Save the kva from memremap because we need it for iomap rw support.

Prior to famfs, there were no iomap users of /dev/dax - so the virtual
address from memremap was not needed.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: John Groves <john@groves.net>
---
 drivers/dax/dax-private.h | 2 ++
 drivers/dax/fsdev.c       | 1 +
 2 files changed, 3 insertions(+)

diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
index c6ae27c982f4..7a3727d76a68 100644
--- a/drivers/dax/dax-private.h
+++ b/drivers/dax/dax-private.h
@@ -69,6 +69,7 @@ struct dev_dax_range {
  * data while the device is activated in the driver.
  * @region: parent region
  * @dax_dev: core dax functionality
+ * @virt_addr: kva from memremap; used by fsdev_dax
  * @align: alignment of this instance
  * @target_node: effective numa node if dev_dax memory range is onlined
  * @dyn_id: is this a dynamic or statically created instance
@@ -83,6 +84,7 @@ struct dev_dax_range {
 struct dev_dax {
 	struct dax_region *region;
 	struct dax_device *dax_dev;
+	void *virt_addr;
 	unsigned int align;
 	int target_node;
 	bool dyn_id;
diff --git a/drivers/dax/fsdev.c b/drivers/dax/fsdev.c
index e5b4396ce401..d2f6c0341c24 100644
--- a/drivers/dax/fsdev.c
+++ b/drivers/dax/fsdev.c
@@ -212,6 +212,7 @@ static int fsdev_dax_probe(struct dev_dax *dev_dax)
 		pr_debug("%s: offset detected phys=%llx pgmap_phys=%llx offset=%llx\n",
 		       __func__, phys, pgmap_phys, data_offset);
 	}
+	dev_dax->virt_addr = addr + data_offset;
 
 	inode = dax_inode(dax_dev);
 	cdev = inode->i_cdev;
-- 
2.53.0