linux-kernel - Re: [REGRESSION] NFSv4: open(O

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Message-ID: <1333647115.4573.3.camel@lade.trondhjem.org>
Date:	Thu, 5 Apr 2012 17:31:58 +0000
From:	"Myklebust, Trond" <Trond.Myklebust@...app.com>
To:	Miklos Szeredi <miklos@...redi.hu>
CC:	"bfields@...ldses.org" <bfields@...ldses.org>,
	"linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [REGRESSION] NFSv4: open(O_TRUNC) hangs

On Tue, 2012-04-03 at 18:26 +0200, Miklos Szeredi wrote:
> Now this test program hangs on latest git.
> 
> Thanks,
> Miklos
> ---
> 
> #include <stdio.h>
> #include <unistd.h>
> #include <fcntl.h>
> 
> int main(int argc, char *argv[])
> {
> 	int res;
> 	char *name = argv[1];
> 	int fd;
> 
> 	unlink(name);
> 	fd = creat(name, 0644);
> 	write(fd, "123", 3);
> 	close(fd);
> 	close(open(name, O_RDONLY | O_TRUNC));
> 
> 	return 0;
> }

Hi Miklos,

The following client patch fixes the regression for me.

Cheers
  Trond
8<----------------------------------------------------
From 5ec0ed6cd88c65464092533787706d9ecfb85320 Mon Sep 17 00:00:00 2001
From: Trond Myklebust <Trond.Myklebust@...app.com>
Date: Wed, 4 Apr 2012 10:51:33 -0700
Subject: [PATCH 1/2] NFSv4: Don't use open stateids that have the wrong open
 mode

If the client is doing an operation that needs a particular open
mode, then nfs4_select_rw_stateid() should only copy the
open stateid if the latter has the correct open mode.

Otherwise we should just use the zero stateid.

Reported-by: Miklos Szeredi <miklos@...redi.hu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@...app.com>
---
 fs/nfs/nfs4state.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 0f43414..71dcfd4 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -932,6 +932,13 @@ void nfs4_select_rw_stateid(nfs4_stateid *dst, struct nfs4_state *state,
 {
 	if (nfs4_copy_delegation_stateid(dst, state->inode, fmode))
 		return;
+
+	fmode &= FMODE_READ|FMODE_WRITE;
+	if ((state->state & fmode) != fmode) {
+		nfs4_stateid_copy(dst, &zero_stateid);
+		return;
+	}
+
 	if (nfs4_copy_lock_stateid(dst, state, fl_owner, fl_pid))
 		return;
 	nfs4_copy_open_stateid(dst, state);
-- 
1.7.7.6


-- 
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust@...app.com
www.netapp.com