dm-crypt: simplify cc_pending

This patch removes one extra cc_pending reference from crypt_convert.
Now, cc_pending represents real number of pending operations.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

---
 drivers/md/dm-crypt.c |   61 +++++++++++++++++++++++---------------------------
 1 file changed, 29 insertions(+), 32 deletions(-)

Index: linux-3.2-fast/drivers/md/dm-crypt.c
===================================================================
--- linux-3.2-fast.orig/drivers/md/dm-crypt.c	2012-02-10 09:06:14.000000000 +0100
+++ linux-3.2-fast/drivers/md/dm-crypt.c	2012-02-10 09:07:43.000000000 +0100
@@ -814,6 +814,20 @@ static void crypt_flush_batch(struct cry
 
 }
 
+static void crypt_dec_pending(struct dm_crypt_io *io);
+static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io, int async);
+
+static void crypt_dec_cc_pending(struct dm_crypt_io *io)
+{
+	if (!atomic_dec_and_test(&io->ctx.cc_pending))
+		return;
+
+	if (bio_data_dir(io->base_bio) == READ)
+		crypt_dec_pending(io);
+	else
+		kcryptd_crypt_write_io_submit(io, 1);
+}
+
 /*
  * Encrypt / decrypt data from one bio to another one (can be the same one)
  */
@@ -826,9 +840,7 @@ static int crypt_convert(struct crypt_co
 
 	atomic_set(&ctx->cc_pending, 1);
 
-	while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
-	      ctx->idx_out < ctx->bio_out->bi_vcnt) {
-
+	while (1) {
 		struct ablkcipher_request *req = crypt_alloc_req(cc, ctx, GFP_NOWAIT);
 		if (!req) {
 			/*
@@ -840,25 +852,30 @@ static int crypt_convert(struct crypt_co
 			req = crypt_alloc_req(cc, ctx, GFP_NOIO);
 		}
 
-		atomic_inc(&ctx->cc_pending);
-
 		r = crypt_convert_block(cc, ctx, req, &batch);
 		if (unlikely(r < 0)) {
-			atomic_dec(&ctx->cc_pending);
-			goto flush_ret;
+			crypt_flush_batch(cc, &batch);
+			crypt_dec_cc_pending(container_of(ctx, struct dm_crypt_io, ctx));
+			goto ret;
 		}
 
 		ctx->sector++;
 
-		if (unlikely(++batch_count >= DMREQ_PUSH_BATCH)) {
-			batch_count = 0;
-			crypt_flush_batch(cc, &batch);
+		if (ctx->idx_in < ctx->bio_in->bi_vcnt &&
+		    ctx->idx_out < ctx->bio_out->bi_vcnt) {
+			atomic_inc(&ctx->cc_pending);
+			if (unlikely(++batch_count >= DMREQ_PUSH_BATCH)) {
+				batch_count = 0;
+				crypt_flush_batch(cc, &batch);
+			}
+			continue;
 		}
+		break;
 	}
 	r = 0;
 
-flush_ret:
 	crypt_flush_batch(cc, &batch);
+ret:
 
 	return r;
 }
@@ -1121,7 +1138,6 @@ static void kcryptd_crypt_write_convert(
 {
 	struct crypt_config *cc = io->cc;
 	struct bio *clone;
-	int crypt_finished;
 	unsigned remaining = io->base_bio->bi_size;
 	sector_t sector = io->sector;
 	int r;
@@ -1148,21 +1164,11 @@ static void kcryptd_crypt_write_convert(
 	r = crypt_convert(cc, &io->ctx);
 	if (r)
 		io->error = -EIO;
-	crypt_finished = atomic_dec_and_test(&io->ctx.cc_pending);
-
-	/* Encryption was already finished, submit io now */
-	if (crypt_finished)
-		kcryptd_crypt_write_io_submit(io, 0);
 
 dec:
 	crypt_dec_pending(io);
 }
 
-static void kcryptd_crypt_read_done(struct dm_crypt_io *io)
-{
-	crypt_dec_pending(io);
-}
-
 static void kcryptd_crypt_read_convert(struct dm_crypt_io *io)
 {
 	struct crypt_config *cc = io->cc;
@@ -1178,9 +1184,6 @@ static void kcryptd_crypt_read_convert(s
 	if (r < 0)
 		io->error = -EIO;
 
-	if (atomic_dec_and_test(&io->ctx.cc_pending))
-		kcryptd_crypt_read_done(io);
-
 	crypt_dec_pending(io);
 }
 
@@ -1205,13 +1208,7 @@ static void kcryptd_async_done(struct cr
 
 	mempool_free(req_of_dmreq(cc, dmreq), cc->req_pool);
 
-	if (!atomic_dec_and_test(&ctx->cc_pending))
-		return;
-
-	if (bio_data_dir(io->base_bio) == READ)
-		kcryptd_crypt_read_done(io);
-	else
-		kcryptd_crypt_write_io_submit(io, 1);
+	crypt_dec_cc_pending(io);
 }
 
 static void kcryptd_crypt(struct work_struct *work)