linux-imx

/*

 * Copyright (C) 2015 Google, Inc.

 *

 * Author: Sami Tolvanen <samitolvanen@google.com>

 *

 * 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 of the License, or (at your option)

 * any later version.

 */

​

#ifndef DM_VERITY_FEC_H

#define DM_VERITY_FEC_H

​

#include "dm-verity.h"

#include <linux/rslib.h>

​

/* Reed-Solomon(M, N) parameters */

#define DM_VERITY_FEC_RSM       255

#define DM_VERITY_FEC_MAX_RSN       253

#define DM_VERITY_FEC_MIN_RSN       231 /* ~10% space overhead */

​

/* buffers for deinterleaving and decoding */

#define DM_VERITY_FEC_BUF_PREALLOC  1   /* buffers to preallocate */

#define DM_VERITY_FEC_BUF_RS_BITS   4   /* 1 << RS blocks per buffer */

/* we need buffers for at most 1 << block size RS blocks */

#define DM_VERITY_FEC_BUF_MAX \

    (1 << (PAGE_SHIFT - DM_VERITY_FEC_BUF_RS_BITS))

​

/* maximum recursion level for verity_fec_decode */

#define DM_VERITY_FEC_MAX_RECURSION 4

​

#define DM_VERITY_OPT_FEC_DEV       "use_fec_from_device"

#define DM_VERITY_OPT_FEC_BLOCKS    "fec_blocks"

#define DM_VERITY_OPT_FEC_START     "fec_start"

#define DM_VERITY_OPT_FEC_ROOTS     "fec_roots"

​

/* configuration */

struct dm_verity_fec {

    struct dm_dev *dev; /* parity data device */

    struct dm_bufio_client *data_bufio; /* for data dev access */

    struct dm_bufio_client *bufio;      /* for parity data access */

    sector_t start;     /* parity data start in blocks */

    sector_t blocks;    /* number of blocks covered */

    sector_t rounds;    /* number of interleaving rounds */

    sector_t hash_blocks;   /* blocks covered after v->hash_start */

    unsigned char roots;    /* number of parity bytes, M-N of RS(M, N) */

    unsigned char rsn;  /* N of RS(M, N) */

    mempool_t rs_pool;  /* mempool for fio->rs */

    mempool_t prealloc_pool;    /* mempool for preallocated buffers */

    mempool_t extra_pool;   /* mempool for extra buffers */

    mempool_t output_pool;  /* mempool for output */

    struct kmem_cache *cache;   /* cache for buffers */

};

​

/* per-bio data */

struct dm_verity_fec_io {

    struct rs_control *rs;  /* Reed-Solomon state */

    int erasures[DM_VERITY_FEC_MAX_RSN];    /* erasures for decode_rs8 */

    u8 *bufs[DM_VERITY_FEC_BUF_MAX];    /* bufs for deinterleaving */

    unsigned nbufs;     /* number of buffers allocated */

    u8 *output;     /* buffer for corrected output */

    size_t output_pos;