nfsd: eliminate "to_delegation" define

We now have cb_to_delegation and to_delegation, which do the same thing
and are defined separately in different .c files. Move the
cb_to_delegation definition into a header file and eliminate the
redundant to_delegation definition.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>

fs/nfsd/nfs4callback.c

@@ -49,9 +49,6 @@ static void nfsd4_mark_cb_fault(struct nfs4_client *, int reason);
 
 /* Index of predefined Linux callback client operations */
 
-#define to_delegation(cb) \
-	container_of(cb, struct nfs4_delegation, dl_recall)
-
 struct nfs4_cb_compound_hdr {
 	/* args */
 	u32		ident;	/* minorversion 0 only */
@@ -491,7 +488,7 @@ static void nfs4_xdr_enc_cb_null(struct rpc_rqst *req, struct xdr_stream *xdr,
 static void nfs4_xdr_enc_cb_recall(struct rpc_rqst *req, struct xdr_stream *xdr,
 				   const struct nfsd4_callback *cb)
 {
-	const struct nfs4_delegation *dp = to_delegation(cb);
+	const struct nfs4_delegation *dp = cb_to_delegation(cb);
 	struct nfs4_cb_compound_hdr hdr = {
 		.ident = cb->cb_clp->cl_cb_ident,
 		.minorversion = cb->cb_minorversion,

fs/nfsd/nfs4state.c

@@ -3360,9 +3360,6 @@ nfs4_share_conflict(struct svc_fh *current_fh, unsigned int deny_type)
 	return ret;
 }
 
-#define cb_to_delegation(cb) \
-	container_of(cb, struct nfs4_delegation, dl_recall)
-
 static void nfsd4_cb_recall_prepare(struct nfsd4_callback *cb)
 {
 	struct nfs4_delegation *dp = cb_to_delegation(cb);

fs/nfsd/state.h

@@ -132,6 +132,9 @@ struct nfs4_delegation {
 	struct nfsd4_callback	dl_recall;
 };
 
+#define cb_to_delegation(cb) \
+	container_of(cb, struct nfs4_delegation, dl_recall)
+
 /* client delegation callback info */
 struct nfs4_cb_conn {
 	/* SETCLIENTID info */