[linux-2.6-block.git] / drivers / md / dm-verity-fec.h

/*
 * 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))

#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;
};

#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 */
Commit	Line	Data
a739ff3f ST	1	/*
	2	* Copyright (C) 2015 Google, Inc.
	3	*
	4	* Author: Sami Tolvanen <samitolvanen@google.com>
	5	*
	6	* This program is free software; you can redistribute it and/or modify it
	7	* under the terms of the GNU General Public License as published by the Free
	8	* Software Foundation; either version 2 of the License, or (at your option)
	9	* any later version.
	10	*/
	11
	12	#ifndef DM_VERITY_FEC_H
	13	#define DM_VERITY_FEC_H
	14
	15	#include "dm-verity.h"
	16	#include <linux/rslib.h>
	17
	18	/* Reed-Solomon(M, N) parameters */
	19	#define DM_VERITY_FEC_RSM 255
	20	#define DM_VERITY_FEC_MAX_RSN 253
	21	#define DM_VERITY_FEC_MIN_RSN 231 /* ~10% space overhead */
	22
	23	/* buffers for deinterleaving and decoding */
	24	#define DM_VERITY_FEC_BUF_PREALLOC 1 /* buffers to preallocate */
	25	#define DM_VERITY_FEC_BUF_RS_BITS 4 /* 1 << RS blocks per buffer */
	26	/* we need buffers for at most 1 << block size RS blocks */
	27	#define DM_VERITY_FEC_BUF_MAX \
	28	(1 << (PAGE_SHIFT - DM_VERITY_FEC_BUF_RS_BITS))
	29
	30	#define DM_VERITY_OPT_FEC_DEV "use_fec_from_device"
	31	#define DM_VERITY_OPT_FEC_BLOCKS "fec_blocks"
	32	#define DM_VERITY_OPT_FEC_START "fec_start"
	33	#define DM_VERITY_OPT_FEC_ROOTS "fec_roots"
	34
	35	/* configuration */
	36	struct dm_verity_fec {
	37	struct dm_dev dev; / parity data device */
	38	struct dm_bufio_client data_bufio; / for data dev access */
	39	struct dm_bufio_client bufio; / for parity data access */
	40	sector_t start; /* parity data start in blocks */
	41	sector_t blocks; /* number of blocks covered */
	42	sector_t rounds; /* number of interleaving rounds */
	43	sector_t hash_blocks; /* blocks covered after v->hash_start */
	44	unsigned char roots; /* number of parity bytes, M-N of RS(M, N) */
	45	unsigned char rsn; /* N of RS(M, N) */
	46	mempool_t rs_pool; / mempool for fio->rs */
	47	mempool_t prealloc_pool; / mempool for preallocated buffers */
	48	mempool_t extra_pool; / mempool for extra buffers */
	49	mempool_t output_pool; / mempool for output */
	50	struct kmem_cache cache; / cache for buffers */
	51	};
	52
	53	/* per-bio data */
	54	struct dm_verity_fec_io {
	55	struct rs_control rs; / Reed-Solomon state */
	56	int erasures[DM_VERITY_FEC_MAX_RSN]; /* erasures for decode_rs8 */
	57	u8 bufs[DM_VERITY_FEC_BUF_MAX]; / bufs for deinterleaving */
	58	unsigned nbufs; /* number of buffers allocated */
	59	u8 output; / buffer for corrected output */
	60	size_t output_pos;
	61	};
	62
	63	#ifdef CONFIG_DM_VERITY_FEC
	64
65	/* each feature parameter requires a value */
66	#define DM_VERITY_OPTS_FEC 8
67
68	extern bool verity_fec_is_enabled(struct dm_verity *v);
69
70	extern int verity_fec_decode(struct dm_verity v, struct dm_verity_io io,
71	enum verity_block_type type, sector_t block,
72	u8 dest, struct bvec_iter iter);
73
74	extern unsigned verity_fec_status_table(struct dm_verity *v, unsigned sz,
75	char *result, unsigned maxlen);
76
77	extern void verity_fec_finish_io(struct dm_verity_io *io);
78	extern void verity_fec_init_io(struct dm_verity_io *io);
79
80	extern bool verity_is_fec_opt_arg(const char *arg_name);
81	extern int verity_fec_parse_opt_args(struct dm_arg_set *as,
82	struct dm_verity v, unsigned argc,
83	const char *arg_name);
84
85	extern void verity_fec_dtr(struct dm_verity *v);
86
87	extern int verity_fec_ctr_alloc(struct dm_verity *v);
88	extern int verity_fec_ctr(struct dm_verity *v);
89
90	#else /* !CONFIG_DM_VERITY_FEC */
91
92	#define DM_VERITY_OPTS_FEC 0
93
94	static inline bool verity_fec_is_enabled(struct dm_verity *v)
95	{
96	return false;
97	}
98
99	static inline int verity_fec_decode(struct dm_verity *v,
100	struct dm_verity_io *io,
101	enum verity_block_type type,
102	sector_t block, u8 *dest,
103	struct bvec_iter *iter)
104	{
105	return -EOPNOTSUPP;
106	}
107
108	static inline unsigned verity_fec_status_table(struct dm_verity *v,
109	unsigned sz, char *result,
110	unsigned maxlen)
111	{
112	return sz;
113	}
114
115	static inline void verity_fec_finish_io(struct dm_verity_io *io)
116	{
117	}
118
119	static inline void verity_fec_init_io(struct dm_verity_io *io)
120	{
121	}
122
123	static inline bool verity_is_fec_opt_arg(const char *arg_name)
124	{
125	return false;
126	}
127
128	static inline int verity_fec_parse_opt_args(struct dm_arg_set *as,
129	struct dm_verity *v,
130	unsigned *argc,
131	const char *arg_name)
132	{
133	return -EINVAL;
134	}
135
136	static inline void verity_fec_dtr(struct dm_verity *v)
137	{
138	}
139
140	static inline int verity_fec_ctr_alloc(struct dm_verity *v)
141	{
142	return 0;
143	}
144
145	static inline int verity_fec_ctr(struct dm_verity *v)
146	{
147	return 0;
148	}
149
150	#endif /* CONFIG_DM_VERITY_FEC */
151
152	#endif /* DM_VERITY_FEC_H */