From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 071BCC433F5 for ; Wed, 4 May 2022 15:46:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352703AbiEDPuS (ORCPT ); Wed, 4 May 2022 11:50:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47274 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230413AbiEDPuP (ORCPT ); Wed, 4 May 2022 11:50:15 -0400 Received: from NAM04-MW2-obe.outbound.protection.outlook.com (mail-mw2nam08on2078.outbound.protection.outlook.com [40.107.101.78]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2F2501F638; Wed, 4 May 2022 08:46:37 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=SgEtl0VHlkdr+lEj8jOgEOQ6WIuLczAV1+W84ySeHaQTg46lRIQ9zSLBsUR7nVwFo9KtJTZqTlZzFXeMt7SkPvcQS2/2/KQHaRoMI7hX8rmzEbZ//8pmrUAZrt/peAxH4VRuQiMSksFmgSfH/7n3+5TjJvqHAj6VrueLqTelkqm85Aii6cyrgmm7avB5qDfiMK0STi9sKrzQ/ylj3nwU7HhEXhX3f/qLL9BU7tatCwqWHzByhERbJTbXxUwIGwLhVAjtseeBS7ynvzWfIctUK3piaeHfIL70QNZdwwOSVkyTbMuZ/TI4Muj75QfSF6s7XjHTxlsom5qHMhETTT9j2Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=x7P5dNERTvhSMprfndxUcfc50a0PSZm4rbgO5m1FSO8=; b=mwPpNqzCcfcEHgBM4csmpq50HMjNcDMnKPEuULkLa8cfPCtcdXWdDuNCIwuYiUooNfnLtiTb/Rb5037V+M5n45YyY24N9kMh9wUZkMvSXb1UewIwA3Ohv2/tjUod0SSV3XmNNl8pV7m+9sPMw/AV9HNiB9zEWbUTwSV+HrzyJLFWR8hoi2T7Wj6algGSs6kTaeVWMSwVypafRUTaWLM106w5pKOukn3tscn4kA25JIDT1h8f3No3T3BoSKZALzITMMGHuk6+QC3w/PHvxOm1hWehOm7EA7BPL8itWlSqlPnITfSFvE40RnX5NUQynQmJnHfXhAatgx9doYfKhzGxCg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=ddn.com; dmarc=pass action=none header.from=ddn.com; dkim=pass header.d=ddn.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ddn.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=x7P5dNERTvhSMprfndxUcfc50a0PSZm4rbgO5m1FSO8=; b=fbfLLzlw0YeUNDg0mfKTEQU4c5GoyqxzlhKHeJ8IsyRggoiMCtlQlm+tqRG5P+cwC3N/KXu/Mjd0y3N/vC0SYSD3+EywJ/iKcFbsXsRPG+LcdLzbK283XuqeqfDSPYufLTnqu/MpNVSjihbpgs7QZ4uZ3aBION/5oNlFcziZkfg= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=ddn.com; Received: from DM5PR1901MB2037.namprd19.prod.outlook.com (2603:10b6:4:aa::29) by DM5PR19MB0057.namprd19.prod.outlook.com (2603:10b6:4:61::30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.5206.27; Wed, 4 May 2022 15:46:33 +0000 Received: from DM5PR1901MB2037.namprd19.prod.outlook.com ([fe80::8072:43ab:7fd0:26a]) by DM5PR1901MB2037.namprd19.prod.outlook.com ([fe80::8072:43ab:7fd0:26a%4]) with mapi id 15.20.5186.028; Wed, 4 May 2022 15:46:33 +0000 Message-ID: <8003098d-6b17-5cdf-866d-06fefdf1ca31@ddn.com> Date: Wed, 4 May 2022 17:46:27 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [PATCH v4 1/3] FUSE: Implement atomic lookup + create Content-Language: en-US To: Vivek Goyal , Dharmendra Hans Cc: Miklos Szeredi , linux-fsdevel@vger.kernel.org, fuse-devel , linux-kernel@vger.kernel.org, Dharmendra Singh References: <20220502102521.22875-1-dharamhans87@gmail.com> <20220502102521.22875-2-dharamhans87@gmail.com> From: Bernd Schubert In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: AM6PR10CA0027.EURPRD10.PROD.OUTLOOK.COM (2603:10a6:209:89::40) To DM5PR1901MB2037.namprd19.prod.outlook.com (2603:10b6:4:aa::29) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 2242c03d-a16a-4b11-8f54-08da2de543a2 X-MS-TrafficTypeDiagnostic: DM5PR19MB0057:EE_ X-Microsoft-Antispam-PRVS: X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DM5PR1901MB2037.namprd19.