/* * 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 */