[PATCH 6/6] dm: Ensure dm honors DAXDEV_F_RECOVERY flag on dax only

[Jane Chu]

dm_dax_direct_access() supports DAXDEV_F_RECOVERY, so it may
translate a poisoned range. But if dm_dax_copy_to/from_iter()
don't have a dax_copy_to/from_iter() foundation underneath,
performing load/store over poisoned range is dangerous and
should be avoided.

Signed-off-by: Jane Chu <jane....@oracle.com>
---
 drivers/md/dm.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 764183ddebc1..5f7fe64d3c37 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1058,6 +1058,8 @@ static size_t dm_dax_copy_from_iter(struct dax_device 
*dax_dev, pgoff_t pgoff,
        if (!ti)
                goto out;
        if (!ti->type->dax_copy_from_iter) {
+               if (flags & DAXDEV_F_RECOVERY)
+                       goto out;
                ret = copy_from_iter(addr, bytes, i);
                goto out;
        }
@@ -1082,6 +1084,8 @@ static size_t dm_dax_copy_to_iter(struct dax_device 
*dax_dev, pgoff_t pgoff,
        if (!ti)
                goto out;
        if (!ti->type->dax_copy_to_iter) {
+               if (flags & DAXDEV_F_RECOVERY)
+                       goto out;
                ret = copy_to_iter(addr, bytes, i);
                goto out;
        }
-- 
2.18.4