a/blockjob.c
> +++ b/blockjob.c
> @@ -304,6 +304,19 @@ static void block_job_completed_single(BlockJob *job)
> block_job_unref(job);
> }
>
> +static void block_job_cancel_async(BlockJob *job)
> +{
> + if (job->iostatus != BLOCK_DEVICE_IO_STATUS_OK) {
> + block_job_iostatus_reset(job);
> + }
> + if (job->user_paused) {
> + /* Do not call block_job_enter here, the caller will handle it. */
> + job->user_paused = false;
> + job->pause_count--;
> + }
> + job->cancelled = true;
> +}
> +
> static void block_job_completed_txn_abort(BlockJob *job)
> {
> AioContext *ctx;
> @@ -328,7 +341,7 @@ static void block_job_completed_txn_abort(BlockJob *job)
> * them; this job, however, may or may not be cancelled,
> depending
> * on the caller, so leave it. */
> if (other_job != job) {
> - other_job->cancelled = true;
> + block_job_cancel_async(other_job);
> }
> continue;
> }
> @@ -411,8 +424,8 @@ bool block_job_user_paused(BlockJob *job)
> void block_job_user_resume(BlockJob *job)
> {
> if (job && job->user_paused && job->pause_count > 0) {
> - job->user_paused = false;
> block_job_iostatus_reset(job);
> + job->user_paused = false;
> block_job_resume(job);
> }
> }
> @@ -420,8 +433,7 @@ void block_job_user_resume(BlockJob *job)
> void block_job_cancel(BlockJob *job)
> {
> if (block_job_started(job)) {
> - job->cancelled = true;
> - block_job_iostatus_reset(job);
> + block_job_cancel_async(job);
> block_job_enter(job);> } else {
> block_job_completed(job, -ECANCELED);
> @@ -765,6 +777,10 @@ void block_job_yield(BlockJob *job)
>
> void block_job_iostatus_reset(BlockJob *job)
> {
> + if (job->iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
> + return;
> + }
> + assert(job->user_paused && job->pause_count > 0);
Why assert that it's user-paused? Will that be true from:
(A) All users of block_job_cancel_async, including:
- block_job_cancel
- block_job_completed
block_job_completed_txn_abort
(B) all users of blk_iostatus_reset:
- blk_do_attach_dev
- qmp_cont
It's ... not really clear to me that this is true, can you help me out?
> job->iostatus = BLOCK_DEVICE_IO_STATUS_OK;
> }
>
>
