[mirror_ubuntu-bionic-kernel.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))

/* 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 */
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
f1a880a9 ST	30	/* maximum recursion level for verity_fec_decode */
	31	#define DM_VERITY_FEC_MAX_RECURSION 4
	32
a739ff3f ST	33	#define DM_VERITY_OPT_FEC_DEV "use_fec_from_device"
	34	#define DM_VERITY_OPT_FEC_BLOCKS "fec_blocks"
	35	#define DM_VERITY_OPT_FEC_START "fec_start"
	36	#define DM_VERITY_OPT_FEC_ROOTS "fec_roots"
	37
	38	/* configuration */
	39	struct dm_verity_fec {
	40	struct dm_dev dev; / parity data device */
	41	struct dm_bufio_client data_bufio; / for data dev access */
	42	struct dm_bufio_client bufio; / for parity data access */
	43	sector_t start; /* parity data start in blocks */
	44	sector_t blocks; /* number of blocks covered */
	45	sector_t rounds; /* number of interleaving rounds */
	46	sector_t hash_blocks; /* blocks covered after v->hash_start */
	47	unsigned char roots; /* number of parity bytes, M-N of RS(M, N) */
	48	unsigned char rsn; /* N of RS(M, N) */
	49	mempool_t rs_pool; / mempool for fio->rs */
	50	mempool_t prealloc_pool; / mempool for preallocated buffers */
	51	mempool_t extra_pool; / mempool for extra buffers */
	52	mempool_t output_pool; / mempool for output */
	53	struct kmem_cache cache; / cache for buffers */
	54	};
	55
	56	/* per-bio data */
	57	struct dm_verity_fec_io {
	58	struct rs_control rs; / Reed-Solomon state */
	59	int erasures[DM_VERITY_FEC_MAX_RSN]; /* erasures for decode_rs8 */
	60	u8 bufs[DM_VERITY_FEC_BUF_MAX]; / bufs for deinterleaving */
	61	unsigned nbufs; /* number of buffers allocated */
	62	u8 output; / buffer for corrected output */
	63	size_t output_pos;
f1a880a9	64	unsigned level; /* recursion level */
a739ff3f ST	65	};
	66
	67	#ifdef CONFIG_DM_VERITY_FEC
	68
	69	/* each feature parameter requires a value */
	70	#define DM_VERITY_OPTS_FEC 8
	71
	72	extern bool verity_fec_is_enabled(struct dm_verity *v);
	73
	74	extern int verity_fec_decode(struct dm_verity v, struct dm_verity_io io,
	75	enum verity_block_type type, sector_t block,
	76	u8 dest, struct bvec_iter iter);
	77
	78	extern unsigned verity_fec_status_table(struct dm_verity *v, unsigned sz,
	79	char *result, unsigned maxlen);
	80
	81	extern void verity_fec_finish_io(struct dm_verity_io *io);
	82	extern void verity_fec_init_io(struct dm_verity_io *io);
	83
	84	extern bool verity_is_fec_opt_arg(const char *arg_name);
	85	extern int verity_fec_parse_opt_args(struct dm_arg_set *as,
	86	struct dm_verity v, unsigned argc,
	87	const char *arg_name);
	88
	89	extern void verity_fec_dtr(struct dm_verity *v);
	90
	91	extern int verity_fec_ctr_alloc(struct dm_verity *v);
	92	extern int verity_fec_ctr(struct dm_verity *v);
	93
	94	#else /* !CONFIG_DM_VERITY_FEC */
	95
	96	#define DM_VERITY_OPTS_FEC 0
	97
	98	static inline bool verity_fec_is_enabled(struct dm_verity *v)
	99	{
	100	return false;
	101	}
	102
	103	static inline int verity_fec_decode(struct dm_verity *v,
	104	struct dm_verity_io *io,
	105	enum verity_block_type type,
	106	sector_t block, u8 *dest,
	107	struct bvec_iter *iter)
	108	{
	109	return -EOPNOTSUPP;
	110	}
	111
	112	static inline unsigned verity_fec_status_table(struct dm_verity *v,
	113	unsigned sz, char *result,
	114	unsigned maxlen)
	115	{
	116	return sz;
	117	}
	118
	119	static inline void verity_fec_finish_io(struct dm_verity_io *io)
	120	{
	121	}
	122
	123	static inline void verity_fec_init_io(struct dm_verity_io *io)
	124	{
	125	}
	126
	127	static inline bool verity_is_fec_opt_arg(const char *arg_name)
	128	{
129	return false;
130	}
131
132	static inline int verity_fec_parse_opt_args(struct dm_arg_set *as,
133	struct dm_verity *v,
134	unsigned *argc,
135	const char *arg_name)
136	{
137	return -EINVAL;
138	}
139
140	static inline void verity_fec_dtr(struct dm_verity *v)
141	{
142	}
143
144	static inline int verity_fec_ctr_alloc(struct dm_verity *v)
145	{
146	return 0;
147	}
148
149	static inline int verity_fec_ctr(struct dm_verity *v)
150	{
151	return 0;
152	}
153
154	#endif /* CONFIG_DM_VERITY_FEC */
155
156	#endif /* DM_VERITY_FEC_H */