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Subject[PATCH v8 13/20] dm: move dm-verity to generic async completion
Date
dm-verity is starting async. crypto ops and waiting for them to complete.
Move it over to generic code doing the same.

This also avoids a future potential data coruption bug created
by the use of wait_for_completion_interruptible() without dealing
correctly with an interrupt aborting the wait prior to the
async op finishing, should this code ever move to a context
where signals are not masked.

Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
CC: Mikulas Patocka <mpatocka@redhat.com>
---
drivers/md/dm-verity-target.c | 81 +++++++++++--------------------------------
drivers/md/dm-verity.h | 5 ---
2 files changed, 20 insertions(+), 66 deletions(-)

diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index bda3cac..811ad28 100644
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -92,74 +92,33 @@ static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
return block >> (level * v->hash_per_block_bits);
}

-/*
- * Callback function for asynchrnous crypto API completion notification
- */
-static void verity_op_done(struct crypto_async_request *base, int err)
-{
- struct verity_result *res = (struct verity_result *)base->data;
-
- if (err == -EINPROGRESS)
- return;
-
- res->err = err;
- complete(&res->completion);
-}
-
-/*
- * Wait for async crypto API callback
- */
-static inline int verity_complete_op(struct verity_result *res, int ret)
-{
- switch (ret) {
- case 0:
- break;
-
- case -EINPROGRESS:
- case -EBUSY:
- ret = wait_for_completion_interruptible(&res->completion);
- if (!ret)
- ret = res->err;
- reinit_completion(&res->completion);
- break;
-
- default:
- DMERR("verity_wait_hash: crypto op submission failed: %d", ret);
- }
-
- if (unlikely(ret < 0))
- DMERR("verity_wait_hash: crypto op failed: %d", ret);
-
- return ret;
-}
-
static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
const u8 *data, size_t len,
- struct verity_result *res)
+ struct crypto_wait *wait)
{
struct scatterlist sg;

sg_init_one(&sg, data, len);
ahash_request_set_crypt(req, &sg, NULL, len);

- return verity_complete_op(res, crypto_ahash_update(req));
+ return crypto_wait_req(crypto_ahash_update(req), wait);
}

/*
* Wrapper for crypto_ahash_init, which handles verity salting.
*/
static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
- struct verity_result *res)
+ struct crypto_wait *wait)
{
int r;

ahash_request_set_tfm(req, v->tfm);
ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
CRYPTO_TFM_REQ_MAY_BACKLOG,
- verity_op_done, (void *)res);
- init_completion(&res->completion);
+ crypto_req_done, (void *)wait);
+ crypto_init_wait(wait);

- r = verity_complete_op(res, crypto_ahash_init(req));
+ r = crypto_wait_req(crypto_ahash_init(req), wait);

if (unlikely(r < 0)) {
DMERR("crypto_ahash_init failed: %d", r);
@@ -167,18 +126,18 @@ static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
}

if (likely(v->salt_size && (v->version >= 1)))
- r = verity_hash_update(v, req, v->salt, v->salt_size, res);
+ r = verity_hash_update(v, req, v->salt, v->salt_size, wait);

return r;
}

static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
- u8 *digest, struct verity_result *res)
+ u8 *digest, struct crypto_wait *wait)
{
int r;

if (unlikely(v->salt_size && (!v->version))) {
- r = verity_hash_update(v, req, v->salt, v->salt_size, res);
+ r = verity_hash_update(v, req, v->salt, v->salt_size, wait);

if (r < 0) {
DMERR("verity_hash_final failed updating salt: %d", r);
@@ -187,7 +146,7 @@ static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
}

ahash_request_set_crypt(req, NULL, digest, 0);
- r = verity_complete_op(res, crypto_ahash_final(req));
+ r = crypto_wait_req(crypto_ahash_final(req), wait);
out:
return r;
}
@@ -196,17 +155,17 @@ int verity_hash(struct dm_verity *v, struct ahash_request *req,
const u8 *data, size_t len, u8 *digest)
{
int r;
- struct verity_result res;
+ struct crypto_wait wait;

- r = verity_hash_init(v, req, &res);
+ r = verity_hash_init(v, req, &wait);
if (unlikely(r < 0))
goto out;

- r = verity_hash_update(v, req, data, len, &res);
+ r = verity_hash_update(v, req, data, len, &wait);
if (unlikely(r < 0))
goto out;

- r = verity_hash_final(v, req, digest, &res);
+ r = verity_hash_final(v, req, digest, &wait);

out:
return r;
@@ -389,7 +348,7 @@ int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
* Calculates the digest for the given bio
*/
int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
- struct bvec_iter *iter, struct verity_result *res)
+ struct bvec_iter *iter, struct crypto_wait *wait)
{
unsigned int todo = 1 << v->data_dev_block_bits;
struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
@@ -414,7 +373,7 @@ int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
*/
sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
ahash_request_set_crypt(req, &sg, NULL, len);
- r = verity_complete_op(res, crypto_ahash_update(req));
+ r = crypto_wait_req(crypto_ahash_update(req), wait);

if (unlikely(r < 0)) {
DMERR("verity_for_io_block crypto op failed: %d", r);
@@ -482,7 +441,7 @@ static int verity_verify_io(struct dm_verity_io *io)
struct dm_verity *v = io->v;
struct bvec_iter start;
unsigned b;
- struct verity_result res;
+ struct crypto_wait wait;

for (b = 0; b < io->n_blocks; b++) {
int r;
@@ -507,17 +466,17 @@ static int verity_verify_io(struct dm_verity_io *io)
continue;
}

- r = verity_hash_init(v, req, &res);
+ r = verity_hash_init(v, req, &wait);
if (unlikely(r < 0))
return r;

start = io->iter;
- r = verity_for_io_block(v, io, &io->iter, &res);
+ r = verity_for_io_block(v, io, &io->iter, &wait);
if (unlikely(r < 0))
return r;

r = verity_hash_final(v, req, verity_io_real_digest(v, io),
- &res);
+ &wait);
if (unlikely(r < 0))
return r;

diff --git a/drivers/md/dm-verity.h b/drivers/md/dm-verity.h
index a59e0ad..b675bc0 100644
--- a/drivers/md/dm-verity.h
+++ b/drivers/md/dm-verity.h
@@ -90,11 +90,6 @@ struct dm_verity_io {
*/
};

-struct verity_result {
- struct completion completion;
- int err;
-};
-
static inline struct ahash_request *verity_io_hash_req(struct dm_verity *v,
struct dm_verity_io *io)
{
--
2.1.4
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