linux-kernel - Re: [PATCH RFC -next 03/26] md/md-bitmap: merge md_bitmap_load() into bitmap

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Message-ID: <8f561148-761a-a487-5dc2-1567588c49b0@huaweicloud.com>
Date: Tue, 13 Aug 2024 15:30:57 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: Mariusz Tkaczyk <mariusz.tkaczyk@...ux.intel.com>,
 Yu Kuai <yukuai1@...weicloud.com>
Cc: song@...nel.org, linux-kernel@...r.kernel.org,
 linux-raid@...r.kernel.org, yi.zhang@...wei.com, yangerkun@...wei.com,
 "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH RFC -next 03/26] md/md-bitmap: merge md_bitmap_load() into
 bitmap_operations

Hi,

在 2024/08/13 15:07, Mariusz Tkaczyk 写道:
> On Sat, 10 Aug 2024 10:08:31 +0800
> Yu Kuai <yukuai1@...weicloud.com> wrote:
> 
>> From: Yu Kuai <yukuai3@...wei.com>
>>
>> So that the implementation won't be exposed, and it'll be possible
>> to invent a new bitmap by replacing bitmap_operations.
> 
> I don't like repeating same commit message for few patches.
> 
>>
>> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
>> ---
>>   drivers/md/md-bitmap.c |  6 +++---
>>   drivers/md/md-bitmap.h | 10 +++++++++-
>>   2 files changed, 12 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
>> index d731f7d4bbbb..9a9f0fe3ebd0 100644
>> --- a/drivers/md/md-bitmap.c
>> +++ b/drivers/md/md-bitmap.c
>> @@ -1965,7 +1965,7 @@ static struct bitmap *bitmap_create(struct mddev
>> *mddev, int slot) return ERR_PTR(err);
>>   }
>>   
>> -int md_bitmap_load(struct mddev *mddev)
>> +static int bitmap_load(struct mddev *mddev)
>>   {
>>   	int err = 0;
>>   	sector_t start = 0;
>> @@ -2021,7 +2021,6 @@ int md_bitmap_load(struct mddev *mddev)
>>   out:
>>   	return err;
>>   }
>> -EXPORT_SYMBOL_GPL(md_bitmap_load);
>>   
>>   /* caller need to free returned bitmap with md_bitmap_free() */
>>   struct bitmap *get_bitmap_from_slot(struct mddev *mddev, int slot)
>> @@ -2411,7 +2410,7 @@ location_store(struct mddev *mddev, const char *buf,
>> size_t len) }
>>   
>>   			mddev->bitmap = bitmap;
>> -			rv = md_bitmap_load(mddev);
>> +			rv = bitmap_load(mddev);
>>   			if (rv) {
>>   				mddev->bitmap_info.offset = 0;
>>   				md_bitmap_destroy(mddev);
>> @@ -2710,6 +2709,7 @@ const struct attribute_group md_bitmap_group = {
>>   
>>   static struct bitmap_operations bitmap_ops = {
>>   	.create			= bitmap_create,
>> +	.load			= bitmap_load,
>>   };
>>   
>>   void mddev_set_bitmap_ops(struct mddev *mddev)
>> diff --git a/drivers/md/md-bitmap.h b/drivers/md/md-bitmap.h
>> index a7cbf0c692fc..de7fbe5903dd 100644
>> --- a/drivers/md/md-bitmap.h
>> +++ b/drivers/md/md-bitmap.h
>> @@ -236,6 +236,7 @@ struct bitmap {
>>   
>>   struct bitmap_operations {
>>   	struct bitmap* (*create)(struct mddev *mddev, int slot);
>> +	int (*load)(struct mddev *mddev);
>>   };
>>   
>>   /* the bitmap API */
>> @@ -250,7 +251,14 @@ static inline struct bitmap *md_bitmap_create(struct
>> mddev *mddev, int slot) return mddev->bitmap_ops->create(mddev, slot);
>>   }
>>   
>> -int md_bitmap_load(struct mddev *mddev);
>> +static inline int md_bitmap_load(struct mddev *mddev)
>> +{
>> +	if (!mddev->bitmap_ops->load)
>> +		return -EOPNOTSUPP;
>> +
>> +	return mddev->bitmap_ops->load(mddev);
>> +}
> 
> At this point we have only on bitmpa op (at that probably won't change), so if
> we we have bitmap_ops assigned (mddev->bitmap_ops != NULL) then ->load is must
> have, hence I don't see a need for this wrapper.

Yes, we must define the load op otherwise the bitmap_ops is meaningless.

> 
> you probably made this to avoid changes across code. If yes, please mention it
> in commit message but I still would prefer to replace them all by calls to
> mddev->bitmap_ops->load().

I'll replace to use mddev->bitmap_ops->load() directly, and other
places. And I'll keep this inline helper for some ops that is used for
md-cluster, because I'm not planning to support md-cluster for the new
bitmap first.

Thanks,
Kuai

> 
> Mariusz
> 
> 
> .
>