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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5749BC433E0 for ; Mon, 11 Jan 2021 11:57:22 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DFF58224BD for ; Mon, 11 Jan 2021 11:57:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DFF58224BD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=ACULAB.COM Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvdimm-bounces@lists.01.org Received: from ml01.vlan13.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 64693100EBBA0; Mon, 11 Jan 2021 03:57:21 -0800 (PST) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=185.58.86.151; helo=eu-smtp-delivery-151.mimecast.com; envelope-from=david.laight@aculab.com; receiver= Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.86.151]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 9C3F4100EC1E8 for ; Mon, 11 Jan 2021 03:57:16 -0800 (PST) Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-37-qTe83McBMiCWIf7m7BZI6A-1; Mon, 11 Jan 2021 11:57:11 +0000 X-MC-Unique: qTe83McBMiCWIf7m7BZI6A-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Mon, 11 Jan 2021 11:57:08 +0000 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Mon, 11 Jan 2021 11:57:08 +0000 From: David Laight To: 'Mikulas Patocka' Subject: RE: [RFC v2] nvfs: a filesystem for persistent memory Thread-Topic: [RFC v2] nvfs: a filesystem for persistent memory Thread-Index: AQHW52zcFLyucqAcQUmnqwhwPozPcaoiOfvQgAAVUICAAALF8A== Date: Mon, 11 Jan 2021 11:57:08 +0000 Message-ID: <57dad96341d34822a7943242c9bcad71@AcuMS.aculab.com> References: <20210110162008.GV3579531@ZenIV.linux.org.uk> 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 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Message-ID-Hash: Z3SRIJFTW4TWFUYHDMAQMWAZCE4JOQCE X-Message-ID-Hash: Z3SRIJFTW4TWFUYHDMAQMWAZCE4JOQCE X-MailFrom: david.laight@aculab.com X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation CC: 'Al Viro' , Andrew Morton , "Vishal Verma , Dave Jiang , Ira Weiny , Matthew Wilcox , Jan Kara" , Steven Whitehouse , Eric Sandeen , Dave Chinner , Theodore Ts'o , Wang Jianchao , "Tadakamadla,"@ml01.01.org, Rajesh@ml01.01.org, " , "@ml01.01.org, linux-kernel@vger.kernel.org, linux-kernel@vger.kernel.org, "linux-fsdevel@vger.kernel.org" , "linux-nvdimm@lists.01.org" X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit From: Mikulas Patocka > Sent: 11 January 2021 11:44 > On Mon, 11 Jan 2021, David Laight wrote: > > > From: Al Viro On Behalf Of Al Viro > > > Sent: 10 January 2021 16:20 ... ... > > > while (iov_iter_count(to)) { ... > > > size = copy_to_iter(to, ptr, size); > > > if (unlikely(!size)) { > > > r = -EFAULT; > > > goto ret_r; > > > } > > > > > > pos += size; > > > total += size; > > > } while (iov_iter_count(to)); > > > > That isn't the best formed loop! > > > > David > > I removed the second "while" statement and fixed the arguments to > copy_to_iter - other than that, Al's function works. The extra while is easy to write and can be difficult to spot. I've found them looking as the object code before now! Oh - the error return for copy_to_iter() is wrong. It should (probably) return 'total' if it is nonzero. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org