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 16C09C64EC7 for ; Fri, 10 Feb 2023 22:41:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233852AbjBJWl4 (ORCPT ); Fri, 10 Feb 2023 17:41:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36078 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229620AbjBJWly (ORCPT ); Fri, 10 Feb 2023 17:41:54 -0500 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.85.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BE95117174 for ; Fri, 10 Feb 2023 14:41:51 -0800 (PST) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with both STARTTLS and AUTH (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-318-uEi7rd_bNiCq5v_5lLrP5A-1; Fri, 10 Feb 2023 22:41:48 +0000 X-MC-Unique: uEi7rd_bNiCq5v_5lLrP5A-1 Received: from AcuMS.Aculab.com (10.202.163.6) by AcuMS.aculab.com (10.202.163.6) with Microsoft SMTP Server (TLS) id 15.0.1497.45; Fri, 10 Feb 2023 22:41:46 +0000 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.045; Fri, 10 Feb 2023 22:41:46 +0000 From: David Laight To: 'Linus Torvalds' , Dave Chinner CC: Stefan Metzmacher , Jens Axboe , linux-fsdevel , Linux API Mailing List , io-uring , "linux-kernel@vger.kernel.org" , Al Viro , Samba Technical Subject: RE: copy on write for splice() from file to pipe? Thread-Topic: copy on write for splice() from file to pipe? Thread-Index: AQHZPXSEPyXic8n4vkmqtvVlaYw2Fq7Ivx9Q Date: Fri, 10 Feb 2023 22:41:46 +0000 Message-ID: <304d5286b6364da48a2bb1125155b7e5@AcuMS.aculab.com> References: <0cfd9f02-dea7-90e2-e932-c8129b6013c7@samba.org> <20230210021603.GA2825702@dread.disaster.area> <20230210040626.GB2825702@dread.disaster.area> <20230210061953.GC2825702@dread.disaster.area> In-Reply-To: Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: base64 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org RnJvbTogTGludXMgVG9ydmFsZHMNCj4gU2VudDogMTAgRmVicnVhcnkgMjAyMyAxNzoyNA0KLi4u DQo+IEFuZCB3aGVuIGl0IGNvbWVzIHRvIG5ldHdvcmtpbmcsIGluIGdlbmVyYWwgdGhpbmdzIGxp a2UgVENQIGNoZWNrc3Vtcw0KPiBldGMgc2hvdWxkIGJlIG9rIGV2ZW4gd2l0aCBkYXRhIHRoYXQg aXNuJ3Qgc3RhYmxlLiAgV2hlbiBkb2luZyB0aGluZ3MNCj4gYnkgaGFuZCwgbmV0d29ya2luZyBz aG91bGQgYWx3YXlzIHVzZSB0aGUgImNvcHktYW5kLWNoZWNrc3VtIg0KPiBmdW5jdGlvbnMgdGhh dCBkbyB0aGUgY2hlY2tzdW0gd2hpbGUgY29weWluZyAoc28gZXZlbiBpZiB0aGUgc291cmNlDQo+ IGRhdGEgY2hhbmdlcywgdGhlIGNoZWNrc3VtIGlzIGdvaW5nIHRvIGJlIHRoZSBjaGVja3N1bSBm b3IgdGhlIGRhdGENCj4gdGhhdCB3YXMgY29waWVkKS4NCj4gDQo+IEFuZCBpbiBtYW55IChtb3N0 Pykgc21hcnRlciBuZXR3b3JrIGNhcmRzLCB0aGUgY2FyZCBpdHNlbGYgZG9lcyB0aGUNCj4gY2hl Y2tzdW0sIGFnYWluIG9uIHRoZSBkYXRhIGFzIGl0IGlzIHRyYW5zZmVycmVkIGZyb20gbWVtb3J5 Lg0KPiANCj4gU28gaXQncyBub3QgbGlrZSAibmV0d29ya2luZyBuZWVkcyBhIHN0YWJsZSBzb3Vy Y2UiIGlzIHNvbWUgcmVhbGx5DQo+IF9mdW5kYW1lbnRhbF8gcmVxdWlyZW1lbnQgZm9yIHRoaW5n cyBsaWtlIHRoYXQgdG8gd29yay4NCg0KSXQgaXMgYWxzbyB3b3J0aCByZW1lbWJlcmluZyB0aGF0 IFRDUCBuZWVkcyB0byBiZSBhYmxlDQp0byByZXRyYW5zbWl0IHRoZSBkYXRhIGFuZCBhIG11Y2gg bGF0ZXIgdGltZS4NClNvIHRoZSBhcHBsaWNhdGlvbiBtdXN0IG5vdCBjaGFuZ2UgdGhlIGRhdGEg dW50aWwgaXQgaGFzDQpiZWVuIGFja2VkIGJ5IHRoZSByZW1vdGUgc3lzdGVtLg0KDQpPcGVyYXRp bmcgc3lzdGVtcyB0aGF0IGRvIGFzeW5jaHJvbm91cyBJTyBkaXJlY3RseSBmcm9tDQphcHBsaWNh dGlvbiBidWZmZXJzIGhhdmUgY2FsbGJhY2tzL2V2ZW50cyB0byB0ZWxsIHRoZQ0KYXBwbGljYXRp b24gd2hlbiBpdCBpcyBhbGxvd2VkIHRvIG1vZGlmeSB0aGUgYnVmZmVycy4NCkZvciBUQ1AgdGhp cyB3b24ndCBiZSBpbmRpY2F0ZWQgdW50aWwgYWZ0ZXIgdGhlIEFDSw0KaXMgcmVjZWl2ZWQuDQpJ IGRvbid0IHRoaW5rIGlvX3VyaW5nIGhhcyBhbnkgd2F5IHRvIGluZGljYXRlIGFueXRoaW5nDQpv dGhlciB0aGFuICd0aGUgZGF0YSBoYXMgYmVlbiBhY2NlcHRlZCBieSB0aGUgc29ja2V0Jy4NCg0K SWYgeW91IGhhdmUgJ2tlcm5lbCBwYWdlcyBjb250YWluaW5nIGRhdGEnIChlZyBmcm9tIHdyaXRl cw0KaW50byBhIHBpcGUsIG9yIGRhdGEgcmVjZWl2ZWQgZnJvbSBhIG5ldHdvcmspIHRoZW4gdGhl eSBoYXZlDQphIHNpbmdsZSAnb3duZXInIGFuZCBjYW4gYmUgcGFzc2VkIGFib3V0Lg0KQnV0IHVz ZXItcGFnZXMgKGluY2x1ZGluZyBtbWFwcGVkIGZpbGVzKSBoYXZlIG11bHRpcGxlIG93bmVycw0K c28geW91IGFyZSBuZXZlciBnb2luZyB0byBiZSBhYmxlIHRvIHBhc3MgdGhlbSBhcyAnaW1tdXRh YmxlDQpkYXRhJy4NCklmIHlvdSBtbWFwIGEgdmVyeSBsYXJnZSAoYW5kIG1heWJlIHNwYXJzZSkg ZmlsZSBhbmQgdGhlbg0KdHJ5IHRvIGRvIGEgdmVyeSBsYXJnZSAobXVsdGktR0IpIHNlbmQoKSAo d2l0aCBvciB3aXRob3V0DQphbnkga2luZCBvZiBwYWdlIGxvYW5pbmcpIHRoZXJlIGlzIGFsd2F5 cyB0aGUgcG9zc2liaWxpdHkNCnRoYXQgdGhlIGRhdGEgdGhhdCBpcyBhY3R1YWxseSBzZW50IHdh cyB3cml0dGVuIHdoaWxlIHRoZQ0Kc2VuZCgpIGNhbGwgd2FzIGluIHByb2dyZXNzLg0KQW55IGtp bmQgb2YgYXN5bmNocm9ub3VzIHNlbmQoKSBqdXN0IG1ha2VzIGl0IG1vcmUgb2J2aW91cy4NCg0K CURhdmlkDQoNCi0NClJlZ2lzdGVyZWQgQWRkcmVzcyBMYWtlc2lkZSwgQnJhbWxleSBSb2FkLCBN b3VudCBGYXJtLCBNaWx0b24gS2V5bmVzLCBNSzEgMVBULCBVSw0KUmVnaXN0cmF0aW9uIE5vOiAx Mzk3Mzg2IChXYWxlcykNCg==