Squashfs: add LZ4 compression support

/*

 * Copyright (c) 2013, 2014

 * Phillip Lougher <phillip@squashfs.org.uk>

 *

 * This work is licensed under the terms of the GNU GPL, version 2. See

 * the COPYING file in the top-level directory.

 */

#include <linux/buffer_head.h>

#include <linux/mutex.h>

#include <linux/slab.h>

#include <linux/vmalloc.h>

#include <linux/lz4.h>

#include "squashfs_fs.h"

#include "squashfs_fs_sb.h"

#include "squashfs.h"

#include "decompressor.h"

#include "page_actor.h"

#define LZ4_LEGACY	1

struct lz4_comp_opts {

	__le32 version;

	__le32 flags;

};

struct squashfs_lz4 {

	void *input;

	void *output;

};

static void *lz4_comp_opts(struct squashfs_sb_info *msblk,

	void *buff, int len)

{

	struct lz4_comp_opts *comp_opts = buff;

	/* LZ4 compressed filesystems always have compression options */

	if (comp_opts == NULL || len < sizeof(*comp_opts))

		return ERR_PTR(-EIO);

	if (le32_to_cpu(comp_opts->version) != LZ4_LEGACY) {

		/* LZ4 format currently used by the kernel is the 'legacy'

		 * format */

		ERROR("Unknown LZ4 version\n");

		return ERR_PTR(-EINVAL);

	}

	return NULL;

}

static void *lz4_init(struct squashfs_sb_info *msblk, void *buff)

{

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

	struct squashfs_lz4 *stream;

	stream = kzalloc(sizeof(*stream), GFP_KERNEL);

	if (stream == NULL)

		goto failed;

	stream->input = vmalloc(block_size);

	if (stream->input == NULL)

		goto failed2;

	stream->output = vmalloc(block_size);

	if (stream->output == NULL)

		goto failed3;

	return stream;

failed3:

	vfree(stream->input);

failed2:

	kfree(stream);

failed:

	ERROR("Failed to initialise LZ4 decompressor\n");

	return ERR_PTR(-ENOMEM);

}

static void lz4_free(void *strm)

{

	struct squashfs_lz4 *stream = strm;

	if (stream) {

		vfree(stream->input);

		vfree(stream->output);

	}

	kfree(stream);

}

static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,

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

	struct squashfs_page_actor *output)

{

	struct squashfs_lz4 *stream = strm;

	void *buff = stream->input, *data;

	int avail, i, bytes = length, res;

	size_t dest_len = output->length;

	for (i = 0; i < b; i++) {

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

		memcpy(buff, bh[i]->b_data + offset, avail);

		buff += avail;

		bytes -= avail;

		offset = 0;

		put_bh(bh[i]);

	}

	res = lz4_decompress_unknownoutputsize(stream->input, length,

					stream->output, &dest_len);

	if (res)

		return -EIO;

	bytes = dest_len;

	data = squashfs_first_page(output);

	buff = stream->output;

	while (data) {

		if (bytes <= PAGE_CACHE_SIZE) {

			memcpy(data, buff, bytes);

			break;

		}

		memcpy(data, buff, PAGE_CACHE_SIZE);

		buff += PAGE_CACHE_SIZE;

		bytes -= PAGE_CACHE_SIZE;

		data = squashfs_next_page(output);

	}

	squashfs_finish_page(output);

	return dest_len;

}

const struct squashfs_decompressor squashfs_lz4_comp_ops = {

	.init = lz4_init,

	.comp_opts = lz4_comp_opts,

	.free = lz4_free,

	.decompress = lz4_uncompress,

	.id = LZ4_COMPRESSION,

	.name = "lz4",

	.supported = 1

};

#define LZMA_COMPRESSION	2

#define LZO_COMPRESSION		3

#define XZ_COMPRESSION		4

#define LZ4_COMPRESSION		5

struct squashfs_super_block {

	__le32			s_magic;