1 files changed, 23 insertions, 1 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 1fb1333fefec..5475081dcbd6 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1107,6 +1107,25 @@ static long dm_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
         return ret;
 }
 
+static bool dm_dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
+                int blocksize, sector_t start, sector_t len)
+{
+        struct mapped_device *md = dax_get_private(dax_dev);
+        struct dm_table *map;
+        int srcu_idx;
+        bool ret;
+
+        map = dm_get_live_table(md, &srcu_idx);
+        if (!map)
+                return false;
+
+        ret = dm_table_supports_dax(map, blocksize);
+
+        dm_put_live_table(md, srcu_idx);
+
+        return ret;
+}
+
 static size_t dm_dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
                                     void *addr, size_t bytes, struct iov_iter *i)
 {
@@ -1469,7 +1488,7 @@ static unsigned get_num_write_zeroes_bios(struct dm_target *ti)
 static int __send_changing_extent_only(struct clone_info *ci, struct dm_target *ti,
                                        unsigned num_bios)
 {
-        unsigned len = ci->sector_count;
+        unsigned len;
 
         /*
          * Even though the device advertised support for this type of
@@ -1480,6 +1499,8 @@ static int __send_changing_extent_only(struct clone_info *ci, struct dm_target *
         if (!num_bios)
                 return -EOPNOTSUPP;
 
+        len = min((sector_t)ci->sector_count, max_io_len_target_boundary(ci->sector, ti));
+
         __send_duplicate_bios(ci, ti, num_bios, &len);
 
         ci->sector += len;
@@ -3192,6 +3213,7 @@ static const struct block_device_operations dm_blk_dops = {
 
 static const struct dax_operations dm_dax_ops = {
         .direct_access = dm_dax_direct_access,
+        .dax_supported = dm_dax_supported,
         .copy_from_iter = dm_dax_copy_from_iter,
         .copy_to_iter = dm_dax_copy_to_iter,
 };