From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D9062C4338F for ; Thu, 5 Aug 2021 17:39:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A5DC261104 for ; Thu, 5 Aug 2021 17:39:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239498AbhHERjS (ORCPT ); Thu, 5 Aug 2021 13:39:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:58478 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233039AbhHERjR (ORCPT ); Thu, 5 Aug 2021 13:39:17 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 72FBD60F42; Thu, 5 Aug 2021 17:39:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1628185143; bh=mpOGezB+SXuAsFVVC6lA3bwptRrmzQF001+TM4vmdWc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=E4QaeFt7YNA89dhbokWqs7ATP7Bj82GlnLNx+wA6LzxkM82xHT+Gaz8dFXwAGiNc2 hFoeWzLsIX7QCVOuY2bfl+FzVv0Nw7pZhBmebhbRxAW4cbCw5kD1wPflm2BVQ3RIv7 gLz5yq/Nq3mZlZZn0xTDrvTrIvMFQ2YMzZbXq8qchCnNpR4B2xI0ZSdJwhP63P9a9b 1+K2C2qALwsm1SUwWvD2OBwEgeE6iTeKAV5hu6zqpTafqN0a3w+eEb5EKxuOcSp09B RUkjjWo0avlBGuKVhJ3jwP6gFRmPQ8LsP6e33F4dDJUU3rMZgQUET9pioKaChkYjIC mO5wNW5NB0Q7w== Date: Thu, 5 Aug 2021 10:39:03 -0700 From: "Darrick J. Wong" To: "Matthew Wilcox (Oracle)" Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 1/2] iomap: Use kmap_local_page instead of kmap_atomic Message-ID: <20210805173903.GH3601405@magnolia> References: <20210803193134.1198733-1-willy@infradead.org> <20210805173104.GF3601405@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210805173104.GF3601405@magnolia> Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Thu, Aug 05, 2021 at 10:31:04AM -0700, Darrick J. Wong wrote: > On Tue, Aug 03, 2021 at 08:31:33PM +0100, Matthew Wilcox (Oracle) wrote: > > kmap_atomic() has the side-effect of disabling pagefaults and > > preemption. kmap_local_page() does not do this and is preferred. > > > > Signed-off-by: Matthew Wilcox (Oracle) > > Pretty straightforward. > Reviewed-by: Darrick J. Wong > > --D > > > --- > > fs/iomap/buffered-io.c | 10 +++++----- > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > > index c1c8cd41ea81..8ee0211bea86 100644 > > --- a/fs/iomap/buffered-io.c > > +++ b/fs/iomap/buffered-io.c > > @@ -223,10 +223,10 @@ static int iomap_read_inline_data(struct inode *inode, struct page *page, > > if (poff > 0) > > iomap_page_create(inode, page); > > > > - addr = kmap_atomic(page) + poff; > > + addr = kmap_local_page(page) + poff; Though now that I think about it: Why does iomap_write_actor still use copy_page_from_iter_atomic? Can that be converted to use regular copy_page_from_iter, which at least sometimes uses kmap_local_page? --D > > memcpy(addr, iomap->inline_data, size); > > memset(addr + size, 0, PAGE_SIZE - poff - size); > > - kunmap_atomic(addr); > > + kunmap_local(addr); > > iomap_set_range_uptodate(page, poff, PAGE_SIZE - poff); > > return PAGE_SIZE - poff; > > } > > @@ -682,9 +682,9 @@ static size_t iomap_write_end_inline(struct inode *inode, struct page *page, > > BUG_ON(!iomap_inline_data_valid(iomap)); > > > > flush_dcache_page(page); > > - addr = kmap_atomic(page); > > - memcpy(iomap_inline_data(iomap, pos), addr + pos, copied); > > - kunmap_atomic(addr); > > + addr = kmap_local_page(page) + pos; > > + memcpy(iomap_inline_data(iomap, pos), addr, copied); > > + kunmap_local(addr); > > > > mark_inode_dirty(inode); > > return copied; > > -- > > 2.30.2 > >