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 6601BC388F2 for ; Fri, 6 Nov 2020 17:52:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 08838217A0 for ; Fri, 6 Nov 2020 17:52:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604685130; bh=+rTplTiRHCg1rSJZZILvtbrGwQkXqYXlY1s1r0lYRj8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=e1W8FB5FQyWUG0IWk59pCrVT4uqVRByX/u+ouaf0pVpnq+JR09vF0ZG1dMvGpAzmp ojvNnvCBssM0x45GNnkCkVqv9HKbSt8NMqSFZc/q9wKgoL7SwSz3yVZw9zJkhwIkzg 1tYJRoeWiRchiEBiL2LmoCWKrwnpH/R5yFykgWYs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727708AbgKFRwI (ORCPT ); Fri, 6 Nov 2020 12:52:08 -0500 Received: from mail.kernel.org ([198.145.29.99]:55760 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726034AbgKFRwI (ORCPT ); Fri, 6 Nov 2020 12:52:08 -0500 Received: from sol.localdomain (172-10-235-113.lightspeed.sntcca.sbcglobal.net [172.10.235.113]) (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 2C12C206F4; Fri, 6 Nov 2020 17:52:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604685127; bh=+rTplTiRHCg1rSJZZILvtbrGwQkXqYXlY1s1r0lYRj8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=F+nspiyMoaHUdjgkHdvyFN7TjbEJuDH6E5/gsmZuQpTJ6Mks2/ZX4fEULddQILtyV C7jt0GUYyptvY1wCY7opIUGuK05/rWJKZ2Nq2AKh4tIxtV2snaP7LPmb7Zl/GVdo80 PcEgKyh7Eeuuc2cdyoVGCZzROsapb3faNVR4/9Wg= Date: Fri, 6 Nov 2020 09:52:05 -0800 From: Eric Biggers To: Alexander Viro , linux-fsdevel@vger.kernel.org Cc: linux-fscrypt@vger.kernel.org, linux-ext4@vger.kernel.org Subject: Re: [PATCH] fs/inode.c: make inode_init_always() initialize i_ino to 0 Message-ID: <20201106175205.GE845@sol.localdomain> References: <20201031004420.87678-1-ebiggers@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201031004420.87678-1-ebiggers@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Fri, Oct 30, 2020 at 05:44:20PM -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); > Al, any thoughts on this? - Eric