Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit ff750311 authored by Phillip Lougher's avatar Phillip Lougher
Browse files

Squashfs: add compression options support to xz decompressor 



Pass the dictionary size used to compress datablocks.  Using a
dictionary size less than the block size saves memory overhead, in many
cases without adversely affecting compression ratio.

Signed-off-by: default avatarPhillip Lougher <phillip@lougher.demon.co.uk>
parent b7fc0ff0

fs/squashfs/xz_wrapper.c

+41 −8
Original line number Original line Diff line number Diff line
@@ -26,6 +26,7 @@ 
#include <linux/buffer_head.h>

#include <linux/buffer_head.h>

#include <linux/slab.h>

#include <linux/slab.h>

#include <linux/xz.h>

#include <linux/xz.h>

#include <linux/bitops.h>





#include "squashfs_fs.h"

#include "squashfs_fs.h"

#include "squashfs_fs_sb.h"

#include "squashfs_fs_sb.h"
@@ -38,25 +39,57 @@ struct squashfs_xz { 
	struct xz_buf buf;

	struct xz_buf buf;

};

};





struct comp_opts {

	__le32 dictionary_size;

	__le32 flags;

};



static void *squashfs_xz_init(struct squashfs_sb_info *msblk, void *buff,

static void *squashfs_xz_init(struct squashfs_sb_info *msblk, void *buff,

	int len)

	int len)

{

{

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

	struct comp_opts *comp_opts = buff;

	struct squashfs_xz *stream;

	int dict_size = msblk->block_size;

	int err, n;



	if (comp_opts) {

		/* check compressor options are the expected length */

		if (len < sizeof(*comp_opts)) {

			err = -EIO;

			goto failed;

		}



		dict_size = le32_to_cpu(comp_opts->dictionary_size);



		/* the dictionary size should be 2^n or 2^n+2^(n+1) */

		n = ffs(dict_size) - 1;

		if (dict_size != (1 << n) && dict_size != (1 << n) +

						(1 << (n + 1))) {

			err = -EIO;

			goto failed;

		}

	}





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

	dict_size = max_t(int, dict_size, SQUASHFS_METADATA_SIZE);

	if (stream == NULL)



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

	if (stream == NULL) {

		err = -ENOMEM;

		goto failed;

		goto failed;

	}





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

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

	if (stream->state == NULL)

	if (stream->state == NULL) {

		kfree(stream);

		err = -ENOMEM;

		goto failed;

		goto failed;

	}





	return stream;

	return stream;





failed:

failed:

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

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

	kfree(stream);

	return ERR_PTR(err);

	return ERR_PTR(-ENOMEM);

}

}