# Linux 2.6.33 and "Use ext4 for ext2/ext3 file systems"

## Etal

Hi,

I installed Kernel 2.6.33 today, and it contains a new feature - "Use ext4 for ext2/ext3 file systems".

I thought, neat, now I don't need the old ext2 driver, so I enabled it and disabled ext2.

The problem is that when I booted, and ran "mount", it says that my ext4 filesystem is mounted as ext2! I disabled it and rebooted, and now it correctly says ext4.

Anyone have the same problem?

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## cruzki123

now that you said that, mine is also mounted as ext2...

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## d2_racing

I will test that tomorrow, I use a ext2 /boot partition and a ext4 / partition.

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## cruzki123

have anyone found a solution? I have seen it in another system.

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## gentoo_ram

I used that option on the ext4 fs filesystem driver and also disabled my ext2 and ext3 drivers.  I'm not seeing the same behavior.

$ mount

/dev/md12 on / type ext4 (rw,noatime)

...

/dev/mapper/vg-home on /home type ext4 (rw,nosuid,nodev,noatime)

/dev/mapper/vg-tmp on /tmp type ext2 (rw,nosuid,nodev,noatime)

...

Couple of questions:

1.  Did you format your root filesystem as ext4 or ext2?

2.  Did you include the command line parameter on the kernel command line "rootfstype=ext4"?  Maybe the behavior is different now.  I've always included it, maybe it's required now.

My boot command line:

root=/dev/md12 vga=ext rootfstype=ext4

3.  If it isn't the root filesystem, what is the filesystem field in /etc/fstab?  "auto"?  "ext4"?

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## pigeon768

```
localhost ~ # uname -a

Linux localhost 2.6.33-gentoo #2 SMP PREEMPT Tue Mar 2 15:12:06 AST 2010 x86_64 Intel(R) Core(TM)2 Duo CPU T9600 @ 2.80GHz GenuineIntel GNU/Linux

localhost ~ # zgrep EXT2 /proc/config.gz 

# CONFIG_EXT2_FS is not set

CONFIG_EXT4_USE_FOR_EXT23=y

localhost ~ # mount

[...]

/dev/sdb1 on /boot type ext2 (rw,sync)

/dev/sdb5 on /var type ext4 (rw,noatime,commit=600)

[...]

localhost ~ # 
```

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## Bill Cosby

Funny, my root partition is now ext2 as well, however, my home partition is still being mounted as ext4.

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## Etal

 *gentoo_ram wrote:*   

> 2.  Did you include the command line parameter on the kernel command line "rootfstype=ext4"?  Maybe the behavior is different now.  I've always included it, maybe it's required now.
> 
> My boot command line:
> 
> root=/dev/md12 vga=ext rootfstype=ext4

 

Thanks, I'll try it later today.

By the way, I also noticed this in my dmesg:

```
EXT2-fs (sda5): error: couldn't mount because of unsupported optional features (240)

EXT4-fs (sda5): mounted filesystem with ordered data mode

VFS: Mounted root (ext4 filesystem) readonly on device 259:131072.
```

I guess you must be right  :Smile: 

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## s4e8

ext4 always mount ext2/ext3 filesystems, but named it as ext4.

the new "Use ext4 for ext2/ext3 file systems" option give it the old name ext2/ext3.

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## cruzki123

There is a bug report about this

http://bugzilla.kernel.org/show_bug.cgi?id=15391

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## V-Li

Don't rely on filesystem autodetection.  Specify the file system to be used...I assume you have auto as file system in your fstab and kernel line.

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## Ant P.

It's just a cosmetic error, the filesystem is defined by what `tune2fs -l` lists in the features line, as long as the ext4 code is being used it'll make no difference.

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## d2_racing

Yeah, make sure that you mount the right FS inside /etc/fstab just to be sure.

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## Etal

 *V-Li wrote:*   

> Don't rely on filesystem autodetection.  Specify the file system to be used...I assume you have auto as file system in your fstab and kernel line.

 

Nope, it's ext4 in fstab.

Anyhow, adding "rootfstype=ext4" solved the problem, cosmetic or not.

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