There is a regular need in the kernel to provide a way to declare having
a dynamically sized set of trailing elements in a structure. Kernel code
should always use “flexible array members”[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].
Refactor the code according to the use of a flexible-array member in
struct f2fs_checkpoint, instead of a one-element arrays.
Notice that a temporary pointer to void '*tmp_ptr' was used in order to
fix the following errors when using a flexible array instead of a one
element array in struct f2fs_checkpoint:
CC [M] fs/f2fs/dir.o
In file included from fs/f2fs/dir.c:13:
fs/f2fs/f2fs.h: In function ‘__bitmap_ptr’:
fs/f2fs/f2fs.h:2227:40: error: invalid use of flexible array member
2227 | return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32);
| ^
fs/f2fs/f2fs.h:2227:49: error: invalid use of flexible array member
2227 | return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32);
| ^
fs/f2fs/f2fs.h:2238:40: error: invalid use of flexible array member
2238 | return &ckpt->sit_nat_version_bitmap + offset;
| ^
make[2]: *** [scripts/Makefile.build:287: fs/f2fs/dir.o] Error 1
make[1]: *** [scripts/Makefile.build:530: fs/f2fs] Error 2
make: *** [Makefile:1819: fs] Error 2
[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and-one-element-arrays
Link: https://github.com/KSPP/linux/issues/79
Build-tested-by: kernel test robot <[email protected]>
Link: https://lore.kernel.org/lkml/603647e4.DeEFbl4eqljuwAUe%[email protected]/
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
fs/f2fs/f2fs.h | 5 +++--
include/linux/f2fs_fs.h | 2 +-
2 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index e2d302ae3a46..3f5cb097c30f 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2215,6 +2215,7 @@ static inline block_t __cp_payload(struct f2fs_sb_info *sbi)
static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
{
struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
+ void *tmp_ptr = &ckpt->sit_nat_version_bitmap;
int offset;
if (is_set_ckpt_flags(sbi, CP_LARGE_NAT_BITMAP_FLAG)) {
@@ -2224,7 +2225,7 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
* if large_nat_bitmap feature is enabled, leave checksum
* protection for all nat/sit bitmaps.
*/
- return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32);
+ return tmp_ptr + offset + sizeof(__le32);
}
if (__cp_payload(sbi) > 0) {
@@ -2235,7 +2236,7 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
} else {
offset = (flag == NAT_BITMAP) ?
le32_to_cpu(ckpt->sit_ver_bitmap_bytesize) : 0;
- return &ckpt->sit_nat_version_bitmap + offset;
+ return tmp_ptr + offset;
}
}
diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
index c6cc0a566ef5..5487a80617a3 100644
--- a/include/linux/f2fs_fs.h
+++ b/include/linux/f2fs_fs.h
@@ -168,7 +168,7 @@ 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;
#define CP_CHKSUM_OFFSET 4092 /* default chksum offset in checkpoint */
--
2.27.0
Hello, Gustavo,
On 2021/2/25 3:03, Gustavo A. R. Silva wrote:
> There is a regular need in the kernel to provide a way to declare having
> a dynamically sized set of trailing elements in a structure. Kernel code
> should always use “flexible array members”[1] for these cases. The older
> style of one-element or zero-length arrays should no longer be used[2].
I proposal to do the similar cleanup, and I've no objection on doing this.
https://lore.kernel.org/patchwork/patch/869440/
Let's ask for Jaegeuk' opinion.
>
> Refactor the code according to the use of a flexible-array member in
> struct f2fs_checkpoint, instead of a one-element arrays.
