Functionality of extended file system:
- Test directory support.
1	dir-mkdir
3	dir-mk-tree

1	dir-rmdir
3	dir-rm-tree

5	dir-vine

- Test file growth.
1	grow-create
1	grow-seq-sm
3	grow-seq-lg
3	grow-sparse
3	grow-two-files
1	grow-tell
1	grow-file-size

- Test directory growth.
1	grow-dir-lg
1	grow-root-sm
1	grow-root-lg

- Test writing from multiple processes.
5	syn-rw