From nobody Mon Feb 9 02:14:18 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 64BFBEB64DD for ; Thu, 29 Jun 2023 21:51:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230476AbjF2VvB (ORCPT ); Thu, 29 Jun 2023 17:51:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60372 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229742AbjF2Vu6 (ORCPT ); Thu, 29 Jun 2023 17:50:58 -0400 Received: from msg-4.mailo.com (msg-4.mailo.com [213.182.54.15]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F2AE30C5 for ; Thu, 29 Jun 2023 14:50:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=mailo.com; s=mailo; t=1688075453; bh=oLlIroBMRDkkKoSKm/jnig64fpkTQsUV8Vs7jXlV6S4=; h=X-EA-Auth:Date:From:To:Cc:Subject:Message-ID:References: MIME-Version:Content-Type:Content-Transfer-Encoding:In-Reply-To; b=RKNVi0JK9yb6y9ikoObZVDdxHNI2S5uutZblCHSGincf4Psj2Ag97vTYB5aVbRMcc UrrHBFMqhOnr34uVCquYANjyCyOuq2cOBJitjHzlTIduyd8E1sd62ksQ/gDaTJBvC/ PNM1qd/6Uo+B49nl1VgykaL04dtw4uwhJhusDBCY= Received: by b221-6.in.mailobj.net [192.168.90.26] with ESMTP via ip-20.mailobj.net [213.182.54.20] Thu, 29 Jun 2023 23:50:53 +0200 (CEST) X-EA-Auth: ZFhqXnP7AsOSoIr/Ef0GqN9/yMiSC8/ZRNPogc47fkLBPnGNkvMpik0u2PJ2NVJJPLCdjVVzGTceRqslXnom3aOt+GdSlj3f Date: Fri, 30 Jun 2023 03:20:43 +0530 From: Deepak R Varma To: Bob Peterson , Andreas Gruenbacher , cluster-devel@redhat.com, linux-kernel@vger.kernel.org Cc: Ira Weiny , "Fabio M. De Francesco" , Sumitra Sharma , Deepak R Varma Subject: [PATCH v3 3/6] gfs2: Replace kmap() by kmap_local_page() in gfs2_unstuffer_page Message-ID: <063721a02d5e226d1e9e9782f76ce94c16d73e93.1688073459.git.drv@mailo.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The use of kmap() is being deprecated in favor of kmap_local_page(). There are two main problems with kmap(): (1) It comes with an overhead as the mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmap=E2=80=99s pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and still valid. Therefore, replace kmap() with kmap_local_page() in gfs2_unstuffer_page(). Suggested-by: Fabio M. De Francesco Signed-off-by: Deepak R Varma --- Changes in v3: - Patch included in the patch series Changes in v2: - None fs/gfs2/bmap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c index 8d611fbcf0bd..6b850e2ba5c8 100644 --- a/fs/gfs2/bmap.c +++ b/fs/gfs2/bmap.c @@ -58,12 +58,12 @@ static int gfs2_unstuffer_page(struct gfs2_inode *ip, s= truct buffer_head *dibh, struct inode *inode =3D &ip->i_inode; =20 if (!PageUptodate(page)) { - void *kaddr =3D kmap(page); + void *kaddr =3D kmap_local_page(page); u64 dsize =3D i_size_read(inode); =20 memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize); memset(kaddr + dsize, 0, PAGE_SIZE - dsize); - kunmap(page); + kunmap_local(kaddr); =20 SetPageUptodate(page); } --=20 2.34.1