dm-verity: make verity_hash() take dm_verity_io instead of ahash_request

In preparation for adding shash support to dm-verity, change
verity_hash() to take a pointer to a struct dm_verity_io instead of a
pointer to the ahash_request embedded inside it.

Reviewed-by: Sami Tolvanen <[e-mail]>
Acked-by: Ard Biesheuvel <[e-mail]>
Signed-off-by: Eric Biggers <[e-mail]>
Signed-off-by: Mikulas Patocka <[e-mail]>

drivers/md/dm-verity-fec.c

···
 static int fec_is_erasure(struct dm_verity *v, struct dm_verity_io *io,
 			  u8 *want_digest, u8 *data)
 {
-	if (unlikely(verity_hash(v, verity_io_hash_req(v, io),
-				 data, 1 << v->data_dev_block_bits,
+	if (unlikely(verity_hash(v, io, data, 1 << v->data_dev_block_bits,
 				 verity_io_real_digest(v, io), true)))
 		return 0;
 
···
 	}
 
 	/* Always re-validate the corrected block against the expected hash */
-	r = verity_hash(v, verity_io_hash_req(v, io), fio->output,
-			1 << v->data_dev_block_bits,
+	r = verity_hash(v, io, fio->output, 1 << v->data_dev_block_bits,
 			verity_io_real_digest(v, io), true);
 	if (unlikely(r < 0))
 		return r;

drivers/md/dm-verity-target.c

···
 	return r;
 }
 
-int verity_hash(struct dm_verity *v, struct ahash_request *req,
+int verity_hash(struct dm_verity *v, struct dm_verity_io *io,
 		const u8 *data, size_t len, u8 *digest, bool may_sleep)
 {
+	struct ahash_request *req = verity_io_hash_req(v, io);
 	int r;
 	struct crypto_wait wait;
 
···
 			goto release_ret_r;
 		}
 
-		r = verity_hash(v, verity_io_hash_req(v, io),
-				data, 1 << v->hash_dev_block_bits,
+		r = verity_hash(v, io, data, 1 << v->hash_dev_block_bits,
 				verity_io_real_digest(v, io), !io->in_bh);
 		if (unlikely(r < 0))
 			goto release_ret_r;
···
 	if (unlikely(r))
 		goto free_ret;
 
-	r = verity_hash(v, verity_io_hash_req(v, io), buffer,
-			1 << v->data_dev_block_bits,
+	r = verity_hash(v, io, buffer, 1 << v->data_dev_block_bits,
 			verity_io_real_digest(v, io), true);
 	if (unlikely(r))
 		goto free_ret;
···
 			continue;
 		}
 
-		r = verity_hash(v, verity_io_hash_req(v, io), data, block_size,
+		r = verity_hash(v, io, data, block_size,
 				verity_io_real_digest(v, io), !io->in_bh);
 		if (unlikely(r < 0)) {
 			kunmap_local(data);
···
 static int verity_alloc_zero_digest(struct dm_verity *v)
 {
 	int r = -ENOMEM;
-	struct ahash_request *req;
+	struct dm_verity_io *io;
 	u8 *zero_data;
 
 	v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
···
 	if (!v->zero_digest)
 		return r;
 
-	req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
+	io = kmalloc(sizeof(*io) + v->ahash_reqsize, GFP_KERNEL);
 
-	if (!req)
+	if (!io)
 		return r; /* verity_dtr will free zero_digest */
 
 	zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
···
 	if (!zero_data)
 		goto out;
 
-	r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
+	r = verity_hash(v, io, zero_data, 1 << v->data_dev_block_bits,
 			v->zero_digest, true);
 
 out:
-	kfree(req);
+	kfree(io);
 	kfree(zero_data);
 
 	return r;

drivers/md/dm-verity.h

···
 	return io->want_digest;
 }
 
-extern int verity_hash(struct dm_verity *v, struct ahash_request *req,
+extern int verity_hash(struct dm_verity *v, struct dm_verity_io *io,
 		       const u8 *data, size_t len, u8 *digest, bool may_sleep);
 
 extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,