fix double free in disk cache

ChangeLog

@@ -1,3 +1,4 @@
+	* fix double free in disk cache
 	* forward declaring libtorrent types is discouraged. a new fwd.hpp header is provided
 
 1.1.3 release

src/disk_io_thread.cpp

@@ -757,13 +757,13 @@ namespace libtorrent
 		--pe->piece_refcount;
 		iovec_flushed(pe, flushing, iov_len, 0, error, completed_jobs);
 
+		m_disk_cache.maybe_free_piece(pe);
+
 		// if the cache is under high pressure, we need to evict
 		// the blocks we just flushed to make room for more write pieces
 		int evict = m_disk_cache.num_to_evict(0);
 		if (evict > 0) m_disk_cache.try_evict_blocks(evict);
 
-		m_disk_cache.maybe_free_piece(pe);
-
 		return iov_len;
 	}