Re: Corrupt ext4 fs after creation

[Andreas Dilger <adilger@dilger.ca>]

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On Mar 14, 2017, at 4:34 AM, Daniel Schultz <d.schultz@phytec.de> wrote:
> 
> Hi,
> 
> we use the Yocto Project to create custom BSPs for a AM335x SoC. After they upgraded the e2fsprogs from 1.42.9 to 1.43 we run into problems with our ext4 root file system. During the first boot systemd checks the rootfs with fsck.ext4 and needs a restart beacause of an error.

This isn't really an "error"...

> The fs is created with mkfs.ext4 and direct I/O and is available on ftp://ftp.phytec.de/pub/Test/phytec-headless-image-phyboard-wega-am335x-2.ext4
> 
> $ du -ks /home/schultz/yocto/PD17.1.0/build/tmp/work/phyboard_wega_am335x_2-phytec-linux-gnueabi/phytec-headless-image/1.0-r0/rootfs
> 109708
> $ truncate /var/tmp/wic/build/rootfs_root.2.ext4 -s 159674777
> $ mkfs.ext4 -F -i 8192 /var/tmp/wic/build/rootfs_root.2.ext4 -L root -d /home/schultz/yocto/PD17.1.0/build/tmp/work/phyboard_wega_am335x_2-phytec-linux-gnueabi/phytec-headless-image/1.0-r0/rootfs
> mke2fs 1.43 (17-May-2016)
> Discarding device blocks: done
> Creating filesystem with 155932 1k blocks and 19520 inodes
> Filesystem UUID: 6728344f-aa6d-4bbb-a06d-e649e36024d3
> Superblock backups stored on blocks:
> 	8193, 24577, 40961, 57345, 73729
> 
> Allocating group tables: done
> Writing inode tables: done
> Creating journal (4096 blocks): done
> Copying files into the device: done
> Writing superblocks and filesystem accounting information: done
> $ du -Lbks /var/tmp/wic/build/rootfs_root.2.ext4
> 155933
> 
> 
> I figured out that when I run fsck.ext4 it will perform a directory optimizing which leads to a non-zero error code of 1 (File system errors corrected).

> Also, I figured out that this optimizing only occurres on the first boot and not after creating a lot of new files and dirs. After checking the fs it contains more blocks than before.
> 
> root@phyboard-wega-am335x-2:~# fsck.ext4 -V
> e2fsck 1.43 (17-May-2016)
>        Using EXT2FS Library version 1.43, 17-May-2016
> root@phyboard-wega-am335x-2:~# fsck.ext4 /dev/disk/by-id/mmc-NCard_0x2519026e-part2
> e2fsck 1.43 (17-May-2016)
> Superblock last write time (Mon Mar 13 10:53:39 2017,
>        now = Wed Jan 25 11:07:23 2017) is in the future.

This is the real error - your system clock is at Jan 25, but the superblock
was modified yesterday (which is likely correct), so e2fsck thinks the
superblock is wrong.

Fix your clock before running e2fsck, or use the magic setting for embedded
systems so that this check is skipped.  I believe something like the following
in /etc/e2fsck.conf would fix this (see e2fsck.conf(5) man page):

[options]
     broken_system_clock=true

I suspect once this is fixed, e2fsck will not complain about the directory
optimization step anymore.

Cheers, Andreas

> Fix<y>? yes
> Pass 1: Checking inodes, blocks, and sizes
> Pass 2: Checking directory structure
> Pass 3: Checking directory connectivity
> Pass 3A: Optimizing directories
> Pass 4: Checking reference counts
> Pass 5: Checking group summary information
> 
> root: ***** FILE SYSTEM WAS MODIFIED *****
> root: 5221/19520 files (0.9% non-contiguous), 105503/155932 blocks
> root@phyboard-wega-am335x-2:~# fsck.ext4 /dev/disk/by-id/mmc-NCard_0x2519026e-part2
> e2fsck 1.43 (17-May-2016)
> root: clean, 5221/19520 files, 105503/155932 blocks
> 
> 
> Can anyone give me more informations about what's wrong with our fs and if I can forbid (without problems) the directory optimization?
> 
> Thanks
> 
> --
> Mit freundlichen Grüßen,
> With best regards,
>  Daniel Schultz


Cheers, Andreas






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