From bbf6a566920e1b0244b27b5f9882fb7f8bc83a31 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Wed, 5 Dec 2018 20:54:13 -0800 Subject: [PATCH] dm verity: log the hash algorithm implementation Log the hash algorithm's driver name when a dm-verity target is created. This will help people determine whether the expected implementation is being used. It can make an enormous difference; e.g., SHA-256 on ARM can be 8x faster with the crypto extensions than without. It can also be useful to know if an implementation using an external crypto accelerator is being used instead of a software implementation. Example message: [ 35.281945] device-mapper: verity: sha256 using implementation "sha256-ce" We've already found the similar message in fs/crypto/keyinfo.c to be very useful. Signed-off-by: Eric Biggers Signed-off-by: Mike Snitzer --- drivers/md/dm-verity-target.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c index fc65f0d..f4c31ff 100644 --- a/drivers/md/dm-verity-target.c +++ b/drivers/md/dm-verity-target.c @@ -1040,6 +1040,15 @@ static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv) v->tfm = NULL; goto bad; } + + /* + * dm-verity performance can vary greatly depending on which hash + * algorithm implementation is used. Help people debug performance + * problems by logging the ->cra_driver_name. + */ + DMINFO("%s using implementation \"%s\"", v->alg_name, + crypto_hash_alg_common(v->tfm)->base.cra_driver_name); + v->digest_size = crypto_ahash_digestsize(v->tfm); if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { ti->error = "Digest size too big"; -- 2.7.4