NFS: Always call nfs_inode_find_state_and_recover() when revoking a delegation

Don't rely on nfs_inode_detach_delegation() succeeding. That can race...
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
Tested-by: NOleg Drokin <green@linuxhacker.ru>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/delegation.c

@@ -662,18 +662,24 @@ static bool nfs_revoke_delegation(struct inode *inode,
 		const nfs4_stateid *stateid)
 {
 	struct nfs_delegation *delegation;
+	nfs4_stateid tmp;
 	bool ret = false;
 
 	rcu_read_lock();
 	delegation = rcu_dereference(NFS_I(inode)->delegation);
 	if (delegation == NULL)
 		goto out;
-	if (stateid && !nfs4_stateid_match(stateid, &delegation->stateid))
+	if (stateid == NULL) {
+		nfs4_stateid_copy(&tmp, &delegation->stateid);
+		stateid = &tmp;
+	} else if (!nfs4_stateid_match(stateid, &delegation->stateid))
 		goto out;
 	nfs_mark_delegation_revoked(NFS_SERVER(inode), delegation);
 	ret = true;
 out:
 	rcu_read_unlock();
+	if (ret)
+		nfs_inode_find_state_and_recover(inode, stateid);
 	return ret;
 }
 
@@ -685,10 +691,8 @@ void nfs_remove_bad_delegation(struct inode *inode,
 	if (!nfs_revoke_delegation(inode, stateid))
 		return;
 	delegation = nfs_inode_detach_delegation(inode);
-	if (delegation) {
-		nfs_inode_find_state_and_recover(inode, &delegation->stateid);
+	if (delegation)
 		nfs_free_delegation(delegation);
-	}
 }
 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);