linux-kernel - Re: [PATCH] f2fs: introduce f2fs_kmem_cache_alloc to hide the unfailed kmem cache allocation

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Date:	Tue, 22 Oct 2013 14:26:58 +0800
From:	Gu Zheng <guz.fnst@...fujitsu.com>
To:	Haicheng Li <haicheng.li@...ux.intel.com>
CC:	Gao feng <gaofeng@...fujitsu.com>, Kim <jaegeuk.kim@...sung.com>,
	f2fs <linux-f2fs-devel@...ts.sourceforge.net>,
	fsdevel <linux-fsdevel@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] f2fs: introduce f2fs_kmem_cache_alloc to hide the unfailed
 kmem cache allocation

On 10/22/2013 02:15 PM, Haicheng Li wrote:

> On Tue, Oct 22, 2013 at 01:34:26PM +0800, Gu Zheng wrote:
>> On 10/22/2013 01:16 PM, Haicheng Li wrote:
>>
>>> On Tue, Oct 22, 2013 at 11:49:58AM +0800, Gao feng wrote:
>>>> On 10/21/2013 03:24 PM, Gu Zheng wrote:
>>>>> +static inline void *f2fs_kmem_cache_alloc(struct kmem_cache *cachep,
>>>>> +						gfp_t flags)
>>>>> +{
>>>>> +	void *entry = kmem_cache_alloc(cachep, flags);
>>>>> +retry:
>>>>
>>>> retry after kmem_cache_alloc?
>>>
>>> Good catch.
>>>
>>> Sorry for the carelessness in my previous review. 
>>> Besides this, I also found another issue as below:
>>>  
>>>> On Mon, Oct 21, 2013 at 03:24:55PM +0800, Gu Zheng wrote: 
>>>>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c 
>>>>> index ef80f79..fe3cf8e 100644 
>>>>> --- a/fs/f2fs/node.c 
>>>>> +++ b/fs/f2fs/node.c 
>>>>> @@ -1308,11 +1308,7 @@ static int add_free_nid(struct f2fs_nm_info *nm_i, nid_t nid, bool build) 
>>>>>     if (allocated) 
>>>>>             return 0; 
>>>>>  retry: 
>>> -retry?
>>
>> Can be removed here, this tag still used by front goto jumping. But it
>> seems that we need to use another suitable name rather than "retry".
> 
> how about like this?
> ---
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index fe3cf8e..4fa3fd5 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -1296,18 +1296,17 @@ static int add_free_nid(struct f2fs_nm_info *nm_i, nid_t nid, bool build)
>  	if (nid == 0)
>  		return 0;
>  
> -	if (!build)
> -		goto retry;
> +	if (build) {
> +		/* do not add allocated nids */
> +		read_lock(&nm_i->nat_tree_lock);
> +		ne = __lookup_nat_cache(nm_i, nid);
> +		if (ne && nat_get_blkaddr(ne) != NULL_ADDR)
> +			allocated = true;
> +		read_unlock(&nm_i->nat_tree_lock);
> +		if (allocated)
> +			return 0;
> +	}

Good, it's more neat, I'll take this, thanks.:)

Regards,
Gu

>  
> -	/* do not add allocated nids */
> -	read_lock(&nm_i->nat_tree_lock);
> -	ne = __lookup_nat_cache(nm_i, nid);
> -	if (ne && nat_get_blkaddr(ne) != NULL_ADDR)
> -		allocated = true;
> -	read_unlock(&nm_i->nat_tree_lock);
> -	if (allocated)
> -		return 0;
> -retry:
>  	i = f2fs_kmem_cache_alloc(free_nid_slab, GFP_NOFS);
>  	i->nid = nid;
>  	i->state = NID_NEW;
> 


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