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Subject: Re: [PATCH RFC 00/17] ubifs: Add filesystem repair support
From: Zhihao Cheng <chengzhihao1@huawei.com>
To: Richard Weinberger <richard@nod.at>
CC: david oberhollenzer <david.oberhollenzer@sigma-star.at>, Miquel Raynal
	<miquel.raynal@bootlin.com>, Sascha Hauer <s.hauer@pengutronix.de>, Tudor
 Ambarus <Tudor.Ambarus@linaro.org>, linux-kernel
	<linux-kernel@vger.kernel.org>, linux-mtd <linux-mtd@lists.infradead.org>
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Message-ID: <cc6e93a3-3d3c-6bae-51d9-d8cdd8ca0e4c@huawei.com>
Date: Wed, 3 Jan 2024 20:44:01 +0800
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在 2024/1/3 11:18, Zhihao Cheng 写道:
> 在 2024/1/3 4:45, Richard Weinberger 写道:
>> ----- Ursprüngliche Mail -----
>>> Von: "chengzhihao1" <chengzhihao1@huawei.com>
>>> I come up with another way to implement fsck.ubifs:
>>>
>>> There are three modes:
>>>
>>> 1. common mode(no options): Ask user whether to fix as long as a problem
>>> is detected.
>>
>> Makes sense.
>>
>>> 2. safe mode(-a option): Auto repair as long as no data/files lost(eg.
>>> nlink, isize, xattr_cnt, which can be corrected without dropping nodes),
>>> otherwise returns error code.
>>
>> Makes sense.
>>> 3. dangerous mode(-y option): Fix is always successful, unless
>>> superblock is corrupted. There are 2 situations:
>>
>> Please not use "-y". Usually "-y" stands for "answer yes to all 
>> questions".
>> But selecting names for command line flags is currently my least concern.
>>>    a) TNC is valid: fsck will print which file is dropped and which
>>> file's data is dropped
>>
>> Sounds also good.
>>>    b) TNC is invalid: fsck will scan all nodes without referencing TNC,
>>> same as this patchset does
>>
>> I'd make this a distinct mode.
>> It can be used to rebuild index and LEB property trees.
>> This is basically a "drop trees and rebuild" mode.
>>
> 
> OK, then fsck will have four modes.

How about merging 3(a) and 3(b) as one mode(dangerous mode)? If fsck can 
get a good TNC(all non-leaf index nodes are valid), fsck executes as 
3(a) describes. If fsck cannot find a good TNC, fsck executes as 3(b) 
and reminds user that "TNC is damaged, nodes dropping is not awared".