Re: [PATCH v2 4/5] md: skip ID_BITMAP_NONE when show available bitmap types

[Su Yue <l@damenly.org>]

On Mon 13 Apr 2026 at 16:15, Li Nan <linan666@huaweicloud.com> 
wrote:

> 在 2026/4/7 18:26, Su Yue 写道:
>> As none_bitmap_ops is introduced, ID_BITMAP_NONE should be 
>> skipped while
>> iterating md submodules, otherwise:
>> $ cat /sys/block/md0/md/bitmap_type
>> [none] bitmap llbitmap [none]
>> Signed-off-by: Su Yue <glass.su@suse.com>
>> ---
>>   drivers/md/md.c | 2 ++
>>   1 file changed, 2 insertions(+)
>> diff --git a/drivers/md/md.c b/drivers/md/md.c
>> index 55a95b227b83..20a953676319 100644
>> --- a/drivers/md/md.c
>> +++ b/drivers/md/md.c
>> @@ -4269,6 +4269,8 @@ bitmap_type_show(struct mddev *mddev, 
>> char *page)
>>   	xa_for_each(&md_submodule, i, head) {
>>   		if (head->type != MD_BITMAP)
>>   			continue;
>> +		if (head->id == ID_BITMAP_NONE)
>> +			continue;
>>     		if (mddev->bitmap_id == head->id)
>>   			len += sprintf(page + len, "[%s] ", head->name);
>
> If we indeed add ID_BITMAP_NONE as patch 3, would it be better 
> to delete
> this piece of code instead?
>
I dont' think so. There is one case CONFIG_MD_BITMAP is not 
enabled which
means register_md_submodule(&none_bitmap_ops.head) is not called 
but in
mddev_init():

int mddev_init(struct mddev *mddev) 
|
 { 
 |
         int err = 0; 
         |
                                                                                 |
         if (!IS_ENABLED(CONFIG_MD_BITMAP)) 
         |
                 mddev->bitmap_id = ID_BITMAP_NONE;
...
}

--
Su
>
>         if (mddev->bitmap_id == ID_BITMAP_NONE)
>                 len += sprintf(page + len, "[none] ");
>         else
>                 len += sprintf(page + len, "none ");