On Mon, Dec 11, 2017 at 06:46:09PM -0500, John Snow wrote:
> If users set an unreasonably low speed (like one byte per second), the
> calculated delay may exceed many hours. While we like to punish users
> for asking for stupid things, we do also like to allow users to correct
> their wicked ways.
>
> When a user provides a new speed, kick the job to allow it to recalculate
> its delay.
>
> Signed-off-by: John Snow <js...@redhat.com>
> ---
> blockjob.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/blockjob.c b/blockjob.c
> index 715c2c2680..43f01ad190 100644
> --- a/blockjob.c
> +++ b/blockjob.c
> @@ -483,6 +483,7 @@ static void block_job_completed_txn_success(BlockJob *job)
> void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp)
> {
> Error *local_err = NULL;
> + int64_t old_speed = job->speed;
>
> if (!job->driver->set_speed) {
> error_setg(errp, QERR_UNSUPPORTED);
> @@ -495,6 +496,10 @@ void block_job_set_speed(BlockJob *job, int64_t speed,
> Error **errp)
> }
>
> job->speed = speed;
> + /* Kick the job to recompute its delay */
> + if ((speed > old_speed) && timer_pending(&job->sleep_timer)) {
job->sleep_timer is protected by block_job_mutex (via
block_job_lock/unlock); is it safe for us to check it here outside the
mutex?
But in any case, I think we could get rid of the timer_pending check, and
just always kick the job if we have a speed increase. block_job_enter()
should do the right thing (mutex protected check on job->busy and
job->sleep_timer).
> + block_job_enter(job);
> + }
> }
>
> void block_job_complete(BlockJob *job, Error **errp)
> --
> 2.14.3
>
