linux-kernel - Re: [PATCH 3/7] f2fs: rename free nid cache operation

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Date:   Wed, 12 Oct 2016 23:14:42 +0800
From:   Chao Yu <chao@...nel.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Chao Yu <yuchao0@...wei.com>
Subject: Re: [PATCH 3/7] f2fs: rename free nid cache operation

Hi Jaegeuk,

On 2016/10/12 1:19, Jaegeuk Kim wrote:
> Hi Chao,
> 
> On Tue, Oct 11, 2016 at 10:31:32PM +0800, Chao Yu wrote:
>> From: Chao Yu <yuchao0@...wei.com>
>>
>> Rename free nid cache operation for readability, no functionality change.
> 
> Well, I don't think this can be a *cache*, since there is no cache-related
> operations such as reordering by cache hit, whereas it is more likely to

This is because we do not record any nids which has been allocated to node
blocks, otherwise we will recored the status of nid in the cache and also it can
be hitted during lookup.

In original patches, free_nid_list is split to two separate lists: free_nid_list
and alloc_nid_list, __lookup_free_nid_list looks like just search the first one,
so in order to avoid misunderstanding, I proposal this change.

Anyway, what about using __{lookup,insert_to,remove_from}_nid_list instead?

Thanks,

> be a singled one-way list.
> 
> Thanks,
> 
>>
>> Signed-off-by: Chao Yu <yuchao0@...wei.com>
>> ---
>>  fs/f2fs/node.c | 28 +++++++++++++++++-----------
>>  1 file changed, 17 insertions(+), 11 deletions(-)
>>
>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>> index ea9ff8c..92c9aa4 100644
>> --- a/fs/f2fs/node.c
>> +++ b/fs/f2fs/node.c
>> @@ -1689,13 +1689,19 @@ const struct address_space_operations f2fs_node_aops = {
>>  #endif
>>  };
>>  
>> -static struct free_nid *__lookup_free_nid_list(struct f2fs_nm_info *nm_i,
>> +static struct free_nid *__lookup_free_nid_cache(struct f2fs_nm_info *nm_i,
>>  						nid_t n)
>>  {
>>  	return radix_tree_lookup(&nm_i->free_nid_root, n);
>>  }
>>  
>> -static void __del_from_free_nid_list(struct f2fs_nm_info *nm_i,
>> +static int __insert_to_free_nid_cache(struct f2fs_nm_info *nm_i,
>> +						struct free_nid *i)
>> +{
>> +	return radix_tree_insert(&nm_i->free_nid_root, i->nid, i);
>> +}
>> +
>> +static void __del_from_free_nid_cache(struct f2fs_nm_info *nm_i,
>>  						struct free_nid *i)
>>  {
>>  	radix_tree_delete(&nm_i->free_nid_root, i->nid);
>> @@ -1763,7 +1769,7 @@ static int add_free_nid(struct f2fs_sb_info *sbi, nid_t nid, bool build)
>>  	}
>>  
>>  	spin_lock(&nm_i->free_nid_list_lock);
>> -	if (radix_tree_insert(&nm_i->free_nid_root, i->nid, i)) {
>> +	if (__insert_to_free_nid_cache(nm_i, i)) {
>>  		spin_unlock(&nm_i->free_nid_list_lock);
>>  		radix_tree_preload_end();
>>  		kmem_cache_free(free_nid_slab, i);
>> @@ -1782,10 +1788,10 @@ static void remove_free_nid(struct f2fs_sb_info *sbi, nid_t nid)
>>  	bool need_free = false;
>>  
>>  	spin_lock(&nm_i->free_nid_list_lock);
>> -	i = __lookup_free_nid_list(nm_i, nid);
>> +	i = __lookup_free_nid_cache(nm_i, nid);
>>  	if (i && i->state == NID_NEW) {
>>  		__remove_nid_from_list(sbi, i, FREE_NID_LIST);
>> -		__del_from_free_nid_list(nm_i, i);
>> +		__del_from_free_nid_cache(nm_i, i);
>>  		need_free = true;
>>  	}
>>  	spin_unlock(&nm_i->free_nid_list_lock);
>> @@ -1922,10 +1928,10 @@ void alloc_nid_done(struct f2fs_sb_info *sbi, nid_t nid)
>>  	struct free_nid *i;
>>  
>>  	spin_lock(&nm_i->free_nid_list_lock);
>> -	i = __lookup_free_nid_list(nm_i, nid);
>> +	i = __lookup_free_nid_cache(nm_i, nid);
>>  	f2fs_bug_on(sbi, !i);
>>  	__remove_nid_from_list(sbi, i, ALLOC_NID_LIST);
>> -	__del_from_free_nid_list(nm_i, i);
>> +	__del_from_free_nid_cache(nm_i, i);
>>  	spin_unlock(&nm_i->free_nid_list_lock);
>>  
>>  	kmem_cache_free(free_nid_slab, i);
>> @@ -1944,13 +1950,13 @@ void alloc_nid_failed(struct f2fs_sb_info *sbi, nid_t nid)
>>  		return;
>>  
>>  	spin_lock(&nm_i->free_nid_list_lock);
>> -	i = __lookup_free_nid_list(nm_i, nid);
>> +	i = __lookup_free_nid_cache(nm_i, nid);
>>  	f2fs_bug_on(sbi, !i);
>>  
>>  	__remove_nid_from_list(sbi, i, ALLOC_NID_LIST);
>>  
>>  	if (!available_free_memory(sbi, FREE_NIDS)) {
>> -		__del_from_free_nid_list(nm_i, i);
>> +		__del_from_free_nid_cache(nm_i, i);
>>  		need_free = true;
>>  	} else {
>>  		i->state = NID_NEW;
>> @@ -1980,7 +1986,7 @@ int try_to_free_nids(struct f2fs_sb_info *sbi, int nr_shrink)
>>  			break;
>>  
>>  		__remove_nid_from_list(sbi, i, FREE_NID_LIST);
>> -		__del_from_free_nid_list(nm_i, i);
>> +		__del_from_free_nid_cache(nm_i, i);
>>  
>>  		kmem_cache_free(free_nid_slab, i);
>>  		nr_shrink--;
>> @@ -2368,7 +2374,7 @@ void destroy_node_manager(struct f2fs_sb_info *sbi)
>>  	spin_lock(&nm_i->free_nid_list_lock);
>>  	list_for_each_entry_safe(i, next_i, &nm_i->free_nid_list, list) {
>>  		__remove_nid_from_list(sbi, i, FREE_NID_LIST);
>> -		__del_from_free_nid_list(nm_i, i);
>> +		__del_from_free_nid_cache(nm_i, i);
>>  		spin_unlock(&nm_i->free_nid_list_lock);
>>  		kmem_cache_free(free_nid_slab, i);
>>  		spin_lock(&nm_i->free_nid_list_lock);
>> -- 
>> 2.10.1