From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?Q?P=c3=a1draig_Brady?= Subject: Re: [PATCH v3 8/9] vfs: copy_file_range() can do a pagecache copy with splice Date: Fri, 25 Sep 2015 22:58:42 +0100 Message-ID: <5605C392.80008@draigBrady.com> References: <1443214096-12769-1-git-send-email-Anna.Schumaker@Netapp.com> <1443214096-12769-9-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: <1443214096-12769-9-git-send-email-Anna.Schumaker-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Anna Schumaker , linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-btrfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, zab-ugsP4Wv/S6ZeoWH0uzbU5w@public.gmane.org, viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org, clm-b10kYP2dOMg@public.gmane.org, darrick.wong-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, andros-HgOvQuBEEgTQT0dZR+AlfA@public.gmane.org, hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org List-Id: linux-api@vger.kernel.org On 25/09/15 21:48, Anna Schumaker wrote: > The NFS server will need some kind offallback for filesystems that do= n't > have any kind of copy acceleration, and it should be generally useful= to > have an in-kernel copy to avoid lots of switches between kernel and u= ser > space. >=20 > I make this configurable by adding two new flags. Users who only wan= t a > reflink can pass COPY_FR_REFLINK, and users who want a full data copy= can > pass COPY_FR_COPY. The default (flags=3D0) means to first attempt a > reflink, but use the pagecache if that fails. >=20 > I moved the rw_verify_area() calls into the fallback code since some > filesystems can handle reflinking a large range. >=20 > Signed-off-by: Anna Schumaker Reviewed-by: P=E1draig Brady LGTM. For my reference, for cp(1), mv(1), install(1), this will avoid user space copies in the normal case, client side copies in the network file system case, and provide a more generalized interface to reflink()= =2E coreutils pseudo code is: unsigned int cfr_flags =3D COPY_FR_COPY; if (mode =3D=3D mv) cfr_flags =3D 0; /* reflink falling back to normal */ else if (mode =3D=3D cp) { if --reflink || --reflink=3D=3Dalways cfr_flags =3D COPY_FR_REFLINK; else if --reflink=3D=3Dauto cfr_flags =3D 0; /* reflink falling back to normal */ } if vfs_copy_file_range(..., cfr_flags) =3D=3D ENOTSUP normal_user_space_copy(); thanks, P=E1draig. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail2.vodafone.ie ([213.233.128.44]:52357 "EHLO mail2.vodafone.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750906AbbIYV6r (ORCPT ); Fri, 25 Sep 2015 17:58:47 -0400 Subject: Re: [PATCH v3 8/9] vfs: copy_file_range() can do a pagecache copy with splice 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: <1443214096-12769-1-git-send-email-Anna.Schumaker@Netapp.com> <1443214096-12769-9-git-send-email-Anna.Schumaker@Netapp.com> From: =?UTF-8?Q?P=c3=a1draig_Brady?= Message-ID: <5605C392.80008@draigBrady.com> Date: Fri, 25 Sep 2015 22:58:42 +0100 MIME-Version: 1.0 In-Reply-To: <1443214096-12769-9-git-send-email-Anna.Schumaker@Netapp.com> Content-Type: text/plain; charset=windows-1252 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 25/09/15 21:48, Anna Schumaker wrote: > The NFS server will need some kind offallback for filesystems that don't > have any kind of copy acceleration, and it should be generally useful to > have an in-kernel copy to avoid lots of switches between kernel and user > space. > > I make this configurable by adding two new flags. Users who only want a > reflink can pass COPY_FR_REFLINK, and users who want a full data copy can > pass COPY_FR_COPY. The default (flags=0) means to first attempt a > reflink, but use the pagecache if that fails. > > I moved the rw_verify_area() calls into the fallback code since some > filesystems can handle reflinking a large range. > > Signed-off-by: Anna Schumaker Reviewed-by: Pádraig Brady LGTM. For my reference, for cp(1), mv(1), install(1), this will avoid user space copies in the normal case, client side copies in the network file system case, and provide a more generalized interface to reflink(). coreutils pseudo code is: unsigned int cfr_flags = COPY_FR_COPY; if (mode == mv) cfr_flags = 0; /* reflink falling back to normal */ else if (mode == cp) { if --reflink || --reflink==always cfr_flags = COPY_FR_REFLINK; else if --reflink==auto cfr_flags = 0; /* reflink falling back to normal */ } if vfs_copy_file_range(..., cfr_flags) == ENOTSUP normal_user_space_copy(); thanks, Pádraig.