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gerrit-public.fairphone.software / kernel / msm-4.19 / bbbe775ec5b5dace43a35886da9924837da09ddd / . / drivers / md / dm-verity-fec.h
blob: 7fa0298b995e9e3f1ac25c2356c758fad8b65d34 [file] [log] [blame]
Sami Tolvanena739ff32015-12-03 14:26:30 +0000[diff] [blame]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 */
36struct 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 */
54struct 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
68extern bool verity_fec_is_enabled(struct dm_verity *v);
69
70extern 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
74extern unsigned verity_fec_status_table(struct dm_verity *v, unsigned sz,
75 char *result, unsigned maxlen);
76
77extern void verity_fec_finish_io(struct dm_verity_io *io);
78extern void verity_fec_init_io(struct dm_verity_io *io);
79
80extern bool verity_is_fec_opt_arg(const char *arg_name);
81extern int verity_fec_parse_opt_args(struct dm_arg_set *as,
82 struct dm_verity *v, unsigned *argc,
83 const char *arg_name);
84
85extern void verity_fec_dtr(struct dm_verity *v);
86
87extern int verity_fec_ctr_alloc(struct dm_verity *v);
88extern int verity_fec_ctr(struct dm_verity *v);
89
90#else /* !CONFIG_DM_VERITY_FEC */
91
92#define DM_VERITY_OPTS_FEC 0
93
94static inline bool verity_fec_is_enabled(struct dm_verity *v)
95{
96 return false;
97}
98
99static 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
108static inline unsigned verity_fec_status_table(struct dm_verity *v,
109 unsigned sz, char *result,
110 unsigned maxlen)
111{
112 return sz;
113}
114
115static inline void verity_fec_finish_io(struct dm_verity_io *io)
116{
117}
118
119static inline void verity_fec_init_io(struct dm_verity_io *io)
120{
121}
122
123static inline bool verity_is_fec_opt_arg(const char *arg_name)
124{
125 return false;
126}
127
128static 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
136static inline void verity_fec_dtr(struct dm_verity *v)
137{
138}
139
140static inline int verity_fec_ctr_alloc(struct dm_verity *v)
141{
142 return 0;
143}
144
145static 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 */