Re: EXT4: new warnings from 4.3.0-rc2

[Chris Clayton]

On 09/21/15 15:55, Chris Clayton wrote:
> Thanks Ortwin.
> 
> On 09/21/15 14:27, Ortwin GlÃÂck wrote:
>>> [    2.481399] EXT4-fs (sda2): couldn't mount as ext3 due to feature incompatibilities
>>> [    2.482426] EXT4-fs (sda2): couldn't mount as ext2 due to feature incompatibilities
>>
>> As the kernel doesn't know which FS your root is, it tries the whole list of filesystems (init/do_mounts.c
>> mount_block_root()). Since the removal of ext3, now the ext4 code is responsbile for mounting ext3. Since your FS is
>> ext4 and not ext3, the probe for ext3 fails. That's what the message tells you. You get these even in previous kernels
>> if you say N to ext3 during config.
>>
> No, I do not get the messages from 4.2.0 even though it is configured the same as 4.3.0-rc3 as far as EXT{2,3,4} is
> concerned:
> 
> # CONFIG_EXT2_FS is not set
> # CONFIG_EXT3_FS is not set
> CONFIG_EXT4_FS=y
> CONFIG_EXT4_USE_FOR_EXT2=y
> # CONFIG_EXT4_FS_POSIX_ACL is not set
> # CONFIG_EXT4_FS_SECURITY is not set
> # CONFIG_EXT4_ENCRYPTION is not set
> # CONFIG_EXT4_DEBUG is not set
> [chris:~/kernel/linux]$ cd ../linux-4.2.0/
> [chris:~/kernel/linux-4.2.0]$ grep EXT[234] .config
> # CONFIG_EXT2_FS is not set
> # CONFIG_EXT3_FS is not set
> CONFIG_EXT4_FS=y
> CONFIG_EXT4_USE_FOR_EXT23=y
> # CONFIG_EXT4_FS_POSIX_ACL is not set
> # CONFIG_EXT4_FS_SECURITY is not set
> # CONFIG_EXT4_ENCRYPTION is not set
> # CONFIG_EXT4_DEBUG is not set
> 
> That's why I said they are new messages.
> 
> I've just booted 4.1.7 and I get the messages from that kernel too. I wonder if there's a recent fix that has made it
> into 4.1.7, but not into 4.2.0. I'll apply Greg's 4.2.1-rc1 patch and see what I get with that.
> 

Applying the 4.2.1-rc1 patch results in a kernel that emits the messages, so I guess my fix-not-yet-in-4.2 theory is right.

I'll just ignore the messages. Sorry for the noise.

> Chris
> 
> 
>> If it bugs you, you can add a hint to your kernel command line: rootfstype=ext4
>>
>> Ortwin
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