Commit 9c06a46f authored by Phillip Lougher's avatar Phillip Lougher

Squashfs: add LZ4 compression support

Add support for reading file systems compressed with the
LZ4 compression algorithm.

This patch adds the LZ4 decompressor wrapper code.
Signed-off-by: 's avatarPhillip Lougher <phillip@squashfs.org.uk>
parent 5d01410f
/*
* 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
};
......@@ -240,6 +240,7 @@ struct meta_index {
#define LZMA_COMPRESSION 2
#define LZO_COMPRESSION 3
#define XZ_COMPRESSION 4
#define LZ4_COMPRESSION 5
struct squashfs_super_block {
__le32 s_magic;
......
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