fsdax: add dax_iomap_cow_copy() for dax zero

Punch hole on a reflinked file needs dax_iomap_cow_copy() too.  Otherwise,
data in not aligned area will be not correct.  So, add the CoW operation
for not aligned case in dax_memzero().

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Shiyang Ruan <[email protected]>
Reviewed-by: Ritesh Harjani <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Goldwyn Rodrigues <[email protected]>
Cc: Goldwyn Rodrigues <[email protected]>
Cc: Jane Chu <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Miaohe Lin <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 19 insertions, 8 deletions

diff --git a/fs/dax.c b/fs/dax.c
index 04fee1569328..0aab32300531 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1221,17 +1221,28 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
 }
 #endif /* CONFIG_FS_DAX_PMD */
 
-static int dax_memzero(struct dax_device *dax_dev, pgoff_t pgoff,
-		unsigned int offset, size_t size)
+static int dax_memzero(struct iomap_iter *iter, loff_t pos, size_t size)
 {
+	const struct iomap *iomap = &iter->iomap;
+	const struct iomap *srcmap = iomap_iter_srcmap(iter);
+	unsigned offset = offset_in_page(pos);
+	pgoff_t pgoff = dax_iomap_pgoff(iomap, pos);
 	void *kaddr;
 	long ret;
 
-	ret = dax_direct_access(dax_dev, pgoff, 1, DAX_ACCESS, &kaddr, NULL);
-	if (ret > 0) {
-		memset(kaddr + offset, 0, size);
-		dax_flush(dax_dev, kaddr + offset, size);
-	}
+	ret = dax_direct_access(iomap->dax_dev, pgoff, 1, DAX_ACCESS, &kaddr,
+				NULL);
+	if (ret < 0)
+		return ret;
+	memset(kaddr + offset, 0, size);
+	if (srcmap->addr != iomap->addr) {
+		ret = dax_iomap_cow_copy(pos, size, PAGE_SIZE, srcmap,
+					 kaddr);
+		if (ret < 0)
+			return ret;
+		dax_flush(iomap->dax_dev, kaddr, PAGE_SIZE);
+	} else
+		dax_flush(iomap->dax_dev, kaddr + offset, size);
 	return ret;
 }
 
@@ -1258,7 +1269,7 @@ static s64 dax_zero_iter(struct iomap_iter *iter, bool *did_zero)
 		if (IS_ALIGNED(pos, PAGE_SIZE) && size == PAGE_SIZE)
 			rc = dax_zero_page_range(iomap->dax_dev, pgoff, 1);
 		else
-			rc = dax_memzero(iomap->dax_dev, pgoff, offset, size);
+			rc = dax_memzero(iter, pos, size);
 		dax_read_unlock(id);
 
 		if (rc < 0)