linux-kernel - Re: Remounting filesystem read-only

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Date:   Fri, 27 Jul 2018 13:34:31 -0700
From:   Sodagudi Prasad <psodagud@...eaurora.org>
To:     Sodagudi Prasad <psodagud@...eaurora.org>
Cc:     adilger.kernel@...ger.ca, wen.xu@...ech.edu,
        linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: Remounting filesystem read-only

On 2018-07-27 12:52, Theodore Y. Ts'o wrote:
> On Fri, Jul 27, 2018 at 12:26:25PM -0700, Sodagudi Prasad wrote:
>> On 2018-07-26 18:04, Sodagudi Prasad wrote:
>> > Hi All,
>> >
>> 
>> +linux-kernel@...r.kernel.org list.
>> 
>> Hi All,
>> 
>> Observing the following issue with one of the partition on android 
>> device
>> with 4.14.56 kernel.  When I try to remount this partition using the 
>> command
>> - mount -o rw,remount /vendor/dsp, it is remounting as read-only.
>> 
>> [  191.364358] EXT4-fs error (device sde9): 
>> ext4_has_uninit_itable:3108:
>> comm mount: Inode table for bg 0 marked as needing zeroing
>> [  191.364762] Aborting journal on device sde9-8.
>> [  191.365226] EXT4-fs (sde9): Remounting filesystem read-only
>> [  191.365232] EXT4-fs (sde9): re-mounted. Opts: data=ordere
>> 
>> If I revert this commit [1] -"ext4: only look at the bg_flags field if 
>> it is
>> valid", the issue is not observed. It is just giving following warning
>> message.
>> [1] - https://patchwork.ozlabs.org/patch/929239/.
>> 
>> [  123.373456] EXT4-fs (sde9): warning: mounting fs with errors, 
>> running
>> e2fsck is recommendedt
>> [  123.389649] EXT4-fs (sde9): re-mounted. Opts: data=ordered
>> 
>> Can you provide some inputs what could be the issue with this 
>> partition?
> 
> The error should be pretty clear: "Inode table for bg 0 marked as
> needing zeroing".  That should never happen.

Hi Ted,

Can you provide any debug patch to detect when this corruption is 
happening?
Source of this corruption and how this is partition getting corrupted?
Or which file system operation lead to this corruption?

I am digging code a bit around this warning to understand more.

Thanks in advance for your help.

-Thanks, Prasad

> The warning "mounting fs
> with errors" means the file system was corrupted.  The commit is now
> telling more about how the file system was corrupted, and is
> protecting you from further data loss.  (You shoud never, ever, ever,
> allow a file system to be mounted read/write with corruptions.  The
> file system should have been checked using fsck.ext4, aka e2fsck,
> before the file system was allowed to be mounted.)
> 
>        	   	       	   	      - Ted

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