block: move dif_prepare/dif_complete functions to block layer

Currently these functions are implemented in the scsi layer, but their
actual place should be the block layer since T10-PI is a general data
integrity feature that is used in the nvme protocol as well. Also, use
the tuple size from the integrity profile since it may vary between
integrity types.

Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/t10-pi.c

diff --git a/block/t10-pi.c b/block/t10-pi.c
index a98db38..62aed77 100644
--- a/block/t10-pi.c
+++ b/block/t10-pi.c
@@ -184,3 +184,113 @@ const struct blk_integrity_profile t10_pi_type3_ip = {
 	.verify_fn		= t10_pi_type3_verify_ip,
 };
 EXPORT_SYMBOL(t10_pi_type3_ip);
+
+/**
+ * t10_pi_prepare - prepare PI prior submitting request to device
+ * @rq:              request with PI that should be prepared
+ * @protection_type: PI type (Type 1/Type 2/Type 3)
+ *
+ * For Type 1/Type 2, the virtual start sector is the one that was
+ * originally submitted by the block layer for the ref_tag usage. Due to
+ * partitioning, MD/DM cloning, etc. the actual physical start sector is
+ * likely to be different. Remap protection information to match the
+ * physical LBA.
+ *
+ * Type 3 does not have a reference tag so no remapping is required.
+ */
+void t10_pi_prepare(struct request *rq, u8 protection_type)
+{
+	const int tuple_sz = rq->q->integrity.tuple_size;
+	u32 ref_tag = t10_pi_ref_tag(rq);
+	struct bio *bio;
+
+	if (protection_type == T10_PI_TYPE3_PROTECTION)
+		return;
+
+	__rq_for_each_bio(bio, rq) {
+		struct bio_integrity_payload *bip = bio_integrity(bio);
+		u32 virt = bip_get_seed(bip) & 0xffffffff;
+		struct bio_vec iv;
+		struct bvec_iter iter;
+
+		/* Already remapped? */
+		if (bip->bip_flags & BIP_MAPPED_INTEGRITY)
+			break;
+
+		bip_for_each_vec(iv, bip, iter) {
+			void *p, *pmap;
+			unsigned int j;
+
+			pmap = kmap_atomic(iv.bv_page);
+			p = pmap + iv.bv_offset;
+			for (j = 0; j < iv.bv_len; j += tuple_sz) {
+				struct t10_pi_tuple *pi = p;
+
+				if (be32_to_cpu(pi->ref_tag) == virt)
+					pi->ref_tag = cpu_to_be32(ref_tag);
+				virt++;
+				ref_tag++;
+				p += tuple_sz;
+			}
+
+			kunmap_atomic(pmap);
+		}
+
+		bip->bip_flags |= BIP_MAPPED_INTEGRITY;
+	}
+}
+EXPORT_SYMBOL(t10_pi_prepare);
+
+/**
+ * t10_pi_complete - prepare PI prior returning request to the block layer
+ * @rq:              request with PI that should be prepared
+ * @protection_type: PI type (Type 1/Type 2/Type 3)
+ * @intervals:       total elements to prepare
+ *
+ * For Type 1/Type 2, the virtual start sector is the one that was
+ * originally submitted by the block layer for the ref_tag usage. Due to
+ * partitioning, MD/DM cloning, etc. the actual physical start sector is
+ * likely to be different. Since the physical start sector was submitted
+ * to the device, we should remap it back to virtual values expected by the
+ * block layer.
+ *
+ * Type 3 does not have a reference tag so no remapping is required.
+ */
+void t10_pi_complete(struct request *rq, u8 protection_type,
+		     unsigned int intervals)
+{
+	const int tuple_sz = rq->q->integrity.tuple_size;
+	u32 ref_tag = t10_pi_ref_tag(rq);
+	struct bio *bio;
+
+	if (protection_type == T10_PI_TYPE3_PROTECTION)
+		return;
+
+	__rq_for_each_bio(bio, rq) {
+		struct bio_integrity_payload *bip = bio_integrity(bio);
+		u32 virt = bip_get_seed(bip) & 0xffffffff;
+		struct bio_vec iv;
+		struct bvec_iter iter;
+
+		bip_for_each_vec(iv, bip, iter) {
+			void *p, *pmap;
+			unsigned int j;
+
+			pmap = kmap_atomic(iv.bv_page);
+			p = pmap + iv.bv_offset;
+			for (j = 0; j < iv.bv_len && intervals; j += tuple_sz) {
+				struct t10_pi_tuple *pi = p;
+
+				if (be32_to_cpu(pi->ref_tag) == ref_tag)
+					pi->ref_tag = cpu_to_be32(virt);
+				virt++;
+				ref_tag++;
+				intervals--;
+				p += tuple_sz;
+			}
+
+			kunmap_atomic(pmap);
+		}
+	}
+}
+EXPORT_SYMBOL(t10_pi_complete);