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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
CC:     Trond Myklebust <trond.myklebust@primarydata.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.4 019/167] NFSv4.1: Work around a Linux server
 bug...
Thread-Topic: [PATCH AUTOSEL for 4.4 019/167] NFSv4.1: Work around a Linux
 server bug...
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Date:   Mon, 19 Mar 2018 16:05:45 +0000
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From: Trond Myklebust <trond.myklebust@primarydata.com>

[ Upstream commit f4b23de3dda1536590787c9e5c3d16b8738ab108 ]

It turns out the Linux server has a bug in its implementation of
supattr_exclcreat; it returns the set of all attributes, whether
or not they are supported by minor version 1.
In order to avoid a regression, we therefore apply the supported_attrs
as a mask on top of whatever the server sent us.

Reported-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 fs/nfs/nfs4proc.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index bcfddfc7a1f4..0f397e62de5a 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3025,6 +3025,7 @@ static int _nfs4_server_capabilities(struct nfs_serve=
r *server, struct nfs_fh *f
 		.rpc_resp =3D &res,
 	};
 	int status;
+	int i;
=20
 	bitmask[0] =3D FATTR4_WORD0_SUPPORTED_ATTRS |
 		     FATTR4_WORD0_FH_EXPIRE_TYPE |
@@ -3090,8 +3091,13 @@ static int _nfs4_server_capabilities(struct nfs_serv=
er *server, struct nfs_fh *f
 		server->cache_consistency_bitmask[0] &=3D FATTR4_WORD0_CHANGE|FATTR4_WOR=
D0_SIZE;
 		server->cache_consistency_bitmask[1] &=3D FATTR4_WORD1_TIME_METADATA|FAT=
TR4_WORD1_TIME_MODIFY;
 		server->cache_consistency_bitmask[2] =3D 0;
+
+		/* Avoid a regression due to buggy server */
+		for (i =3D 0; i < ARRAY_SIZE(res.exclcreat_bitmask); i++)
+			res.exclcreat_bitmask[i] &=3D res.attr_bitmask[i];
 		memcpy(server->exclcreat_bitmask, res.exclcreat_bitmask,
 			sizeof(server->exclcreat_bitmask));
+
 		server->acl_bitmask =3D res.acl_bitmask;
 		server->fh_expire_type =3D res.fh_expire_type;
 	}
--=20
2.14.1