diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index b12850b31cb3cd..1f58debb9a0486 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4863,9 +4863,6 @@ int btrfs_truncate_block(struct btrfs_inode *inode, loff_t from, loff_t len,
 		ret = -ENOMEM;
 		goto out;
 	}
-	ret = set_page_extent_mapped(page);
-	if (ret < 0)
-		goto out_unlock;
 
 	if (!PageUptodate(page)) {
 		ret = btrfs_read_folio(NULL, page_folio(page));
@@ -4880,6 +4877,17 @@ int btrfs_truncate_block(struct btrfs_inode *inode, loff_t from, loff_t len,
 			goto out_unlock;
 		}
 	}
+
+	/*
+	 * We unlock the page after the io is completed and then re-lock it
+	 * above.  release_folio() could have come in between that and cleared
+	 * PagePrivate(), but left the page in the mapping.  Set the page mapped
+	 * here to make sure it's properly set for the subpage stuff.
+	 */
+	ret = set_page_extent_mapped(page);
+	if (ret < 0)
+		goto out_unlock;
+
 	wait_on_page_writeback(page);
 
 	lock_extent(io_tree, block_start, block_end, &cached_state);