libnvdimm, btt: add support for blk integrity

Support multiple block sizes (sector + metadata) using the blk integrity
framework. This registers a new integrity template that defines the
protection information tuple size based on the configured metadata size,
and simply acts as a passthrough for protection information generated by
another layer. The metadata is written to the storage as-is, and read back
with each sector.

Signed-off-by: Vishal Verma <vishal.l.verma@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/drivers/nvdimm/core.c b/drivers/nvdimm/core.c
index dd824d7..1d96b9a 100644
--- a/drivers/nvdimm/core.c
+++ b/drivers/nvdimm/core.c
@@ -13,6 +13,7 @@
 #include <linux/libnvdimm.h>
 #include <linux/export.h>
 #include <linux/module.h>
+#include <linux/blkdev.h>
 #include <linux/device.h>
 #include <linux/ctype.h>
 #include <linux/ndctl.h>
@@ -361,6 +362,42 @@
 }
 EXPORT_SYMBOL_GPL(nvdimm_bus_unregister);
 
+#ifdef CONFIG_BLK_DEV_INTEGRITY
+static int nd_pi_nop_generate_verify(struct blk_integrity_iter *iter)
+{
+	return 0;
+}
+
+int nd_integrity_init(struct gendisk *disk, unsigned long meta_size)
+{
+	struct blk_integrity integrity = {
+		.name = "ND-PI-NOP",
+		.generate_fn = nd_pi_nop_generate_verify,
+		.verify_fn = nd_pi_nop_generate_verify,
+		.tuple_size = meta_size,
+		.tag_size = meta_size,
+	};
+	int ret;
+
+	ret = blk_integrity_register(disk, &integrity);
+	if (ret)
+		return ret;
+
+	blk_queue_max_integrity_segments(disk->queue, 1);
+
+	return 0;
+}
+EXPORT_SYMBOL(nd_integrity_init);
+
+#else /* CONFIG_BLK_DEV_INTEGRITY */
+int nd_integrity_init(struct gendisk *disk, unsigned long meta_size)
+{
+	return 0;
+}
+EXPORT_SYMBOL(nd_integrity_init);
+
+#endif
+
 static __init int libnvdimm_init(void)
 {
 	int rc;