dax: export dax_dev_get()

famfs needs to look up a dax_device by dev_t when resolving fmap
entries that reference character dax devices.

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: John Groves <john@groves.net>
Link: https://patch.msgid.link/0100019d311daab5-bb212f0b-4e05-4668-bf53-d76fab56be68-000000@email.amazonses.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

Author: jagalactic

drivers/dax/super.c

@@ -521,7 +521,7 @@ static int dax_set(struct inode *inode, void *data)
 	return 0;
 }
 
-static struct dax_device *dax_dev_get(dev_t devt)
+struct dax_device *dax_dev_get(dev_t devt)
 {
 	struct dax_device *dax_dev;
 	struct inode *inode;
@@ -544,6 +544,7 @@ static struct dax_device *dax_dev_get(dev_t devt)
 
 	return dax_dev;
 }
+EXPORT_SYMBOL_GPL(dax_dev_get);
 
 struct dax_device *alloc_dax(void *private, const struct dax_operations *ops)
 {

include/linux/dax.h

@@ -54,6 +54,7 @@ struct dax_device *alloc_dax(void *private, const struct dax_operations *ops);
 void *dax_holder(struct dax_device *dax_dev);
 void put_dax(struct dax_device *dax_dev);
 void kill_dax(struct dax_device *dax_dev);
+struct dax_device *dax_dev_get(dev_t devt);
 void dax_write_cache(struct dax_device *dax_dev, bool wc);
 bool dax_write_cache_enabled(struct dax_device *dax_dev);
 bool dax_synchronous(struct dax_device *dax_dev);