[PATCH 1/2] f2fs: use flexible array for f2fs_checkpoint::sit_nat_version_bitmap

[PATCH 1/2] f2fs: use flexible array for f2fs_checkpoint::sit_nat_version_bitmap

[Chao Yu]

If we need an array with variable size in the end of structure, we
can utilize flexible array feature which is supported in C99, so
let's change sit_nat_version_bitmap[] to flexible array in struct
f2fs_checkpoint for readability.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
 fs/f2fs/f2fs.h          | 4 ++--
 include/linux/f2fs_fs.h | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 83d1f697388b..ad19d29688ae 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1719,13 +1719,13 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
 
 	if (__cp_payload(sbi) > 0) {
 		if (flag == NAT_BITMAP)
-			return &ckpt->sit_nat_version_bitmap;
+			return ckpt->sit_nat_version_bitmap;
 		else
 			return (unsigned char *)ckpt + F2FS_BLKSIZE;
 	} else {
 		offset = (flag == NAT_BITMAP) ?
 			le32_to_cpu(ckpt->sit_ver_bitmap_bytesize) : 0;
-		return &ckpt->sit_nat_version_bitmap + offset;
+		return ckpt->sit_nat_version_bitmap + offset;
 	}
 }
 
diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
index 43e98d30d2df..564f65fc192f 100644
--- a/include/linux/f2fs_fs.h
+++ b/include/linux/f2fs_fs.h
@@ -157,7 +157,7 @@ struct f2fs_checkpoint {
 	unsigned char alloc_type[MAX_ACTIVE_LOGS];
 
 	/* SIT and NAT version bitmap */
-	unsigned char sit_nat_version_bitmap[1];
+	unsigned char sit_nat_version_bitmap[];
 } __packed;
 
 /*
-- 
2.15.0.55.gc2ece9dc4de6

[PATCH 2/2] f2fs: clean up unneeded declaration

[Chao Yu]

Commit 6afc662e68b5 ("f2fs: support flexible inline xattr size")
declared f2fs_sb_has_flexible_inline_xattr in f2fs.h for latter being
used in get_inline_xattr_addrs, but in latter version, related code
has been changed, leave f2fs_sb_has_flexible_inline_xattr w/o any
users. Let's remove it for cleanup.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
 fs/f2fs/f2fs.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index ad19d29688ae..c082ae905f08 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2449,7 +2449,6 @@ static inline int get_extra_isize(struct inode *inode)
 	return F2FS_I(inode)->i_extra_isize / sizeof(__le32);
 }
 
-static inline int f2fs_sb_has_flexible_inline_xattr(struct super_block *sb);
 static inline int get_inline_xattr_addrs(struct inode *inode)
 {
 	return F2FS_I(inode)->i_inline_xattr_size;
-- 
2.15.0.55.gc2ece9dc4de6

Re: [PATCH 1/2] f2fs: use flexible array for f2fs_checkpoint::sit_nat_version_bitmap

[Jaegeuk Kim]

On 01/03, Chao Yu wrote:
> If we need an array with variable size in the end of structure, we
> can utilize flexible array feature which is supported in C99, so
> let's change sit_nat_version_bitmap[] to flexible array in struct
> f2fs_checkpoint for readability.
> 
> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> ---
>  fs/f2fs/f2fs.h          | 4 ++--
>  include/linux/f2fs_fs.h | 2 +-
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 83d1f697388b..ad19d29688ae 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1719,13 +1719,13 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
>  
>  	if (__cp_payload(sbi) > 0) {
>  		if (flag == NAT_BITMAP)
> -			return &ckpt->sit_nat_version_bitmap;
> +			return ckpt->sit_nat_version_bitmap;
>  		else
>  			return (unsigned char *)ckpt + F2FS_BLKSIZE;
>  	} else {
>  		offset = (flag == NAT_BITMAP) ?
>  			le32_to_cpu(ckpt->sit_ver_bitmap_bytesize) : 0;
> -		return &ckpt->sit_nat_version_bitmap + offset;
> +		return ckpt->sit_nat_version_bitmap + offset;
>  	}
>  }
>  
> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> index 43e98d30d2df..564f65fc192f 100644
> --- a/include/linux/f2fs_fs.h
> +++ b/include/linux/f2fs_fs.h
> @@ -157,7 +157,7 @@ struct f2fs_checkpoint {
>  	unsigned char alloc_type[MAX_ACTIVE_LOGS];
>  
>  	/* SIT and NAT version bitmap */
> -	unsigned char sit_nat_version_bitmap[1];
> +	unsigned char sit_nat_version_bitmap[];

I cannot find any benefit to do this. Moreover, it just makes the header
structure be different from the one in f2fs-tools.

