@@ -1,7 +1,7 @@
/*
* Copyright (C) 2003 Jana Saout <jana@saout.de>
* Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
- * Copyright (C) 2006-2009 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2006-2015 Red Hat, Inc. All rights reserved.
* Copyright (C) 2013 Milan Broz <gmazyland@gmail.com>
*
* This file is released under the GPL.
@@ -891,6 +891,11 @@ static void crypt_alloc_req(struct crypt_config *cc,
ctx->req = mempool_alloc(cc->req_pool, GFP_NOIO);
ablkcipher_request_set_tfm(ctx->req, cc->tfms[key_index]);
+
+ /*
+ * Use REQ_MAY_BACKLOG so a cipher driver internally backlogs
+ * requests if driver request queue is full.
+ */
ablkcipher_request_set_callback(ctx->req,
CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
kcryptd_async_done, dmreq_of_req(cc, ctx->req));
@@ -924,24 +929,32 @@ static int crypt_convert(struct crypt_config *cc,
r = crypt_convert_block(cc, ctx, ctx->req);
switch (r) {
- /* async */
+ /*
+ * The request was queued by a crypto driver
+ * but the driver request queue is full, let's wait.
+ */
case -EBUSY:
wait_for_completion(&ctx->restart);
reinit_completion(&ctx->restart);
- /* fall through*/
+ /* fall through */
+ /*
+ * The request is queued and processed asynchronously,
+ * completion function kcryptd_async_done() will be called.
+ */
case -EINPROGRESS:
ctx->req = NULL;
ctx->cc_sector++;
continue;
-
- /* sync */
+ /*
+ * The request was already processed (synchronously).
+ */
case 0:
atomic_dec(&ctx->cc_pending);
ctx->cc_sector++;
cond_resched();
continue;
- /* error */
+ /* There was an error while processing the request. */
default:
atomic_dec(&ctx->cc_pending);
return r;
@@ -1346,6 +1359,11 @@ static void kcryptd_async_done(struct crypto_async_request *async_req,
struct dm_crypt_io *io = container_of(ctx, struct dm_crypt_io, ctx);
struct crypt_config *cc = io->cc;
+ /*
+ * A request from crypto driver backlog is going to be processed now,
+ * finish the completion and continue in crypt_convert().
+ * (Callback will be called for the second time for this request.)
+ */
if (error == -EINPROGRESS) {
complete(&ctx->restart);
return;
A crypto driver can process request synchronously or asynchronously and can use internal driver queue to backlog requests. Add some comments to clarify internal logic and completion return codes. Signed-off-by: Milan Broz <mbroz@redhat.com> --- drivers/md/dm-crypt.c | 30 ++++++++++++++++++++++++------ 1 file changed, 24 insertions(+), 6 deletions(-)