NFSD add nfs4 inter ssc to nfsd4_copy

Given a universal address, mount the source server from the destination
server.  Use an internal mount. Call the NFS client nfs42_ssc_open to
obtain the NFS struct file suitable for nfsd_copy_range.

Ability to do "inter" server-to-server depends on the an nfsd kernel
parameter "inter_copy_offload_enable".
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>

fs/nfsd/nfs4state.c

@@ -5681,8 +5681,9 @@ _free_cpntf_state_locked(struct nfsd_net *nn, struct nfs4_cpntf_state *cps)
  * copy stateid. Look up the copy notify stateid from the
  * idr structure and take a reference on it.
  */
-static __be32 _find_cpntf_state(struct nfsd_net *nn, stateid_t *st,
-		     struct nfs4_cpntf_state **cps)
+__be32 manage_cpntf_state(struct nfsd_net *nn, stateid_t *st,
+			  struct nfs4_client *clp,
+			  struct nfs4_cpntf_state **cps)
 {
 	copy_stateid_t *cps_t;
 	struct nfs4_cpntf_state *state = NULL;
@@ -5696,12 +5697,16 @@ static __be32 _find_cpntf_state(struct nfsd_net *nn, stateid_t *st,
 				     cp_stateid);
 		if (state->cp_stateid.sc_type != NFS4_COPYNOTIFY_STID)
 			return nfserr_bad_stateid;
-		refcount_inc(&state->cp_stateid.sc_count);
+		if (!clp)
+			refcount_inc(&state->cp_stateid.sc_count);
+		else
+			_free_cpntf_state_locked(nn, state);
 	}
 	spin_unlock(&nn->s2s_cp_lock);
 	if (!state)
 		return nfserr_bad_stateid;
-	*cps = state;
+	if (!clp && state)
+		*cps = state;
 	return 0;
 }
 
@@ -5712,7 +5717,7 @@ static __be32 find_cpntf_state(struct nfsd_net *nn, stateid_t *st,
 	struct nfs4_cpntf_state *cps = NULL;
 	struct nfsd4_compound_state cstate;
 
-	status = _find_cpntf_state(nn, st, &cps);
+	status = manage_cpntf_state(nn, st, NULL, &cps);
 	if (status)
 		return status;
 

fs/nfsd/nfssvc.c

@@ -31,6 +31,12 @@
 
 #define NFSDDBG_FACILITY	NFSDDBG_SVC
 
+bool inter_copy_offload_enable;
+EXPORT_SYMBOL_GPL(inter_copy_offload_enable);
+module_param(inter_copy_offload_enable, bool, 0644);
+MODULE_PARM_DESC(inter_copy_offload_enable,
+		 "Enable inter server to server copy offload. Default: false");
+
 extern struct svc_program	nfsd_program;
 static int			nfsd(void *vrqstp);
 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)

fs/nfsd/state.h

@@ -680,6 +680,9 @@ extern struct nfsd4_copy *
 find_async_copy(struct nfs4_client *clp, stateid_t *staetid);
 extern void nfs4_put_cpntf_state(struct nfsd_net *nn,
 				 struct nfs4_cpntf_state *cps);
+extern __be32 manage_cpntf_state(struct nfsd_net *nn, stateid_t *st,
+				 struct nfs4_client *clp,
+				 struct nfs4_cpntf_state **cps);
 static inline void get_nfs4_file(struct nfs4_file *fi)
 {
 	refcount_inc(&fi->fi_ref);

fs/nfsd/xdr4.h

@@ -549,7 +549,12 @@ struct nfsd4_copy {
 	struct task_struct	*copy_task;
 	refcount_t		refcount;
 	bool			stopped;
+
+	struct vfsmount		*ss_mnt;
+	struct nfs_fh		c_fh;
+	nfs4_stateid		stateid;
 };
+extern bool inter_copy_offload_enable;
 
 struct nfsd4_seek {
 	/* request */