Re: [PATCH v2 2/6] exfat: introduce exfat_fat_walk helper

[Chi Zhiling <chizhiling@163.com>]

On 4/3/26 10:34 AM, Yuezhang.Mo@sony.com wrote:
>> From: Chi Zhiling <chizhiling@kylinos.cn>
>>
>> Introduce exfat_fat_walk() to walk the FAT chain by a given step,
>> handling both ALLOC_NO_FAT_CHAIN and ALLOC_FAT_CHAIN modes. Also
>> redefine exfat_get_next_cluster as a thin wrapper around it for
>> backward compatibility.
>>
>> Signed-off-by: Chi Zhiling <chizhiling@kylinos.cn>
>> ---
>>   fs/exfat/exfat_fs.h | 23 ++++++++++++++++++++++-
>>   1 file changed, 22 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
>> index 9fed9fb33cae..530459ab9acc 100644
>> --- a/fs/exfat/exfat_fs.h
>> +++ b/fs/exfat/exfat_fs.h
>> @@ -437,7 +437,8 @@ int exfat_set_volume_dirty(struct super_block *sb);
>>   int exfat_clear_volume_dirty(struct super_block *sb);
>>
>>   /* fatent.c */
>> -#define exfat_get_next_cluster(sb, pclu) exfat_ent_get(sb, *(pclu), pclu, NULL)
>> +#define exfat_get_next_cluster(sb, pclu) \
>> +       exfat_fat_walk(sb, (pclu), 1, ALLOC_FAT_CHAIN)
>>
>>   int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
>>                  struct exfat_chain *p_chain, bool sync_bmap);
>> @@ -456,6 +457,26 @@ int exfat_count_num_clusters(struct super_block *sb,
>>   int exfat_blk_readahead(struct super_block *sb, sector_t sec,
>>                  sector_t *ra, blkcnt_t *ra_cnt, sector_t end);
>>
>> +static inline int
>> +exfat_fat_walk(struct super_block *sb, unsigned int *clu,
>> +               unsigned int step, int flags)
>> +{
>> +       struct buffer_head *bh = NULL;
>> +
>> +       if (flags == ALLOC_NO_FAT_CHAIN) {
>> +               (*clu) += step;
>> +               return 0;
>> +       }
> 
> For ALLOC_NO_FAT_CHAIN, since the FAT region is not accessed, it would be
> better to use a more general function name, such as exfat_cluster_walk.

Okay,

> 
>> +
>> +       while (step--) {
>> +               if (exfat_ent_get(sb, *clu, clu, &bh))
>> +                       return -EIO;
>> +       }
>> +       brelse(bh);
>> +
>> +       return 0;
>> +}
>> +
>>   /* balloc.c */
>>   int exfat_load_bitmap(struct super_block *sb);
>>   void exfat_free_bitmap(struct exfat_sb_info *sbi);
>> --
>> 2.43.0
> 
> 
>