Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754493AbcDYLEA (ORCPT ); Mon, 25 Apr 2016 07:04:00 -0400 Received: from mail-oi0-f50.google.com ([209.85.218.50]:35146 "EHLO mail-oi0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752322AbcDYLD6 (ORCPT ); Mon, 25 Apr 2016 07:03:58 -0400 MIME-Version: 1.0 X-Originating-IP: [217.173.44.24] In-Reply-To: <20160420154323.GA13463@ubuntu-hedt> References: <1461105785-83223-1-git-send-email-seth.forshee@canonical.com> <5716B7F0.8000304@oracle.com> <20160420154323.GA13463@ubuntu-hedt> Date: Mon, 25 Apr 2016 13:03:57 +0200 Message-ID: Subject: Re: [fuse-devel] [PATCH] fuse: Fix fuse_get_user_pages() return value From: Miklos Szeredi To: Seth Forshee Cc: Ashish Samant , fuse-devel , Kernel Mailing List Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1785 Lines: 47 On Wed, Apr 20, 2016 at 5:43 PM, Seth Forshee wrote: > On Tue, Apr 19, 2016 at 03:57:52PM -0700, Ashish Samant wrote: >> Hi Seth, >> On 04/19/2016 03:43 PM, Seth Forshee wrote: >> >fuse_direct_io() expects this to return either 0 or a negative >> >error code, but on success it may return a positive value. >> >fuse_direct_io() may return this same value when the subsequent >> >I/O operation doesn't transfer any data, which means that it will >> >return a positive value when no bytes were transferred. This is >> >obviously problematic. >> > >> >Fix fuse_get_user_pages() to return 0 on success. This will in >> >turn make it so that fuse_direct_io() returns 0 if no bytes are >> >transferred. >> > >> >Fixes: 742f992708df ("fuse: return patrial success from fuse_direct_io()") >> >Signed-off-by: Seth Forshee >> >--- >> > fs/fuse/file.c | 2 +- >> > 1 file changed, 1 insertion(+), 1 deletion(-) >> > >> >diff --git a/fs/fuse/file.c b/fs/fuse/file.c >> >index b5c616c5ec98..78af5c0996b8 100644 >> >--- a/fs/fuse/file.c >> >+++ b/fs/fuse/file.c >> >@@ -1295,7 +1295,7 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii, >> > *nbytesp = nbytes; >> >- return ret; >> >+ return ret < 0 ? ret : 0; >> > } >> > static inline int fuse_iter_npages(const struct iov_iter *ii_p) >> >> >> I have already sent a patch to the list that does exactly the same thing :) >> >> https://sourceforge.net/p/fuse/mailman/message/34966327/ > > Oops, should have checked the list first I guess :-) > > But that's from several weeks ago, and it's still not applied? This is > causing big problems for lxcfs on 4.6-rc kernels, so it's definitely a > regression and needs to get fixed. Applied, thanks. Miklos