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
16 #include "dm-verity.h"
17 #include <linux/rslib.h>
19 /* Reed-Solomon(M, N) parameters */
20 #define DM_VERITY_FEC_RSM 255
21 #define DM_VERITY_FEC_MAX_RSN 253
22 #define DM_VERITY_FEC_MIN_RSN 231 /* ~10% space overhead */
24 /* buffers for deinterleaving and decoding */
25 #define DM_VERITY_FEC_BUF_PREALLOC 1 /* buffers to preallocate */
26 #define DM_VERITY_FEC_BUF_RS_BITS 4 /* 1 << RS blocks per buffer */
27 /* we need buffers for at most 1 << block size RS blocks */
28 #define DM_VERITY_FEC_BUF_MAX \
29 (1 << (PAGE_SHIFT - DM_VERITY_FEC_BUF_RS_BITS))
31 #define DM_VERITY_OPT_FEC_DEV "use_fec_from_device"
32 #define DM_VERITY_OPT_FEC_BLOCKS "fec_blocks"
33 #define DM_VERITY_OPT_FEC_START "fec_start"
34 #define DM_VERITY_OPT_FEC_ROOTS "fec_roots"
37 struct dm_verity_fec {
38 struct dm_dev *dev; /* parity data device */
39 struct dm_bufio_client *data_bufio; /* for data dev access */
40 struct dm_bufio_client *bufio; /* for parity data access */
41 sector_t start; /* parity data start in blocks */
42 sector_t blocks; /* number of blocks covered */
43 sector_t rounds; /* number of interleaving rounds */
44 sector_t hash_blocks; /* blocks covered after v->hash_start */
45 unsigned char roots; /* number of parity bytes, M-N of RS(M, N) */
46 unsigned char rsn; /* N of RS(M, N) */
47 mempool_t *rs_pool; /* mempool for fio->rs */
48 mempool_t *prealloc_pool; /* mempool for preallocated buffers */
49 mempool_t *extra_pool; /* mempool for extra buffers */
50 mempool_t *output_pool; /* mempool for output */
51 struct kmem_cache *cache; /* cache for buffers */
52 atomic_t corrected; /* corrected errors */
53 struct dm_kobject_holder kobj_holder; /* for sysfs attributes */
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 */
66 #ifdef CONFIG_DM_VERITY_FEC
68 /* each feature parameter requires a value */
69 #define DM_VERITY_OPTS_FEC 8
71 extern bool verity_fec_is_enabled(struct dm_verity *v);
73 extern int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io,
74 enum verity_block_type type, sector_t block,
75 u8 *dest, struct bvec_iter *iter);
77 extern unsigned verity_fec_status_table(struct dm_verity *v, unsigned sz,
78 char *result, unsigned maxlen);
80 extern void verity_fec_finish_io(struct dm_verity_io *io);
81 extern void verity_fec_init_io(struct dm_verity_io *io);
83 extern bool verity_is_fec_opt_arg(const char *arg_name);
84 extern int verity_fec_parse_opt_args(struct dm_arg_set *as,
85 struct dm_verity *v, unsigned *argc,
86 const char *arg_name);
88 extern void verity_fec_dtr(struct dm_verity *v);
90 extern int verity_fec_ctr_alloc(struct dm_verity *v);
91 extern int verity_fec_ctr(struct dm_verity *v);
93 #else /* !CONFIG_DM_VERITY_FEC */
95 #define DM_VERITY_OPTS_FEC 0
97 static inline bool verity_fec_is_enabled(struct dm_verity *v)
102 static inline int verity_fec_decode(struct dm_verity *v,
103 struct dm_verity_io *io,
104 enum verity_block_type type,
105 sector_t block, u8 *dest,
106 struct bvec_iter *iter)
111 static inline unsigned verity_fec_status_table(struct dm_verity *v,
112 unsigned sz, char *result,
118 static inline void verity_fec_finish_io(struct dm_verity_io *io)
122 static inline void verity_fec_init_io(struct dm_verity_io *io)
126 static inline bool verity_is_fec_opt_arg(const char *arg_name)
131 static inline int verity_fec_parse_opt_args(struct dm_arg_set *as,
134 const char *arg_name)
139 static inline void verity_fec_dtr(struct dm_verity *v)
143 static inline int verity_fec_ctr_alloc(struct dm_verity *v)
148 static inline int verity_fec_ctr(struct dm_verity *v)
153 #endif /* CONFIG_DM_VERITY_FEC */
155 #endif /* DM_VERITY_FEC_H */