tree 1de5689485baeaac6b66822c57a519021a203469
parent fd39073dba8632575b920edefba2577e1b84262a
author Eric Biggers <ebiggers@google.com> 1577814945 -0600
committer Eric Biggers <ebiggers@google.com> 1579037285 -0800

fs-verity: use mempool for hash requests

When initializing an fs-verity hash algorithm, also initialize a mempool
that contains a single preallocated hash request object.  Then replace
the direct calls to ahash_request_alloc() and ahash_request_free() with
allocating and freeing from this mempool.

This eliminates the possibility of the allocation failing, which is
desirable for the I/O path.

This doesn't cause deadlocks because there's no case where multiple hash
requests are needed at a time to make forward progress.

Link: https://lore.kernel.org/r/20191231175545.20709-1-ebiggers@kernel.org
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Eric Biggers <ebiggers@google.com>