30.07.2019 22:11, John Snow wrote:
>
>
> On 7/24/19 5:40 AM, Vladimir Sementsov-Ogievskiy wrote:
>> Instead of draining additional nodes in each job code, let's do it in
>> common block_job_drain, draining just all job's children.
>> BlockJobDriver.drain becomes unused, so, drop it at all.
>>
>> It's also a first step to finally get rid of blockjob->blk.
>>
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
>> ---
>>
>> v3: just resend, as I've some auto returned mails and not sure that
>> v2 reached recipients.
>>
>> v2: apply Max's suggestions:
>> - drop BlockJobDriver.drain
>> - do firtly loop of bdrv_drained_begin and then separate loop
>> of bdrv_drained_end.
>>
>> Hmm, a question here: should I call bdrv_drained_end in reverse
>> order? Or it's OK as is?
>>
>
> I think it should be OK. These nodes don't necessarily have a well
> defined relationship between each other, do they?
>
>> include/block/blockjob_int.h | 11 -----------
>> block/backup.c | 18 +-----------------
>> block/mirror.c | 26 +++-----------------------
>> blockjob.c | 13 ++++++++-----
>> 4 files changed, 12 insertions(+), 56 deletions(-)
>>
>
> Nice diffstat :)
>
>> diff --git a/include/block/blockjob_int.h b/include/block/blockjob_int.h
>> index e4a318dd15..e1abf4ee85 100644
>> --- a/include/block/blockjob_int.h
>> +++ b/include/block/blockjob_int.h
>> @@ -52,17 +52,6 @@ struct BlockJobDriver {
>> * besides job->blk to the new AioContext.
>> */
>> void (*attached_aio_context)(BlockJob *job, AioContext *new_context);
>> -
>> - /*
>> - * If the callback is not NULL, it will be invoked when the job has to
>> be
>> - * synchronously cancelled or completed; it should drain
>> BlockDriverStates
>> - * as required to ensure progress.
>> - *
>> - * Block jobs must use the default implementation for job_driver.drain,
>> - * which will in turn call this callback after doing generic block job
>> - * stuff.
>> - */
>> - void (*drain)(BlockJob *job);
>
> I was about to say "huh?" ... but then realized you're deleting this
> confusing glob. Good.
>
>> };
>>
>> /**
>> diff --git a/block/backup.c b/block/backup.c
>> index 715e1d3be8..7930004bbd 100644
>> --- a/block/backup.c
>> +++ b/block/backup.c
>> @@ -320,21 +320,6 @@ void backup_do_checkpoint(BlockJob *job, Error **errp)
>> hbitmap_set(backup_job->copy_bitmap, 0, backup_job->len);
>> }
>>
>> -static void backup_drain(BlockJob *job)
>> -{
>> - BackupBlockJob *s = container_of(job, BackupBlockJob, common);
>> -
>> - /* Need to keep a reference in case blk_drain triggers execution
>> - * of backup_complete...
>> - */
>> - if (s->target) {
>> - BlockBackend *target = s->target;
>> - blk_ref(target);
>> - blk_drain(target);
>> - blk_unref(target);
>> - }
>> -}
>> -
>
> Adios ...
>
>> static BlockErrorAction backup_error_action(BackupBlockJob *job,
>> bool read, int error)
>> {
>> @@ -493,8 +478,7 @@ static const BlockJobDriver backup_job_driver = {
>> .commit = backup_commit,
>> .abort = backup_abort,
>> .clean = backup_clean,
>> - },
>> - .drain = backup_drain,
>> + }
>> };
>>
>
> This pleases the eyes.
>
>> static int64_t backup_calculate_cluster_size(BlockDriverState *target,
>> diff --git a/block/mirror.c b/block/mirror.c
>> index 8cb75fb409..8456ccd89d 100644
>> --- a/block/mirror.c
>> +++ b/block/mirror.c
>> @@ -644,14 +644,11 @@ static int mirror_exit_common(Job *job)
>> bdrv_ref(mirror_top_bs);
>> bdrv_ref(target_bs);
>>
>> - /* Remove target parent that still uses BLK_PERM_WRITE/RESIZE before
>> + /*
>> + * Remove target parent that still uses BLK_PERM_WRITE/RESIZE before
>
> (Thanks, patchew...)
>
>> * inserting target_bs at s->to_replace, where we might not be able to
>> get
>> * these permissions.
>> - *
>> - * Note that blk_unref() alone doesn't necessarily drop permissions
>> because
>> - * we might be running nested inside mirror_drain(), which takes an
>> extra
>> - * reference, so use an explicit blk_set_perm() first. */
>> - blk_set_perm(s->target, 0, BLK_PERM_ALL, &error_abort);
>> + */
>> blk_unref(s->target);
>> s->target = NULL;
>>
>> @@ -1143,21 +1140,6 @@ static bool mirror_drained_poll(BlockJob *job)
>> return !!s->in_flight;
>> }
>>
>> -static void mirror_drain(BlockJob *job)
>> -{
>> - MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
>> -
>> - /* Need to keep a reference in case blk_drain triggers execution
>> - * of mirror_complete...
>> - */
>> - if (s->target) {
>> - BlockBackend *target = s->target;
>> - blk_ref(target);
>> - blk_drain(target);
>> - blk_unref(target);
>> - }
>> -}
>> -
>> static const BlockJobDriver mirror_job_driver = {
>> .job_driver = {
>> .instance_size = sizeof(MirrorBlockJob),
>> @@ -1172,7 +1154,6 @@ static const BlockJobDriver mirror_job_driver = {
>> .complete = mirror_complete,
>> },
>> .drained_poll = mirror_drained_poll,
>> - .drain = mirror_drain,
>> };
>>
>> static const BlockJobDriver commit_active_job_driver = {
>> @@ -1189,7 +1170,6 @@ static const BlockJobDriver commit_active_job_driver =
>> {
>> .complete = mirror_complete,
>> },
>> .drained_poll = mirror_drained_poll,
>> - .drain = mirror_drain,
>> };
>>
>> static void coroutine_fn
>> diff --git a/blockjob.c b/blockjob.c
>> index 20b7f557da..78cf71d6c8 100644
>> --- a/blockjob.c
>> +++ b/blockjob.c
>> @@ -92,12 +92,15 @@ void block_job_free(Job *job)
>> void block_job_drain(Job *job)
>> {
>> BlockJob *bjob = container_of(job, BlockJob, job);
>> - const JobDriver *drv = job->driver;
>> - BlockJobDriver *bjdrv = container_of(drv, BlockJobDriver, job_driver);
>> + GSList *l;
>>
>> - blk_drain(bjob->blk);
>> - if (bjdrv->drain) {
>> - bjdrv->drain(bjob);
>> + for (l = bjob->nodes; l; l = l->next) {
>> + BdrvChild *c = l->data;
>> + bdrv_drained_begin(c->bs);
>> + }
>> + for (l = bjob->nodes; l; l = l->next) {
>> + BdrvChild *c = l->data;
>> + bdrv_drained_end(c->bs);
>> }
>> }
>>
>>
>
> Seems much nicer to me. What becomes of the ref/unref pairs?
>
> I guess not needed anymore?, since job cleanup necessarily happens in
> the main loop context now and we don't have a backup_complete function
> anymore ...?
What pairs do you mean?
>
> In the cases where auto_finalize=true, do we have any guarantee that the
> completion callbacks cannot be scheduled while we are here?
>
Hmm, not simple for me to assume.. Is it a problem? And is it about this patch?
--
Best regards,
Vladimir
