nfs: Use ida_simple API

Allocate the owner_id when we allocate the state and free it when we free
the state.  That lets us get rid of a gnarly ida_pre_get() / ida_get_new()
loop.
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/nfs4state.c

@@ -428,7 +428,6 @@ nfs4_insert_state_owner_locked(struct nfs4_state_owner *new)
 	struct rb_node **p = &server->state_owners.rb_node,
 		       *parent = NULL;
 	struct nfs4_state_owner *sp;
-	int err;
 
 	while (*p != NULL) {
 		parent = *p;
@@ -445,9 +444,6 @@ nfs4_insert_state_owner_locked(struct nfs4_state_owner *new)
 			return sp;
 		}
 	}
-	err = ida_get_new(&server->openowner_id, &new->so_seqid.owner_id);
-	if (err)
-		return ERR_PTR(err);
 	rb_link_node(&new->so_server_node, parent, p);
 	rb_insert_color(&new->so_server_node, &server->state_owners);
 	return new;
@@ -460,7 +456,6 @@ nfs4_remove_state_owner_locked(struct nfs4_state_owner *sp)
 
 	if (!RB_EMPTY_NODE(&sp->so_server_node))
 		rb_erase(&sp->so_server_node, &server->state_owners);
-	ida_remove(&server->openowner_id, sp->so_seqid.owner_id);
 }
 
 static void
@@ -495,6 +490,12 @@ nfs4_alloc_state_owner(struct nfs_server *server,
 	sp = kzalloc(sizeof(*sp), gfp_flags);
 	if (!sp)
 		return NULL;
+	sp->so_seqid.owner_id = ida_simple_get(&server->openowner_id, 0, 0,
+						gfp_flags);
+	if (sp->so_seqid.owner_id < 0) {
+		kfree(sp);
+		return NULL;
+	}
 	sp->so_server = server;
 	sp->so_cred = get_rpccred(cred);
 	spin_lock_init(&sp->so_lock);
@@ -526,6 +527,7 @@ static void nfs4_free_state_owner(struct nfs4_state_owner *sp)
 {
 	nfs4_destroy_seqid_counter(&sp->so_seqid);
 	put_rpccred(sp->so_cred);
+	ida_simple_remove(&sp->so_server->openowner_id, sp->so_seqid.owner_id);
 	kfree(sp);
 }
 
@@ -576,13 +578,9 @@ struct nfs4_state_owner *nfs4_get_state_owner(struct nfs_server *server,
 	new = nfs4_alloc_state_owner(server, cred, gfp_flags);
 	if (new == NULL)
 		goto out;
-	do {
-		if (ida_pre_get(&server->openowner_id, gfp_flags) == 0)
-			break;
-		spin_lock(&clp->cl_lock);
-		sp = nfs4_insert_state_owner_locked(new);
-		spin_unlock(&clp->cl_lock);
-	} while (sp == ERR_PTR(-EAGAIN));
+	spin_lock(&clp->cl_lock);
+	sp = nfs4_insert_state_owner_locked(new);
+	spin_unlock(&clp->cl_lock);
 	if (sp != new)
 		nfs4_free_state_owner(new);
 out: