[ANNOUNCE] bcachefs!

Short announcement, because I'm in the process of moving - but I wanted to get
this out there because the code is up and I think it's reasonably stable right
now.

Bcachefs is a posix filesystem that I've been working towards for - well, quite
awhile now: it's intended as a competitor/replacement for ext4/xfs/btrfs.

Current features
 - multiple devices
 - replication
 - tiering
 - data checksumming and compression (zlib only; also the code doesn't work with
   tiering yet)
 - most of the normal posix fs features (no fallocate or quotas yet)

Planned features:
 - snapshots!
 - erasure coding
 - more

There will be a longer announcement on LKML/linux-fs in the near future (after
I'm finished moving) - but I'd like to get it a bit more testing from a wider
audience first, if possible.

You need the bcache-dev branch, and the new bcache tools - be warned, this code
is _not_ compatible with the upstream bcache on disk format:

$ git clone -b bcache-dev http://evilpiepirate.org/git/linux-bcache.git
$ git clone -b dev http://evilpiepirate.org/git/bcache-tools.git

Then do the usual compiling...

# bcacheadm format -C /dev/sda1
# mount /dev/sda1 /mnt

The usual caveats apply - it might eat your data, the on disk format has _not_
been stabilized yet, etc. But it's been reasonably stable for me, and passes all
but 2-3 of the supported xfstests.

Try it out and let me know how it goes!

Also, programmers please check out the bcache guide - feedback is appreciated:

http://bcache.evilpiepirate.org/BcacheGuide/

Thanks!