diff --git a/source/include/smb.h b/source/include/smb.h
index 7484efd..9999682 100644
--- a/source/include/smb.h
+++ b/source/include/smb.h
@@ -652,6 +652,9 @@ typedef struct connection_struct {
 	BOOL ipc;
 	BOOL read_only; /* Attributes for the current user of the share. */
 	BOOL admin_user; /* Attributes for the current user of the share. */
+	BOOL hires_timestamps_avail; /* Does this filesystem honor
+					sub second timestamps on files
+					and directories ? */
 	char *dirpath;
 	char *connectpath;
 	char *origpath;
diff --git a/source/lib/time.c b/source/lib/time.c
index 8e28fcc..d3de771 100644
--- a/source/lib/time.c
+++ b/source/lib/time.c
@@ -1145,6 +1145,17 @@ int timespec_compare(const struct timespec *ts1, const struct timespec *ts2)
 }
 
 /****************************************************************************
+ Round up a timespec if nsec > 500000000, round down if lower,
+ then zero nsec.
+****************************************************************************/
+
+void round_timespec(struct timespec *ts)
+{
+	ts->tv_sec += ts->tv_nsec >= 500000000 ? 1 : 0;
+	ts->tv_nsec = 0;
+}
+
+/****************************************************************************
  Interprets an nt time into a unix struct timespec.
  Differs from nt_time_to_unix in that an 8 byte value of 0xffffffffffffffff
  will be returned as (time_t)-1, whereas nt_time_to_unix returns 0 in this case.
diff --git a/source/smbd/service.c b/source/smbd/service.c
index bfe9649..4386458 100644
--- a/source/smbd/service.c
+++ b/source/smbd/service.c
@@ -1010,7 +1010,30 @@ static connection_struct *make_connection_snum(int snum, user_struct *vuser,
 		*status = NT_STATUS_BAD_NETWORK_NAME;
 		return NULL;
 	}
-	
+
+	{
+		struct timespec atime_ts = get_atimespec(&st);
+		struct timespec ctime_ts = get_ctimespec(&st);
+		struct timespec mtime_ts = get_mtimespec(&st);
+
+		if (mtime_ts.tv_nsec ||
+				atime_ts.tv_nsec ||
+				ctime_ts.tv_nsec) {
+			/* If any of the normal UNIX directory timestamps
+			 * have a non-zero tv_nsec component assume
+			 * we can fully store hires timestamps. We need
+			 * to make a runtime/share level distinction
+			 * as on Linux ext3 doesn't have hires timestamps, but
+			 * ext4 does, so a compile time test won't work. JRA.
+			 */
+			DEBUG(10,("make_connection_snum: hires timestamps "
+				"available on share %s, directory %s\n",
+				lp_servicename(snum),
+				conn->connectpath ));
+			conn->hires_timestamps_avail = true;
+		}
+	}
+
 	string_set(&conn->origpath,conn->connectpath);
 	
 #if SOFTLINK_OPTIMISATION
diff --git a/source/smbd/trans2.c b/source/smbd/trans2.c
index d3b4fb9..1399213 100644
--- a/source/smbd/trans2.c
+++ b/source/smbd/trans2.c
@@ -4133,6 +4133,13 @@ static NTSTATUS smb_set_file_time(connection_struct *conn,
 		}
 	}
 
+	if (!conn->hires_timestamps_avail) {
+		/* We can't store sub second timestamps
+		* on this share. Round to seconds. */
+		round_timespec(&ts[0]);
+		round_timespec(&ts[1]);
+	}
+
 	if(fsp != NULL) {
 		/*
 		 * This was a setfileinfo on an open file.