dm: add snapshot of dm-req-crypt

This snapshot is taken as of msm-3.18 commit:
5684450d70 ("Promotion of kernel.lnx.3.18-151201").
dm-req-crypt is necessary for full disk encryption.

Signed-off-by: Gilad Broner <gbroner@codeaurora.org>

block/blk-core.c

@@ -1475,6 +1475,9 @@ void __blk_put_request(struct request_queue *q, struct request *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,
 	 * it didn't come out of our reserved rq pools
@@ -2647,6 +2650,15 @@ bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
 	blk_account_io_completion(req, nr_bytes);
 
 	total_bytes = 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 (req->bio) {
 		struct bio *bio = req->bio;
 		unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes);

block/blk-merge.c

@@ -467,6 +467,93 @@ int blk_rq_map_sg(struct request_queue *q, struct request *rq,
 }
 EXPORT_SYMBOL(blk_rq_map_sg);
 
+/*
+ * map a request to scatterlist without combining PHY CONT
+ * blocks, return number of sg entries setup. Caller
+ * must make sure sg can hold rq->nr_phys_segments entries
+ */
+int blk_rq_map_sg_no_cluster(struct request_queue *q, struct request *rq,
+		  struct scatterlist *sglist)
+{
+	struct bio_vec bvec, bvprv = { NULL };
+	struct req_iterator iter;
+	struct scatterlist *sg;
+	int nsegs, cluster = 0;
+
+	nsegs = 0;
+
+	/*
+	 * for each bio in rq
+	 */
+	sg = NULL;
+	rq_for_each_segment(bvec, rq, iter) {
+		__blk_segment_map_sg(q, &bvec, sglist, &bvprv, &sg,
+				     &nsegs, &cluster);
+	} /* segments in rq */
+
+
+	if (!sg)
+		return nsegs;
+
+	if (unlikely(rq->cmd_flags & REQ_COPY_USER) &&
+	    (blk_rq_bytes(rq) & q->dma_pad_mask)) {
+		unsigned int pad_len =
+			(q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1;
+
+		sg->length += pad_len;
+		rq->extra_len += pad_len;
+	}
+
+	if (q->dma_drain_size && q->dma_drain_needed(rq)) {
+		if (rq->cmd_flags & REQ_WRITE)
+			memset(q->dma_drain_buffer, 0, q->dma_drain_size);
+
+		sg->page_link &= ~0x02;
+		sg = sg_next(sg);
+		sg_set_page(sg, virt_to_page(q->dma_drain_buffer),
+			    q->dma_drain_size,
+			    ((unsigned long)q->dma_drain_buffer) &
+			    (PAGE_SIZE - 1));
+		nsegs++;
+		rq->extra_len += q->dma_drain_size;
+	}
+
+	if (sg)
+		sg_mark_end(sg);
+
+	return nsegs;
+}
+EXPORT_SYMBOL(blk_rq_map_sg_no_cluster);
+
+/**
+ * blk_bio_map_sg - map a bio to a scatterlist
+ * @q: request_queue in question
+ * @bio: bio being mapped
+ * @sglist: scatterlist being mapped
+ *
+ * Note:
+ *    Caller must make sure sg can hold bio->bi_phys_segments entries
+ *
+ * Will return the number of sg entries setup
+ */
+int blk_bio_map_sg(struct request_queue *q, struct bio *bio,
+		   struct scatterlist *sglist)
+{
+	struct scatterlist *sg = NULL;
+	int nsegs;
+	struct bio *next = bio->bi_next;
+
+	bio->bi_next = NULL;
+	nsegs = __blk_bios_map_sg(q, bio, sglist, &sg);
+	bio->bi_next = next;
+	if (sg)
+		sg_mark_end(sg);
+
+	WARN_ON(bio->bi_phys_segments && nsegs > bio->bi_phys_segments);
+	return nsegs;
+}
+EXPORT_SYMBOL(blk_bio_map_sg);
+
 static inline int ll_new_hw_segment(struct request_queue *q,
 				    struct request *req,
 				    struct bio *bio)

block/blk.h

@@ -214,7 +214,6 @@ int attempt_back_merge(struct request_queue *q, struct request *rq);
 int attempt_front_merge(struct request_queue *q, struct request *rq);
 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
 				struct request *next);
-void blk_recalc_rq_segments(struct request *rq);
 void blk_rq_set_mixed_merge(struct request *rq);
 bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
 int blk_try_merge(struct request *rq, struct bio *bio);

drivers/md/Kconfig

@@ -267,6 +267,23 @@ config DM_CRYPT
 
 	  If unsure, say N.
 
+config DM_REQ_CRYPT
+	tristate "Req 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

@@ -59,6 +59,7 @@ obj-$(CONFIG_DM_CACHE_SMQ)	+= dm-cache-smq.o
 obj-$(CONFIG_DM_CACHE_CLEANER)	+= dm-cache-cleaner.o
 obj-$(CONFIG_DM_ERA)		+= dm-era.o
 obj-$(CONFIG_DM_LOG_WRITES)	+= dm-log-writes.o
+obj-$(CONFIG_DM_REQ_CRYPT)	+= dm-req-crypt.o
 
 ifeq ($(CONFIG_DM_UEVENT),y)
 dm-mod-objs			+= dm-uevent.o