From: Milan Broz <mbroz@redhat.com>

Add results of operation (error code) into convert_context.
Now crypt_convert can be void.

[AGK FIXME: I'm not happy about this yet - is there a problem passing the
error code around normally when we reach the async patches?]

Introduce read/write functions called at the end
of io operation. 

Create new write endio function and move the related code
from write loop.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Milan Broz <mbroz@redhat.com>
---
 drivers/md/dm-crypt.c |   73 +++++++++++++++++++++++++++++++++-----------------
 1 files changed, 49 insertions(+), 24 deletions(-)

Index: linux-2.6.23/drivers/md/dm-crypt.c
===================================================================
--- linux-2.6.23.orig/drivers/md/dm-crypt.c	2007-10-10 17:20:57.000000000 +0100
+++ linux-2.6.23/drivers/md/dm-crypt.c	2007-10-10 17:20:57.000000000 +0100
@@ -39,6 +39,7 @@ struct convert_context {
 	unsigned int idx_out;
 	sector_t sector;
 	int write;
+	int err;
 };
 
 /*
@@ -344,8 +345,8 @@ static void crypt_convert_init(struct cr
 /*
  * Encrypt / decrypt data from one bio to another one (can be the same one)
  */
-static int crypt_convert(struct crypt_config *cc,
-			 struct convert_context *ctx)
+static void crypt_convert(struct crypt_config *cc,
+			  struct convert_context *ctx)
 {
 	int r = 0;
 
@@ -384,7 +385,7 @@ static int crypt_convert(struct crypt_co
 		ctx->sector++;
 	}
 
-	return r;
+	ctx->err = r;
 }
 
 static void dm_crypt_bio_destructor(struct bio *bio)
@@ -611,6 +612,40 @@ static void process_read(struct dm_crypt
 	generic_make_request(clone);
 }
 
+static void process_write_endio(struct dm_crypt_io *io)
+{
+	struct bio *clone = io->ctx.bio_out;
+	unsigned remaining = io->remaining;
+
+	/* Grab another reference to the io struct
+	 * before we kick off the request */
+	if (remaining)
+		atomic_inc(&io->pending);
+
+	generic_make_request(clone);
+
+	/* Do not reference clone after this - it
+	 * may be gone already. */
+
+	/* out of memory -> run queues */
+	if (remaining)
+		congestion_wait(WRITE, HZ / 100);
+}
+
+static void crypt_write_done(struct dm_crypt_io *io)
+{
+	struct bio *clone = io->ctx.bio_out;
+	struct crypt_config *cc = io->target->private;
+
+	/* crypt_convert should have filled the clone bio */
+
+	BUG_ON(io->ctx.idx_out < clone->bi_vcnt);
+
+	clone->bi_sector = cc->start + io->sector;
+	io->remaining -= clone->bi_size;
+	io->sector += bio_sectors(clone);
+}
+
 static void crypt_write_loop(struct dm_crypt_io *io)
 {
 	struct crypt_config *cc = io->target->private;
@@ -632,33 +667,17 @@ static void crypt_write_loop(struct dm_c
 		io->ctx.bio_out = clone;
 		io->ctx.idx_out = 0;
 
-		if (unlikely(crypt_convert(cc, &io->ctx) < 0)) {
+		crypt_convert(cc, &io->ctx);
+		if (unlikely(io->ctx.err < 0)) {
 			crypt_free_buffer_pages(cc, clone, clone->bi_size);
 			bio_put(clone);
 			crypt_dec_pending(io, -EIO);
 			break;
 		}
 
-		/* crypt_convert should have filled the clone bio */
-		BUG_ON(io->ctx.idx_out < clone->bi_vcnt);
+		crypt_write_done(io);
 
-		clone->bi_sector = cc->start + io->sector;
-		io->remaining -= clone->bi_size;
-		io->sector += bio_sectors(clone);
-
-		/* Grab another reference to the io struct
-		 * before we kick off the request */
-		if (io->remaining)
-			atomic_inc(&io->pending);
-
-		generic_make_request(clone);
-
-		/* Do not reference clone after this - it
-		 * may be gone already. */
-
-		/* out of memory -> run queues */
-		if (io->remaining)
-			congestion_wait(WRITE, HZ/100);
+		process_write_endio(io);
 	}
 
 	crypt_dec_pending(io, 0);
@@ -678,6 +697,11 @@ static void process_write(struct dm_cryp
 	crypt_write_loop(io);
 }
 
+static void crypt_read_done(struct dm_crypt_io *io)
+{
+	crypt_dec_pending(io, io->ctx.err);
+}
+
 static void process_read_endio(struct dm_crypt_io *io)
 {
 	struct crypt_config *cc = io->target->private;
@@ -685,7 +709,8 @@ static void process_read_endio(struct dm
 	crypt_convert_init(cc, &io->ctx, io->base_bio, io->base_bio,
 			   io->base_bio->bi_sector - io->target->begin, 0);
 
-	crypt_dec_pending(io, crypt_convert(cc, &io->ctx));
+	crypt_convert(cc, &io->ctx);
+	crypt_read_done(io);
 }
 
 static void kcryptd_do_work(struct work_struct *work)