From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40807) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZMK8W-0000as-6D for qemu-devel@nongnu.org; Mon, 03 Aug 2015 14:06:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZMK8S-000269-Ul for qemu-devel@nongnu.org; Mon, 03 Aug 2015 14:06:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59289) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZMK8S-000263-L3 for qemu-devel@nongnu.org; Mon, 03 Aug 2015 14:06:52 -0400 References: <1438238370-16212-1-git-send-email-famz@redhat.com> <1438238370-16212-10-git-send-email-famz@redhat.com> From: Max Reitz Message-ID: <55BFADB7.5040803@redhat.com> Date: Mon, 3 Aug 2015 20:06:47 +0200 MIME-Version: 1.0 In-Reply-To: <1438238370-16212-10-git-send-email-famz@redhat.com> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v4 09/14] block: add block job transactions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng , qemu-devel@nongnu.org Cc: Kevin Wolf , Jeff Cody , vsementsov@parallels.com, stefanha@redhat.com, John Snow On 30.07.2015 08:39, Fam Zheng wrote: > Sometimes block jobs must execute as a transaction group. Finishing > jobs wait until all other jobs are ready to complete successfully. > Failure or cancellation of one job cancels the other jobs in the group. > > Signed-off-by: Stefan Hajnoczi > [Rewrite the implementation which is now contained in block_job_completed. > --Fam] > Signed-off-by: Fam Zheng > --- > blockjob.c | 115 ++++++++++++++++++++++++++++++++++++++++++++++- > include/block/block.h | 1 + > include/block/blockjob.h | 29 ++++++++++++ > 3 files changed, 143 insertions(+), 2 deletions(-) > > diff --git a/blockjob.c b/blockjob.c > index 36c18e0..c78ad0a 100644 > --- a/blockjob.c > +++ b/blockjob.c > @@ -36,6 +36,16 @@ > #include "qemu/timer.h" > #include "qapi-event.h" > > +/* Transactional group of block jobs */ > +struct BlockJobTxn { > + > + /* Is this txn being cancelled? */ > + bool aborting; > + > + /* List of jobs */ > + QLIST_HEAD(, BlockJob) jobs; > +}; > + > void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs, > int64_t speed, BlockCompletionFunc *cb, > void *opaque, Error **errp) > @@ -90,6 +100,83 @@ void block_job_unref(BlockJob *job) > } > } > > +static void block_job_completed_single(BlockJob *job) > +{ > + if (!job->ret) { > + if (job->driver->commit) { > + job->driver->commit(job); > + } > + } else { > + if (job->driver->abort) { > + job->driver->abort(job); > + } > + } > + job->cb(job->opaque, job->ret); > + block_job_unref(job); > +} > + > +static void block_job_completed_txn_abort(BlockJob *job) > +{ > + AioContext *ctx; > + BlockJobTxn *txn = job->txn; > + BlockJob *other_job, *next; > + > + if (txn->aborting) { > + /* > + * We are cancelled by another job, who will handle everything. s/who/which/ > + */ > + return; > + } > + txn->aborting = true; > + /* We are the first failed job. Cancel other jobs. */ > + QLIST_FOREACH(other_job, &txn->jobs, txn_list) { > + ctx = bdrv_get_aio_context(other_job->bs); > + aio_context_acquire(ctx); > + } > + QLIST_FOREACH(other_job, &txn->jobs, txn_list) { > + if (other_job == job || other_job->completed) { > + /* Other are "effectively" cancelled by us, so set the status for s/Other/Other jobs/? > + * them; this job, however, may or may not be cancelled, depending > + * on the caller, so leave it. */ > + other_job->cancelled = other_job != job; If other_job == job, this is not left as it was, but set to false. > + continue; > + } > + block_job_cancel_sync(other_job); > + assert(other_job->completed); > + } > + QLIST_FOREACH_SAFE(other_job, &txn->jobs, txn_list, next) { > + ctx = bdrv_get_aio_context(other_job->bs); > + block_job_completed_single(other_job); > + aio_context_release(ctx); > + } > + g_free(txn); > +} > + > +static