linux-ext4 - Re: [PATCH, RFC] ext3: don't clear orphan list on ro mount with errors

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Message-ID: <50464DCD.2020209@redhat.com>
Date:	Tue, 04 Sep 2012 13:51:57 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	Jan Kara <jack@...e.cz>
CC:	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH, RFC] ext3: don't clear orphan list on ro mount with errors

On 8/28/12 3:02 AM, Jan Kara wrote:
> On Mon 27-08-12 14:30:40, Eric Sandeen wrote:
>> When we have a filesystem with an orphan inode list *and* in error
>> state, things behave differently if:
>>
>> 1) e2fsck -p is done prior to mount: e2fsck fixes things and exits
>>    happily (barring other significant problems)
>>
>> vs.
>>
>> 2) mount is done first, then e2fsck -p: due to the orphan inode
>>    list removal, more errors are found and e2fsck exits with
>>    UNEXPECTED INCONSISTENCY.
>>
>> The 2nd case above, on the root filesystem, has the tendency to halt
>> the boot process, which is unfortunate.
>>
>> The situation can be improved by not clearing the orphan
>> inode list when the fs is mounted readonly.
>   Yeah, makes sense. I've added the patch to my tree. Thanks.
> 
> 								Honza

After a little more investigation, I'm now wondering if this is really
worth doing.

e2fsck zaps the orphan list just like the kernel does:

         * If the filesystem contains errors, don't run the orphan
         * list, since the orphan list can't be trusted; and we're
         * going to be running a full e2fsck run anyway...

and my 1) and 2) differences above were due to testing an older version
of e2fsck which didn't properly propagate the error flag.  (Sorry...)

Since upstream e2fsck will _also_ ignore the orphan inode list, there's
probably no great reason for preserving it on a readonly mount after all,
unless it's just to minimize changes when mounting RO (which may be a
sufficient reason, I suppose).  So feel free to take it or leave it,
I guess.

Thanks,
-Eric
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