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=-17.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 41AB0C4338F for ; Thu, 19 Aug 2021 10:35:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0A68E61152 for ; Thu, 19 Aug 2021 10:35:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237730AbhHSKfm (ORCPT ); Thu, 19 Aug 2021 06:35:42 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:40604 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236149AbhHSKfl (ORCPT ); Thu, 19 Aug 2021 06:35:41 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 6708D2209B; Thu, 19 Aug 2021 10:35:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1629369304; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=p1/YjMtunmntj17IgarF8r82HsoYyHTF0J/qAPFpnFw=; b=tboh7SBNbEvFQy8ofVvQ/LHbFcEb2QdNW/t4oH7mU6XjQDcGU0Qxz39jCQr9UgFGeQwwlt kFJOZgZrYc0v3JtXz9FzhpBKI+rcje2ZS4gZj7LwFwUGt1zC+Zv7zltuxi5eaFB6fe6dwE /hgODNN/k9EQHMCcUn0ur/ir3XT7J38= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1629369304; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=p1/YjMtunmntj17IgarF8r82HsoYyHTF0J/qAPFpnFw=; b=icC8cjY07IHHsIct7uGGvl8SvNr/rociHdyu5uhEk8y0GEliX57wi0LK69XD9A/gOSNGHC X9q9hoELCZgyqpDA== Received: from quack2.suse.cz (unknown [10.100.224.230]) by relay2.suse.de (Postfix) with ESMTP id C3628A3BC7; Thu, 19 Aug 2021 10:34:46 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 30E6E1E0679; Thu, 19 Aug 2021 12:35:04 +0200 (CEST) Date: Thu, 19 Aug 2021 12:35:04 +0200 From: Jan Kara To: Zhang Yi Cc: linux-ext4@vger.kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca, jack@suse.cz, yukuai3@huawei.com Subject: Re: [PATCH v2 4/4] ext4: prevent getting empty inode buffer Message-ID: <20210819103504.GB32435@quack2.suse.cz> References: <20210819065704.1248402-1-yi.zhang@huawei.com> <20210819065704.1248402-5-yi.zhang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210819065704.1248402-5-yi.zhang@huawei.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Thu 19-08-21 14:57:04, Zhang Yi wrote: > In ext4_get_inode_loc(), we may skip IO and get an zero && uptodate > inode buffer when the inode monopolize an inode block for performance > reason. For most cases, ext4_mark_iloc_dirty() will fill the inode > buffer to make it fine, but we could miss this call if something bad > happened. Finally, __ext4_get_inode_loc_noinmem() may probably get an > empty inode buffer and trigger ext4 error. > > For example, if we remove a nonexistent xattr on inode A, > ext4_xattr_set_handle() will return ENODATA before invoking > ext4_mark_iloc_dirty(), it will left an uptodate but zero buffer. We > will get checksum error message in ext4_iget() when getting inode again. > > EXT4-fs error (device sda): ext4_lookup:1784: inode #131074: comm cat: iget: checksum invalid > > Even worse, if we allocate another inode B at the same inode block, it > will corrupt the inode A on disk when write back inode B. > > So this patch postpone the init and mark buffer uptodate logic until > before filling correct inode data in ext4_do_update_inode() if skip read > I/O, ensure the buffer is real uptodate. > > Signed-off-by: Zhang Yi Looks good. Just some language fixes below. Feel free to add: Reviewed-by: Jan Kara > --- > fs/ext4/inode.c | 26 +++++++++++++++++++++++--- > 1 file changed, 23 insertions(+), 3 deletions(-) > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index d0d7a5295bf9..02d910c9d8f1 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -4367,9 +4367,11 @@ static int __ext4_get_inode_loc(struct super_block *sb, unsigned long ino, > } > brelse(bitmap_bh); > if (i == start + inodes_per_block) { > - /* all other inodes are free, so skip I/O */ > - memset(bh->b_data, 0, bh->b_size); > - set_buffer_uptodate(bh); > + /* > + * All other inodes are free, skip I/O. Return > + * un-inited buffer (which is postponed until I'd repharse this sentence as: Return uninitialized buffer immediately, initialization is postponed until shortly before we fill inode contents. > + * before filling inode data) immediately. > + */ > unlock_buffer(bh); > goto has_buffer; > } > @@ -5026,6 +5028,24 @@ static int ext4_do_update_inode(handle_t *handle, > gid_t i_gid; > projid_t i_projid; > > + /* > + * If the buffer is not uptodate, it means all information of inode ^^^^^^^^ of the inode is > + * in memory and we got this buffer without reading the block. We > + * must be cautious that once we mark the buffer as uptodate, we > + * rely on filling in the correct inode data later in this function. > + * Otherwise if we getting the left falsepositive buffer when I'd rephrase this sentence as: Otherwise if we left uptodate buffer without copying proper inode contents, we could corrupt the inode on disk after allocating another inode in the same block. Honza -- Jan Kara SUSE Labs, CR