From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from fieldses.org ([173.255.197.46]:34577 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753202AbbDNSTM (ORCPT ); Tue, 14 Apr 2015 14:19:12 -0400 Date: Tue, 14 Apr 2015 14:19:11 -0400 To: Anna Schumaker Cc: Christoph Hellwig , Jeff Layton , Trond Myklebust , Zach Brown , Linux Kernel Mailing List , Linux FS-devel Mailing List , linux-btrfs@vger.kernel.org, Linux NFS Mailing List , linux-scsi@vger.kernel.org Subject: Re: [PATCH RFC 1/3] vfs: add copy_file_range syscall and vfs helper Message-ID: <20150414181911.GA2080@fieldses.org> References: <1428703236-24735-1-git-send-email-zab@redhat.com> <1428703236-24735-2-git-send-email-zab@redhat.com> <20150411000208.GA20949@lenny.home.zabbo.net> <20150411090402.67d22d02@tlielax.poochiereds.net> <20150414165344.GA21421@infradead.org> <552D4B5D.3090904@Netapp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <552D4B5D.3090904@Netapp.com> From: bfields@fieldses.org (J. Bruce Fields) Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Tue, Apr 14, 2015 at 01:16:13PM -0400, Anna Schumaker wrote: > On 04/14/2015 12:53 PM, Christoph Hellwig wrote: > > On Sat, Apr 11, 2015 at 09:04:02AM -0400, Jeff Layton wrote: > >> Yuck! How the heck do you clean up the mess if that happens? I > >> guess you're just stuck redoing the copy with normal READ/WRITE? > >> > >> Maybe we need to have the interface return a hard error in that > >> case and not try to give back any sort of offset? > > > > The NFSv4.2 COPY interface is a train wreck. At least for Linux I'd > > expect us to simply ignore it and only implement my new CLONE > > operation with sane semantics. That is unless someone can show some > > real life use case for the inter server copy, in which case we'll > > have to deal with that mess. But getting that one right at the VFS > > level will be a nightmare anyway. > > > > Make this a vote from me to not support partial copies and just > > return and error in that case. > > Agreed. Looking at the v4.2 spec, COPY does take ca_consecutive and a > ca_synchronous flags that let the client state if the copy should be > done consecutively or synchronously. I expected to always set > consecutive to "true" for the Linux client. That's supposed to mean results are well-defined in the partial-copy case, but I think Christoph's suggesting eliminating the partial-copy case entirely? Which would be fine with me. It might actually have been me advocating for partial copies. But that was only because a partial-copy-handling-loop seemed simpler to me than progress callbacks if we were going to support long-running copies. I'm happy enough not to have it at all. --b. From mboxrd@z Thu Jan 1 00:00:00 1970 From: bfields-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org (J. Bruce Fields) Subject: Re: [PATCH RFC 1/3] vfs: add copy_file_range syscall and vfs helper Date: Tue, 14 Apr 2015 14:19:11 -0400 Message-ID: <20150414181911.GA2080@fieldses.org> References: <1428703236-24735-1-git-send-email-zab@redhat.com> <1428703236-24735-2-git-send-email-zab@redhat.com> <20150411000208.GA20949@lenny.home.zabbo.net> <20150411090402.67d22d02@tlielax.poochiereds.net> <20150414165344.GA21421@infradead.org> <552D4B5D.3090904@Netapp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Christoph Hellwig , Jeff Layton , Trond Myklebust , Zach Brown , Linux Kernel Mailing List , Linux FS-devel Mailing List , linux-btrfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Linux NFS Mailing List , linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Anna Schumaker Return-path: Content-Disposition: inline In-Reply-To: <552D4B5D.3090904-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org> Sender: linux-nfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-fsdevel.vger.kernel.org On Tue, Apr 14, 2015 at 01:16:13PM -0400, Anna Schumaker wrote: > On 04/14/2015 12:53 PM, Christoph Hellwig wrote: > > On Sat, Apr 11, 2015 at 09:04:02AM -0400, Jeff Layton wrote: > >> Yuck! How the heck do you clean up the mess if that happens? I > >> guess you're just stuck redoing the copy with normal READ/WRITE? > >> > >> Maybe we need to have the interface return a hard error in that > >> case and not try to give back any sort of offset? > > > > The NFSv4.2 COPY interface is a train wreck. At least for Linux I'd > > expect us to simply ignore it and only implement my new CLONE > > operation with sane semantics. That is unless someone can show some > > real life use case for the inter server copy, in which case we'll > > have to deal with that mess. But getting that one right at the VFS > > level will be a nightmare anyway. > > > > Make this a vote from me to not support partial copies and just > > return and error in that case. > > Agreed. Looking at the v4.2 spec, COPY does take ca_consecutive and a > ca_synchronous flags that let the client state if the copy should be > done consecutively or synchronously. I expected to always set > consecutive to "true" for the Linux client. That's supposed to mean results are well-defined in the partial-copy case, but I think Christoph's suggesting eliminating the partial-copy case entirely? Which would be fine with me. It might actually have been me advocating for partial copies. But that was only because a partial-copy-handling-loop seemed simpler to me than progress callbacks if we were going to support long-running copies. I'm happy enough not to have it at all. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html