--- IO-AIO/AIO.xs	2012/07/27 17:24:06	1.217
+++ IO-AIO/AIO.xs	2012/07/27 17:54:40	1.218
@@ -169,9 +169,9 @@
 #if HAVE_FIEMAP
   int count = req->int3;
 
-  /* heuristic: first try with 64 extents if we don't know how many, */
+  /* heuristic: first try with 72 extents if we don't know how many, */
   /* as most files have (hopefully) fewer than this many extents */
-  /* in fact, most should have <= 2, so maybe the 72 below is probably overkill */
+  /* in fact, most should have <= 2, so the 72 below is probably overkill */
   if (count < 0)
     count = 72; /* for what it's worth, 72 extents fit nicely into 4kb */
 
@@ -196,6 +196,9 @@
       if (req->int3 >= 0)
         break; /* when not autosizing we are done */
 
+      if (!fiemap->fm_mapped_extents)
+        break; /* if file has no segments, we are done */
+
       if (fiemap->fm_extents [fiemap->fm_mapped_extents - 1].fe_flags & FIEMAP_EXTENT_LAST)
         break; /* autosizing successful, we are done */