>
> Notice that a temporary pointer to void '*tmp_ptr' was used in order to
> fix the following errors when using a flexible array instead of a one
> element array in struct f2fs_checkpoint:
>
> CC [M] fs/f2fs/dir.o
> In file included from fs/f2fs/dir.c:13:
> fs/f2fs/f2fs.h: In function ‘__bitmap_ptr’:
> fs/f2fs/f2fs.h:2227:40: error: invalid use of flexible array member
> 2227 | return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32);
> | ^
> fs/f2fs/f2fs.h:2227:49: error: invalid use of flexible array member
> 2227 | return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32);
> | ^
> fs/f2fs/f2fs.h:2238:40: error: invalid use of flexible array member
> 2238 | return &ckpt->sit_nat_version_bitmap + offset;
> | ^
> make[2]: *** [scripts/Makefile.build:287: fs/f2fs/dir.o] Error 1
> make[1]: *** [scripts/Makefile.build:530: fs/f2fs] Error 2
> make: *** [Makefile:1819: fs] Error 2
>
> [1] https://en.wikipedia.org/wiki/Flexible_array_member
> [2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and-one-element-arrays
>
> Link: https://github.com/KSPP/linux/issues/79
> Build-tested-by: kernel test robot <[email protected]>
> Link: https://lore.kernel.org/lkml/603647e4.DeEFbl4eqljuwAUe%[email protected]/
> Signed-off-by: Gustavo A. R. Silva <[email protected]>
> ---
> fs/f2fs/f2fs.h | 5 +++--
> include/linux/f2fs_fs.h | 2 +-
> 2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index e2d302ae3a46..3f5cb097c30f 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -2215,6 +2215,7 @@ static inline block_t __cp_payload(struct f2fs_sb_info *sbi)
> static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
> {
> struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
> + void *tmp_ptr = &ckpt->sit_nat_version_bitmap;
> int offset;
>
> if (is_set_ckpt_flags(sbi, CP_LARGE_NAT_BITMAP_FLAG)) {
> @@ -2224,7 +2225,7 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
> * if large_nat_bitmap feature is enabled, leave checksum
> * protection for all nat/sit bitmaps.
> */
> - return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32);
> + return tmp_ptr + offset + sizeof(__le32);
> }
>
> if (__cp_payload(sbi) > 0) {
> @@ -2235,7 +2236,7 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
> } else {
> offset = (flag == NAT_BITMAP) ?
> le32_to_cpu(ckpt->sit_ver_bitmap_bytesize) : 0;
> - return &ckpt->sit_nat_version_bitmap + offset;
> + return tmp_ptr + offset;
> }
> }
>
> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> index c6cc0a566ef5..5487a80617a3 100644
> --- a/include/linux/f2fs_fs.h
> +++ b/include/linux/f2fs_fs.h
> @@ -168,7 +168,7 @@ 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;
>
> #define CP_CHKSUM_OFFSET 4092 /* default chksum offset in checkpoint */
>
On 02/25, Chao Yu wrote:
> Hello, Gustavo,
>
> On 2021/2/25 3:03, Gustavo A. R. Silva wrote:
> > There is a regular need in the kernel to provide a way to declare having
> > a dynamically sized set of trailing elements in a structure. Kernel code
> > should always use “flexible array members”[1] for these cases. The older
> > style of one-element or zero-length arrays should no longer be used[2].
>
> I proposal to do the similar cleanup, and I've no objection on doing this.
>
> https://lore.kernel.org/patchwork/patch/869440/
>
> Let's ask for Jaegeuk' opinion.
Merged, thanks.
This looks better reason than code readability. :)
>
> >
> > Refactor the code according to the use of a flexible-array member in
> > struct f2fs_checkpoint, instead of a one-element arrays.
