NFSv4: Fix a bug when the server returns NFS4ERR_RESOURCE

RFC 3530 states that when we recieve the error NFS4ERR_RESOURCE, we are not
supposed to bump the sequence number on OPEN, LOCK, LOCKU, CLOSE, etc
operations. The problem is that we map that error into EREMOTEIO in the XDR
layer, and so the NFSv4 middle-layer routines like seqid_mutating_err(),
and nfs_increment_seqid() don't recognise it.

The fix is to defer the mapping until after the middle layers have
processed the error.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4proc.c

@@ -72,12 +72,17 @@ static int _nfs4_proc_getattr(struct nfs_server *server, struct nfs_fh *fhandle,
 /* Prevent leaks of NFSv4 errors into userland */
 static int nfs4_map_errors(int err)
 {
-	if (err < -1000) {
+	if (err >= -1000)
+		return err;
+	switch (err) {
+	case -NFS4ERR_RESOURCE:
+		return -EREMOTEIO;
+	default:
 		dprintk("%s could not handle NFSv4 error %d\n",
 				__func__, -err);
-		return -EIO;
+		break;
 	}
-	return err;
+	return -EIO;
 }
 
 /*

fs/nfs/nfs4xdr.c

@@ -5681,7 +5681,6 @@ static struct {
 	{ NFS4ERR_SERVERFAULT,	-ESERVERFAULT	},
 	{ NFS4ERR_BADTYPE,	-EBADTYPE	},
 	{ NFS4ERR_LOCKED,	-EAGAIN		},
-	{ NFS4ERR_RESOURCE,	-EREMOTEIO	},
 	{ NFS4ERR_SYMLINK,	-ELOOP		},
 	{ NFS4ERR_OP_ILLEGAL,	-EOPNOTSUPP	},
 	{ NFS4ERR_DEADLOCK,	-EDEADLK	},