knfsd: Allow lockless lookups of the exports

Convert structs svc_expkey and svc_export to allow RCU protected lookups.

Signed-off-by: Trond Myklebust <[e-mail]>
Signed-off-by: J. Bruce Fields <[e-mail]>

fs/nfsd/export.c

···
 	    !test_bit(CACHE_NEGATIVE, &key->h.flags))
 		path_put(&key->ek_path);
 	auth_domain_put(key->ek_client);
-	kfree(key);
+	kfree_rcu(key, ek_rcu);
 }
 
 static void expkey_request(struct cache_detail *cd,
···
 	struct cache_head *ch;
 	int hash = svc_expkey_hash(item);
 
-	ch = sunrpc_cache_lookup(cd, &item->h, hash);
+	ch = sunrpc_cache_lookup_rcu(cd, &item->h, hash);
 	if (ch)
 		return container_of(ch, struct svc_expkey, h);
 	else
···
 	auth_domain_put(exp->ex_client);
 	nfsd4_fslocs_free(&exp->ex_fslocs);
 	kfree(exp->ex_uuid);
-	kfree(exp);
+	kfree_rcu(exp, ex_rcu);
 }
 
 static void svc_export_request(struct cache_detail *cd,
···
 	struct cache_head *ch;
 	int hash = svc_export_hash(exp);
 
-	ch = sunrpc_cache_lookup(exp->cd, &exp->h, hash);
+	ch = sunrpc_cache_lookup_rcu(exp->cd, &exp->h, hash);
 	if (ch)
 		return container_of(ch, struct svc_export, h);
 	else
···
 }
 
 const struct seq_operations nfs_exports_op = {
-	.start	= cache_seq_start,
-	.next	= cache_seq_next,
-	.stop	= cache_seq_stop,
+	.start	= cache_seq_start_rcu,
+	.next	= cache_seq_next_rcu,
+	.stop	= cache_seq_stop_rcu,
 	.show	= e_show,
 };
 

fs/nfsd/export.h

···
 	u32			ex_layout_types;
 	struct nfsd4_deviceid_map *ex_devid_map;
 	struct cache_detail	*cd;
+	struct rcu_head		ex_rcu;
 };
 
 /* an "export key" (expkey) maps a filehandlefragement to an
···
 	u32			ek_fsid[6];
 
 	struct path		ek_path;
+	struct rcu_head		ek_rcu;
 };
 
 #define EX_ISSYNC(exp)		(!((exp)->ex_flags & NFSEXP_ASYNC))