diff --git a/c_defs_linux.go b/c_defs_linux.go
index d2de397..748d1c5 100644
--- a/c_defs_linux.go
+++ b/c_defs_linux.go
@@ -32,6 +32,7 @@ package scoutfs
 // typedef uint32_t __le32;
 // typedef uint64_t __le64;
 // typedef int32_t __s32;
+// typedef int64_t __s64;
 // #define __packed
 // #include "/usr/include/scoutfs/ioctl.h"
 // typedef struct scoutfs_ioctl_walk_inodes_entry scoutfs_ioctl_walk_inodes_entry_t;
@@ -44,6 +45,7 @@ package scoutfs
 // typedef struct scoutfs_fid scoutfs_fid_t;
 // typedef struct scoutfs_ioctl_data_waiting_entry scoutfs_ioctl_data_waiting_entry_t;
 // typedef struct scoutfs_ioctl_data_waiting scoutfs_ioctl_data_waiting_t;
+// typedef struct scoutfs_ioctl_data_wait_err scoutfs_ioctl_data_wait_err_t;
 // typedef struct scoutfs_ioctl_setattr_more scoutfs_ioctl_setattr_more_t;
 // typedef struct scoutfs_ioctl_listxattr_hidden scoutfs_ioctl_listxattr_hidden_t;
 // typedef struct scoutfs_ioctl_find_xattrs scoutfs_ioctl_find_xattrs_t;
@@ -60,6 +62,7 @@ const IOCSETATTRMORE = C.SCOUTFS_IOC_SETATTR_MORE
 const IOCLISTXATTRHIDDEN = C.SCOUTFS_IOC_LISTXATTR_HIDDEN
 const IOCFINDXATTRS = C.SCOUTFS_IOC_FIND_XATTRS
 const IOCSTATFSMORE = C.SCOUTFS_IOC_STATFS_MORE
+const IOCDATAWAITERR = C.SCOUTFS_IOC_DATA_WAIT_ERR
 
 const QUERYINODESMETASEQ = C.SCOUTFS_IOC_WALK_INODES_META_SEQ
 const QUERYINODESDATASEQ = C.SCOUTFS_IOC_WALK_INODES_DATA_SEQ
@@ -76,6 +79,7 @@ type iocStage C.scoutfs_ioctl_stage_t
 type Stat C.scoutfs_ioctl_stat_more_t
 type DataWaitingEntry C.scoutfs_ioctl_data_waiting_entry_t
 type dataWaiting C.scoutfs_ioctl_data_waiting_t
+type dataWaitErr C.scoutfs_ioctl_data_wait_err_t
 type setattrMore C.scoutfs_ioctl_setattr_more_t
 type listXattrHidden C.scoutfs_ioctl_listxattr_hidden_t
 type findXattrs C.scoutfs_ioctl_find_xattrs_t
diff --git a/scoutfs.go b/scoutfs.go
index 03e0168..1f3366d 100644
--- a/scoutfs.go
+++ b/scoutfs.go
@@ -399,6 +399,27 @@ func (w *Waiters) Reset() {
 	w.iblock = 0
 }
 
+// SendDataWaitErr sends an error to the data waiter task indicating that
+// the data is no longer aviable.
+// An open file within scoutfs is supplied for ioctls
+// (usually just the base mount point directory)
+func SendDataWaitErr(dirfd *os.File, ino, version, offset, op, count uint64, errno int64) error {
+	derr := dataWaitErr{
+		Ino:     ino,
+		Version: version,
+		Offset:  offset,
+		Count:   count,
+		Op:      op,
+		Err:     errno,
+	}
+
+	_, err := scoutfsctl(dirfd, IOCDATAWAITERR, unsafe.Pointer(&derr))
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
 // XattrQuery to keep track of in-process xattr query
 type XattrQuery struct {
 	next  uint64
diff --git a/scoutfsdefs.go b/scoutfsdefs.go
index 9c62eaf..32973d1 100644
--- a/scoutfsdefs.go
+++ b/scoutfsdefs.go
@@ -13,6 +13,7 @@ const IOCSETATTRMORE = 0x40287307
 const IOCLISTXATTRHIDDEN = 0x80187308
 const IOCFINDXATTRS = 0x80207309
 const IOCSTATFSMORE = 0x8018730a
+const IOCDATAWAITERR = 0x8030730b
 
 const QUERYINODESMETASEQ = 0x0
 const QUERYINODESDATASEQ = 0x1
@@ -77,6 +78,14 @@ type dataWaiting struct {
 	Ents_nr		uint16
 	X_pad		[6]uint8
 }
+type dataWaitErr struct {
+	Ino	uint64
+	Version	uint64
+	Offset	uint64
+	Count	uint64
+	Op	uint64
+	Err	int64
+}
 type setattrMore struct {
 	Data_version	uint64
 	I_size		uint64