diff --git a/include/nuttx/fs.h b/include/nuttx/fs.h
index 9c4a538df4..043514034c 100644
--- a/include/nuttx/fs.h
+++ b/include/nuttx/fs.h
@@ -136,16 +136,23 @@ struct mountpt_operations
   off_t   (*seek)(FAR struct file *filp, off_t offset, int whence);
   int     (*ioctl)(FAR struct file *filp, int cmd, unsigned long arg);
 
+  /* The two structures need not be common after this point. The following
+   * are extended methods needed to deal with the unique needs of mounted
+   * file systems.
+   */
+
+  int     (*sync)(FAR struct file *filp);
+
   /* The two structures need not be common after this point.  For the
    * case of struct mountpt_operations, additional operations are included
    * that used only for mounting and unmounting the volume.
    */
 
-  int   (*bind)(FAR struct inode *blkdriver, const void *data, void **handle);
-  int   (*unbind)(void *handle);
+  int     (*bind)(FAR struct inode *blkdriver, const void *data, void **handle);
+  int     (*unbind)(void *handle);
 
-  /* NOTE:  More operations will be needed here to support:  disk usage stats, stat(),
-   * sync(), unlink(), mkdir(), chmod(), rename(), etc.
+  /* NOTE:  More operations will be needed here to support:  disk usage stats
+   * stat(), unlink(), mkdir(), chmod(), rename(), etc.
    */
 };
 
diff --git a/include/unistd.h b/include/unistd.h
index 164b5368e0..16414fc773 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -94,7 +94,7 @@
 #undef  _POSIX_ASYNC_IO
 #undef  _POSIX_PRIO_IO
 
-#define fsync(f)
+#define fdatasync(f) fsync(f)
 
 /************************************************************
  * Global Function Prototypes
@@ -118,8 +118,9 @@ EXTERN void  usleep(unsigned long usec);
 /* File descriptor operations */
 
 EXTERN int   close(int fd);
-EXTERN int   dup(int fildes);
-EXTERN int   dup2(int fildes1, int fildes2);
+EXTERN int   dup(int fd);
+EXTERN int   dup2(int fd1, int fd2);
+EXTERN int   fsync(int fd);
 EXTERN off_t lseek(int fd, off_t offset, int whence);
 EXTERN int   read(int fd, void *buf, unsigned int nbytes);
 EXTERN int   unlink(const char *path);