2 - support asynchronous operation -- add a per-fs 'reserved_space' count,
   3   let each outstanding write reserve the _maximum_ amount of physical
   4   space it could take. Let GC flush the outstanding writes because the
   5   reservations will necessarily be pessimistic. With this we could even
   6   do shared writable mmap, if we can have a fs hook for do_wp_page() to
   7   make the reservation.
   8 - disable compression in commit_write()?
   9 - fine-tune the allocation / GC thresholds
  10 - chattr support - turning on/off and tuning compression per-inode
  11 - checkpointing (do we need this? scan is quite fast)
  12 - make the scan code populate real inodes so read_inode just after 
  13        mount doesn't have to read the flash twice for large files.
  14        Make this a per-inode option, changeable with chattr, so you can
  15        decide which inodes should be in-core immediately after mount.
  16 - test, test, test
  18 - NAND flash support:
  19        - almost done :)
  20        - use bad block check instead of the hardwired byte check
  22 - Optimisations:
  23   - Split writes so they go to two separate blocks rather than just c->nextblock.
  24        By writing _new_ nodes to one block, and garbage-collected REF_PRISTINE
  25        nodes to a different one, we can separate clean nodes from those which
  26        are likely to become dirty, and end up with blocks which are each far
  27        closer to 100% or 0% clean, hence speeding up later GC progress dramatically.
  28   - Stop keeping name in-core with struct jffs2_full_dirent. If we keep the hash in 
  29     the full dirent, we only need to go to the flash in lookup() when we think we've
  30     got a match, and in readdir(). 
  31   - Doubly-linked next_in_ino list to allow us to free obsoleted raw_node_refs immediately?
  32   - Remove size from jffs2_raw_node_frag. 
  351. __jffs2_flush_wbuf() has a strange 'pad' parameter. Eliminate.
  362. get_sb()->build_fs()->scan() path... Why get_sb() removes scan()'s crap in
  37   case of failure? scan() does not clean everything. Fix.