unshare copies data from source to destination. But if the source is
HOLE or UNWRITTEN extents, we should zero the destination, otherwise the
result will be unexpectable.
Fixes: d984648e428b ("fsdax,xfs: port unshare to fsdax")
Signed-off-by: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx>
---
fs/dax.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index 9800b93ee14d..5d2e9b10030e 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1258,15 +1258,20 @@ static s64 dax_unshare_iter(struct iomap_iter *iter)
/* don't bother with blocks that are not shared to start with */
if (!(iomap->flags & IOMAP_F_SHARED))
return length;
- /* don't bother with holes or unwritten extents */
- if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN)
- return length;
id = dax_read_lock();
ret = dax_iomap_direct_access(iomap, pos, length, &daddr, NULL);
if (ret < 0)
goto out_unlock;
+ /* zero the distance if srcmap is HOLE or UNWRITTEN */
+ if (srcmap->flags & IOMAP_F_SHARED || srcmap->type == IOMAP_UNWRITTEN) {
+ memset(daddr, 0, length);
+ dax_flush(iomap->dax_dev, daddr, length);
+ ret = length;
+ goto out_unlock;
+ }
+
ret = dax_iomap_direct_access(srcmap, pos, length, &saddr, NULL);
if (ret < 0)
goto out_unlock;
--
2.39.2
