--- IO-AIO/AIO.xs	2012/07/25 16:12:28	1.216
+++ IO-AIO/AIO.xs	2012/07/27 18:43:25	1.219
@@ -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 */
 
@@ -196,16 +196,23 @@
       if (req->int3 >= 0)
         break; /* when not autosizing 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);
     }
@@ -1534,7 +1541,7 @@
 aio_fiemap (SV *fh, off_t start, SV *length, U32 flags, SV *count, SV *callback=&PL_sv_undef)
         PPCODE:
 {
-  	int fd = s_fileno_croak (fh, 0);
+	int fd = s_fileno_croak (fh, 0);
 	dREQ;
 
         req->type = EIO_CUSTOM;