[PATCH v3 06/10] fsdax: Add dax_iomap_cow_copy() for dax_iomap_zero

[Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx>]

Punch hole on a reflinked file needs dax_copy_edge() too.  Otherwise,
data in not aligned area will be not correct.  So, add the srcmap to
dax_iomap_zero() and replace memset() as dax_copy_edge().

Signed-off-by: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx>
---
 fs/dax.c               | 9 +++++++--
 fs/iomap/buffered-io.c | 2 +-
 include/linux/dax.h    | 3 ++-
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index cfe513eb111e..348297b38f76 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1174,7 +1174,8 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
 }
 #endif /* CONFIG_FS_DAX_PMD */
 
-s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap)
+s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap,
+		struct iomap *srcmap)
 {
 	sector_t sector = iomap_sector(iomap, pos & PAGE_MASK);
 	pgoff_t pgoff;
@@ -1204,7 +1205,11 @@ s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap)
 	}
 
 	if (!page_aligned) {
-		memset(kaddr + offset, 0, size);
+		if (iomap->addr != srcmap->addr)
+			dax_iomap_cow_copy(offset, size, PAGE_SIZE, srcmap,
+					   kaddr, true);
+		else
+			memset(kaddr + offset, 0, size);
 		dax_flush(iomap->dax_dev, kaddr + offset, size);
 	}
 	dax_read_unlock(id);
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 16a1e82e3aeb..d754b1f1a05d 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -933,7 +933,7 @@ static loff_t iomap_zero_range_actor(struct inode *inode, loff_t pos,
 		s64 bytes;
 
 		if (IS_DAX(inode))
-			bytes = dax_iomap_zero(pos, length, iomap);
+			bytes = dax_iomap_zero(pos, length, iomap, srcmap);
 		else
 			bytes = iomap_zero(inode, pos, length, iomap, srcmap);
 		if (bytes < 0)
diff --git a/include/linux/dax.h b/include/linux/dax.h
index b52f084aa643..3275e01ed33d 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -237,7 +237,8 @@ vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf,
 int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index);
 int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
 				      pgoff_t index);
-s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap);
+s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap,
+		struct iomap *srcmap);
 static inline bool dax_mapping(struct address_space *mapping)
 {
 	return mapping->host && IS_DAX(mapping->host);
-- 
2.30.1