To compute 'rsb', verity_fec_decode() divides 'offset' by 'v->fec->region_blocks << v->data_dev_block_bits', then subtracts the quotient times that divisor. That's simply the long way to do a modulo operation, i.e. a - b * floor(a / b) instead of just a % b. Use div64_u64_rem() to get the remainder more concisely.
Signed-off-by: Eric Biggers <[email protected]> --- drivers/md/dm-verity-fec.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/md/dm-verity-fec.c b/drivers/md/dm-verity-fec.c index 28b47497c3d3f..63eeef26a3999 100644 --- a/drivers/md/dm-verity-fec.c +++ b/drivers/md/dm-verity-fec.c @@ -375,11 +375,11 @@ int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io, enum verity_block_type type, const u8 *want_digest, sector_t block, u8 *dest) { int r; struct dm_verity_fec_io *fio; - u64 offset, res, rsb; + u64 offset, rsb; if (!verity_fec_is_enabled(v)) return -EOPNOTSUPP; fio = io->fec_io; @@ -403,17 +403,17 @@ int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io, * and each code is interleaved over k blocks to make it less likely * that bursty corruption will leave us in unrecoverable state. */ offset = block << v->data_dev_block_bits; - res = div64_u64(offset, v->fec->region_blocks << v->data_dev_block_bits); /* * The base RS block we can feed to the interleaver to find out all * blocks required for decoding. */ - rsb = offset - res * (v->fec->region_blocks << v->data_dev_block_bits); + div64_u64_rem(offset, v->fec->region_blocks << v->data_dev_block_bits, + &rsb); /* * Locating erasures is slow, so attempt to recover the block without * them first. Do a second attempt with erasures if the corruption is * bad enough. -- 2.52.0
