-/**
- * run_list_element - in memory vcn to lcn mapping array element
- * @vcn: starting vcn of the current array element
- * @lcn: starting lcn of the current array element
- * @length: length in clusters of the current array element
- *
- * The last vcn (in fact the last vcn + 1) is reached when length == 0.
- *
- * When lcn == -1 this means that the count vcns starting at vcn are not
- * physically allocated (i.e. this is a hole / data is sparse).
- */
-typedef struct { /* In memory vcn to lcn mapping structure element. */
- VCN vcn; /* vcn = Starting virtual cluster number. */
- LCN lcn; /* lcn = Starting logical cluster number. */
- s64 length; /* Run length in clusters. */
-} run_list_element;
-
-/**
- * run_list - in memory vcn to lcn mapping array including a read/write lock
- * @rl: pointer to an array of run list elements
- * @lock: read/write spinlock for serializing access to @rl
- *
+/*
+ * The NTFS transaction log $UsnJrnl uses usn which are signed 64-bit values.
+ * We define our own type USN, to allow for type checking and better code
+ * readability.