[XFS] Dmapi preunmount event references null pointer

SGI Modid: xfs-linux:xfs-kern:171047a

fs/xfs/xfs_mount.h

@@ -95,7 +95,8 @@ typedef int	(*xfs_send_data_t)(int, struct vnode *,
 			xfs_off_t, size_t, int, vrwlock_t *);
 typedef int	(*xfs_send_mmap_t)(struct vm_area_struct *, uint);
 typedef int	(*xfs_send_destroy_t)(struct vnode *, dm_right_t);
-typedef int	(*xfs_send_namesp_t)(dm_eventtype_t, struct vnode *,
+typedef int	(*xfs_send_namesp_t)(dm_eventtype_t, struct vfs *,
+			struct vnode *,
 			dm_right_t, struct vnode *, dm_right_t,
 			char *, char *, mode_t, int, int);
 typedef void	(*xfs_send_unmount_t)(struct vfs *, struct vnode *,
@@ -116,7 +117,9 @@ typedef struct xfs_dmops {
 #define XFS_SEND_DESTROY(mp, vp,right) \
 	(*(mp)->m_dm_ops.xfs_send_destroy)(vp,right)
 #define XFS_SEND_NAMESP(mp, ev,b1,r1,b2,r2,n1,n2,mode,rval,fl) \
-	(*(mp)->m_dm_ops.xfs_send_namesp)(ev,b1,r1,b2,r2,n1,n2,mode,rval,fl)
+	(*(mp)->m_dm_ops.xfs_send_namesp)(ev,NULL,b1,r1,b2,r2,n1,n2,mode,rval,fl)
+#define XFS_SEND_PREUNMOUNT(mp, vfs,b1,r1,b2,r2,n1,n2,mode,rval,fl) \
+	(*(mp)->m_dm_ops.xfs_send_namesp)(DM_EVENT_PREUNMOUNT,vfs,b1,r1,b2,r2,n1,n2,mode,rval,fl)
 #define XFS_SEND_UNMOUNT(mp, vfsp,vp,right,mode,rval,fl) \
 	(*(mp)->m_dm_ops.xfs_send_unmount)(vfsp,vp,right,mode,rval,fl)
 

fs/xfs/xfs_vfsops.c

@@ -536,7 +536,7 @@ xfs_unmount(
 	rvp = XFS_ITOV(rip);
 
 	if (vfsp->vfs_flag & VFS_DMI) {
-		error = XFS_SEND_NAMESP(mp, DM_EVENT_PREUNMOUNT,
+		error = XFS_SEND_PREUNMOUNT(mp, vfsp,
 				rvp, DM_RIGHT_NULL, rvp, DM_RIGHT_NULL,
 				NULL, NULL, 0, 0,
 				(mp->m_dmevmask & (1<<DM_EVENT_PREUNMOUNT))?