--- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -4983,6 +4983,10 @@ static int put_file_data(struct send_ctx lock_page(page); if (!PageUptodate(page)) { unlock_page(page); + btrfs_err(fs_info, + "send: IO error at offset %llu for inode %llu root %llu", + page_offset(page), sctx->cur_ino, + sctx->send_root->root_key.objectid); put_page(page); ret = -EIO; break;