NFS client broken in Linus' tip

On Thu, 2014-01-30 at 15:38 +0000, Russell King - ARM Linux wrote:

On Thu, Jan 30, 2014 at 06:32:08AM -0800, Christoph Hellwig wrote:

quoted

On Thu, Jan 30, 2014 at 02:27:52PM +0000, Russell King - ARM Linux wrote:

quoted

Yes and no.  I still end up with an empty /etc/mtab, but the file now
exists.  However, I can create and echo data into /etc/mtab, but it seems
that can't happen at boot time.

Odd.  Can you disable CONFIG_NFSD_V3_ACL for now to isolate the issue?

Unfortunately, that results in some problem at boot time, which
ultimately ends up with the other three CPUs being stopped, and
hence the original reason scrolls off the screen before it can be
read... even at 1920p.

Hi Russell,

The following patch fixes the issue for me.

Cheers
  Trond

8<-------------------------------------------------------------

From 59bc20fe862bd85fcad61427e8669603e789d163 Mon Sep 17 00:00:00 2001

From: Trond Myklebust <redacted>
Date: Fri, 31 Jan 2014 14:25:19 -0500
Subject: [PATCH] fs: get_acl() must be allowed to return EOPNOTSUPP

posix_acl_xattr_get requires get_acl() to return EOPNOTSUPP if the
filesystem cannot support acls. This is needed for NFS, which can't
know whether or not the server supports acls until it tries to get/set
one.
This patch converts posix_acl_chmod and posix_acl_create to deal with
EOPNOTSUPP return values from get_acl().

Reported-by: Russell King <redacted>
Link: http://lkml.kernel.org/r/20140130140834.GW15937 at n2100.arm.linux.org.uk
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro viro at zeniv.linux.org.uk>
Signed-off-by: Trond Myklebust <redacted>
---
 fs/posix_acl.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 38bae5a0ea25..11c54fd51e16 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c

@@ -521,8 +521,11 @@ posix_acl_chmod(struct inode *inode, umode_t mode)
 		return -EOPNOTSUPP;
 
 	acl = get_acl(inode, ACL_TYPE_ACCESS);
-	if (IS_ERR_OR_NULL(acl))
+	if (IS_ERR_OR_NULL(acl)) {
+		if (acl == ERR_PTR(-EOPNOTSUPP))
+			return 0;
 		return PTR_ERR(acl);
+	}
 
 	ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
 	if (ret)

@@ -544,14 +547,15 @@ posix_acl_create(struct inode *dir, umode_t *mode,
 		goto no_acl;
 
 	p = get_acl(dir, ACL_TYPE_DEFAULT);
-	if (IS_ERR(p))
+	if (IS_ERR(p)) {
+		if (p == ERR_PTR(-EOPNOTSUPP))
+			goto apply_umask;
 		return PTR_ERR(p);
-
-	if (!p) {
-		*mode &= ~current_umask();
-		goto no_acl;
 	}
 
+	if (!p)
+		goto apply_umask;
+
 	*acl = posix_acl_clone(p, GFP_NOFS);
 	if (!*acl)
 		return -ENOMEM;

@@ -575,6 +579,8 @@ posix_acl_create(struct inode *dir, umode_t *mode,
 	}
 	return 0;
 
+apply_umask:
+	*mode &= ~current_umask();
 no_acl:
 	*default_acl = NULL;
 	*acl = NULL;

-- 
1.8.5.3



-- 
Trond Myklebust
Linux NFS client maintainer