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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3B04BC433EF for ; Wed, 9 Mar 2022 22:32:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238696AbiCIWdv (ORCPT ); Wed, 9 Mar 2022 17:33:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35430 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238709AbiCIWdu (ORCPT ); Wed, 9 Mar 2022 17:33:50 -0500 Received: from mail105.syd.optusnet.com.au (mail105.syd.optusnet.com.au [211.29.132.249]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 7B7452B191 for ; Wed, 9 Mar 2022 14:32:47 -0800 (PST) Received: from dread.disaster.area (pa49-186-150-27.pa.vic.optusnet.com.au [49.186.150.27]) by mail105.syd.optusnet.com.au (Postfix) with ESMTPS id 91C3E10E2CEF; Thu, 10 Mar 2022 09:32:46 +1100 (AEDT) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1nS4rN-003YXP-Dw; Thu, 10 Mar 2022 09:32:45 +1100 Date: Thu, 10 Mar 2022 09:32:45 +1100 From: Dave Chinner To: "Darrick J. Wong" Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH 2/2] xfs: constify xfs_name_dotdot Message-ID: <20220309223245.GK661808@dread.disaster.area> References: <164685375609.496011.2754821878646256374.stgit@magnolia> <164685376731.496011.1567771444928519597.stgit@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <164685376731.496011.1567771444928519597.stgit@magnolia> X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.4 cv=VuxAv86n c=1 sm=1 tr=0 ts=62292b0e a=sPqof0Mm7fxWrhYUF33ZaQ==:117 a=sPqof0Mm7fxWrhYUF33ZaQ==:17 a=kj9zAlcOel0A:10 a=o8Y5sQTvuykA:10 a=VwQbUJbxAAAA:8 a=7-415B0cAAAA:8 a=teNfEa-P9VIzn0qQ3soA:9 a=CjuIK1q_8ugA:10 a=AjGcO6oz07-iQ99wixmX:22 a=biEYGPWJfzWAr4FL6Ov7:22 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Wed, Mar 09, 2022 at 11:22:47AM -0800, Darrick J. Wong wrote: > From: Darrick J. Wong > > The symbol xfs_name_dotdot is a global variable that the xfs codebase > uses here and there to look up directory dotdot entries. Currently it's > a non-const variable, which means that it's a mutable global variable. > So far nobody's abused this to cause problems, but let's use the > compiler to enforce that. > > Signed-off-by: Darrick J. Wong > --- > fs/xfs/libxfs/xfs_dir2.c | 6 +++++- > fs/xfs/libxfs/xfs_dir2.h | 2 +- > fs/xfs/scrub/parent.c | 6 ++++-- > fs/xfs/xfs_export.c | 3 ++- > 4 files changed, 12 insertions(+), 5 deletions(-) > > > diff --git a/fs/xfs/libxfs/xfs_dir2.c b/fs/xfs/libxfs/xfs_dir2.c > index a77d931d65a3..cf9fa07e62d5 100644 > --- a/fs/xfs/libxfs/xfs_dir2.c > +++ b/fs/xfs/libxfs/xfs_dir2.c > @@ -19,7 +19,11 @@ > #include "xfs_error.h" > #include "xfs_trace.h" > > -struct xfs_name xfs_name_dotdot = { (unsigned char *)"..", 2, XFS_DIR3_FT_DIR }; > +const struct xfs_name xfs_name_dotdot = { > + .name = (unsigned char *)"..", > + .len = 2, > + .type = XFS_DIR3_FT_DIR, > +}; *nod* > diff --git a/fs/xfs/scrub/parent.c b/fs/xfs/scrub/parent.c > index ab182a5cd0c0..e9549d998cdc 100644 > --- a/fs/xfs/scrub/parent.c > +++ b/fs/xfs/scrub/parent.c > @@ -131,6 +131,7 @@ xchk_parent_validate( > xfs_ino_t dnum, > bool *try_again) > { > + struct xfs_name dotdot = xfs_name_dotdot; > struct xfs_mount *mp = sc->mp; > struct xfs_inode *dp = NULL; > xfs_nlink_t expected_nlink; > @@ -230,7 +231,7 @@ xchk_parent_validate( > expected_nlink = VFS_I(sc->ip)->i_nlink == 0 ? 0 : 1; > > /* Look up '..' to see if the inode changed. */ > - error = xfs_dir_lookup(sc->tp, sc->ip, &xfs_name_dotdot, &dnum, NULL); > + error = xfs_dir_lookup(sc->tp, sc->ip, &dotdot, &dnum, NULL); > if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, 0, &error)) > goto out_rele; > Why can't xfs_dir_lookup() be defined as a const xname for the input name? All it does is extract the contents into the da_args fields, and pass it to xfs_dir_hashname() which you converted to const in the previous patch. Or does the compiler then complain at all the other callsites that you're passing non-const stuff to const function parameters? i.e. am I just pulling on another dangling end of the ball of string at this point? > @@ -263,6 +264,7 @@ int > xchk_parent( > struct xfs_scrub *sc) > { > + struct xfs_name dotdot = xfs_name_dotdot; > struct xfs_mount *mp = sc->mp; > xfs_ino_t dnum; > bool try_again; > @@ -293,7 +295,7 @@ xchk_parent( > xfs_iunlock(sc->ip, XFS_ILOCK_EXCL | XFS_MMAPLOCK_EXCL); > > /* Look up '..' */ > - error = xfs_dir_lookup(sc->tp, sc->ip, &xfs_name_dotdot, &dnum, NULL); > + error = xfs_dir_lookup(sc->tp, sc->ip, &dotdot, &dnum, NULL); > if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, 0, &error)) > goto out; > if (!xfs_verify_dir_ino(mp, dnum)) { > diff --git a/fs/xfs/xfs_export.c b/fs/xfs/xfs_export.c > index 1064c2342876..8939119191f4 100644 > --- a/fs/xfs/xfs_export.c > +++ b/fs/xfs/xfs_export.c > @@ -206,10 +206,11 @@ STATIC struct dentry * > xfs_fs_get_parent( > struct dentry *child) > { > + struct xfs_name dotdot = xfs_name_dotdot; > int error; > struct xfs_inode *cip; > > - error = xfs_lookup(XFS_I(d_inode(child)), &xfs_name_dotdot, &cip, NULL); > + error = xfs_lookup(XFS_I(d_inode(child)), &dotdot, &cip, NULL); > if (unlikely(error)) > return ERR_PTR(error); This only calls xfs_dir_lookup() with name, so if xfs_dir_lookup() can have a const name, so can xfs_lookup().... Cheers, Dave. -- Dave Chinner david@fromorbit.com