Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752040AbdDLBPg (ORCPT ); Tue, 11 Apr 2017 21:15:36 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:40402 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751564AbdDLBPe (ORCPT ); Tue, 11 Apr 2017 21:15:34 -0400 Date: Wed, 12 Apr 2017 02:15:32 +0100 From: Al Viro To: Dave Jones , Linux Kernel Subject: Re: iov_iter_pipe warning. Message-ID: <20170412011532.GN29622@ZenIV.linux.org.uk> References: <20170411205336.uyz5vfw52twhh6ob@codemonkey.org.uk> <20170411211216.GH29622@ZenIV.linux.org.uk> <20170411222502.ldgahltwvrrxdbbw@codemonkey.org.uk> <20170411232842.GI29622@ZenIV.linux.org.uk> <20170411234558.zyzxznzaas3ge7qe@codemonkey.org.uk> <20170411235158.GK29622@ZenIV.linux.org.uk> <20170411235641.GL29622@ZenIV.linux.org.uk> <20170412000607.ob4cjv7vof3f64uu@codemonkey.org.uk> <20170412001746.GM29622@ZenIV.linux.org.uk> <20170412005853.vqyuo6722tmthn5u@codemonkey.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170412005853.vqyuo6722tmthn5u@codemonkey.org.uk> User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1194 Lines: 40 On Tue, Apr 11, 2017 at 08:58:53PM -0400, Dave Jones wrote: > [ 462.696557] in->f_op = ffffffffa02df980, ->splice_write = ffffffff812b2b20 > $ grep ffffffffa02df980 /proc/kallsyms > ffffffffa02df980 r nfs4_file_operations [nfsv4] > $ grep ffffffff812b2b20 /proc/kallsyms > ffffffff812b2b20 T iter_file_splice_write Let's try to figure out whether it's read or write side going wrong. diff --git a/fs/splice.c b/fs/splice.c index 006ba50f4ece..0a7c0bd3e164 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -970,10 +970,26 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, while (len) { size_t read_len; loff_t pos = sd->pos, prev_pos = pos; + if (WARN_ON(pipe->nrbufs)) { + printk(KERN_ERR "in->f_op = %p, ->splice_write = %p\n", + in->f_op, + sd->u.file->f_op->splice_write); + } ret = do_splice_to(in, &pos, pipe, len, flags); if (unlikely(ret <= 0)) goto out_release; + { + int idx = pipe->curbuf; + int n = pipe->nrbufs; + size_t size = 0; + while (n--) { + size += pipe->bufs[idx++].len; + if (idx == pipe->buffers) + idx = 0; + } + WARN_ON(size != ret); + } read_len = ret; sd->total_len = read_len;