Explain why itrunc() is OK w.r.t. crashes.

8eb20827 · rtm · 15a26936 · 8eb20827
--- a/fs.c
+++ b/fs.c
@@ -359,6 +359,8 @@ bmap(struct inode *ip, uint bn, int alloc)
 }

 // Truncate inode (discard contents).
+// Only called after the last dirent referring
+// to this inode has been erased on disk.
 static void
 itrunc(struct inode *ip)
 {