2 * Copyright (C) 2015 Google, Inc.
4 * Author: Sami Tolvanen <samitolvanen@google.com>
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)
12 #ifndef DM_VERITY_FEC_H
13 #define DM_VERITY_FEC_H
15 #include "dm-verity.h"
16 #include <linux/rslib.h>
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 */
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))
30 /* maximum recursion level for verity_fec_decode */
31 #define DM_VERITY_FEC_MAX_RECURSION 4
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"
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 size_t io_size; /* IO size for roots */
44 sector_t start; /* parity data start in blocks */
45 sector_t blocks; /* number of blocks covered */
46 sector_t rounds; /* number of interleaving rounds */
47 sector_t hash_blocks; /* blocks covered after v->hash_start */
48 unsigned char roots; /* number of parity bytes, M-N of RS(M, N) */
49 unsigned char rsn; /* N of RS(M, N) */
50 mempool_t rs_pool; /* mempool for fio->rs */
51 mempool_t prealloc_pool; /* mempool for preallocated buffers */
52 mempool_t extra_pool; /* mempool for extra buffers */
53 mempool_t output_pool; /* mempool for output */
54 struct kmem_cache *cache; /* cache for buffers */
58 struct dm_verity_fec_io {
59 struct rs_control *rs; /* Reed-Solomon state */
60 int erasures[DM_VERITY_FEC_MAX_RSN]; /* erasures for decode_rs8 */
61 u8 *bufs[DM_VERITY_FEC_BUF_MAX]; /* bufs for deinterleaving */
62 unsigned nbufs; /* number of buffers allocated */
63 u8 *output; /* buffer for corrected output */
65 unsigned level; /* recursion level */
68 #ifdef CONFIG_DM_VERITY_FEC
70 /* each feature parameter requires a value */
71 #define DM_VERITY_OPTS_FEC 8
73 extern bool verity_fec_is_enabled(struct dm_verity *v);
75 extern int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io,
76 enum verity_block_type type, sector_t block,
77 u8 *dest, struct bvec_iter *iter);
79 extern unsigned verity_fec_status_table(struct dm_verity *v, unsigned sz,
80 char *result, unsigned maxlen);
82 extern void verity_fec_finish_io(struct dm_verity_io *io);
83 extern void verity_fec_init_io(struct dm_verity_io *io);
85 extern bool verity_is_fec_opt_arg(const char *arg_name);
86 extern int verity_fec_parse_opt_args(struct dm_arg_set *as,
87 struct dm_verity *v, unsigned *argc,
88 const char *arg_name);
90 extern void verity_fec_dtr(struct dm_verity *v);
92 extern int verity_fec_ctr_alloc(struct dm_verity *v);
93 extern int verity_fec_ctr(struct dm_verity *v);
95 #else /* !CONFIG_DM_VERITY_FEC */
97 #define DM_VERITY_OPTS_FEC 0
99 static inline bool verity_fec_is_enabled(struct dm_verity *v)
104 static inline int verity_fec_decode(struct dm_verity *v,
105 struct dm_verity_io *io,
106 enum verity_block_type type,
107 sector_t block, u8 *dest,
108 struct bvec_iter *iter)
113 static inline unsigned verity_fec_status_table(struct dm_verity *v,
114 unsigned sz, char *result,
120 static inline void verity_fec_finish_io(struct dm_verity_io *io)
124 static inline void verity_fec_init_io(struct dm_verity_io *io)
128 static inline bool verity_is_fec_opt_arg(const char *arg_name)
133 static inline int verity_fec_parse_opt_args(struct dm_arg_set *as,
136 const char *arg_name)
141 static inline void verity_fec_dtr(struct dm_verity *v)
145 static inline int verity_fec_ctr_alloc(struct dm_verity *v)
150 static inline int verity_fec_ctr(struct dm_verity *v)
155 #endif /* CONFIG_DM_VERITY_FEC */
157 #endif /* DM_VERITY_FEC_H */