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 ...?
In the cases where auto_finalize=true, do we have any guarantee that the
completion callbacks cannot be scheduled while we are here?
