Re: [PATCH v5 3/7] fsdax: Add dax_iomap_cow_copy() for dax_iomap_zero

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Hi,

On 11.5.2021 6.09, Shiyang Ruan wrote:
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>
Reviewed-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
---
  fs/dax.c               | 25 +++++++++++++++----------
  fs/iomap/buffered-io.c |  2 +-
  include/linux/dax.h    |  3 ++-
  3 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index ef0e564e7904..ee9d28a79bfb 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1186,7 +1186,8 @@ 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;
@@ -1208,19 +1209,23 @@ s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap)
if (page_aligned)
  		rc = dax_zero_page_range(iomap->dax_dev, pgoff, 1);
-	else
+	else {
  		rc = dax_direct_access(iomap->dax_dev, pgoff, 1, &kaddr, NULL);
-	if (rc < 0) {
-		dax_read_unlock(id);
-		return rc;
-	}
-
-	if (!page_aligned) {
-		memset(kaddr + offset, 0, size);
+		if (rc < 0)
+			goto out;
+		if (iomap->addr != srcmap->addr) {
+			rc = dax_iomap_cow_copy(offset, size, PAGE_SIZE, srcmap,
+						kaddr);

offset above is offset in page, think dax_iomap_cow_copy() expects absolute pos

+			if (rc < 0)
+				goto out;
+		} else
+			memset(kaddr + offset, 0, size);
  		dax_flush(iomap->dax_dev, kaddr + offset, size);
  	}
+
+out:
  	dax_read_unlock(id);
-	return size;
+	return rc < 0 ? rc : size;
  }
static loff_t
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index f2cd2034a87b..2734955ea67f 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);




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