From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?Q?P=c3=a1draig_Brady?= Subject: Re: [PATCH v5 8/9] vfs: Add vfs_copy_file_range() support for pagecache copies Date: Fri, 16 Oct 2015 13:02:23 +0100 Message-ID: <5620E74F.50006@draigBrady.com> References: <1443634014-3026-1-git-send-email-Anna.Schumaker@Netapp.com> <1443634014-3026-9-git-send-email-Anna.Schumaker@Netapp.com> <20151011142203.GA31867@infradead.org> <20151012231749.GC11398@birch.djwong.org> <561E980C.9010509@Netapp.com> <20151014182701.GC31225@infradead.org> <561EA83E.8080000@gmail.com> <20151015063621.GA3025@infradead.org> <561F9B13.7020804@gmail.com> <20151016053808.GA29510@infradead.org> <5620E3A1.90408@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <5620E3A1.90408@gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org To: Austin S Hemmelgarn , Christoph Hellwig Cc: Andy Lutomirski , Anna Schumaker , "Darrick J. Wong" , linux-nfs@vger.kernel.org, Linux btrfs Developers List , Linux FS Devel , Linux API , Zach Brown , Al Viro , Chris Mason , Michael Kerrisk-manpages , andros@netapp.com List-Id: linux-api@vger.kernel.org On 16/10/15 12:46, Austin S Hemmelgarn wrote: > On 2015-10-16 01:38, Christoph Hellwig wrote: >> On Thu, Oct 15, 2015 at 08:24:51AM -0400, Austin S Hemmelgarn wrote: >>> My only point with saying we shouldn't reflink by default is that t= here are >>> many (unintelligent) people who will assume that since the syscall = has copy >>> in it's name, that's what it will do; and, while I don't think we s= hould >>> cater to such individuals, it does make sense to have a syscall tha= t says in >>> it's name that it copies data actually do so by default. >> >> As far as the user is concerned a reflink is a copy. A very efficie= nt >> copy. > I should have been specific, what I meant was that some people will=20 > assume that it actually creates a physical, on-disk byte-for-byte cop= y=20 > of the data. There are many people out there (and sadly I have to de= al=20 > with some at work) who are absolutely terrified of the concept of dat= a=20 > deduplication, and will likely refuse to use this syscall for _anythi= ng_=20 > if it reflinks by default on filesystems that support it. Right. reflinking is transparent to the user, though its consequences a= re not. Consequences being the possible extra latency or ENOSPC on CoW. Therefore reflinking should be an explicit action/flag IMHO. cheers, P=C3=A1draig. -- 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