Squashfs: add XZ compression support

#define ZLIB_COMPRESSION	1

#define LZMA_COMPRESSION	2

#define LZO_COMPRESSION		3

#define XZ_COMPRESSION		4

struct squashfs_super_block {

	__le32			s_magic;

/*

 * Squashfs - a compressed read only filesystem for Linux

 *

 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010

 * Phillip Lougher <phillip@lougher.demon.co.uk>

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2,

 * or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

 *

 * xz_wrapper.c

 */

#include <linux/mutex.h>

#include <linux/buffer_head.h>

#include <linux/slab.h>

#include <linux/xz.h>

#include "squashfs_fs.h"

#include "squashfs_fs_sb.h"

#include "squashfs_fs_i.h"

#include "squashfs.h"

#include "decompressor.h"

struct squashfs_xz {

	struct xz_dec *state;

	struct xz_buf buf;

};

static void *squashfs_xz_init(struct squashfs_sb_info *msblk)

{

	int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);

	struct squashfs_xz *stream = kmalloc(sizeof(*stream), GFP_KERNEL);

	if (stream == NULL)

		goto failed;

	stream->state = xz_dec_init(XZ_PREALLOC, block_size);

	if (stream->state == NULL)

		goto failed;

	return stream;

failed:

	ERROR("Failed to allocate xz workspace\n");

	kfree(stream);

	return NULL;

}

static void squashfs_xz_free(void *strm)

{

	struct squashfs_xz *stream = strm;

	if (stream) {

		xz_dec_end(stream->state);

		kfree(stream);

	}

}

static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void **buffer,

	struct buffer_head **bh, int b, int offset, int length, int srclength,

	int pages)

{

	enum xz_ret xz_err;

	int avail, total = 0, k = 0, page = 0;

	struct squashfs_xz *stream = msblk->stream;

	mutex_lock(&msblk->read_data_mutex);

	xz_dec_reset(stream->state);

	stream->buf.in_pos = 0;

	stream->buf.in_size = 0;

	stream->buf.out_pos = 0;

	stream->buf.out_size = PAGE_CACHE_SIZE;

	stream->buf.out = buffer[page++];

	do {

		if (stream->buf.in_pos == stream->buf.in_size && k < b) {

			avail = min(length, msblk->devblksize - offset);

			length -= avail;

			wait_on_buffer(bh[k]);

			if (!buffer_uptodate(bh[k]))

				goto release_mutex;

			if (avail == 0) {

				offset = 0;

				put_bh(bh[k++]);

				continue;

			}

			stream->buf.in = bh[k]->b_data + offset;

			stream->buf.in_size = avail;

			stream->buf.in_pos = 0;

			offset = 0;

		}

		if (stream->buf.out_pos == stream->buf.out_size

							&& page < pages) {

			stream->buf.out = buffer[page++];

			stream->buf.out_pos = 0;

			total += PAGE_CACHE_SIZE;

		}

		xz_err = xz_dec_run(stream->state, &stream->buf);

		if (stream->buf.in_pos == stream->buf.in_size && k < b)

			put_bh(bh[k++]);

	} while (xz_err == XZ_OK);

	if (xz_err != XZ_STREAM_END) {

		ERROR("xz_dec_run error, data probably corrupt\n");

		goto release_mutex;

	}

	if (k < b) {

		ERROR("xz_uncompress error, input remaining\n");

		goto release_mutex;

	}

	total += stream->buf.out_pos;

	mutex_unlock(&msblk->read_data_mutex);

	return total;

release_mutex:

	mutex_unlock(&msblk->read_data_mutex);

	for (; k < b; k++)

		put_bh(bh[k]);

	return -EIO;

}

const struct squashfs_decompressor squashfs_xz_comp_ops = {

	.init = squashfs_xz_init,

	.free = squashfs_xz_free,

	.decompress = squashfs_xz_uncompress,

	.id = XZ_COMPRESSION,

	.name = "xz",

	.supported = 1

};