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fsverity: store log2(digest_size) precomputed

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Add log_digestsize to struct merkle_tree_params so that it can be used
in verify.c.  Also save memory by using u8 for all the log_* fields.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Andrey Albershteyn <aalbersh@redhat.com>
Tested-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/20221223203638.41293-4-ebiggers@kernel.org
This commit is contained in:
Eric Biggers 2022-12-23 12:36:30 -08:00
parent 9098f36b73
commit 579a12f78d
3 changed files with 6 additions and 4 deletions
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5
fs/verity/fsverity_private.h
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@ -42,8 +42,9 @@ struct merkle_tree_params {
unsigned int digest_size; /* same as hash_alg->digest_size */
unsigned int block_size; /* size of data and tree blocks */
unsigned int hashes_per_block; /* number of hashes per tree block */
unsigned int log_blocksize; /* log2(block_size) */
unsigned int log_arity; /* log2(hashes_per_block) */
u8 log_digestsize; /* log2(digest_size) */
u8 log_blocksize; /* log2(block_size) */
u8 log_arity; /* log2(hashes_per_block) */
unsigned int num_levels; /* number of levels in Merkle tree */
u64 tree_size; /* Merkle tree size in bytes */
unsigned long tree_pages; /* Merkle tree size in pages */

3
fs/verity/open.c
View file

@ -76,7 +76,8 @@ int fsverity_init_merkle_tree_params(struct merkle_tree_params *params,
err = -EINVAL;
goto out_err;
}
params->log_arity = params->log_blocksize - ilog2(params->digest_size);
params->log_digestsize = ilog2(params->digest_size);
params->log_arity = log_blocksize - params->log_digestsize;
params->hashes_per_block = 1 << params->log_arity;
/*

2
fs/verity/verify.c
View file

@ -35,7 +35,7 @@ static void hash_at_level(const struct merkle_tree_params *params,
/* Offset of the wanted hash (in bytes) within the hash block */
*hoffset = (position & ((1 << params->log_arity) - 1)) <<
(params->log_blocksize - params->log_arity);
params->log_digestsize;
}
static inline int cmp_hashes(const struct fsverity_info *vi,