From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EBEB32CA5 for ; Wed, 2 Feb 2022 13:44:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=g4vUH6EzyLT2vaGYwlen5+OHvw9Zb7oDiztQ44k8gOY=; b=taz5SADOs9Pfi14hGDnEcDNHDC qPdeN8oYaj1zKm1GTA8AvbbszJ99pctasgAt+q64guHYT/RAxDVg1543f4Fkgb64xN1y7CYxxfR/z X/WEwPUQmi/0ZWKYb9iSzDz2OHM1dxmGFYDQ+67c8IZ4ZNdPTQ/t7zhx5KrHrFPEgk4YqIbmeITIG /iNDlc2pDVeJXerurYMgHnhflHW1/wZRcXuX5c8LGZjufWsrG593L6XNNCwmawN2pdoQ3EvjXD+j+ 5rliuRKcexGGJexwyWQz4oDlGocfsFbHyFPEijUawPGjyE8Oe0G5Vyg07U4/rmtLwKJA1TDwAC+6l mQE48Q3Q==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nFFvW-00FNmE-0j; Wed, 02 Feb 2022 13:44:02 +0000 Date: Wed, 2 Feb 2022 05:44:01 -0800 From: Christoph Hellwig To: Jane Chu Cc: david@fromorbit.com, djwong@kernel.org, dan.j.williams@intel.com, hch@infradead.org, vishal.l.verma@intel.com, dave.jiang@intel.com, agk@redhat.com, snitzer@redhat.com, dm-devel@redhat.com, ira.weiny@intel.com, willy@infradead.org, vgoyal@redhat.com, linux-fsdevel@vger.kernel.org, nvdimm@lists.linux.dev, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org Subject: Re: [PATCH v5 6/7] dax: add recovery_write to dax_iomap_iter in failure path Message-ID: References: <20220128213150.1333552-1-jane.chu@oracle.com> <20220128213150.1333552-7-jane.chu@oracle.com> Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220128213150.1333552-7-jane.chu@oracle.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Fri, Jan 28, 2022 at 02:31:49PM -0700, Jane Chu wrote: > +typedef size_t (*iter_func_t)(struct dax_device *dax_dev, pgoff_t pgoff, > + void *addr, size_t bytes, struct iov_iter *i); > static loff_t dax_iomap_iter(const struct iomap_iter *iomi, > struct iov_iter *iter) > { > @@ -1210,6 +1212,7 @@ static loff_t dax_iomap_iter(const struct iomap_iter *iomi, > ssize_t ret = 0; > size_t xfer; > int id; > + iter_func_t write_func = dax_copy_from_iter; This use of a function pointer causes indirect call overhead. A simple "bool in_recovery" or do_recovery does the trick in a way that is both more readable and generates faster code. > + if ((map_len == -EIO) && (iov_iter_rw(iter) == WRITE)) { No need for the braces. > if (iov_iter_rw(iter) == WRITE) > - xfer = dax_copy_from_iter(dax_dev, pgoff, kaddr, > - map_len, iter); > + xfer = write_func(dax_dev, pgoff, kaddr, map_len, iter); > else > xfer = dax_copy_to_iter(dax_dev, pgoff, kaddr, > map_len, iter); i.e. if (iov_iter_rw(iter) == READ) xfer = dax_copy_to_iter(dax_dev, pgoff, kaddr, map_len, iter); else if (unlikely(do_recovery)) xfer = dax_recovery_write(dax_dev, pgoff, kaddr, map_len, iter); else xfer = dax_copy_from_iter(dax_dev, pgoff, kaddr, map_len, iter);