From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761472AbYEIL1T (ORCPT ); Fri, 9 May 2008 07:27:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754017AbYEIL07 (ORCPT ); Fri, 9 May 2008 07:26:59 -0400 Received: from brick.kernel.dk ([87.55.233.238]:27094 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753651AbYEIL06 (ORCPT ); Fri, 9 May 2008 07:26:58 -0400 Date: Fri, 9 May 2008 13:26:53 +0200 From: Jens Axboe To: Tom Zanussi Cc: Dan Williams , linux-kernel Subject: Re: [regression?] distcc says: (dcc_pump_sendfile) ERROR: sendfile returned 0? can't cope (bisected) Message-ID: <20080509112651.GR16217@kernel.dk> References: <1210194811.16427.6.camel@dwillia2-linux.ch.intel.com> <20080507211641.GR16217@kernel.dk> <1210231275.7301.17.camel@charm-linux> <1210306939.7205.9.camel@charm-linux> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1210306939.7205.9.camel@charm-linux> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 08 2008, Tom Zanussi wrote: > > On Thu, 2008-05-08 at 02:21 -0500, Tom Zanussi wrote: > > On Wed, 2008-05-07 at 23:16 +0200, Jens Axboe wrote: > > > On Wed, May 07 2008, Dan Williams wrote: > > > > Hi Tom, Jens, > > > > > > > > My build system started reporting these error messages recently. > > > > Reverting commit c3270e577c18b3d0e984c3371493205a4807db9d on top of > > > > 2.6.26-rc1 gets things working for me again. > > > > > > Irk, that patch did scare me a bit (hence I asked Tom to double check as > > > wel :-). I'll take a look in the morning, all test boxes are off at this > > > point in time. > > > > > > > I did, and it still looks ok to me, but obviously it's not, so I'll have > > to do some more digging. > > > > The only thing I can think of right now that might be a possible cause > > would be in splice_direct_to_actor(), if we had an incomplete transfer, > > the sd->pos returned and assigned would have the value set by the failed > > actor(). Maybe something like the following would take care of that > > case, but I haven't had a chance to test it yet - will do that tomorrow > > night... > > > > Looks like I was on the right track - can you try this patch out > instead? It makes sure sd.pos is updated correctly if the transfer was > incomplete or failed. I ran some kernel compiles using distcc while > running blktrace in sendfile mode and didn't see any problems with > either. Dan, can I talk you into re-trying current git with this patch applied? It's basically the (now) reverted broken bits plus the fix from Tom from this email. diff --git a/fs/splice.c b/fs/splice.c index 7815003..a048ad2 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -983,7 +983,7 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, while (len) { size_t read_len; - loff_t pos = sd->pos; + loff_t pos = sd->pos, prev_pos = pos; ret = do_splice_to(in, &pos, pipe, len, flags); if (unlikely(ret <= 0)) @@ -998,15 +998,19 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, * could get stuck data in the internal pipe: */ ret = actor(pipe, sd); - if (unlikely(ret <= 0)) + if (unlikely(ret <= 0)) { + sd->pos = prev_pos; goto out_release; + } bytes += ret; len -= ret; sd->pos = pos; - if (ret < read_len) + if (ret < read_len) { + sd->pos = prev_pos + ret; goto out_release; + } } done: @@ -1072,7 +1076,7 @@ long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, ret = splice_direct_to_actor(in, &sd, direct_splice_actor); if (ret > 0) - *ppos += ret; + *ppos = sd.pos; return ret; } diff --git a/kernel/relay.c b/kernel/relay.c index bc24dcd..7de644c 100644 --- a/kernel/relay.c +++ b/kernel/relay.c @@ -1191,7 +1191,7 @@ static ssize_t relay_file_splice_read(struct file *in, ret = 0; spliced = 0; - while (len) { + while (len && !spliced) { ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret); if (ret < 0) break; -- Jens Axboe