linux-kernel - Re: [RFC PATCH] ext4: increase the protection of drop nlink and ext4 inode destroy

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Message-ID: <20170104215424.GB14021@birch.djwong.org>
Date:   Wed, 4 Jan 2017 13:54:24 -0800
From:   "Darrick J. Wong" <darrick.wong@...cle.com>
To:     "zhangyi (F)" <yi.zhang@...wei.com>
Cc:     Valdis.Kletnieks@...edu, linux-ext4@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        tytso@....edu, adilger.kernel@...ger.ca
Subject: Re: [RFC PATCH] ext4: increase the protection of drop nlink and ext4
 inode destroy

On Wed, Jan 04, 2017 at 04:29:33PM +0800, zhangyi (F) wrote:
> On 2017/1/1 6:59, Valdis.Kletnieks@...edu said:
> > On Mon, 26 Dec 2016 20:34:17 +0800, yi zhang said:
> >> Because of the disk and hardware issue, the ext4 filesystem have
> >> many errors, the inode->i_nlink of ext4 becomes zero abnormally
> >> but the dentry is still positive, it will cause memory corruption
> >> after the following process:
> >>
> >>  1) Due to the inode->i_nlink is 0, this inode will be added into
> >> the orhpan list,
> > 
> >> +	if (WARN(inode->i_nlink == 0, "inode %lu nlink"
> >> +		" is already 0", inode->i_ino))
> > 
> > Can we get the filesystem? Or at least the device major/minor? If a system
> > has multiple large ext4 filesystems, it would be helpful to know which
> > one is having the problem.
> > 
> 
>         if (WARN(inode->i_nlink == 0,
> -               "inode %lu nlink is already 0", inode->i_ino))
> +               "inode %lu nlink is already 0, dev=%u:%u",
> +               inode->i_ino, MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev)))
>                 return;
> 
> We can modify as above, it's enough to know which filesystem is having the
> problem, what do you think?

Why not:

if (inode->i_nlink == 0) {
	ext4_warning_inode(inode, "nlink is already 0");
	return;
}

?

--D

> 
> yi zhang
> 
> --
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