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SubjectRe: [PATCH 10/15] mm/swap: break the loop if matching device is found
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On 2022/5/10 5:16, Andrew Morton wrote:
> On Mon, 9 May 2022 21:14:11 +0800 Miaohe Lin <linmiaohe@huawei.com> wrote:
>
>> We can break the loop if matching device is found to save some possible
>> cpu cycles because there should be only one matching device and there is
>> no need to continue if the matching one is already found.
>>
>> ...
>>
>> --- a/mm/swapfile.c
>> +++ b/mm/swapfile.c
>> @@ -1692,6 +1692,8 @@ int swap_type_of(dev_t device, sector_t offset)
>> spin_unlock(&swap_lock);
>> return type;
>> }
>> +
>> + break;
>> }
>> }
>> spin_unlock(&swap_lock);
>
> Are you sure? If we have two S_ISREG swapfiles on the same device,
> don't they have the same sis->bdev?

Oh, I missed this use case. Sorry about it! :(

>
> If not, why bother passing `offset' into this function at all?

Yes, you're right. 'offset' indicates the swap header location. Will drop this patch.

Thanks!

> .
>

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