dax: export a low-level __dax_zero_page_range helper

This allows XFS to perform zeroing using the iomap infrastructure and
avoid buffer heads.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
[vishal: fix conflicts with dax-error-handling]
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/dax.h b/include/linux/dax.h
index 7f853ffaa987..90fbc99e5313 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -14,12 +14,19 @@ int __dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t);
 
 #ifdef CONFIG_FS_DAX
 struct page *read_dax_sector(struct block_device *bdev, sector_t n);
+int __dax_zero_page_range(struct block_device *bdev, sector_t sector,
+                unsigned int offset, unsigned int length);
 #else
 static inline struct page *read_dax_sector(struct block_device *bdev,
                 sector_t n)
 {
         return ERR_PTR(-ENXIO);
 }
+static inline int __dax_zero_page_range(struct block_device *bdev,
+                sector_t sector, unsigned int offset, unsigned int length)
+{
+        return -ENXIO;
+}
 #endif
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE