Re: [PATCH v2 2/4] md-raid0: conditional mddev->queue access to suit dm-raid

[Heinz Mauelshagen <heinzm@redhat.com>]

On 05/08/2015 06:00 PM, Brassow Jonathan wrote:
>> On Apr 29, 2015, at 7:03 AM, heinzm@redhat.com wrote:
>>
>> From: Heinz Mauelshagen <heinzm@redhat.com>
>>
>>
>> This patch is a prerequisite for dm-raid "raid0" support to allow
>> dm-raid to access the MD RAID0 personality doing unconditional
>> accesses to mddev->queue, which is NULL in case of dm-raid stacked
>> on top of MD.
>>
>> Most of the conditional mddev->queue accesses made it to upstream
>> but this missing one, which prohibits md raid0 to set disk stack limits
>> (being done in dm core in case of md underneath dm).
>>
>>
>> Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
>> Tested-by: Heinz Mauelshagen <heinzm@redhat.com>
>>
>> ---
>> drivers/md/raid0.c | 5 +++--
>> 1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
>> index 2cb59a6..6a68ef5 100644
>> --- a/drivers/md/raid0.c
>> +++ b/drivers/md/raid0.c
>> @@ -188,8 +188,9 @@ static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
>> 		}
>> 		dev[j] = rdev1;
>>
>> -		disk_stack_limits(mddev->gendisk, rdev1->bdev,
>> -				  rdev1->data_offset << 9);
>> +		if (mddev->queue)
>> +			disk_stack_limits(mddev->gendisk, rdev1->bdev,
>> +					  rdev1->data_offset << 9);
>>
>> 		if (rdev1->bdev->bd_disk->queue->merge_bvec_fn)
>> 			conf->has_merge_bvec = 1;
> Aren’t you missing a condition?
>
>  From the code:
>          /*
>           * now since we have the hard sector sizes, we can make sure
>           * chunk size is a multiple of that sector size
>           */
>          if ((mddev->chunk_sectors << 9) % queue_logical_block_size(mddev->queue)) {
>                  printk(KERN_ERR "md/raid0:%s: chunk_size of %d not valid\n",
>                         mdname(mddev),
>                         mddev->chunk_sectors << 9);
>                  goto abort;
>          }
>
>          if (mddev->queue) {
>
> Shouldn’t that ‘queue_logical_block_size be inside the lower ‘if’?

queue_logical_block_size is safe when mddev->queue == NULL,
so its no problem.

Heinz

>
>   brassow

-- 
===============================================================
Heinz Mauelshagen                               +49 2626 141200
Consulting Development Engineer             FAX +49 2626 924446
Red Hat GmbH
Am Sonnenhang 11
56242 Marienrachdorf
Germany                                       heinzm@redhat.com
===============================================================

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