actually use [update_fblock_d] in fuse.hs!
actually use [update_fblock_d] in fuse.hs!

we were still using [update_fblock], from before we had actually fully
implemented the new direct-write plan...

mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl