add documentation
diff --git a/include/fuse.h b/include/fuse.h
index 84c0341..d16135e 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -185,6 +185,9 @@
* should be treated equally. Multiple write-flush sequences are
* relatively rare, so this shouldn't be a problem.
*
+ * Filesystems shouldn't assume that flush will allways be called
+ * after some writes, or that if will be called at all.
+ *
* Changed in version 2.2
*/
int (*flush) (const char *, struct fuse_file_info *);
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index 02e3806..93712f5 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -412,6 +412,9 @@
* Since file descriptors can be duplicated (dup, dup2, fork), for
* one open call there may be many flush calls.
*
+ * Filesystems shouldn't assume that flush will allways be called
+ * after some writes, or that if will be called at all.
+ *
* fi->fh will contain the value set by the open method, or will
* be undefined if the open method didn't set any value.
*