Re: problem with open(name, O_RDWR|O_CREAT|O_EXCL, 0666) on NetApp servers

[Matthieu Herrb <matthieu.herrb@laas.fr>]

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On Tue, Jan 24, 2017 at 11:48:33AM -0500, Benjamin Coddington wrote:
> Hi Matthieu, are you willing to test this one:
> 
> http://marc.info/?l=linux-nfs&m=148527567624411&w=2
> 

Hi,

sorry for the delay in answering. This patch does fix the problem for
my  configuration. 

Thanks.

> Ben
> 
> On 5 Jan 2017, at 9:24, Matthieu Herrb wrote:
> 
> >Hi,
> >
> >After upgrading my machine to Ubuntu 16.04, I noticed that 'git clone'
> >started creating files with wrong mode (0700 instead of 0644
> >typically) on NFSv4 partitions mounted from our NetApp servers.
> >
> >I've first tracked this down to the fact that git uses
> >
> > open(name, O_RDWR|O_CREAT|O_EXCL, 0666);
> >
> >to create files. If O_EXCL is not present, the files are created
> >normally.
> >
> >I've tried various kernels from Ubuntu and the problems appeared
> >between their 4.2.0-42-generic kernel-image (as found on willy) and
> >the 4.4.0 kernels found on xenial. I tried building 4.9 from
> >kernel.org and the problem is also there.
> >
> >I've then bisected the kernel to figure out that this is caused by the
> >following commit:
> >
> >https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=5334c5bdac926c5f8d89729beccb46fe88eda9e7
> >
> >ie NFS: Send attributes in OPEN request for NFS4_CREATE_EXCLUSIVE4_1
> >
> >Our NetApp filers are running:
> >
> >NetApp Release 8.2.3P3 7-Mode: Tue Apr 28 14:48:22 PDT 2015
> >
> >Any idea on how to fix the problem (either on the NetApp side, or on
> >Linux kernel side)?
> >
> >Appended is a small program to reproduce the issue:
> >
> >Thanks in advance,
> >
> >#include <sys/types.h>
> >#include <sys/stat.h>
> >#include <err.h>
> >#include <fcntl.h>
> >#include <stdio.h>
> >#include <stdlib.h>
> >#include <string.h>
> >#include <unistd.h>
> >
> >/*
> > * Demonstrate file creation bug on NFS v4 and linux kernel 4.4+
> > *
> > * mktemp() is used on purpose.
> > */
> >int
> >main(int argc, char *argv[])
> >{
> >	const char *name = argv[1];
> >	char tmp[] = "./tmpXXXXXXXXXX";
> >	struct stat buf;
> >	mode_t expected;
> >	int fd, i, n = 40;
> >
> >	umask(S_IWGRP | S_IWOTH);
> >	expected = 0666 & ~(S_IWGRP | S_IWOTH);
> >	if (argv[1] == NULL)
> >		name = mktemp(tmp);
> >	for (i = 0; i < n; i++) {
> >		fd = open(name, O_RDWR|O_CREAT|O_EXCL, 0666);
> >		if (fd < 0)
> >			err(1, "open %s", name);
> >		memset(&buf, 0, sizeof(buf));
> >		if (stat(name, &buf) < 0)
> >			err(1, "stat %s", name);
> >		if ((buf.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != expected)
> >			printf("%s: %o\n", name,
> >			    (int)buf.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO));
> >		else
> >			printf("%s: ok\n", name);
> >		unlink(name);
> >	}
> >	exit(0);
> >}
> >-- 
> >Matthieu Herrb
> 

-- 
Matthieu Herrb

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