Re: [PATCH v5 5/7] pmem: add pmem_recovery_write() dax op

[Jane Chu <jane.chu@oracle.com>]

On 2/2/2022 5:43 AM, Christoph Hellwig wrote:
>> @@ -257,10 +263,15 @@ static int pmem_rw_page(struct block_device *bdev, sector_t sector,
>>   __weak long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
>>   		long nr_pages, void **kaddr, pfn_t *pfn)
>>   {
>> +	bool bad_pmem;
>> +	bool do_recovery = false;
>>   	resource_size_t offset = PFN_PHYS(pgoff) + pmem->data_offset;
>>   
>> -	if (unlikely(is_bad_pmem(&pmem->bb, PFN_PHYS(pgoff) / 512,
>> -					PFN_PHYS(nr_pages))))
>> +	bad_pmem = is_bad_pmem(&pmem->bb, PFN_PHYS(pgoff) / 512,
>> +				PFN_PHYS(nr_pages));
>> +	if (bad_pmem && kaddr)
>> +		do_recovery = dax_recovery_started(pmem->dax_dev, kaddr);
>> +	if (bad_pmem && !do_recovery)
>>   		return -EIO;
> 
> I find the passing of the recovery flag through the address very
> cumbersome.  I remember there was some kind of discussion, but this looks
> pretty ugly.
> 
> Also no need for the bad_pmem variable:
> 
> 	if (is_bad_pmem(&pmem->bb, PFN_PHYS(pgoff) / 512, PFN_PHYS(nr_pages)) &&
> 	    (!kaddr | !dax_recovery_started(pmem->dax_dev, kaddr)))
> 		return -EIO;

Okay.

>
> Also:  the !kaddr check could go into dax_recovery_started.  That way
> even if we stick with the overloading kaddr could also be used just for
> the flag if needed.

The !kaddr check is in dax_recovery_started(), and that reminded me the
check should be in dax_prep_recovery() too.

Thanks!
-jane