Btrfs: Documentation update

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 the crypto manager interface in the kernel for file and

metadata checksums.  You need to compile the kernel with:

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

to compile the kernel with:

CONFIG_CRYPTO=y

CONFIG_CRYPTO_MANAGER=m

CONFIG_CRYPTO_CRC32C=m

CONFIG_LIBCRC32C=m

cryptomanager and crc32c 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:

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 crc32c

modprobe cryptomgr

modprobe libcrc32c

insmod btrfs.ko

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

	memcpy(item, btrfs_item_ptr(l, slot, struct btrfs_root_item),

		sizeof(*item));

	btrfs_disk_key_to_cpu(key, &l->items[slot].key);

printk("find last finds key %Lu %u %Lu slot %d search for obj %Lu\n", key->objectid, key->flags, key->offset, slot, objectid);

	ret = 0;

out:

	btrfs_release_path(root, path);

			ret = PTR_ERR(root);

			goto err;

		}

printk("found dead root %Lu %u %Lu\n", key.objectid, key.flags, key.offset);

		ret = btrfs_add_dead_root(dead_root,

					  &root->fs_info->dead_roots);

		if (ret)

		list_del_init(&dirty->list);

		trans = btrfs_start_transaction(tree_root, 1);

printk("deleting root %Lu %u %Lu\n", dirty->snap_key.objectid, dirty->snap_key.flags, dirty->snap_key.offset);

		ret = btrfs_drop_snapshot(trans, dirty->root,

					  dirty->commit_root);

		BUG_ON(ret);