summaryrefslogtreecommitdiffstats
path: root/drivers/md/dm-verity-fec.h
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/md/dm-verity-fec.h')
-rw-r--r--drivers/md/dm-verity-fec.h152
1 files changed, 152 insertions, 0 deletions
diff --git a/drivers/md/dm-verity-fec.h b/drivers/md/dm-verity-fec.h
new file mode 100644
index 000000000000..7fa0298b995e
--- /dev/null
+++ b/drivers/md/dm-verity-fec.h
@@ -0,0 +1,152 @@
+/*
+ * 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))
+
+#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;
+};
+
+#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 */