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230001)(4636009)(366004)(6512007)(31696002)(2616005)(316002)(66556008)(66476007)(31686004)(66946007)(54906003)(4326008)(8676002)(186003)(110136005)(5660300002)(38100700002)(86362001)(6506007)(8936002)(53546011)(36756003)(83380400001)(6486002)(508600001)(2906002)(6666004)(45980500001)(43740500002);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 2 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?M0FOQkNnMjIwTTlhQXY2N2ZzYTRUQ3F1djB5bm5hWkdTYlh4Z3gzcmFhbyt3?= =?utf-8?B?a0Q3dUFGMXZJRFZvdFdMR2pwb0gzZnpjdVlra0d0RUNCZ0hkNnVXdy92ODJ6?= =?utf-8?B?VG8vcW4vaXRkbmVkSG9VRGdXQk1UT3c0dHAwcGVKZk1OQzArUE1WNjBYaVR5?= =?utf-8?B?aUZ1R1FTTllvWk9QV3dNTG5qSnFuUWo1R3g4SzBYaS93emRVMmhpSDhDT2R2?= =?utf-8?B?RjgvMDExTm1sK3JYYy9YZGpLNEovaUVLd3RDZkQycFZnTmNaeFZvTkxJSVR3?= =?utf-8?B?NUpTWjYreHlKSkhPL21FdENsY1dKcE5KN29iMmtqSFNLQWxEd0l0M3hZeWlT?= =?utf-8?B?ZUphbTkySHd3MVZNVi9QZ2taY2dvOGZwRXY2RlhpMTl3SG5JUFUrT3VNc1U3?= =?utf-8?B?TlVvKzZyeXFFLy9MbUNiMCtTODhPT2xlZDhBRDhMNnliNnVvYTUwWmluaVlq?= =?utf-8?B?MkFJaUQzdnk4UVNUcDhGazlDVmdSUDMwTndGYWhPdk93akNOQ25lM0k0VWh2?= =?utf-8?B?YUxpSENmSUJBUXN2clpyT3hJSDNPUDVPSFVUdllqOVNnUThZY3RnVHlsbktG?= =?utf-8?B?UTY3TTVsMkdmb243TE1uODhGU3k0TTcyZHFiZncxZEVwS2JPN2ovQzVud1U3?= =?utf-8?B?MXRPZDZqb0syMVFMZ1JNRHpkZ0dWc3hFc2ZOMjduN3ovVHFZMnpmaHZxVlBG?= =?utf-8?B?YWcwclV6cWo3Sy9vamw1aXI3ejFlUUcxbHZzSkMyeGxYSkdKZ204ODFmS0Fs?= =?utf-8?B?WEFSd2IxWlREU1d4ckY1WXN3K1FBcGc1VU96RVdqZDhhanhRMkdUVnp2NmE1?= =?utf-8?B?S0JEZnhjSmhJRjRnaXZXUm1WZlNXY0xjUGlERlV2MVlQNmg5aCt3bXNlVVZY?= =?utf-8?B?Y2VqRTcvZXg2b05obkRLMGwwMVo0cGZ3VXBVRzk1cXpiZVhjdGtCUUZ4bkRQ?= =?utf-8?B?UFA5MDhOZG9IOURqMkZBMHlrUVMxc3BqZHdDTERVbC9kZ0tRWDYxek90U3BN?= =?utf-8?B?SlRYa0E2aXB5ZlJhQU9QZkNzWTYvYmhEZEFqaFJEZmlhcERBVS9NWTBaeHN0?= =?utf-8?B?N3ZhQUpXZGg2NE10dTFId1lCVUs3cWFVRm40amR2N3B2eFdVbkFvM3lKV1Fl?= =?utf-8?B?RXozTk8yeUhiN2pLR0hPT2ZERUd3NExUYUg3MHVqcnNBOFJkckhlZTRsTFJz?= =?utf-8?B?eHhkTjVCbVJsU0FkMlBXZFN5MStPaUFqcFJ5NzEvcFgyM2hPdVIySC9MRFVj?= =?utf-8?B?VHZmbE9nTzY0aTFNdXVwU1JTL0Fna3I4NVNUUjk1QUFSRW9raUZ1bU5rcnVE?= =?utf-8?B?dyt4aDN2Rjc0Sy9mb3BaUVI1NzdJb2hTS3loUCtuT1pPM2ZKUjEzTm8ydzhM?= =?utf-8?B?ckxiWkRNd3NCV21wNGJyZ0hVeWxDNmEwYjN3NUFqMk9hUE4zNTZYNVQzTjJm?= =?utf-8?B?bjRhemRVU0pyNlg0VmsyWWlVdVUzS3kzdUtsSkJnMTVodFJ1cWlDYzhhUWpr?= =?utf-8?B?UHpvWW9SMGlmQU1rSDJEdXBXazBPZm5raGl4cW10Tm80QmR1QkpZYVVRTEM2?= =?utf-8?B?MGpQK2NvUFdlVWFPcVlEb21DMWpVald1eldHY2JBQTYxQVRzTzdZdjZISTlY?= =?utf-8?B?Y25qdFZVeXB5anlIUDVpSVF6dXhwTWRjSHdpYXJvcHJtOFJsVGREVFBGMFY1?= =?utf-8?B?WVpMVW1uQUdURUF3U2lDWnNRS0oxZmpMeXUrRyt5OGpoM1A2OW9wZmlmVWFE?= =?utf-8?B?dVl2T0JVY1JzR091dS9iM0doVGVXbGpLc2IyRHlMY0dSQUxTbHZKYU9pTEJk?= =?utf-8?B?UHBPUFcyOE92dTJLOFBFditNQWlXVUlmWm1kdTdjeU1XZTI2Rkd4T1Z5VzZ6?= =?utf-8?B?SXlZVjJpYU9naHVZS2VNUGd0YjFZanNyenArN2IzWnFyVFozeXFuSktzOW9j?= =?utf-8?B?U1BsbVNrdlNJQldIenh3d0hmSlRtbjJnaDhwWmp0NzU1S0hZWCthZUZ0d1pI?