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Date:	Mon, 03 Jun 2013 15:14:26 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	Autif Khan <autif.mlist@...il.com>
CC:	linux-ext4@...r.kernel.org
Subject: Re: Filesystem state: clean with errors - what errors?

On 6/3/13 3:07 PM, Autif Khan wrote:
> On Mon, Jun 3, 2013 at 3:34 PM, Eric Sandeen <sandeen@...hat.com> wrote:
>> On 6/3/13 2:29 PM, Autif Khan wrote:
>>> On Mon, Jun 3, 2013 at 3:13 PM, Eric Sandeen <sandeen@...hat.com> wrote:
>>>> On 6/3/13 1:45 PM, Autif Khan wrote:
>>>>> Executing dumpe2fs -h on one of the partitions says
>>>>>
>>>>> ...
>>>>> Filesystem features:      has_journal ext_attr resize_inode dir_index
>>>>> filetype extent flex_bg sparse_super large_file huge_file uninit_bg
>>>>> dir_nlink extra_isize
>>>>> Filesystem flags:         signed_directory_hash
>>>>> Default mount options:    user_xattr acl
>>>>> Filesystem state:         clean with errors
>>>>> ...
>>>>>
>>>>> How can I find out what the errors are - the details of the errors.
>>>>
>>>> "clean" means the log has been replayed (log is not dirty)
>>>> "with errors" means that it encountered concistency errors at runtime
>>>>
>>>> run e2fsck -f on it to see what it finds (or e2fsck -fn if you want a no-op
>>>> dry run)
>>>
>>> --- spin ---
>>>
>>> ubuntu@...0013950af6fb:~$ sudo fsck -V -n -f /dev/sda5
>>> fsck from util-linux 2.20.1
>>> [/sbin/fsck.ext4 (1) -- /koko] fsck.ext4 -n -f /dev/sda5
>>> e2fsck 1.42 (29-Nov-2011)
>>> Warning!  /dev/sda5 is mounted.
>>
>> Surprising that it didn't find errors since you ran it on a mounted fs!
>>
>> That's also an older e2fsck, so I suppose it's possible that it missed
>> something.
>>
>>> Pass 1: Checking inodes, blocks, and sizes
>>> Pass 2: Checking directory structure
>>> Pass 3: Checking directory connectivity
>>> Pass 4: Checking reference counts
>>> Pass 5: Checking group summary information
>>> /dev/sda5: 24770/262144 files (0.1% non-contiguous), 328031/1048576 blocks
>>> ubuntu@...0013950af6fb:~$
>>>
>>> I am not sure I see any errors. Is there an error here?
>>
>> No, that didn't report any errors.
>>
>> If you unmount it and do it w/o -n, it should clear the error state.
>> Perhaps it encountered an error for a file that got subsequently deleted,
>> or something - not sure.
>>
> 
> That is true - we are able to fix this - almost trivially - the
> problem is that we are causing this frequently (sometimes always) with
> inexpensive SSDs. I am sure you have seen my other email:
> http://marc.info/?l=linux-ext4&m=137028288823079&w=2
> 
> I assume that there is no other tool that I can use - (short of a hex
> dump of the 4.0G partition using dd) - to further debug this. Is
> there?

"with errors" is printed when the fs state has EXT2_ERROR_FS set.

Looking at the system logs would be a start - when the filesystem was set
into error state, the kernel should have logged that fact, along with
why it did so... you could go from there.

Also, kernels since 2.6.36 save more info:

commit 1c13d5c0872870cca3e612aa045d492ead9ab004
Author: Theodore Ts'o <tytso@....edu>
Date:   Tue Jul 27 11:56:03 2010 -0400

    ext4: Save error information to the superblock for analysis
    
    Save number of file system errors, and the time function name, line
    number, block number, and inode number of the first and most recent
    errors reported on the file system in the superblock.
    
    Signed-off-by: "Theodore Ts'o" <tytso@....edu>

This gets printed daily:

        if (es->s_error_count)
                ext4_msg(sb, KERN_NOTICE, "error count: %u",
                         le32_to_cpu(es->s_error_count));
        if (es->s_first_error_time) {
                printk(KERN_NOTICE "EXT4-fs (%s): initial error at %u: %.*s:%d",
                       sb->s_id, le32_to_cpu(es->s_first_error_time),
                       (int) sizeof(es->s_first_error_func),
                       es->s_first_error_func,
                       le32_to_cpu(es->s_first_error_line));

-Eric

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