Handle data going missing

client.go

@@ -280,8 +280,20 @@ func (cl *Client) torrentReadAt(t *torrent, off int64, p []byte) (n int, err err
 	if len(p) == 0 {
 		panic(len(p))
 	}
-	cl.prepareRead(t, off)
-	return dataReadAt(t.data, p, off)
+	// TODO: ReadAt should always try to fill the buffer.
+	for {
+		avail := cl.prepareRead(t, off)
+		if avail < int64(len(p)) {
+			p = p[:avail]
+		}
+		n, err = dataReadAt(t.data, p, off)
+		if n != 0 || err != io.ErrUnexpectedEOF {
+			break
+		}
+		// If we reach here, the data we thought was ready, isn't. So we
+		// prepare it again, and retry.
+	}
+	return
 }
 
 // Sets priorities to download from the given offset. Returns when the piece

data/blob/store.go

@@ -124,6 +124,10 @@ func (me *store) pieceRead(p metainfo.Piece) (f *os.File) {
 	if !os.IsNotExist(err) {
 		panic(err)
 	}
+	// Ermahgerd, self heal. This occurs when the underlying data goes
+	// missing, likely due to a "cache flush", also known as deleting the
+	// files. TODO: Trigger an asynchronous initCompleted.
+	delete(me.completed, sliceToPieceHashArray(p.Hash()))
 	f, err = os.Open(me.path(p, false))
 	if err == nil {
 		return