[PATCH] fat: Simplify calc_fat_clusters code

[PATCH] fat: Simplify calc_fat_clusters code

[Seunghun Lee]

Code for fat12 and fat16/32 can be merged to one.

Signed-off-by: Seunghun Lee <waydi1@gmail.com>
---
 fs/fat/inode.c |    7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 756aead..6992dea 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -1307,12 +1307,9 @@ static unsigned long calc_fat_clusters(struct super_block *sb)
 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 
 	/* Divide first to avoid overflow */
-	if (sbi->fat_bits != 12) {
-		unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
-		return ent_per_sec * sbi->fat_length;
-	}
+	unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
 
-	return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
+	return ent_per_sec * sbi->fat_length;
 }
 
 static bool fat_bpb_is_zero(struct fat_boot_sector *b)
-- 
1.7.9.5

Re: [PATCH] fat: Simplify calc_fat_clusters code

[OGAWA Hirofumi]

Seunghun Lee <waydi1@gmail.com> writes:

> diff --git a/fs/fat/inode.c b/fs/fat/inode.c
> index 756aead..6992dea 100644
> --- a/fs/fat/inode.c
> +++ b/fs/fat/inode.c
> @@ -1307,12 +1307,9 @@ static unsigned long calc_fat_clusters(struct super_block *sb)
>  	struct msdos_sb_info *sbi = MSDOS_SB(sb);
>  
>  	/* Divide first to avoid overflow */
> -	if (sbi->fat_bits != 12) {
> -		unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
> -		return ent_per_sec * sbi->fat_length;
> -	}
> +	unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
>  
> -	return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
> +	return ent_per_sec * sbi->fat_length;
>  }

When sbi->fat_bits == 12, it doesn't work, right? (there is the remainder)

Thanks.
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

Re: [PATCH] fat: Simplify calc_fat_clusters code

[Seunghun Lee]

On 09/03/2014 12:37 AM, OGAWA Hirofumi wrote:
> Seunghun Lee <waydi1@gmail.com> writes:
>
>> diff --git a/fs/fat/inode.c b/fs/fat/inode.c
>> index 756aead..6992dea 100644
>> --- a/fs/fat/inode.c
>> +++ b/fs/fat/inode.c
>> @@ -1307,12 +1307,9 @@ static unsigned long calc_fat_clusters(struct super_block *sb)
>>  	struct msdos_sb_info *sbi = MSDOS_SB(sb);
>>  
>>  	/* Divide first to avoid overflow */
>> -	if (sbi->fat_bits != 12) {
>> -		unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
>> -		return ent_per_sec * sbi->fat_length;
>> -	}
>> +	unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
>>  
>> -	return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
>> +	return ent_per_sec * sbi->fat_length;
>>  }
> When sbi->fat_bits == 12, it doesn't work, right? (there is the remainder)
>
> Thanks.
Yes, you are right.

I didn't think about the remainder.

Thanks.