Commit 82fbd6a3 authored by Eric Biggers's avatar Eric Biggers Committed by Mikulas Patocka
Browse files

dm-verity-fec: replace {MAX,MIN}_RSN with {MIN,MAX}_ROOTS 



Every time DM_VERITY_FEC_{MAX,MIN}_RSN are used, they are subtracted
from DM_VERITY_FEC_RSM to get the bounds on the number of roots.
Therefore, replace these with {MIN,MAX}_ROOTS constants which are more
directly useful.  (Note the inversion, where MAX_RSN maps to MIN_ROOTS
and MIN_RSN maps to MAX_ROOTS.)  No functional change.

Signed-off-by: default avatarEric Biggers <ebiggers@kernel.org>
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
parent 05777b28

drivers/md/dm-verity-fec.c

+3 −3
Original line number Diff line number Diff line
@@ -73,7 +73,7 @@ static int fec_decode_bufs(struct dm_verity *v, struct dm_verity_io *io, 
	int r, corrected = 0, res;

	struct dm_buffer *buf;

	unsigned int n, i, j, parity_pos, to_copy;

	uint16_t par_buf[DM_VERITY_FEC_RSM - DM_VERITY_FEC_MIN_RSN];

	uint16_t par_buf[DM_VERITY_FEC_MAX_ROOTS];

	u8 *par, *block;

	u64 parity_block;

	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
@@ -572,8 +572,8 @@ int verity_fec_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, 


	} else if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_ROOTS)) {

		if (sscanf(arg_value, "%hhu%c", &num_c, &dummy) != 1 || !num_c ||

		    num_c < (DM_VERITY_FEC_RSM - DM_VERITY_FEC_MAX_RSN) ||

		    num_c > (DM_VERITY_FEC_RSM - DM_VERITY_FEC_MIN_RSN)) {

		    num_c < DM_VERITY_FEC_MIN_ROOTS ||

		    num_c > DM_VERITY_FEC_MAX_ROOTS) {

			ti->error = "Invalid " DM_VERITY_OPT_FEC_ROOTS;

			return -EINVAL;

		}

drivers/md/dm-verity-fec.h

+3 −4
Original line number Diff line number Diff line
@@ -13,8 +13,8 @@ 


/* 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 */

#define DM_VERITY_FEC_MIN_ROOTS	2	/* RS(255, 253): ~0.8% space overhead */

#define DM_VERITY_FEC_MAX_ROOTS	24	/* RS(255, 231): ~10% space overhead */



/* buffers for deinterleaving and decoding */

#define DM_VERITY_FEC_BUF_RS_BITS	4	/* 1 << RS blocks per buffer */
@@ -47,8 +47,7 @@ struct dm_verity_fec { 
/* per-bio data */

struct dm_verity_fec_io {

	struct rs_control *rs;	/* Reed-Solomon state */

	/* erasures for decode_rs8 */

	int erasures[DM_VERITY_FEC_RSM - DM_VERITY_FEC_MIN_RSN + 1];

	int erasures[DM_VERITY_FEC_MAX_ROOTS + 1]; /* erasures for decode_rs8 */

	u8 *output;		/* buffer for corrected output */

	unsigned int level;		/* recursion level */

	unsigned int nbufs;		/* number of buffers allocated */