NFSv4: Safe return of delegations.

 Make sure we return delegations in a safe (and asynchronous) manner
 inside nfs4_clear_inode().

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
---
 fs/nfs/delegation.c |   25 ++++++++++++++++++
 fs/nfs/delegation.h |    1 
 fs/nfs/inode.c      |    6 ++--
 fs/nfs/nfs4proc.c   |   70 ++++++++++++++++++++++++++++++++--------------------
 4 files changed, 73 insertions(+), 29 deletions(-)

Index: linux-2.6.12-rc1/fs/nfs/inode.c
===================================================================
--- linux-2.6.12-rc1.orig/fs/nfs/inode.c
+++ linux-2.6.12-rc1/fs/nfs/inode.c
@@ -1573,9 +1573,6 @@ static void nfs4_clear_inode(struct inod
 {
 	struct nfs_inode *nfsi = NFS_I(inode);
 
-	/* If we are holding a delegation, return it! */
-	if (nfsi->delegation != NULL)
-		nfs_inode_return_delegation(inode);
 	/* First call standard NFS clear_inode() code */
 	nfs_clear_inode(inode);
 	/* Now clear out any remaining state */
@@ -1593,6 +1590,9 @@ static void nfs4_clear_inode(struct inod
 		BUG_ON(atomic_read(&state->count) != 1);
 		nfs4_close_state(state, state->state);
 	}
+	/* If we are holding a delegation, return it! */
+	if (nfsi->delegation != NULL)
+		nfs_inode_clear_delegation(inode);
 }
 
 
Index: linux-2.6.12-rc1/fs/nfs/nfs4proc.c
===================================================================
--- linux-2.6.12-rc1.orig/fs/nfs/nfs4proc.c
+++ linux-2.6.12-rc1/fs/nfs/nfs4proc.c
@@ -2518,38 +2518,56 @@ nfs4_proc_setclientid_confirm(struct nfs
 	return status;
 }
 
-static int _nfs4_proc_delegreturn(struct inode *inode, struct rpc_cred *cred, const nfs4_stateid *stateid)
+struct nfs4_delegreturn_data {
+	struct nfs_server *server;
+	struct nfs_fh fhandle;
+	nfs4_stateid stateid;
+	struct nfs4_delegreturnargs args;
+};
+
+static void nfs4_delegreturn_done(struct rpc_task *task)
 {
-	struct nfs4_delegreturnargs args = {
-		.fhandle = NFS_FH(inode),
-		.stateid = stateid,
-	};
-	struct rpc_message msg = {
-		.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_DELEGRETURN],
-		.rpc_argp = &args,
-		.rpc_cred = cred,
-	};
+	struct nfs4_delegreturn_data *calldata = (struct nfs4_delegreturn_data *)task->tk_calldata;
 
-	return rpc_call_sync(NFS_CLIENT(inode), &msg, 0);
+	switch (task->tk_status) {
+		case 0:
+			break;
+		case -NFS4ERR_STALE_STATEID:
+		case -NFS4ERR_EXPIRED:
+			nfs4_schedule_state_recovery(calldata->server->nfs4_state);
+			break;
+		default:
+			if (nfs4_async_handle_error(task, calldata->server) == -EAGAIN) {
+				rpc_restart_call(task);
+				return;
+			}
+	}
+	kfree(calldata);
 }
 
 int nfs4_proc_delegreturn(struct inode *inode, struct rpc_cred *cred, const nfs4_stateid *stateid)
 {
-	struct nfs_server *server = NFS_SERVER(inode);
-	struct nfs4_exception exception = { };
-	int err;
-	do {
-		err = _nfs4_proc_delegreturn(inode, cred, stateid);
-		switch (err) {
-			case -NFS4ERR_STALE_STATEID:
-			case -NFS4ERR_EXPIRED:
-				nfs4_schedule_state_recovery(server->nfs4_state);
-			case 0:
-				return 0;
-		}
-		err = nfs4_handle_exception(server, err, &exception);
-	} while (exception.retry);
-	return err;
+	struct nfs4_delegreturn_data *calldata;
+	struct rpc_message msg = {
+		.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_DELEGRETURN],
+		.rpc_cred = cred,
+	};
+	int status = -ENOMEM;
+
+	calldata = kmalloc(sizeof(*calldata), GFP_NOFS);
+	if (calldata == NULL)
+		goto out;
+	calldata->server = NFS_SERVER(inode);
+	nfs_copy_fh(&calldata->fhandle, NFS_FH(inode));
+	memcpy(&calldata->stateid, stateid, sizeof(calldata->stateid));
+	calldata->args.fhandle = &calldata->fhandle;
+	calldata->args.stateid = &calldata->stateid;
+	msg.rpc_argp = &calldata->args;
+	status = rpc_call_async(NFS_CLIENT(inode), &msg, 0, nfs4_delegreturn_done, calldata);
+	if (status != 0)
+		kfree(calldata);
+out:
+	return status;
 }
 
 #define NFS4_LOCK_MINTIMEOUT (1 * HZ)
Index: linux-2.6.12-rc1/fs/nfs/delegation.c
===================================================================
--- linux-2.6.12-rc1.orig/fs/nfs/delegation.c
+++ linux-2.6.12-rc1/fs/nfs/delegation.c
@@ -195,6 +195,31 @@ restart:
 }
 
 /*
+ * Return a delegation for clear_inode()
+ */
+void nfs_inode_clear_delegation(struct inode *inode)
+{
+	struct nfs4_client *clp = NFS_SERVER(inode)->nfs4_state;
+	struct nfs_inode *nfsi = NFS_I(inode);
+	struct nfs_delegation *delegation;
+
+	down_read(&clp->cl_sem);
+	spin_lock(&clp->cl_lock);
+	delegation = nfsi->delegation;
+	if (delegation != NULL) {
+		list_del_init(&delegation->super_list);
+		nfsi->delegation = NULL;
+		nfsi->delegation_state = 0;
+	}
+	spin_unlock(&clp->cl_lock);
+	up_read(&clp->cl_sem);
+	if (delegation != NULL) {
+			nfs4_proc_delegreturn(inode, delegation->cred, &delegation->stateid);
+			nfs_free_delegation(delegation);
+	}
+}
+
+/*
  * Return all delegations following an NFS4ERR_CB_PATH_DOWN error.
  */
 void nfs_handle_cb_pathdown(struct nfs4_client *clp)
Index: linux-2.6.12-rc1/fs/nfs/delegation.h
===================================================================
--- linux-2.6.12-rc1.orig/fs/nfs/delegation.h
+++ linux-2.6.12-rc1/fs/nfs/delegation.h
@@ -27,6 +27,7 @@ int nfs_inode_set_delegation(struct inod
 void nfs_inode_reclaim_delegation(struct inode *inode, struct rpc_cred *cred, struct nfs_openres *res);
 int nfs_inode_return_delegation(struct inode *inode);
 int nfs_async_inode_return_delegation(struct inode *inode, const nfs4_stateid *stateid);
+void nfs_inode_clear_delegation(struct inode *inode);
 
 struct inode *nfs_delegation_find_inode(struct nfs4_client *clp, const struct nfs_fh *fhandle);
 void nfs_return_all_delegations(struct super_block *sb);