1 files changed, 16 insertions, 0 deletions

diff --git a/sbin/newfs/newfs.h b/sbin/newfs/newfs.h
index 5c428c412ecf..0d7cb62379dc 100644
--- a/sbin/newfs/newfs.h
+++ b/sbin/newfs/newfs.h
@@ -70,4 +70,20 @@ extern int	avgfilesperdir;	/* expected number of files per directory */
 extern u_char	*volumelabel;	/* volume label for filesystem */
 extern struct uufsd disk;	/* libufs disk structure */
 
+/*
+ * To override a limitation in libufs, export the offset (in sectors) of the
+ * partition on the underlying media (file or disk). The value is used as
+ * an offset for all accesses to the media through bread(), which is only
+ * invoked directly in this program.
+ * For bwrite() we need a different approach, namely override the library
+ * version with one defined here. This is because bwrite() is called also
+ * by the library function sbwrite() which we cannot intercept nor want to
+ * rewrite. As a consequence, the internal version of bwrite() adds the
+ * partition offset itself when calling the underlying function, pwrite().
+ *
+ * XXX This info really ought to go into the struct uufsd, at which point
+ * we can remove the above hack.
+ */
+extern ufs2_daddr_t part_ofs;	/* partition offset in blocks */
+
 void mkfs (struct partition *, char *);