Return-Path: linux-nfs-owner@vger.kernel.org Received: from fieldses.org ([174.143.236.118]:52774 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754587Ab3FKTvl (ORCPT ); Tue, 11 Jun 2013 15:51:41 -0400 Date: Tue, 11 Jun 2013 15:51:41 -0400 To: Sandeep Joshi Cc: linux-nfs@vger.kernel.org Subject: Re: why does nfsd write not use splice Message-ID: <20130611195140.GA29634@fieldses.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: From: "J. Bruce Fields" Sender: linux-nfs-owner@vger.kernel.org List-ID: On Sun, Jun 09, 2013 at 01:05:16PM +0530, Sandeep Joshi wrote: > Is there a reason as to why the nfsd server does not use splice in the > write calls - nfsd_vfs_write() ? Is there some structural limitation > or is it just something nobody got around to implementing ? > > I have looked at the source back to the 2.6.x kernels and it seems > only nfsd_vfs_read() has ever used splice/sendfile. > http://lxr.linux.no/linux+v3.9.5/fs/nfsd/vfs.c I don't actually know how splice_write works.... I assume to avoid a copy we'd have to place the incoming write data into pages already correctly aligned. That would be an interesting trick. --b.