--- IO-AIO/AIO.xs	2012/07/27 17:54:40	1.218
+++ IO-AIO/AIO.xs	2012/07/27 18:43:25	1.219
@@ -196,19 +196,23 @@
       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 */
-
+      if (fiemap->fm_mapped_extents < count)
+        /* either autosizing succeeded,
+         * or the file had no extents
+         * or we luckily had enough space */
+        break;
+
+      /* some kernels overwrite fm_length, so just reset everything */
+      fiemap->fm_start        = req->offs;
+      fiemap->fm_length       = req->size;
       fiemap->fm_flags        = req->int2;
       fiemap->fm_extent_count = 0;
 
       if (ioctl (req->int1, FS_IOC_FIEMAP, fiemap))
         return;
 
-      count = fiemap->fm_mapped_extents;
+      /* to work around a kernel bug, we allocate one more */
+      count = fiemap->fm_mapped_extents + 1;
 
       free (fiemap);
     }