From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp2120.oracle.com ([141.146.126.78]:44712 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726608AbeLCQUq (ORCPT ); Mon, 3 Dec 2018 11:20:46 -0500 Date: Mon, 3 Dec 2018 08:20:30 -0800 From: "Darrick J. Wong" Subject: Re: [PATCH 1/2] io: open pipes in non-blocking mode Message-ID: <20181203162030.GT8125@magnolia> References: <20181202205343.7104-1-david@fromorbit.com> <20181202205343.7104-2-david@fromorbit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181202205343.7104-2-david@fromorbit.com> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Dave Chinner Cc: linux-xfs@vger.kernel.org On Mon, Dec 03, 2018 at 07:53:42AM +1100, Dave Chinner wrote: > From: Dave Chinner > > So that O_RDONLY open commands (such as from copy_range) do not > block forever waiting on a non-existent writer. > > Signed-off-by: Dave Chinner > --- > io/open.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/io/open.c b/io/open.c > index 6ea3e9a2019f..b1d9a0fa317c 100644 > --- a/io/open.c > +++ b/io/open.c > @@ -56,6 +56,7 @@ openfile( > struct fs_path *fs_path) > { > struct fs_path *fsp; > + struct stat st; > int fd; > int oflags; > > @@ -79,6 +80,18 @@ openfile( > if (flags & IO_NOFOLLOW) > oflags |= O_NOFOLLOW; > > + /* > + * if we've been passed a pipe to open, don't block waiting for a > + * reader or writer to appear. We want to either succeed or error out > + * immediately. > + */ > + if (stat(path, &st) < 0 && errno != ENOENT) { > + perror("stat"); > + return -1; > + } > + if (S_ISFIFO(st.st_mode)) Hmm... does stat() set st.st_mode even if it returns ENOENT? Or are we possibly branching on an uninitialized st here? struct stat st = { 0 }; ? The rest seems fine to me. --D > + oflags |= O_NONBLOCK; > + > fd = open(path, oflags, mode); > if (fd < 0) { > if (errno == EISDIR && > -- > 2.19.1 >