linux-ext4 - Re: fsck doesn't seem to understand inline directories

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Message-Id: <AC3B5A45-B5AB-461B-82BD-DDEB0FF6BF3A@dilger.ca>
Date:   Wed, 12 Jun 2019 20:22:18 -0600
From:   Andreas Dilger <adilger@...ger.ca>
To:     Theodore Ts'o <tytso@....edu>,
        Artem Blagodarenko <artem.blagodarenko@...il.com>
Cc:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        linux-ext4 <linux-ext4@...r.kernel.org>,
        Li Dongyang <dongyangli@....com>
Subject: Re: fsck doesn't seem to understand inline directories

On Jun 12, 2019, at 7:50 PM, Theodore Ts'o <tytso@....edu> wrote:
> 
> On Wed, Jun 12, 2019 at 02:40:18PM -0600, Andreas Dilger wrote:
>> On Jun 12, 2019, at 8:07 AM, Rasmus Villemoes <linux@...musvillemoes.dk> wrote:
>>> 
>>> Doing a forced check on an ext4 file system with inline_data results in
>>> lots of warnings - and I think answering yes to "fixing" those would
>>> actually corrupt the fs.
>> 
>> Rasmus,
>> This definitely seems like a bug in e2fsck.  It isn't totally surprising, since
>> the inline_data feature is not widely used.  We are currently investigating using
>> it for regular files, but it doesn't seem worthwhile for directories to me.
> 
> It looks like the problem is the combination of large_dir and
> inline_data, and it does look like the problem is in e2fsck (as
> opposed to the kernel).
> 
> Large_dir is a new feature (even newer than inline_data, and it looks
> like the support for large_dir didn't handle the combination with
> inline_data correctly).

Strange.

Artem, any chance you could look into this?

Cheers, Andreas

> # mke2fs -t ext4 -O inline_data -Fq /tmp/ext4.img 1G
> /tmp/ext4.img contains a ext4 file system
> 	last mounted on Wed Jun 12 21:47:25 2019
> # mount /tmp/ext4.img /mnt ; mkdir /mnt/aa ; umount /mnt
> # e2fsck -fn /tmp/ext4.img
> e2fsck 1.45.2 (27-May-2019)
> Pass 1: Checking inodes, blocks, and sizes
> Pass 2: Checking directory structure
> Pass 3: Checking directory connectivity
> Pass 4: Checking reference counts
> Pass 5: Checking group summary information
> /tmp/ext4.img: 12/65536 files (0.0% non-contiguous), 12954/262144 blocks
> 
> ### So everything is fine with just inline_data, but when you
> ### enable the large_dir features, and rerun e2fsck....
> 
> # debugfs -w -R "features large_dir" /tmp/ext4.img
> debugfs 1.45.2 (27-May-2019)
> Filesystem features: has_journal ext_attr resize_inode dir_index filetype extent 64bit flex_bg large_dir inline_data sparse_super large_file huge_file dir_nlink extra_isize metadata_csum
> # e2fsck -fn /tmp/ext4.img
> e2fsck 1.45.2 (27-May-2019)
> Pass 1: Checking inodes, blocks, and sizes
> Pass 2: Checking directory structure
> Pass 3: Checking directory connectivity
> '..' in /aa (12) is <The NULL inode> (0), should be / (2).
> Fix? no
> 
> Pass 4: Checking reference counts
> Inode 2 ref count is 4, should be 3.  Fix? no
> 
> Inode 12 ref count is 2, should be 1.  Fix? no
> 
> Pass 5: Checking group summary information
> 
> /tmp/ext4.img: ********** WARNING: Filesystem still has errors **********
> 
> /tmp/ext4.img: 12/65536 files (0.0% non-contiguous), 12954/262144 blocks
> 
> 


Cheers, Andreas






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