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/*
* 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;
unsigned level; /* recursion level */
};
#ifdef CONFIG_DM_VERITY_FEC
/* each feature parameter requires a value */
#define DM_VERITY_OPTS_FEC 8
extern bool verity_fec_is_enabled(struct dm_verity *v);
extern int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io,
enum verity_block_type type, sector_t block,
u8 *dest, struct bvec_iter *iter);
extern unsigned verity_fec_status_table(struct dm_verity *v, unsigned sz,
char *result, unsigned maxlen);
extern void verity_fec_finish_io(struct dm_verity_io *io);
extern void verity_fec_init_io(struct dm_verity_io *io);
extern bool verity_is_fec_opt_arg(const char *arg_name);
extern int verity_fec_parse_opt_args(struct dm_arg_set *as,
struct dm_verity *v, unsigned *argc,
const char *arg_name);
extern void verity_fec_dtr(struct dm_verity *v);
extern int verity_fec_ctr_alloc(struct dm_verity *v);
extern int verity_fec_ctr(struct dm_verity *v);
#else /* !CONFIG_DM_VERITY_FEC */
#define DM_VERITY_OPTS_FEC 0
static inline bool verity_fec_is_enabled(struct dm_verity *v)
{
return false;
}
static inline int verity_fec_decode(struct dm_verity *v,
struct dm_verity_io *io,
enum verity_block_type type,
sector_t block, u8 *dest,
struct bvec_iter *iter)
{
return -EOPNOTSUPP;
}
static inline unsigned verity_fec_status_table(struct dm_verity *v,
unsigned sz, char *result,
unsigned maxlen)
{
return sz;
}
static inline void verity_fec_finish_io(struct dm_verity_io *io)
{
}
static inline void verity_fec_init_io(struct dm_verity_io *io)
{
}
static inline bool verity_is_fec_opt_arg(const char *arg_name)
{
return false;
}
static inline int verity_fec_parse_opt_args(struct dm_arg_set *as,
struct dm_verity *v,
unsigned *argc,
const char *arg_name)
{
return -EINVAL;
}
static inline void verity_fec_dtr(struct dm_verity *v)
{
}
static inline int verity_fec_ctr_alloc(struct dm_verity *v)
{
return 0;
}
static inline int verity_fec_ctr(struct dm_verity *v)
{
return 0;
}
#endif /* CONFIG_DM_VERITY_FEC */
#endif /* DM_VERITY_FEC_H */
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