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From: Johannes Thumshirn <Johannes.Thumshirn@wdc.com>
To: "dsterba@suse.cz" <dsterba@suse.cz>
Cc: David Sterba <dsterba@suse.com>,
	"linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH 3/3] btrfs: use u8 type for btrfs_block_rsv::type
Date: Tue, 28 Jun 2022 07:15:14 +0000	[thread overview]
Message-ID: <PH0PR04MB74165A85F6DAD1C596F1F61C9BB89@PH0PR04MB7416.namprd04.prod.outlook.com> (raw)
In-Reply-To: 20220627164018.GZ20633@twin.jikos.cz

On 27.06.22 18:45, David Sterba wrote:
> On Mon, Jun 27, 2022 at 06:51:30AM +0000, Johannes Thumshirn wrote:
>> On 24.06.22 16:15, David Sterba wrote:
>>> diff --git a/fs/btrfs/block-rsv.h b/fs/btrfs/block-rsv.h
>>> index 0702d4087ff6..bb449c75ee4c 100644
>>> --- a/fs/btrfs/block-rsv.h
>>> +++ b/fs/btrfs/block-rsv.h
>>> @@ -27,7 +27,8 @@ struct btrfs_block_rsv {
>>>  	spinlock_t lock;
>>>  	bool full;
>>>  	bool failfast;
>>> -	unsigned short type;
>>> +	/* Block reserve type, one of BTRFS_BLOCK_RSV_* */
>>> +	u8 type;
>>>  
>>
>> Is there any reason to not use the enum?
> 
> Enum would be 'int', 4 bytes to the space optimization would be
> lost. Enum types can be shortened as
> 
> 	enum btrfs_reserve type:8
> 
> but I'm not sure it's an improvement.
> 

Using an enum would give some type safety (I think -Wenum-compare is 
on by default in the kernel). Packing that enum would give us the 1 byte
size you're looking for.

  reply	other threads:[~2022-06-28  7:15 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-24 14:01 [PATCH 0/3] Cleanup short int types in block group reserve David Sterba
2022-06-24 14:01 ` [PATCH 1/3] btrfs: switch btrfs_block_rsv::full to bool David Sterba
2022-06-24 17:12   ` Antonio Pérez
2022-07-07 18:46     ` David Sterba
2022-06-24 14:01 ` [PATCH 2/3] btrfs: switch btrfs_block_rsv::failfast " David Sterba
2022-06-27  6:48   ` Johannes Thumshirn
2022-06-24 14:01 ` [PATCH 3/3] btrfs: use u8 type for btrfs_block_rsv::type David Sterba
2022-06-27  6:51   ` Johannes Thumshirn
2022-06-27 16:40     ` David Sterba
2022-06-28  7:15       ` Johannes Thumshirn [this message]
2022-07-07 18:52         ` David Sterba

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