# ext4 filesystem reported as ext2

## peter4

Hi, 

I have an ext4 root filesystem. Today I noticed, that both kernel and /bin/mount report it as ext2 in a few places. Examples:

```

[    2.499639] EXT4-fs (sda5): mounted filesystem with ordered data mode

[    2.499649] VFS: Mounted root (ext2 filesystem) readonly on device 8:5.
```

```
$ mount

rootfs on / type rootfs (rw)

/dev/root on / type ext2 (rw,noatime,barrier=1,data=ordered)
```

I wonder if someone stumbled into this too, as it looks quite weird.

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## bobspencer123

maybe a dumb question but do you have ext4 support in your kernel?

# cat /usr/src/linux/.config | grep -i ext4

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## peter4

There are no dumb questions, only dumb answers   :Laughing: 

Yes, I do.

```
$ cat /usr/src/linux/.config | grep -i ext4

CONFIG_EXT4_FS=y

CONFIG_EXT4_USE_FOR_EXT23=y

CONFIG_EXT4_FS_XATTR=y

# CONFIG_EXT4_FS_POSIX_ACL is not set

# CONFIG_EXT4_FS_SECURITY is not set

# CONFIG_EXT4_DEBUG is not set
```

And what's more, now you reminded me that I've set this CONFIG_EXT4_USE_FOR_EXT23=y option some time ago, looks like it could be the cause of this bug  :Smile: 

It still looks weird though. I mean, does it really mount it as ext2? I don't think so, but I'd prefer to be sure. Is there a way to check it some other way? Is it even possible to mount ext4 as ext2?

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## bobspencer123

 *peter4 wrote:*   

> There are no dumb questions, only dumb answers  
> 
> Yes, I do.
> 
> ```
> ...

 

I don't seem to have that option in my kernel (gentoo-sources-2.6.32-r7) but it could be the culprit if it does what it sounds like it does.

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## peter4

I filed a bug on bugzilla, thanks for the help.

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## gentoo_ram

Add the parameter "rootfstype=ext4" to your kernel command line in grub.

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## Ant P.

It's just a superficial glitch. If it was really mounted as ext2 the extents wouldn't work at all. It'd crash almost instantly.

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## agent_jdh

I saw this when I converted / to ext4 a couple of months ago.  Ditching the CONFIG_EXT4_USE_FOR_EXT23 option in kernel solved it, but as has been pointed out, it's probably just superficial.

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## mrfree

 *peter4 wrote:*   

> I filed a bug on bugzilla, thanks for the help.

 

which is the bug number?

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## nutbar21

FWIW, we saw this same issue very recently.  In case it helps your bug report at all: https://forums.gentoo.org/viewtopic-t-836667.html

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