From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?Q?P=c3=a1draig_Brady?= Subject: Re: [PATCH v7 5/4] copy_file_range.2: New page documenting copy_file_range() Date: Sat, 24 Oct 2015 13:02:21 +0100 Message-ID: <562B734D.50800@draigBrady.com> References: <1445628736-13058-1-git-send-email-Anna.Schumaker@Netapp.com> <1445628736-13058-6-git-send-email-Anna.Schumaker@Netapp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1445628736-13058-6-git-send-email-Anna.Schumaker@Netapp.com> Sender: linux-fsdevel-owner@vger.kernel.org To: Anna Schumaker , linux-nfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, zab@zabbo.net, viro@zeniv.linux.org.uk, clm@fb.com, darrick.wong@oracle.com, mtk.manpages@gmail.com, andros@netapp.com, hch@infradead.org List-Id: linux-api@vger.kernel.org On 23/10/15 20:32, Anna Schumaker wrote: > + len =3D stat.st_size; > + > + fd_out =3D open(argv[2], O_CREAT|O_WRONLY|O_TRUNC, 0644); > + if (fd_out =3D=3D \-1) { > + perror("open (argv[2])"); > + exit(EXIT_FAILURE); > + } > + > + do { > + ret =3D copy_file_range(fd_in, NULL, fd_out, NULL, len, 0); > + if (ret =3D=3D \-1) { > + perror("copy_file_range"); > + exit(EXIT_FAILURE); > + } > + > + len \-=3D ret; > + } while (len > 0); Is this an infinite loop if len decreases before the copy completes? Perhaps this should be: while (len && ret); Otherwise this set looks good. I'm a bit worried about the sparse expansion and default reflinking which might preclude cp(1) from using this call in most cases, but I wi= ll test and try to use it. coreutils has heuristics for determining if fil= es are remote, which we might use to restrict to that use case. thanks, P=E1draig. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel= " in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail1.vodafone.ie ([213.233.128.43]:58563 "EHLO mail1.vodafone.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751844AbbJXMCZ (ORCPT ); Sat, 24 Oct 2015 08:02:25 -0400 Subject: Re: [PATCH v7 5/4] copy_file_range.2: New page documenting copy_file_range() To: Anna Schumaker , linux-nfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, zab@zabbo.net, viro@zeniv.linux.org.uk, clm@fb.com, darrick.wong@oracle.com, mtk.manpages@gmail.com, andros@netapp.com, hch@infradead.org References: <1445628736-13058-1-git-send-email-Anna.Schumaker@Netapp.com> <1445628736-13058-6-git-send-email-Anna.Schumaker@Netapp.com> From: =?UTF-8?Q?P=c3=a1draig_Brady?= Message-ID: <562B734D.50800@draigBrady.com> Date: Sat, 24 Oct 2015 13:02:21 +0100 MIME-Version: 1.0 In-Reply-To: <1445628736-13058-6-git-send-email-Anna.Schumaker@Netapp.com> Content-Type: text/plain; charset=windows-1252 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 23/10/15 20:32, Anna Schumaker wrote: > + len = stat.st_size; > + > + fd_out = open(argv[2], O_CREAT|O_WRONLY|O_TRUNC, 0644); > + if (fd_out == \-1) { > + perror("open (argv[2])"); > + exit(EXIT_FAILURE); > + } > + > + do { > + ret = copy_file_range(fd_in, NULL, fd_out, NULL, len, 0); > + if (ret == \-1) { > + perror("copy_file_range"); > + exit(EXIT_FAILURE); > + } > + > + len \-= ret; > + } while (len > 0); Is this an infinite loop if len decreases before the copy completes? Perhaps this should be: while (len && ret); Otherwise this set looks good. I'm a bit worried about the sparse expansion and default reflinking which might preclude cp(1) from using this call in most cases, but I will test and try to use it. coreutils has heuristics for determining if files are remote, which we might use to restrict to that use case. thanks, Pádraig.