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dkim=none (message not signed) header.d=none;redhat.com; dmarc=none action=none header.from=virtuozzo.com; Received: from AM7PR08MB5494.eurprd08.prod.outlook.com (2603:10a6:20b:dc::15) by AS8PR08MB6117.eurprd08.prod.outlook.com (2603:10a6:20b:292::22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4352.26; Tue, 27 Jul 2021 13:05:03 +0000 Received: from AM7PR08MB5494.eurprd08.prod.outlook.com ([fe80::44b9:68ac:bdc7:e23c]) by AM7PR08MB5494.eurprd08.prod.outlook.com ([fe80::44b9:68ac:bdc7:e23c%7]) with mapi id 15.20.4352.031; Tue, 27 Jul 2021 13:05:03 +0000 Subject: Re: [PATCH for-6.1? v2 5/7] job: Add job_cancel_requested() To: Max Reitz , qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, Kevin Wolf , John Snow References: <20210726144613.954844-1-mreitz@redhat.com> <20210726144613.954844-6-mreitz@redhat.com> From: Vladimir Sementsov-Ogievskiy Message-ID: Date: Tue, 27 Jul 2021 16:04:59 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 In-Reply-To: <20210726144613.954844-6-mreitz@redhat.com> Content-Type: text/plain; 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envelope-from=vsementsov@virtuozzo.com; helo=EUR05-DB8-obe.outbound.protection.outlook.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, MSGID_FROM_MTA_HEADER=0.001, NICE_REPLY_A=-0.438, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 26.07.2021 17:46, Max Reitz wrote: > Most callers of job_is_cancelled() actually want to know whether the job > is on its way to immediate termination. For example, we refuse to pause > jobs that are cancelled; but this only makes sense for jobs that are > really actually cancelled. > > A mirror job that is cancelled during READY with force=false should > absolutely be allowed to pause. This "cancellation" (which is actually > a kind of completion) may take an indefinite amount of time, and so > should behave like any job during normal operation. For example, with > on-target-error=stop, the job should stop on write errors. (In > contrast, force-cancelled jobs should not get write errors, as they > should just terminate and not do further I/O.) > > Therefore, redefine job_is_cancelled() to only return true for jobs that > are force-cancelled (which as of HEAD^ means any job that interprets the > cancellation request as a request for immediate termination), and add > job_cancel_request() as the general variant, which returns true for any job_cancel_requested() > jobs which have been requested to be cancelled, whether it be > immediately or after an arbitrarily long completion phase. > > Buglink: https://gitlab.com/qemu-project/qemu/-/issues/462 > Signed-off-by: Max Reitz > --- > include/qemu/job.h | 8 +++++++- > block/mirror.c | 10 ++++------ > job.c | 7 ++++++- > 3 files changed, 17 insertions(+), 8 deletions(-) > > diff --git a/include/qemu/job.h b/include/qemu/job.h > index 8aa90f7395..032edf3c5f 100644 > --- a/include/qemu/job.h > +++ b/include/qemu/job.h > @@ -436,9 +436,15 @@ const char *job_type_str(const Job *job); > /** Returns true if the job should not be visible to the management layer. */ > bool job_is_internal(Job *job); > > -/** Returns whether the job is scheduled for cancellation. */ > +/** Returns whether the job is being cancelled. */ > bool job_is_cancelled(Job *job); > > +/** > + * Returns whether the job is scheduled for cancellation (at an > + * indefinite point). > + */ > +bool job_cancel_requested(Job *job); > + > /** Returns whether the job is in a completed state. */ > bool job_is_completed(Job *job); > > diff --git a/block/mirror.c b/block/mirror.c > index e93631a9f6..72e02fa34e 100644 > --- a/block/mirror.c > +++ b/block/mirror.c > @@ -936,7 +936,7 @@ static int coroutine_fn mirror_run(Job *job, Error **errp) > /* Transition to the READY state and wait for complete. */ > job_transition_to_ready(&s->common.job); > s->actively_synced = true; > - while (!job_is_cancelled(&s->common.job) && !s->should_complete) { > + while (!job_cancel_requested(&s->common.job) && !s->should_complete) { > job_yield(&s->common.job); > } > s->common.job.cancelled = false; > @@ -1043,7 +1043,7 @@ static int coroutine_fn mirror_run(Job *job, Error **errp) > } > > should_complete = s->should_complete || > - job_is_cancelled(&s->common.job); > + job_cancel_requested(&s->common.job); > cnt = bdrv_get_dirty_count(s->dirty_bitmap); > } > > @@ -1087,7 +1087,7 @@ static int coroutine_fn mirror_run(Job *job, Error **errp) > trace_mirror_before_sleep(s, cnt, job_is_ready(&s->common.job), > delay_ns); > job_sleep_ns(&s->common.job, delay_ns); > - if (job_is_cancelled(&s->common.job) && s->common.job.force_cancel) { > + if (job_is_cancelled(&s->common.job)) { > break; > } > s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); > @@ -1099,9 +1099,7 @@ immediate_exit: > * or it was cancelled prematurely so that we do not guarantee that > * the target is a copy of the source. > */ > - assert(ret < 0 || > - (s->common.job.force_cancel && > - job_is_cancelled(&s->common.job))); > + assert(ret < 0 || job_is_cancelled(&s->common.job)); > assert(need_drain); > mirror_wait_for_all_io(s); > } > diff --git a/job.c b/job.c > index e78d893a9c..dba17a680f 100644 > --- a/job.c > +++ b/job.c > @@ -216,6 +216,11 @@ const char *job_type_str(const Job *job) > } > > bool job_is_cancelled(Job *job) > +{ > + return job->cancelled && job->force_cancel; can job->cancelled be false when job->force_cancel is true ? I think not and worth an assertion here. Something like if (job->force_cancel) { assert(job->cancelled); return true; } return false; > +} > + > +bool job_cancel_requested(Job *job) > { > return job->cancelled; > } > @@ -1015,7 +1020,7 @@ void job_complete(Job *job, Error **errp) > if (job_apply_verb(job, JOB_VERB_COMPLETE, errp)) { > return; > } > - if (job_is_cancelled(job) || !job->driver->complete) { > + if (job_cancel_requested(job) || !job->driver->complete) { > error_setg(errp, "The active block job '%s' cannot be completed", > job->id); > return; > I think it's a correct change, although there may be unexpected side-effects, it's hard to imagine all consequences of changing job_is_cancelled() semantics called in several places in job.c. Reviewed-by: Vladimir Sementsov-Ogievskiy -- Best regards, Vladimir