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Fri, 27 Mar 2020 06:00:25 +0000 Subject: Re: [PATCH v2 1/3] backup: don't acquire aio_context in backup_clean To: Stefan Reiter , qemu-devel@nongnu.org, qemu-block@nongnu.org References: <20200326155628.859862-1-s.reiter@proxmox.com> <20200326155628.859862-2-s.reiter@proxmox.com> From: Vladimir Sementsov-Ogievskiy X-Tagtoolbar-Keys: D20200327090023209 Message-ID: Date: Fri, 27 Mar 2020 09:00:23 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 In-Reply-To: <20200326155628.859862-2-s.reiter@proxmox.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: AM0PR07CA0024.eurprd07.prod.outlook.com (2603:10a6:208:ac::37) To AM7PR08MB5494.eurprd08.prod.outlook.com (2603:10a6:20b:dc::15) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [192.168.100.2] (185.215.60.35) by AM0PR07CA0024.eurprd07.prod.outlook.com (2603:10a6:208:ac::37) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2878.11 via Frontend Transport; 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The job's context is guaranteed to be the same > as the one used by backup_top via backup_job_create. As we already discussed, this is not quite right. So, may be this patch should be the last one... > > Since the previous logic effectively acquired the lock twice, this > broke cleanup of backups for disks using IO threads, since the BDRV_POLL_WHILE > in bdrv_backup_top_drop -> bdrv_do_drained_begin would only release the lock > once, thus deadlocking with the IO thread. > > This is a partial revert of 0abf2581717a19. > > Signed-off-by: Stefan Reiter > --- > block/backup.c | 4 ---- > 1 file changed, 4 deletions(-) > > diff --git a/block/backup.c b/block/backup.c > index 7430ca5883..a7a7dcaf4c 100644 > --- a/block/backup.c > +++ b/block/backup.c > @@ -126,11 +126,7 @@ static void backup_abort(Job *job) > static void backup_clean(Job *job) > { > BackupBlockJob *s = container_of(job, BackupBlockJob, common.job); > - AioContext *aio_context = bdrv_get_aio_context(s->backup_top); > - > - aio_context_acquire(aio_context); > bdrv_backup_top_drop(s->backup_top); > - aio_context_release(aio_context); > } > > void backup_do_checkpoint(BlockJob *job, Error **errp) > -- Best regards, Vladimir