On Wed, Sep 15, 2021 at 06:44:58PM +0800, Shiyang Ruan wrote: > + rc = dax_direct_access(iomap->dax_dev, pgoff, 1, &kaddr, NULL); > + if (rc < 0) > + goto out; > + memset(kaddr + offset, 0, size); > + if (srcmap->addr != IOMAP_HOLE && srcmap->addr != iomap->addr) { Should we also check that ->dax_dev for iomap and srcmap are different first to deal with case of file system with multiple devices? Otherwise looks good: Reviewed-by: Christoph Hellwig <hch@xxxxxx>