NFSv4: Clean up the asynchronous delegation return

Reuse the state management thread in order to return delegations when we
get a callback.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/delegation.c

@@ -321,6 +321,12 @@ int nfs_inode_return_delegation(struct inode *inode)
 	return err;
 }
 
+static void nfs_mark_return_delegation(struct nfs_client *clp, struct nfs_delegation *delegation)
+{
+	set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
+	set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
+}
+
 /*
  * Return all delegations associated to a super block
  */
@@ -376,66 +382,25 @@ void nfs_handle_cb_pathdown(struct nfs_client *clp)
 	nfs_client_mark_return_all_delegations(clp);
 }
 
-struct recall_threadargs {
-	struct inode *inode;
-	struct nfs_client *clp;
-	const nfs4_stateid *stateid;
-
-	struct completion started;
-	int result;
-};
-
-static int recall_thread(void *data)
-{
-	struct recall_threadargs *args = (struct recall_threadargs *)data;
-	struct inode *inode = igrab(args->inode);
-	struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
-	struct nfs_inode *nfsi = NFS_I(inode);
-	struct nfs_delegation *delegation;
-
-	daemonize("nfsv4-delegreturn");
-
-	nfs_msync_inode(inode);
-	down_write(&nfsi->rwsem);
-	spin_lock(&clp->cl_lock);
-	delegation = nfs_detach_delegation_locked(nfsi, args->stateid);
-	if (delegation != NULL)
-		args->result = 0;
-	else
-		args->result = -ENOENT;
-	spin_unlock(&clp->cl_lock);
-	complete(&args->started);
-	nfs_delegation_claim_opens(inode, args->stateid);
-	up_write(&nfsi->rwsem);
-	nfs_msync_inode(inode);
-
-	if (delegation != NULL)
-		nfs_do_return_delegation(inode, delegation, 1);
-	iput(inode);
-	module_put_and_exit(0);
-}
-
 /*
  * Asynchronous delegation recall!
  */
 int nfs_async_inode_return_delegation(struct inode *inode, const nfs4_stateid *stateid)
 {
-	struct recall_threadargs data = {
-		.inode = inode,
-		.stateid = stateid,
-	};
-	int status;
+	struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
+	struct nfs_delegation *delegation;
 
-	init_completion(&data.started);
-	__module_get(THIS_MODULE);
-	status = kernel_thread(recall_thread, &data, CLONE_KERNEL);
-	if (status < 0)
-		goto out_module_put;
-	wait_for_completion(&data.started);
-	return data.result;
-out_module_put:
-	module_put(THIS_MODULE);
-	return status;
+	rcu_read_lock();
+	delegation = rcu_dereference(NFS_I(inode)->delegation);
+	if (delegation == NULL || memcmp(delegation->stateid.data, stateid->data,
+				sizeof(delegation->stateid.data)) != 0) {
+		rcu_read_unlock();
+		return -ENOENT;
+	}
+	nfs_mark_return_delegation(clp, delegation);
+	rcu_read_unlock();
+	nfs_delegation_run_state_manager(clp);
+	return 0;
 }
 
 /*