Btrfs: Add Documentation/filesystem/btrfs.txt, remove old COPYING

	BTRFS

	=====

Btrfs is a new copy on write filesystem for Linux aimed at

implementing advanced features while focusing on fault tolerance,

repair and easy administration. Initially developed by Oracle, Btrfs

is licensed under the GPL and open for contribution from anyone.

Linux has a wealth of filesystems to choose from, but we are facing a

number of challenges with scaling to the large storage subsystems that

are becoming common in today's data centers. Filesystems need to scale

in their ability to address and manage large storage, and also in

their ability to detect, repair and tolerate errors in the data stored

on disk.  Btrfs is under heavy development, and is not suitable for

any uses other than benchmarking and review. The Btrfs disk format is

not yet finalized.

The main Btrfs features include:

    * Extent based file storage (2^64 max file size)

    * Space efficient packing of small files

    * Space efficient indexed directories

    * Dynamic inode allocation

    * Writable snapshots

    * Subvolumes (separate internal filesystem roots)

    * Object level mirroring and striping

    * Checksums on data and metadata (multiple algorithms available)

    * Compression

    * Integrated multiple device support, with several raid algorithms

    * Online filesystem check (not yet implemented)

    * Very fast offline filesystem check

    * Efficient incremental backup and FS mirroring (not yet implemented)

    * Online filesystem defragmentation

	MAILING LIST

	============

There is a Btrfs mailing list hosted on vger.kernel.org. You can

find details on how to subscribe here:

http://vger.kernel.org/vger-lists.html#linux-btrfs

Mailing list archives are available from gmane:

http://dir.gmane.org/gmane.comp.file-systems.btrfs

	IRC

	===

Discussion of Btrfs also occurs on the #btrfs channel of the Freenode

IRC network.

	UTILITIES

	=========

Userspace tools for creating and manipulating Btrfs file systems are

available from the git repository at the following location:

 http://git.kernel.org/?p=linux/kernel/git/mason/btrfs-progs-unstable.git

 git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-progs-unstable.git

These include the following tools:

mkfs.btrfs: create a filesystem

btrfsctl: control program to create snapshots and subvolumes:

	mount /dev/sda2 /mnt

	btrfsctl -s new_subvol_name /mnt

	btrfsctl -s snapshot_of_default /mnt/default

	btrfsctl -s snapshot_of_new_subvol /mnt/new_subvol_name

	btrfsctl -s snapshot_of_a_snapshot /mnt/snapshot_of_new_subvol

	ls /mnt

	default snapshot_of_a_snapshot snapshot_of_new_subvol

	new_subvol_name snapshot_of_default

	Snapshots and subvolumes cannot be deleted right now, but you can

	rm -rf all the files and directories inside them.

btrfsck: do a limited check of the FS extent trees.

btrfs-debug-tree: print all of the FS metadata in text form.  Example:

	btrfs-debug-tree /dev/sda2 >& big_output_file

   NOTE! This copyright does *not* cover user programs that use kernel

 services by normal system calls - this is merely considered normal use

 of the kernel, and does *not* fall under the heading of "derived work".

 Also note that the GPL below is copyrighted by the Free Software

 Foundation, but the instance of code that it refers to (the Linux

 kernel) is copyrighted by me and others who actually wrote it.

 Also note that the only valid version of the GPL as far as the kernel

 is concerned is _this_ particular version of the license (ie v2, not

 v2.2 or v3.x or whatever), unless explicitly otherwise stated.

			Linus Torvalds

----------------------------------------

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		       Version 2, June 1991

 Copyright (C) 1989, 1991 Free Software Foundation, Inc.

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Install Instructions

Btrfs puts snapshots and subvolumes into the root directory of the FS.  This

directory can only be changed by btrfsctl right now, and normal filesystem

operations do not work on it.  The default subvolume is called 'default',

and you can create files and directories in mount_point/default

Btrfs uses libcrc32c in the kernel for file and metadata checksums.  You need

to compile the kernel with:

CONFIG_LIBCRC32C=m

libcrc32c can be static as well.  Once your kernel is setup, typing make in the

btrfs module sources will build against the running kernel.  When the build is

complete:

modprobe libcrc32c

insmod btrfs.ko

The Btrfs utility programs require libuuid to build.  This can be found

in the e2fsprogs sources, and is usually available as libuuid or

e2fsprogs-devel from various distros.

Building the utilities is just make ; make install.  The programs go

into /usr/local/bin.  The commands available are:

mkfs.btrfs: create a filesystem

btrfsctl: control program to create snapshots and subvolumes:

	mount /dev/sda2 /mnt

	btrfsctl -s new_subvol_name /mnt

	btrfsctl -s snapshot_of_default /mnt/default

	btrfsctl -s snapshot_of_new_subvol /mnt/new_subvol_name

	btrfsctl -s snapshot_of_a_snapshot /mnt/snapshot_of_new_subvol

	ls /mnt

	default snapshot_of_a_snapshot snapshot_of_new_subvol

	new_subvol_name snapshot_of_default

	Snapshots and subvolumes cannot be deleted right now, but you can

	rm -rf all the files and directories inside them.

btrfsck: do a limited check of the FS extent trees.</li>

debug-tree: print all of the FS metadata in text form.  Example:

	debug-tree /dev/sda2 >& big_output_file