NFS: Fix the mapping of the NFSERR_SERVERFAULT error

It was recently pointed out that the NFSERR_SERVERFAULT error, which is
designed to inform the user of a serious internal error on the server, was
being mapped to an error value that is internal to the kernel.

This patch maps it to the error EREMOTEIO, which is exported to userland
through errno.h.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@kernel.org

fs/nfs/mount_clnt.c

@@ -120,7 +120,7 @@ static struct {
 	{ .status = MNT3ERR_INVAL,		.errno = -EINVAL,	},
 	{ .status = MNT3ERR_NAMETOOLONG,	.errno = -ENAMETOOLONG,	},
 	{ .status = MNT3ERR_NOTSUPP,		.errno = -ENOTSUPP,	},
-	{ .status = MNT3ERR_SERVERFAULT,	.errno = -ESERVERFAULT,	},
+	{ .status = MNT3ERR_SERVERFAULT,	.errno = -EREMOTEIO,	},
 };
 
 struct mountres {

fs/nfs/nfs2xdr.c

@@ -699,7 +699,7 @@ static struct {
 	{ NFSERR_BAD_COOKIE,	-EBADCOOKIE	},
 	{ NFSERR_NOTSUPP,	-ENOTSUPP	},
 	{ NFSERR_TOOSMALL,	-ETOOSMALL	},
-	{ NFSERR_SERVERFAULT,	-ESERVERFAULT	},
+	{ NFSERR_SERVERFAULT,	-EREMOTEIO	},
 	{ NFSERR_BADTYPE,	-EBADTYPE	},
 	{ NFSERR_JUKEBOX,	-EJUKEBOX	},
 	{ -1,			-EIO		}

fs/nfs/nfs4xdr.c

@@ -4631,7 +4631,7 @@ static int decode_sequence(struct xdr_stream *xdr,
 	 * If the server returns different values for sessionID, slotID or
 	 * sequence number, the server is looney tunes.
 	 */
-	status = -ESERVERFAULT;
+	status = -EREMOTEIO;
 
 	if (memcmp(id.data, res->sr_session->sess_id.data,
 		   NFS4_MAX_SESSIONID_LEN)) {
@@ -5774,7 +5774,7 @@ static struct {
 	{ NFS4ERR_BAD_COOKIE,	-EBADCOOKIE	},
 	{ NFS4ERR_NOTSUPP,	-ENOTSUPP	},
 	{ NFS4ERR_TOOSMALL,	-ETOOSMALL	},
-	{ NFS4ERR_SERVERFAULT,	-ESERVERFAULT	},
+	{ NFS4ERR_SERVERFAULT,	-EREMOTEIO	},
 	{ NFS4ERR_BADTYPE,	-EBADTYPE	},
 	{ NFS4ERR_LOCKED,	-EAGAIN		},
 	{ NFS4ERR_SYMLINK,	-ELOOP		},
@@ -5801,7 +5801,7 @@ nfs4_stat_to_errno(int stat)
 	}
 	if (stat <= 10000 || stat > 10100) {
 		/* The server is looney tunes. */
-		return -ESERVERFAULT;
+		return -EREMOTEIO;
 	}
 	/* If we cannot translate the error, the recovery routines should
 	 * handle it.