Extend write_buf documentation

diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index caf4020db990b8b4bb9a1a1b932f86bd99c72dcb..8262d38a87d1a4858738706d711da86412bed807 100644 (file)
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -927,6 +927,11 @@ struct fuse_lowlevel_ops {
         * kernel supports splicing from the fuse device, then the
         * data will be made available in pipe for supporting zero
         * copy data transfer.
+         *
+         * buf->count is guaranteed to be one (and thus buf->idx is
+         * always zero). The write_buf handler must ensure that
+         * bufv->off is correctly updated (reflecting the number of
+         * bytes read from bufv->buf[0]).
         *
         * Introduced in version 2.9
         *