--- IO-AIO/AIO.pm	2012/07/27 17:24:06	1.230
+++ IO-AIO/AIO.pm	2012/07/30 16:46:30	1.232
@@ -1294,9 +1294,9 @@
 the data portion.
 
 C<$count> is the maximum number of extent records to return. If it is
-C<undef>, then IO::AIO queries all extents of the file. As a very special
+C<undef>, then IO::AIO queries all extents of the range. As a very special
 case, if it is C<0>, then the callback receives the number of extents
-instead of the extents themselves.
+instead of the extents themselves (which is unreliable, see below).
 
 If an error occurs, the callback receives no arguments. The special
 C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
@@ -1308,7 +1308,7 @@
    [$logical, $physical, $length, $flags]
 
 Flags is any combination of the following flag values (typically either C<0>
-or C<IO::AIO::FIEMAP_EXTENT_LAST>):
+or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
 
 C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
 C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
@@ -1317,6 +1317,11 @@
 C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
 C<IO::AIO::FIEMAP_EXTENT_SHARED>.
 
+At the time of this writing (Linux 3.2), this requets is unreliable unless
+C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
+it to return all extents of a range for files with large number of
+extents. The code works around all these issues if C<$count> is undef.
+
 =item aio_group $callback->(...)
 
 This is a very special aio request: Instead of doing something, it is a