[SAFS]: fix a bug in counting # async I/O.
[SAFS]: fix a bug in counting # async I/O.

flashxio/FlashX,icoming/FlashX,icoming/FlashGraph,icoming/FlashX,icoming/FlashGraph,flashxio/FlashX,icoming/FlashX,zheng-da/FlashX,flashxio/FlashX,flashxio/FlashX,zheng-da/FlashX,zheng-da/FlashX,flashxio/FlashX,icoming/FlashGraph,icoming/FlashX,icoming/FlashX,zheng-da/FlashX,icoming/FlashGraph,flashxio/FlashX,zheng-da/FlashX,icoming/FlashGraph