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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 0C999C55ABD for ; Tue, 10 Nov 2020 15:55:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A4C6F20795 for ; Tue, 10 Nov 2020 15:55:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="NNVASeTW" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730985AbgKJPzM (ORCPT ); Tue, 10 Nov 2020 10:55:12 -0500 Received: from mail.kernel.org ([198.145.29.99]:42812 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726721AbgKJPzL (ORCPT ); Tue, 10 Nov 2020 10:55:11 -0500 Received: from tleilax.poochiereds.net (68-20-15-154.lightspeed.rlghnc.sbcglobal.net [68.20.15.154]) (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 8242B20678; Tue, 10 Nov 2020 15:55:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1605023711; bh=VOtMpxt/g+8QNrCCztO8kyXSNbpXTZU8HKmddESaGao=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=NNVASeTW/+M8rSg7ZJX9jcDT+XxPwzGKXtmSNULif9cdweQckjj4Vhp0auKMB4ZD0 o+sJx5f1LxzPLbGIGUqcKVTvvxuSfJ/auPxyRZc8YNOIGS261LVaSoFOoPQiLdQZa+ EsDd3WtWKtXMGjHmKPNOVhkmV07OaEeYpuB7S3EE= Message-ID: <9860e28cdb88617462912548f1af4dfaecb602ab.camel@kernel.org> Subject: Re: [PATCH] fs/inode.c: make inode_init_always() initialize i_ino to 0 From: Jeff Layton To: Eric Biggers , linux-fsdevel@vger.kernel.org Cc: linux-fscrypt@vger.kernel.org, linux-ext4@vger.kernel.org Date: Tue, 10 Nov 2020 10:55:09 -0500 In-Reply-To: <20201031004420.87678-1-ebiggers@kernel.org> References: <20201031004420.87678-1-ebiggers@kernel.org> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.38.1 (3.38.1-1.fc33) MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Fri, 2020-10-30 at 17:44 -0700, Eric Biggers wrote: > From: Eric Biggers > > Currently inode_init_always() doesn't initialize i_ino to 0. This is > unexpected because unlike the other inode fields that aren't initialized > by inode_init_always(), i_ino isn't guaranteed to end up back at its > initial value after the inode is freed. Only one filesystem (XFS) > actually sets set i_ino back to 0 when freeing its inodes. > > So, callers of new_inode() see some random previous i_ino. Normally > that's fine, since normally i_ino isn't accessed before being set. > There can be edge cases where that isn't necessarily true, though. > > The one I've run into is that on ext4, when creating an encrypted file, > the new file's encryption key has to be set up prior to the jbd2 > transaction, and thus prior to i_ino being set. If something goes > wrong, fs/crypto/ may log warning or error messages, which normally > include i_ino. So it needs to know whether it is valid to include i_ino > yet or not. Also, on some files i_ino needs to be hashed for use in the > crypto, so fs/crypto/ needs to know whether that can be done yet or not. > > There are ways this could be worked around, either in fs/crypto/ or in > fs/ext4/. But, it seems there's no reason not to just fix > inode_init_always() to do the expected thing and initialize i_ino to 0. > > So, do that, and also remove the initialization in jfs_fill_super() that > becomes redundant. > > Signed-off-by: Eric Biggers > --- >  fs/inode.c | 1 + >  fs/jfs/super.c | 1 - >  2 files changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/inode.c b/fs/inode.c > index 9d78c37b00b81..eb001129f157c 100644 > --- a/fs/inode.c > +++ b/fs/inode.c > @@ -142,6 +142,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode) >   atomic_set(&inode->i_count, 1); >   inode->i_op = &empty_iops; >   inode->i_fop = &no_open_fops; > + inode->i_ino = 0; >   inode->__i_nlink = 1; >   inode->i_opflags = 0; >   if (sb->s_xattr) > diff --git a/fs/jfs/super.c b/fs/jfs/super.c > index b2dc4d1f9dcc5..1f0ffabbde566 100644 > --- a/fs/jfs/super.c > +++ b/fs/jfs/super.c > @@ -551,7 +551,6 @@ static int jfs_fill_super(struct super_block *sb, void *data, int silent) >   ret = -ENOMEM; >   goto out_unload; >   } > - inode->i_ino = 0; >   inode->i_size = i_size_read(sb->s_bdev->bd_inode); >   inode->i_mapping->a_ops = &jfs_metapage_aops; >   inode_fake_hash(inode); > > base-commit: 5fc6b075e165f641fbc366b58b578055762d5f8c This seems like a reasonable thing to do. Acked-by: Jeff Layton