in vfs_detach(). vfs_done may free global filesystem's resources,
typically those allocated in respective filesystem's init function.
Needed so those filesystems which went in via LKM have a chance to
clean after themselves before unloading. This fixes random panics
when LKM for filesystem using pools was loaded and unloaded several
times.
For each leaf filesystem, add appropriate vfs_done routine.
about ISO9660 file system structure), and cd9660_extern.h (which now
contains the definitions and data structures used by the kernel).
There's lots of other stuff scattered around this code that should go
into cd9660_extern.h, but doesn't need to right now. This changed patterned
on ffs, which has 'fs.h' which describes the FS structure, and ffs_extern.h
for kernel-internals gunk. Now libsa can include iso.h without the nasty
hack that was there before.
