Request based dm-crypt

dm-crypt provides bios based device mapper module. dm-crypt
operates on packets with 512 bytes size which is not effiicent
way for HW based crypto blocks. dm-req-crypt is developed to
address this. dm-req-crypt works on requests which carry upto
512KB of data for unmerged requests.

Change-Id: I479230b2f0c1ab2e2a1ddb84947ebaf0629dff8c
Signed-off-by: Dinesh K Garg <dineshg@codeaurora.org>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>

block/blk-core.c

@@ -1223,8 +1223,9 @@ void __blk_put_request(struct request_queue *q, struct request *req)
 
 	elv_completed_request(q, req);
 
-	/* this is a bio leak */
-	WARN_ON(req->bio != NULL);
+	/* this is a bio leak if the bio is not tagged with BIO_DONTFREE */
+	WARN_ON(req->bio && !bio_flagged(req->bio, BIO_DONTFREE));
+
 
 	/*
 	 * Request may not have originated from ll_rw_blk. if not,
@@ -2275,6 +2276,15 @@ bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
 	blk_account_io_completion(req, nr_bytes);
 
 	total_bytes = bio_nbytes = 0;
+
+	/*
+	 * Check for this if flagged, Req based dm needs to perform
+	 * post processing, hence dont end bios or request.DM
+	 * layer takes care.
+	 */
+	if (bio_flagged(req->bio, BIO_DONTFREE))
+		return false;
+
 	while ((bio = req->bio) != NULL) {
 		int nbytes;
 

drivers/md/Kconfig

@@ -241,6 +241,23 @@ config DM_CRYPT
 
 	  If unsure, say N.
 
+config DM_REQ_CRYPT
+	tristate "Crypt target support"
+	depends on BLK_DEV_DM
+	select XTS
+	select CRYPTO_XTS
+	---help---
+	  This request based device-mapper target allows you to create a device that
+	  transparently encrypts the data on it. You'll need to activate
+	  the ciphers you're going to use in the cryptoapi configuration.
+          The DM REQ CRYPT operates on requests (bigger payloads) to utilize 
+          crypto hardware better.	  
+
+	  To compile this code as a module, choose M here: the module will
+	  be called dm-req-crypt.
+
+	  If unsure, say N.
+
 config DM_SNAPSHOT
        tristate "Snapshot target"
        depends on BLK_DEV_DM

drivers/md/Makefile

@@ -44,7 +44,7 @@ obj-$(CONFIG_DM_ZERO)		+= dm-zero.o
 obj-$(CONFIG_DM_RAID)	+= dm-raid.o
 obj-$(CONFIG_DM_THIN_PROVISIONING)	+= dm-thin-pool.o
 obj-$(CONFIG_DM_VERITY)		+= dm-verity.o
-
+obj-$(CONFIG_DM_REQ_CRYPT)		+= dm-req-crypt.o
 ifeq ($(CONFIG_DM_UEVENT),y)
 dm-mod-objs			+= dm-uevent.o
 endif