dm crypt: add completion for async

dm-crypt: Use crypto ablkcipher interface
Prepare completion for async crypto request.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 79316580c780..2ea3eb99c91f 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -6,6 +6,7 @@
  * This file is released under the GPL.
  */
 
+#include <linux/completion.h>
 #include <linux/err.h>
 #include <linux/module.h>
 #include <linux/init.h>
@@ -31,6 +32,7 @@
  * context holding the current state of a multi-part conversion
  */
 struct convert_context {
+        struct completion restart;
         struct bio *bio_in;
         struct bio *bio_out;
         unsigned int offset_in;
@@ -38,6 +40,7 @@ struct convert_context {
         unsigned int idx_in;
         unsigned int idx_out;
         sector_t sector;
+        atomic_t pending;
 };
 
 /*
@@ -359,6 +362,15 @@ static void crypt_convert_init(struct crypt_config *cc,
         ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
         ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
         ctx->sector = sector + cc->iv_offset;
+        init_completion(&ctx->restart);
+        /*
+         * Crypto operation can be asynchronous,
+         * ctx->pending is increased after request submission.
+         * We need to ensure that we don't call the crypt finish
+         * operation before pending got incremented
+         * (dependent on crypt submission return code).
+         */
+        atomic_set(&ctx->pending, 2);
 }
 
 static int crypt_convert_block(struct crypt_config *cc,
@@ -418,6 +430,15 @@ static int crypt_convert(struct crypt_config *cc,
                 ctx->sector++;
         }
 
+        /*
+         * If there are pending crypto operation run async
+         * code. Otherwise process return code synchronously.
+         * The step of 2 ensures that async finish doesn't
+         * call crypto finish too early.
+         */
+        if (atomic_sub_return(2, &ctx->pending))
+                return -EINPROGRESS;
+
         return r;
 }