[RFC PATCH 06/12] dax: Add helper to determine if a 'struct file' supports dax

[Dave Jiang <dave.jiang@intel.com>]

Add a helper function that checks of the file_operations is dax.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 include/linux/dax.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/include/linux/dax.h b/include/linux/dax.h
index 9d624f4d9df6..a5e1a3ca1a0d 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -311,4 +311,11 @@ static inline void hmem_register_resource(int target_nid, struct resource *r)
 typedef int (*walk_hmem_fn)(struct device *dev, int target_nid,
 			    const struct resource *res);
 int walk_hmem_resources(struct device *dev, walk_hmem_fn fn);
+
+extern const struct file_operations dax_fops;
+static inline bool is_file_dax(struct file *file)
+{
+	return file->f_op == &dax_fops;
+}
+
 #endif
-- 
2.53.0