linux-kernel - Re: [PATCH v2 1/3] f2fs: avoid opened loop codes in __add_ino

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Date:   Fri, 10 Nov 2017 09:07:11 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
CC:     <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>, <chao@...nel.org>,
        <mhocko@...nel.org>
Subject: Re: [PATCH v2 1/3] f2fs: avoid opened loop codes in __add_ino_entry



On 2017/11/10 1:51, Jaegeuk Kim wrote:
> Hi Chao,
> 
> On 11/07, Chao Yu wrote:
>> We will keep __add_ino_entry success all the time, for ENOMEM failure
>> case, we have already handled it by using  __GFP_NOFAIL flag, so we
>> don't have to use additional opened loop codes here, remove them.
>>
>> Signed-off-by: Chao Yu <yuchao0@...wei.com>
>> ---
>> v2:
>> As Michal Hocko suggested, with __GFP_NOFAIL, MM will do all it can for
>> memory allocation including access memory reserves, so it's better to
>> use it rather than opened loop code, update this patch for it.
>>  fs/f2fs/checkpoint.c | 19 +++++++++++--------
>>  1 file changed, 11 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
>> index 98777c1ae70c..80b90146cff2 100644
>> --- a/fs/f2fs/checkpoint.c
>> +++ b/fs/f2fs/checkpoint.c
>> @@ -405,20 +405,21 @@ static void __add_ino_entry(struct f2fs_sb_info *sbi, nid_t ino,
>>  {
>>  	struct inode_management *im = &sbi->im[type];
>>  	struct ino_entry *e, *tmp;
>> +	bool preloaded;
>> +	int err;
>>  
>>  	tmp = f2fs_kmem_cache_alloc(ino_entry_slab, GFP_NOFS);
>> -retry:
>> -	radix_tree_preload(GFP_NOFS | __GFP_NOFAIL);
>> +
>> +	preloaded = !radix_tree_preload(GFP_NOFS | __GFP_NOFAIL);
>> +	f2fs_bug_on(sbi, !preloaded);
> 
> I don't think we need this by adding new useless variable.

Yup, let me update it.

> 
>>  
>>  	spin_lock(&im->ino_lock);
>>  	e = radix_tree_lookup(&im->ino_root, ino);
>>  	if (!e) {
>>  		e = tmp;
>> -		if (radix_tree_insert(&im->ino_root, ino, e)) {
> 
> How about just adding this?
> 
> 		if (unlikely(radix_tree_insert(&im->ino_root, ino, e)))
> 			f2fs_bug_on(sbi, 1);

Okay.

Thanks,

> 
>> -			spin_unlock(&im->ino_lock);
>> -			radix_tree_preload_end();
>> -			goto retry;
>> -		}
>> +		err = radix_tree_insert(&im->ino_root, ino, e);
>> +		f2fs_bug_on(sbi, err);
>> +
>>  		memset(e, 0, sizeof(struct ino_entry));
>>  		e->ino = ino;
>>  
>> @@ -431,7 +432,9 @@ static void __add_ino_entry(struct f2fs_sb_info *sbi, nid_t ino,
>>  		f2fs_set_bit(devidx, (char *)&e->dirty_device);
>>  
>>  	spin_unlock(&im->ino_lock);
>> -	radix_tree_preload_end();
>> +
>> +	if (preloaded)
>> +		radix_tree_preload_end();
>>  
>>  	if (e != tmp)
>>  		kmem_cache_free(ino_entry_slab, tmp);
>> -- 
>> 2.15.0.55.gc2ece9dc4de6
> 
> .
>