diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index c138d08cce76..320e4362d9cf 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -2899,11 +2899,14 @@ static noinline_for_stack int prealloc_file_extent_cluster(struct reloc_control
 	return ret;
 }
 
-static noinline_for_stack int setup_relocation_extent_mapping(struct inode *inode,
-				u64 start, u64 end, u64 block_start)
+static noinline_for_stack int setup_relocation_extent_mapping(struct reloc_control *rc)
 {
+	struct btrfs_inode *inode = BTRFS_I(rc->data_inode);
 	struct extent_map *em;
 	struct extent_state *cached_state = NULL;
+	u64 offset = inode->reloc_block_group_start;
+	u64 start = rc->cluster.start - offset;
+	u64 end = rc->cluster.end - offset;
 	int ret = 0;
 
 	em = alloc_extent_map();
@@ -2912,14 +2915,14 @@ static noinline_for_stack int setup_relocation_extent_mapping(struct inode *inod
 
 	em->start = start;
 	em->len = end + 1 - start;
-	em->disk_bytenr = block_start;
+	em->disk_bytenr = rc->cluster.start;
 	em->disk_num_bytes = em->len;
 	em->ram_bytes = em->len;
 	em->flags |= EXTENT_FLAG_PINNED;
 
-	lock_extent(&BTRFS_I(inode)->io_tree, start, end, &cached_state);
-	ret = btrfs_replace_extent_map_range(BTRFS_I(inode), em, false);
-	unlock_extent(&BTRFS_I(inode)->io_tree, start, end, &cached_state);
+	lock_extent(&inode->io_tree, start, end, &cached_state);
+	ret = btrfs_replace_extent_map_range(inode, em, false);
+	unlock_extent(&inode->io_tree, start, end, &cached_state);
 	free_extent_map(em);
 
 	return ret;
@@ -3110,8 +3113,7 @@ static int relocate_file_extent_cluster(struct reloc_control *rc)
 
 	file_ra_state_init(ra, inode->i_mapping);
 
-	ret = setup_relocation_extent_mapping(inode, cluster->start - offset,
-				   cluster->end - offset, cluster->start);
+	ret = setup_relocation_extent_mapping(rc);
 	if (ret)
 		goto out;