linux-kernel - Re: [PATCH] btrfs: Simplify the allocation of slab caches in btrfs_delayed_inode

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Date: Thu, 1 Feb 2024 16:34:16 +0800
From: Kunwu Chan <chentao@...inos.cn>
To: Johannes Thumshirn <Johannes.Thumshirn@....com>, "clm@...com"
 <clm@...com>, "josef@...icpanda.com" <josef@...icpanda.com>,
 "dsterba@...e.com" <dsterba@...e.com>, dsterba@...e.cz
Cc: "linux-btrfs@...r.kernel.org" <linux-btrfs@...r.kernel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] btrfs: Simplify the allocation of slab caches in
 btrfs_delayed_inode_init

On 2024/1/31 18:20, Johannes Thumshirn wrote:
> On 31.01.24 07:20, Kunwu Chan wrote:
>> commit 0a31bd5f2bbb ("KMEM_CACHE(): simplify slab cache creation")
>> introduces a new macro.
>> Use the new KMEM_CACHE() macro instead of direct kmem_cache_create
> 
> That commit is 17 years old. Why should we switch to it _now_? I
> wouldn't call it a new macro.
> 
> Don't get me wrong, I don't oppose the patch, but I'd prefer a better
> explanation why now and not 17 years ago when the macro got introduced.
> 
Thanks for your attention.
Like David say in 
https://lore.kernel.org/all/20240131183929.GP31555@twin.jikos.cz/#t.

The main reason is 'it hides all the 0 or NULL parameters', makes the 
code cleaner and more readable.

So i'll update the commit msg to this:

Use the new KMEM_CACHE() macro instead of direct kmem_cache_create
to simplify the creation of SLAB caches.
Make the code cleaner and more readable.

And resend a v2 patch.
Thanks again.
>> to simplify the creation of SLAB caches.
>>
>> Signed-off-by: Kunwu Chan <chentao@...inos.cn>
>> ---
>>    fs/btrfs/delayed-inode.c | 6 +-----
>>    1 file changed, 1 insertion(+), 5 deletions(-)
>>
>> diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
>> index 08102883f560..8c748c6cdf6d 100644
>> --- a/fs/btrfs/delayed-inode.c
>> +++ b/fs/btrfs/delayed-inode.c
>> @@ -28,11 +28,7 @@ static struct kmem_cache *delayed_node_cache;
>>    
>>    int __init btrfs_delayed_inode_init(void)
>>    {
>> -	delayed_node_cache = kmem_cache_create("btrfs_delayed_node",
>> -					sizeof(struct btrfs_delayed_node),
>> -					0,
>> -					SLAB_MEM_SPREAD,
>> -					NULL);
>> +	delayed_node_cache = KMEM_CACHE(btrfs_delayed_node, SLAB_MEM_SPREAD);
>>    	if (!delayed_node_cache)
>>    		return -ENOMEM;
>>    	return 0;
> 
-- 
Thanks,
   Kunwu