= =?utf-8?B?TFJNZVlhRy9DcFhXRUFFQ3lyaVlSZUJ4MjlhRUlNN3ljVFJMQVAwK0h6dHkv?= =?utf-8?B?NFdueFpDUkxVV1lsdzdCb014RkdOZWkyaklWM3BMTVJ0YmFxZVp0TW44NUtX?= =?utf-8?B?MUFFMmxzVnhWazROK0pYSWdLMVNQSGM5azljMGJJZkc4YWdKRzZQUnhRTTdE?= =?utf-8?B?b3JEcWIzRndDTHptaXF6OHJBc3RkaFozSlZnS2oyZVpjV2pVelF3QlNlUTFK?= =?utf-8?B?dHp1MTQ4SEdxemZrQ0lwckVYR3g1RDZ3eklDNEJZUXp1NWR6S1czQW5RaUND?= =?utf-8?B?a0x6ZWNmYzh6UG56cGN1bS9seDBGZ2RNcUJDUEROUVVPcmxrU3JZaUxvRGJX?= =?utf-8?Q?6P1FgDVjN6aTvnWdNTcZhk3Sz+tUqyrpq36aW1T0DufIS?= X-MS-Exchange-AntiSpam-MessageData-1: RpJLJ4otC8Rg7w== X-OriginatorOrg: ddn.com X-MS-Exchange-CrossTenant-Network-Message-Id: 2242c03d-a16a-4b11-8f54-08da2de543a2 X-MS-Exchange-CrossTenant-AuthSource: DM5PR1901MB2037.namprd19.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 May 2022 15:46:33.3396 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 753b6e26-6fd3-43e6-8248-3f1735d59bb4 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 0TDZ3vXmnon5q9H3WWBetTa/whHJK8W72Wivg/xbW+K1UXYOAYZJT+FFmrOmkS5RoPRLVhZ2UETReOQ2BmB1rg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR19MB0057 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/4/22 16:47, Vivek Goyal wrote: > Ok, naming is little confusing. I think we will have to put it in > commit message and where you define FUSE_ATOMIC_CREATE that what's > the difference between FUSE_CREATE and FUSE_ATOMIC_CREATE. This is > ATOMIC w.r.t what? > > May be atomic here means that "lookup + create + open" is a single operation. > But then even FUSE_CREATE is atomic because "creat + open" is a single > operation. > > In fact FUSE_CREATE does lookup anyway and returns all the information > in fuse_entry_out. > > IIUC, only difference between FUSE_CREATE and FUSE_ATOMIC_CREATE is that > later also carries information in reply whether file was actually created > or not (FOPEN_FILE_CREATED). This will be set if file did not exist > already and it was created indeed. Is that right? > > I see FOPEN_FILE_CREATED is being used to avoid calling > fuse_dir_changed(). That sounds like a separate optimization and probably > should be in a separate patch. > > IOW, I think this patch should be broken in to multiple pieces. First > piece seems to be avoiding lookup() and given the way it is implemented, > looks like we can avoid lookup() even by using existing FUSE_CREATE > command. We don't necessarily need FUSE_ATOMIC_CREATE. Is that right? The initial non-published patches had that, but I had actually asked not to go that route, because I'm scared that some user space file system implementations might get broken. Right now there is always a lookup before fuse_create_open() and when the resulting dentry is positive fuse_create_open/FUSE_CREATE is bypassed. I.e. user space implementations didn't need to handle existing files. Out of the sudden user space implementations might need to handle it and some of them might get broken with that kernel update. I guess even a single broken user space implementation would count as regression. So I had asked to change the patch to require a user space flag. -- Bernd