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Date:   Sun, 25 Jun 2023 17:16:32 +0800
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Subject: Re: [PATCH v3 3/4] block/badblocks: fix badblocks loss when badblocks
 combine
To:     Ashok Raj <ashok_raj@linux.intel.com>
Cc:     axboe@kernel.dk, dan.j.williams@intel.com,
        vishal.l.verma@intel.com, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, yukuai3@huawei.com,
        yi.zhang@huawei.com, houtao1@huawei.com, yangerkun@huawei.com,
        Ashok Raj <ashok.raj@intel.com>, linan122@huawei.com
References: <20230621172052.1499919-1-linan666@huaweicloud.com>
 <20230621172052.1499919-4-linan666@huaweicloud.com>
 <ZJMEtGw+FYT8mRG+@araj-dh-work>
From:   Li Nan <linan666@huaweicloud.com>
In-Reply-To: <ZJMEtGw+FYT8mRG+@araj-dh-work>
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在 2023/6/21 22:09, Ashok Raj 写道:
> On Thu, Jun 22, 2023 at 01:20:51AM +0800, linan666@huaweicloud.com wrote:
>> From: Li Nan <linan122@huawei.com>
>>
>> badblocks will loss if we set it as below:
>>
>>    # echo 1 1 > bad_blocks
>>    # echo 3 1 > bad_blocks
>>    # echo 1 5 > bad_blocks
>>    # cat bad_blocks
>>      1 3
>>
>> In badblocks_set(), if there is an intersection between p[lo] and p[hi],
>> we will combine them. The end of new badblocks is p[hi]'s end now. but
>> p[lo] may cross p[hi] and new end should be the larger of p[lo] and p[hi].
> 
> Reconsider rewriting the commit log. It seems you converted code to
> sentence ;-).

I will rewrite log.

> 
> Also it might help to show after the patch how the above example would be
> for cat bad_blocks
> 

after patch:

# cat bad_blocks
   1 5

I will show it in next version. Thanks for your suggestion.

>>
>> Fixes: 9e0e252a048b ("badblocks: Add core badblock management code")
>> Signed-off-by: Li Nan <linan122@huawei.com>
>> ---
>>   block/badblocks.c | 10 ++++------
>>   1 file changed, 4 insertions(+), 6 deletions(-)
>>
>> diff --git a/block/badblocks.c b/block/badblocks.c
>> index 7e6ebe2ac12c..2c2ef8284a3f 100644
>> --- a/block/badblocks.c
>> +++ b/block/badblocks.c
>> @@ -267,16 +267,14 @@ int badblocks_set(struct badblocks *bb, sector_t s, int sectors,
>>   	if (sectors == 0 && hi < bb->count) {
>>   		/* we might be able to combine lo and hi */
>>   		/* Note: 's' is at the end of 'lo' */
>> -		sector_t a = BB_OFFSET(p[hi]);
>> -		int lolen = BB_LEN(p[lo]);
>> -		int hilen = BB_LEN(p[hi]);
>> -		int newlen = lolen + hilen - (s - a);
>> +		sector_t a = BB_OFFSET(p[lo]);
>> +		int newlen = max(s, BB_OFFSET(p[hi]) + BB_LEN(p[hi])) - a;
>>   
>> -		if (s >= a && newlen < BB_MAX_LEN) {
>> +		if (s >= BB_OFFSET(p[hi]) && newlen < BB_MAX_LEN) {
>>   			/* yes, we can combine them */
>>   			int ack = BB_ACK(p[lo]) && BB_ACK(p[hi]);
>>   
>> -			p[lo] = BB_MAKE(BB_OFFSET(p[lo]), newlen, ack);
>> +			p[lo] = BB_MAKE(a, newlen, ack);
>>   			memmove(p + hi, p + hi + 1,
>>   				(bb->count - hi - 1) * 8);
>>   			bb->count--;
>> -- 
>> 2.39.2
>>
> 
> .

-- 
Thanks,
Nan