#TODO

## Kernel developers

### Current priorities

 * Replication

 * Compression is almost done: it's quite thoroughly tested, the only remaining
   issue is a problem with copygc fragmenting existing compressed extents that
   only breaks accounting.

 * NFS export support is almost done: implementing i_generation correctly
   required some new transaction machinery, but that's mostly done. What's left
   is implementing a new kind of reservation of journal space for the new, long
   running transactions.

 * Allocation information (currently just bucket generation numbers & priority
   numbers, for LRU caching) needs to be moved into a btree, and we need to
   start persisting actual allocation information so we don't have to walk all
   extents at mount time.

   Just moving the existing prios/gens to a btree will be a significant
   improvement - besides getting us incrementally closer to persisting full
   allocation information, the existing code is a rather hacky mechanism dating
   from the early days of bcache and has recently been the source of an annoying
   bug due to the design being a bit fragile, and it'll be a performance
   improvement since it'll get rid of the last source of forced journal flushes.

### Other

 * When we're using compression, we end up wasting a fair amount of space on
   internal fragmentation because compressed extents get rounded up to the
   filesystem block size when they're written - usually 4k. It'd be really nice
   if we could pack them in more efficiently - probably 512 byte sector
   granularity.

   On the read side this is no big deal to support - we have to bounce
   compressed extents anyways. The write side is the annoying part. The options
   are:
    * Buffer up writes when we don't have full blocks to write? Highly
      problematic, not going to do this.
    * Read modify write? Not an option for raw flash, would prefer it to not be
      our only option
    * Do data journalling when we don't have a full block to write? Possible
      solution, we want data journalling anyways

 * Inline extents - good for space efficiency for both small files, and
   compression when extents happen to compress particularly well.

 * Full data journalling - we're definitely going to want this for when the
   journal is on an NVRAM device (also need to implement external journalling
   (easy), and direct journal on NVRAM support (what's involved here?)).

   Would be good to get a simple implementation done and tested so we know what
   the on disk format is going to be.

### Low priority

 * NOCOW

### Optional
(Will not be implemented by the lead developer.)

 * It is possible to add bcache functionality to bcachefs.
   If there is someone who wishes to implement this it would be an ok addition.
   However using it as a filesystem should still be better.

## Developers

 * End user documentation needs a lot of work - complete man pages, etc.

 * bcachefs-tools needs some fleshing out in the --help department

## Users

 * Benchmark bcachefs performance on different configurations:
   (Note that these tests will have to be repeated in the future.)
   * SSD
   * HDD
   * SSD + HDD
 
 * Update the website / Documentation
 * Ask questions (so and we can update the documentation / website).