>  } __packed;
>  
>  /*
> -- 
> 2.15.0.55.gc2ece9dc4de6

Re: [PATCH 1/2] f2fs: use flexible array for f2fs_checkpoint::sit_nat_version_bitmap

[Chao Yu]

On 2018/1/4 4:12, Jaegeuk Kim wrote:
> On 01/03, Chao Yu wrote:
>> If we need an array with variable size in the end of structure, we
>> can utilize flexible array feature which is supported in C99, so
>> let's change sit_nat_version_bitmap[] to flexible array in struct
>> f2fs_checkpoint for readability.
>>
>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>> ---
>>  fs/f2fs/f2fs.h          | 4 ++--
>>  include/linux/f2fs_fs.h | 2 +-
>>  2 files changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 83d1f697388b..ad19d29688ae 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -1719,13 +1719,13 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
>>  
>>  	if (__cp_payload(sbi) > 0) {
>>  		if (flag == NAT_BITMAP)
>> -			return &ckpt->sit_nat_version_bitmap;
>> +			return ckpt->sit_nat_version_bitmap;
>>  		else
>>  			return (unsigned char *)ckpt + F2FS_BLKSIZE;
>>  	} else {
>>  		offset = (flag == NAT_BITMAP) ?
>>  			le32_to_cpu(ckpt->sit_ver_bitmap_bytesize) : 0;
>> -		return &ckpt->sit_nat_version_bitmap + offset;
>> +		return ckpt->sit_nat_version_bitmap + offset;
>>  	}
>>  }
>>  
>> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
>> index 43e98d30d2df..564f65fc192f 100644
>> --- a/include/linux/f2fs_fs.h
>> +++ b/include/linux/f2fs_fs.h
>> @@ -157,7 +157,7 @@ struct f2fs_checkpoint {
>>  	unsigned char alloc_type[MAX_ACTIVE_LOGS];
>>  
>>  	/* SIT and NAT version bitmap */
>> -	unsigned char sit_nat_version_bitmap[1];
>> +	unsigned char sit_nat_version_bitmap[];
> 
> I cannot find any benefit to do this. Moreover, it just makes the header

I intend to change both kernel and tools, sorry, I didn't send out the
patch on tools. Anyway, I think it could be used to avoid checkpoint
structure size calculation by "sizeof(struct checkpoint) - 1", with the
patch, readability can be improved. Right?

Thanks,

> structure be different from the one in f2fs-tools.
> 
>>  } __packed;
>>  
>>  /*
>> -- 
>> 2.15.0.55.gc2ece9dc4de6
> 
> .
> 

Re: [PATCH 1/2] f2fs: use flexible array for f2fs_checkpoint::sit_nat_version_bitmap

[Jaegeuk Kim]

On 01/04, Chao Yu wrote:
> On 2018/1/4 4:12, Jaegeuk Kim wrote:
> > On 01/03, Chao Yu wrote:
> >> If we need an array with variable size in the end of structure, we
> >> can utilize flexible array feature which is supported in C99, so
> >> let's change sit_nat_version_bitmap[] to flexible array in struct
> >> f2fs_checkpoint for readability.
> >>
> >> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> >> ---
> >>  fs/f2fs/f2fs.h          | 4 ++--
> >>  include/linux/f2fs_fs.h | 2 +-
> >>  2 files changed, 3 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> >> index 83d1f697388b..ad19d29688ae 100644
> >> --- a/fs/f2fs/f2fs.h
> >> +++ b/fs/f2fs/f2fs.h
> >> @@ -1719,13 +1719,13 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
> >>  
> >>  	if (__cp_payload(sbi) > 0) {
> >>  		if (flag == NAT_BITMAP)
> >> -			return &ckpt->sit_nat_version_bitmap;
> >> +			return ckpt->sit_nat_version_bitmap;
> >>  		else
> >>  			return (unsigned char *)ckpt + F2FS_BLKSIZE;
> >>  	} else {
> >>  		offset = (flag == NAT_BITMAP) ?
> >>  			le32_to_cpu(ckpt->sit_ver_bitmap_bytesize) : 0;
> >> -		return &ckpt->sit_nat_version_bitmap + offset;
> >> +		return ckpt->sit_nat_version_bitmap + offset;
> >>  	}
> >>  }
> >>  
> >> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> >> index 43e98d30d2df..564f65fc192f 100644
> >> --- a/include/linux/f2fs_fs.h
> >> +++ b/include/linux/f2fs_fs.h
> >> @@ -157,7 +157,7 @@ struct f2fs_checkpoint {
> >>  	unsigned char alloc_type[MAX_ACTIVE_LOGS];
> >>  
> >>  	/* SIT and NAT version bitmap */
> >> -	unsigned char sit_nat_version_bitmap[1];
> >> +	unsigned char sit_nat_version_bitmap[];
> > 
> > I cannot find any benefit to do this. Moreover, it just makes the header
> 
> I intend to change both kernel and tools, sorry, I didn't send out the
> patch on tools. Anyway, I think it could be used to avoid checkpoint
> structure size calculation by "sizeof(struct checkpoint) - 1", with the
> patch, readability can be improved. Right?

