--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/buf.h	Fri May 26 23:11:05 2017 +0900
@@ -0,0 +1,18 @@
+#ifndef INCLUDE_BUF_H
+#define INCLUDE_BUF_H
+
+struct buf {
+    int        flags;
+    uint       dev;
+    uint       sector;
+    struct buf *prev;  // LRU cache list
+    struct buf *next;
+    struct buf *qnext; // disk queue
+    uchar      data[512];
+};
+
+#define B_BUSY  0x1  // buffer is locked by some process
+#define B_VALID 0x2  // buffer has been read from disk
+#define B_DIRTY 0x4  // buffer needs to be written to disk
+
+#endif