linux-kernel - Re: [PATCH] f2fs: correct cp_ver for compatibility to old image

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Date:   Mon, 6 Mar 2017 18:23:03 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
CC:     <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>, <chao@...nel.org>
Subject: Re: [PATCH] f2fs: correct cp_ver for compatibility to old image

On 2017/3/3 2:55, Jaegeuk Kim wrote:
> On 03/02, Chao Yu wrote:
>> There is no CP_CRC_RECOVERY_FLAG tagged in checkpoint pack, calculate
>> cp_version as old format.
>>
>> Signed-off-by: Chao Yu <yuchao0@...wei.com>
>> ---
>>  fs/f2fs/node.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>> index 6c027b6833f4..0d46404ca769 100644
>> --- a/fs/f2fs/node.c
>> +++ b/fs/f2fs/node.c
>> @@ -2507,7 +2507,9 @@ static int __get_nat_bitmaps(struct f2fs_sb_info *sbi)
>>  		f2fs_put_page(page, 1);
>>  	}
>>  
>> -	cp_ver |= (cur_cp_crc(ckpt) << 32);
>> +	if (__is_set_ckpt_flags(ckpt, CP_CRC_RECOVERY_FLAG))
>> +		cp_ver |= (cur_cp_crc(ckpt) << 32);
> 
> Well, we always write nat_bits with crc. So if it's different, something is
> wrong and we need to drop it.

Got it. :)

Thanks,

> CP-CRC_RECOVERY_FLAG is used for roll-forward recovery, which is a different context.
> 
>> +
>>  	if (cpu_to_le64(cp_ver) != *(__le64 *)nm_i->nat_bits) {
>>  		disable_nat_bits(sbi, true);
>>  		return 0;
>> -- 
>> 2.8.2.295.g3f1c1d0
> 
> .
>