void block_job_completed_txn_success(BlockJob *job) > +{ > + AioContext *ctx; > + BlockJobTxn *txn = job->txn; > + BlockJob *other_job, *next; > + /* > + * Successful completion, see if there are other running jobs in this > + * txn. > + **/ > + QLIST_FOREACH(other_job, &txn->jobs, txn_list) { > + if (!other_job->completed) { > + return; > + } > + } > + /* We are the last completed job, commit the transaction. */ > + QLIST_FOREACH_SAFE(other_job, &txn->jobs, txn_list, next) { > + ctx = bdrv_get_aio_context(other_job->bs); > + aio_context_acquire(ctx); > + assert(other_job->ret == 0); > + block_job_completed_single(other_job); > + aio_context_release(ctx); > + } > + g_free(txn); > +} > + > void block_job_completed(BlockJob *job, int ret) > { > BlockDriverState *bs = job->bs; > @@ -98,8 +185,13 @@ void block_job_completed(BlockJob *job, int ret) > assert(!job->completed); > job->completed = true; > job->ret = ret; > - job->cb(job->opaque, ret); > - block_job_unref(job); > + if (!job->txn) { > + block_job_completed_single(job); > + } else if (ret < 0 || block_job_is_cancelled(job)) { > + block_job_completed_txn_abort(job); > + } else { > + block_job_completed_txn_success(job); > + } > } > > void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp) > @@ -398,3 +490,22 @@ void block_job_defer_to_main_loop(BlockJob *job, > > qemu_bh_schedule(data->bh); > } > + > +BlockJobTxn *block_job_txn_new(void) > +{ > + BlockJobTxn *txn = g_new0(BlockJobTxn, 1); > + QLIST_INIT(&txn->jobs); > + return txn; > +} > + > +void block_job_txn_add_job(BlockJobTxn *txn, BlockJob *job) > +{ > + if (!txn) { > + return; > + } > + > + assert(!job->txn); > + job->txn = txn; > + > + QLIST_INSERT_HEAD(&txn->jobs, job, txn_list); > +} > diff --git a/include/block/block.h b/include/block/block.h > index b1116e9..b7e06a5 100644 > --- a/include/block/block.h > +++ b/include/block/block.h > @@ -14,6 +14,7 @@ typedef struct BlockDriver BlockDriver; > typedef struct BlockJob BlockJob; > typedef struct BdrvChild BdrvChild; > typedef struct BdrvChildRole BdrvChildRole; > +typedef struct BlockJobTxn BlockJobTxn; > > typedef struct BlockDriverInfo { > /* in bytes, 0 if irrelevant */ > diff --git a/include/block/blockjob.h b/include/block/blockjob.h > index f6e4c86..c6b1bbb 100644 > --- a/include/block/blockjob.h > +++ b/include/block/blockjob.h > @@ -152,6 +152,9 @@ struct BlockJob { > */ > int ret; > > + /** Non-NULL if this job is part of a transaction */ > + BlockJobTxn *txn; > + QLIST_ENTRY(BlockJob) txn_list; > }; > > /** > @@ -395,4 +398,30 @@ void block_job_defer_to_main_loop(BlockJob *job, > BlockJobDeferToMainLoopFn *fn, > void *opaque); > > +/** > + * block_job_txn_new: > + * > + * Allocate and return a new block job transaction. Jobs can be added to the > + * transaction using block_job_txn_add_job(). > + * > + * The transaction is automatically freed when the last job completes or is > + * cancelled. > + * > + * All jobs in the transaction either complete successfully or fail/cancel as a > + * group. Jobs wait for each other before completing. Cancelling one job > + * cancels all jobs in the transaction. > + */ > +BlockJobTxn *block_job_txn_new(void); > + > +/** > + * block_job_txn_add_job: > + * @txn: The transaction (may be NULL) > + * @job: Job to add to the transaction > + * > + * Add @job to the transaction. The @job must not already be in a transaction. > + * The block job driver must call block_job_txn_prepare_to_complete() before > + * final cleanup and completion. I see this function mentioned only here, only in this patch. That doesn't seem right to me. Max > + */ > +void block_job_txn_add_job(BlockJobTxn *txn, BlockJob *job); > + > #endif >