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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 F1BC5C47247 for ; Tue, 5 May 2020 18:19:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BEC31206CC for ; Tue, 5 May 2020 18:19:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588702784; bh=yZzkSmvvKpe0G5yUuD0K6ah1YcmbfcINzZSizvYm2fE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=D8PMlT1OJhT30nM2ghHOe5tiCxWtZK0uZ9v+vFVWziDdQLbM85u5LXcz6RmTGdsvR MtAPo97H89OavmJPwFksGLq7uyODH2FMczNCS4PVTSQ7xowjPvetf0HAzjwz3yl8Ss S2mK6I8dNAVx6chKHd3bE8EUypzeTJPQXrdXub08= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730798AbgEESTo (ORCPT ); Tue, 5 May 2020 14:19:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:33662 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730258AbgEESTn (ORCPT ); Tue, 5 May 2020 14:19:43 -0400 Received: from gmail.com (unknown [104.132.1.76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A218E20663; Tue, 5 May 2020 18:19:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588702782; bh=yZzkSmvvKpe0G5yUuD0K6ah1YcmbfcINzZSizvYm2fE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=R67Z/lbPtsO5THBxKzX2UlLhSUm2vt0TOUX9sbZh4djBdEvxdDZsZKamROXY/lUDk 45RwmPjXsu/PJUGCFkivx2adACAXmQgXLE9PpopTyfNZZUgoXkvJRiKgv2s65OjKWz ZxQGDWUnKqLxY8xjBuFDHX627MfXB7blez9pNJvE= Date: Tue, 5 May 2020 11:19:41 -0700 From: Eric Biggers To: Jaegeuk Kim Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com Subject: Re: [f2fs-dev] [PATCH] f2fs: get parent inode when recovering pino Message-ID: <20200505181941.GC98848@gmail.com> References: <20200505153139.201697-1-jaegeuk@kernel.org> <20200505165847.GA98848@gmail.com> <20200505181323.GA55221@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200505181323.GA55221@google.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 05, 2020 at 11:13:23AM -0700, Jaegeuk Kim wrote: > On 05/05, Eric Biggers wrote: > > On Tue, May 05, 2020 at 08:31:39AM -0700, Jaegeuk Kim wrote: > > > We had to grab the inode before retrieving i_ino. > > > > > > Signed-off-by: Jaegeuk Kim > > > --- > > > fs/f2fs/file.c | 8 +++++++- > > > 1 file changed, 7 insertions(+), 1 deletion(-) > > > > > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > > > index a0a4413d6083b..9d4c3e3503567 100644 > > > --- a/fs/f2fs/file.c > > > +++ b/fs/f2fs/file.c > > > @@ -168,6 +168,7 @@ static const struct vm_operations_struct f2fs_file_vm_ops = { > > > static int get_parent_ino(struct inode *inode, nid_t *pino) > > > { > > > struct dentry *dentry; > > > + struct inode *parent; > > > > > > inode = igrab(inode); > > > dentry = d_find_any_alias(inode); > > > @@ -175,8 +176,13 @@ static int get_parent_ino(struct inode *inode, nid_t *pino) > > > if (!dentry) > > > return 0; > > > > > > - *pino = parent_ino(dentry); > > > + parent = igrab(d_inode(dentry->d_parent)); > > > dput(dentry); > > > + if (!parent) > > > + return 0; > > > + > > > + *pino = parent->i_ino; > > > + iput(parent); > > > return 1; > > Hi Eric, > > > > > This doesn't appear to be necessary. parent_ino() is: > > > > spin_lock(&dentry->d_lock); > > res = dentry->d_parent->d_inode->i_ino; > > spin_unlock(&dentry->d_lock); > > > > Since dentry is locked and referenced, ->d_parent is stable and positive. > > I see, thanks. :) > > > > > In the encrypt+casefold patch I was reviewing, it's indeed necessary, but only > > because there was a check of inode->i_flags added outside the locked region. > > The following would be simpler: > > > > spin_lock(&dentry->d_lock); > > dir = dentry->d_parent->d_inode; > > *pino = dir->i_ino; > > needs_recovery = IS_ENCRYPTED(dir) && IS_CASEFOLDED(dir); > > spin_unlock(&dentry->d_lock); > > Ack. > > > > > BTW, d_find_any_alias() is unnecessary too. This code should just be using > > file_dentry(file) from f2fs_do_sync_file(). > > How about this? > > From 9aee969a413b1ed22b48573071bc93fbb4a2002d Mon Sep 17 00:00:00 2001 > From: Jaegeuk Kim > Date: Tue, 5 May 2020 11:08:58 -0700 > Subject: [PATCH] f2fs: remove unnecessary dentry locks > > As Eric commented, let's kill unnecessary dentry ops when recovering > parent inode number. > > Suggested-by: Eric Biggers > Signed-off-by: Jaegeuk Kim > --- > fs/f2fs/file.c | 26 ++++++-------------------- > 1 file changed, 6 insertions(+), 20 deletions(-) > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > index a0a4413d6083b..711cebad36fc5 100644 > --- a/fs/f2fs/file.c > +++ b/fs/f2fs/file.c > @@ -165,21 +165,6 @@ static const struct vm_operations_struct f2fs_file_vm_ops = { > .page_mkwrite = f2fs_vm_page_mkwrite, > }; > > -static int get_parent_ino(struct inode *inode, nid_t *pino) > -{ > - struct dentry *dentry; > - > - inode = igrab(inode); > - dentry = d_find_any_alias(inode); > - iput(inode); > - if (!dentry) > - return 0; > - > - *pino = parent_ino(dentry); > - dput(dentry); > - return 1; > -} > - > static inline enum cp_reason_type need_do_checkpoint(struct inode *inode) > { > struct f2fs_sb_info *sbi = F2FS_I_SB(inode); > @@ -223,14 +208,15 @@ static bool need_inode_page_update(struct f2fs_sb_info *sbi, nid_t ino) > return ret; > } > > -static void try_to_fix_pino(struct inode *inode) > +static void try_to_fix_pino(struct dentry *dentry) > { > + struct inode *inode = d_inode(dentry); > struct f2fs_inode_info *fi = F2FS_I(inode); > - nid_t pino; > > down_write(&fi->i_sem); > - if (file_wrong_pino(inode) && inode->i_nlink == 1 && > - get_parent_ino(inode, &pino)) { > + if (file_wrong_pino(inode) && inode->i_nlink == 1) { > + nid_t pino = parent_ino(dentry); > + > f2fs_i_pino_write(inode, pino); > file_got_pino(inode); > } > @@ -310,7 +296,7 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end, > * We've secured consistency through sync_fs. Following pino > * will be used only for fsynced inodes after checkpoint. > */ > - try_to_fix_pino(inode); > + try_to_fix_pino(file_dentry(file)); > clear_inode_flag(inode, FI_APPEND_WRITE); > clear_inode_flag(inode, FI_UPDATE_WRITE); > goto out; Actually, I think this is wrong because the fsync can be done via a file descriptor that was opened to a now-deleted link to the file. We need to find the dentry whose parent directory is still exists, i.e. the parent directory that is counting towards 'inode->i_nlink == 1'. I think d_find_alias() is what we're looking for. diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index 6ab8f621a3c5..855f27468baa 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -165,13 +165,13 @@ static int get_parent_ino(struct inode *inode, nid_t *pino) { struct dentry *dentry; - inode = igrab(inode); - dentry = d_find_any_alias(inode); - iput(inode); + dentry = d_find_alias(inode); if (!dentry) return 0;