I don't think so. It's even defined only in f2fs-tools, and well covered by a
macro. There's no reason to spend time to sync it between f2fs and f2fs-tools.

> 
> Thanks,
> 
> > structure be different from the one in f2fs-tools.
> > 
> >>  } __packed;
> >>  
> >>  /*
> >> -- 
> >> 2.15.0.55.gc2ece9dc4de6
> > 
> > .
> > 

Re: [PATCH 1/2] f2fs: use flexible array for f2fs_checkpoint::sit_nat_version_bitmap

[Chao Yu]

On 2018/1/4 14:16, Jaegeuk Kim wrote:
> On 01/04, Chao Yu wrote:
>> On 2018/1/4 4:12, Jaegeuk Kim wrote:
>>> On 01/03, Chao Yu wrote:
>>>> If we need an array with variable size in the end of structure, we
>>>> can utilize flexible array feature which is supported in C99, so
>>>> let's change sit_nat_version_bitmap[] to flexible array in struct
>>>> f2fs_checkpoint for readability.
>>>>
>>>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>>>> ---
>>>>  fs/f2fs/f2fs.h          | 4 ++--
>>>>  include/linux/f2fs_fs.h | 2 +-
>>>>  2 files changed, 3 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>> index 83d1f697388b..ad19d29688ae 100644
>>>> --- a/fs/f2fs/f2fs.h
>>>> +++ b/fs/f2fs/f2fs.h
>>>> @@ -1719,13 +1719,13 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
>>>>  
>>>>  	if (__cp_payload(sbi) > 0) {
>>>>  		if (flag == NAT_BITMAP)
>>>> -			return &ckpt->sit_nat_version_bitmap;
>>>> +			return ckpt->sit_nat_version_bitmap;
>>>>  		else
>>>>  			return (unsigned char *)ckpt + F2FS_BLKSIZE;
>>>>  	} else {
>>>>  		offset = (flag == NAT_BITMAP) ?
>>>>  			le32_to_cpu(ckpt->sit_ver_bitmap_bytesize) : 0;
>>>> -		return &ckpt->sit_nat_version_bitmap + offset;
>>>> +		return ckpt->sit_nat_version_bitmap + offset;
>>>>  	}
>>>>  }
>>>>  
>>>> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
>>>> index 43e98d30d2df..564f65fc192f 100644
>>>> --- a/include/linux/f2fs_fs.h
>>>> +++ b/include/linux/f2fs_fs.h
>>>> @@ -157,7 +157,7 @@ struct f2fs_checkpoint {
>>>>  	unsigned char alloc_type[MAX_ACTIVE_LOGS];
>>>>  
>>>>  	/* SIT and NAT version bitmap */
>>>> -	unsigned char sit_nat_version_bitmap[1];
>>>> +	unsigned char sit_nat_version_bitmap[];
>>>
>>> I cannot find any benefit to do this. Moreover, it just makes the header
>>
>> I intend to change both kernel and tools, sorry, I didn't send out the
>> patch on tools. Anyway, I think it could be used to avoid checkpoint
>> structure size calculation by "sizeof(struct checkpoint) - 1", with the
>> patch, readability can be improved. Right?
> 
> I don't think so. It's even defined only in f2fs-tools, and well covered by a
> macro. There's no reason to spend time to sync it between f2fs and f2fs-tools.

OK, this is only about readability, it's really not a big deal to drop this
patch.

Thanks,

> 
>>
>> Thanks,
>>
>>> structure be different from the one in f2fs-tools.
>>>
>>>>  } __packed;
>>>>  
>>>>  /*
>>>> -- 
>>>> 2.15.0.55.gc2ece9dc4de6
>>>
>>> .
>>>
> 
> .
>