From patchwork Sat Mar 10 08:27:40 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Snow X-Patchwork-Id: 884115 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=2001:4830:134:3::11; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=redhat.com Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3zyyDG369rz9t4H for ; Sat, 10 Mar 2018 19:32:30 +1100 (AEDT) Received: from localhost ([::1]:49659 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1euZvU-0005Rk-9o for incoming@patchwork.ozlabs.org; Sat, 10 Mar 2018 03:32:24 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53676) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1euZrM-0002R9-Rk for qemu-devel@nongnu.org; Sat, 10 Mar 2018 03:28:11 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1euZrK-0000D6-7R for qemu-devel@nongnu.org; Sat, 10 Mar 2018 03:28:08 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:56136 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1euZrF-00008a-1P; Sat, 10 Mar 2018 03:28:01 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8E0CB402277A; Sat, 10 Mar 2018 08:28:00 +0000 (UTC) Received: from probe.redhat.com (ovpn-123-36.rdu2.redhat.com [10.10.123.36]) by smtp.corp.redhat.com (Postfix) with ESMTP id 28ADA1007279; Sat, 10 Mar 2018 08:28:00 +0000 (UTC) From: John Snow To: qemu-block@nongnu.org Date: Sat, 10 Mar 2018 03:27:40 -0500 Message-Id: <20180310082746.24198-16-jsnow@redhat.com> In-Reply-To: <20180310082746.24198-1-jsnow@redhat.com> References: <20180310082746.24198-1-jsnow@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Sat, 10 Mar 2018 08:28:00 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Sat, 10 Mar 2018 08:28:00 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'jsnow@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PATCH v5 15/21] blockjobs: add prepare callback X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, John Snow , pkrempa@redhat.com, jtc@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" Some jobs upon finalization may need to perform some work that can still fail. If these jobs are part of a transaction, it's important that these callbacks fail the entire transaction. We allow for a new callback in addition to commit/abort/clean that allows us the opportunity to have fairly late-breaking failures in the transactional process. The expected flow is: - All jobs in a transaction converge to the PENDING state, added in a forthcoming commit. - Upon being finalized, either automatically or explicitly by the user, jobs prepare to complete. - If any job fails preparation, all jobs call .abort. - Otherwise, they succeed and call .commit. Signed-off-by: John Snow --- blockjob.c | 30 +++++++++++++++++++++++++++--- include/block/blockjob_int.h | 10 ++++++++++ 2 files changed, 37 insertions(+), 3 deletions(-) diff --git a/blockjob.c b/blockjob.c index 7e03824751..1395d8eed1 100644 --- a/blockjob.c +++ b/blockjob.c @@ -415,6 +415,14 @@ static void block_job_update_rc(BlockJob *job) } } +static int block_job_prepare(BlockJob *job) +{ + if (job->ret == 0 && job->driver->prepare) { + job->ret = job->driver->prepare(job); + } + return job->ret; +} + static void block_job_commit(BlockJob *job) { assert(!job->ret); @@ -438,7 +446,7 @@ static void block_job_clean(BlockJob *job) } } -static void block_job_completed_single(BlockJob *job) +static int block_job_completed_single(BlockJob *job) { assert(job->completed); @@ -472,6 +480,7 @@ static void block_job_completed_single(BlockJob *job) QLIST_REMOVE(job, txn_list); block_job_txn_unref(job->txn); block_job_conclude(job); + return 0; } static void block_job_cancel_async(BlockJob *job) @@ -487,17 +496,22 @@ static void block_job_cancel_async(BlockJob *job) job->cancelled = true; } -static void block_job_txn_apply(BlockJobTxn *txn, void fn(BlockJob *)) +static int block_job_txn_apply(BlockJobTxn *txn, int fn(BlockJob *)) { AioContext *ctx; BlockJob *job, *next; + int rc; QLIST_FOREACH_SAFE(job, &txn->jobs, txn_list, next) { ctx = blk_get_aio_context(job->blk); aio_context_acquire(ctx); - fn(job); + rc = fn(job); aio_context_release(ctx); + if (rc) { + break; + } } + return rc; } static int block_job_finish_sync(BlockJob *job, @@ -580,6 +594,8 @@ static void block_job_completed_txn_success(BlockJob *job) { BlockJobTxn *txn = job->txn; BlockJob *other_job; + int rc = 0; + /* * Successful completion, see if there are other running jobs in this * txn. @@ -590,6 +606,14 @@ static void block_job_completed_txn_success(BlockJob *job) } assert(other_job->ret == 0); } + + /* Jobs may require some prep-work to complete without failure */ + rc = block_job_txn_apply(txn, block_job_prepare); + if (rc) { + block_job_completed_txn_abort(job); + return; + } + /* We are the last completed job, commit the transaction. */ block_job_txn_apply(txn, block_job_completed_single); } diff --git a/include/block/blockjob_int.h b/include/block/blockjob_int.h index 259d49b32a..642adce68b 100644 --- a/include/block/blockjob_int.h +++ b/include/block/blockjob_int.h @@ -53,6 +53,16 @@ struct BlockJobDriver { */ void (*complete)(BlockJob *job, Error **errp); + /** + * If the callback is not NULL, prepare will be invoked when all the jobs + * belonging to the same transaction complete; or upon this job's completion + * if it is not in a transaction. + * + * This callback will not be invoked if the job has already failed. + * If it fails, abort and then clean will be called. + */ + int (*prepare)(BlockJob *job); + /** * If the callback is not NULL, it will be invoked when all the jobs * belonging to the same transaction complete; or upon this job's