> >
> > Notice that a temporary pointer to void '*tmp_ptr' was used in order to
> > fix the following errors when using a flexible array instead of a one
> > element array in struct f2fs_checkpoint:
> >
> > CC [M] fs/f2fs/dir.o
> > In file included from fs/f2fs/dir.c:13:
> > fs/f2fs/f2fs.h: In function ‘__bitmap_ptr’:
> > fs/f2fs/f2fs.h:2227:40: error: invalid use of flexible array member
> > 2227 | return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32);
> > | ^
> > fs/f2fs/f2fs.h:2227:49: error: invalid use of flexible array member
> > 2227 | return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32);
> > | ^
> > fs/f2fs/f2fs.h:2238:40: error: invalid use of flexible array member
> > 2238 | return &ckpt->sit_nat_version_bitmap + offset;
> > | ^
> > make[2]: *** [scripts/Makefile.build:287: fs/f2fs/dir.o] Error 1
> > make[1]: *** [scripts/Makefile.build:530: fs/f2fs] Error 2
> > make: *** [Makefile:1819: fs] Error 2
> >
> > [1] https://en.wikipedia.org/wiki/Flexible_array_member
> > [2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and-one-element-arrays
> >
> > Link: https://github.com/KSPP/linux/issues/79
> > Build-tested-by: kernel test robot <[email protected]>
> > Link: https://lore.kernel.org/lkml/603647e4.DeEFbl4eqljuwAUe%[email protected]/
> > Signed-off-by: Gustavo A. R. Silva <[email protected]>
> > ---
> > fs/f2fs/f2fs.h | 5 +++--
> > include/linux/f2fs_fs.h | 2 +-
> > 2 files changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > index e2d302ae3a46..3f5cb097c30f 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -2215,6 +2215,7 @@ static inline block_t __cp_payload(struct f2fs_sb_info *sbi)
> > static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
> > {
> > struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
> > + void *tmp_ptr = &ckpt->sit_nat_version_bitmap;
> > int offset;
> > if (is_set_ckpt_flags(sbi, CP_LARGE_NAT_BITMAP_FLAG)) {
> > @@ -2224,7 +2225,7 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
> > * if large_nat_bitmap feature is enabled, leave checksum
> > * protection for all nat/sit bitmaps.
> > */
> > - return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32);
> > + return tmp_ptr + offset + sizeof(__le32);
> > }
> > if (__cp_payload(sbi) > 0) {
> > @@ -2235,7 +2236,7 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
> > } else {
> > offset = (flag == NAT_BITMAP) ?
> > le32_to_cpu(ckpt->sit_ver_bitmap_bytesize) : 0;
> > - return &ckpt->sit_nat_version_bitmap + offset;
> > + return tmp_ptr + offset;
> > }
> > }
> > diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> > index c6cc0a566ef5..5487a80617a3 100644
> > --- a/include/linux/f2fs_fs.h
> > +++ b/include/linux/f2fs_fs.h
> > @@ -168,7 +168,7 @@ 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;
> > #define CP_CHKSUM_OFFSET 4092 /* default chksum offset in checkpoint */
> >
On 2021/2/28 13:00, Jaegeuk Kim wrote:
> On 02/25, Chao Yu wrote:
>> Hello, Gustavo,
>>
>> On 2021/2/25 3:03, Gustavo A. R. Silva wrote:
>>> There is a regular need in the kernel to provide a way to declare having
>>> a dynamically sized set of trailing elements in a structure. Kernel code
>>> should always use “flexible array members”[1] for these cases. The older
>>> style of one-element or zero-length arrays should no longer be used[2].
>>
>> I proposal to do the similar cleanup, and I've no objection on doing this.
>>
>> https://lore.kernel.org/patchwork/patch/869440/
>>
>> Let's ask for Jaegeuk' opinion.
>
> Merged, thanks.
> This looks better reason than code readability. :)
Agreed.
Reviewed-by: Chao Yu <[email protected]>
Thanks,
>
>>
>>>
>>> Refactor the code according to the use of a flexible-array member in
>>> struct f2fs_checkpoint, instead of a one-element arrays.
>>>
>>> Notice that a temporary pointer to void '*tmp_ptr' was used in order to
>>> fix the following errors when using a flexible array instead of a one
>>> element array in struct f2fs_checkpoint:
>>>
>>> CC [M] fs/f2fs/dir.o
>>> In file included from fs/f2fs/dir.c:13:
>>> fs/f2fs/f2fs.h: In function ‘__bitmap_ptr’:
>>> fs/f2fs/f2fs.h:2227:40: error: invalid use of flexible array member
>>> 2227 | return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32);
>>> | ^
>>> fs/f2fs/f2fs.h:2227:49: error: invalid use of flexible array member
>>> 2227 | return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32);
>>> | ^
>>> fs/f2fs/f2fs.h:2238:40: error: invalid use of flexible array member
>>> 2238 | return &ckpt->sit_nat_version_bitmap + offset;
>>> | ^
>>> make[2]: *** [scripts/Makefile.build:287: fs/f2fs/dir.o] Error 1
>>> make[1]: *** [scripts/Makefile.build:530: fs/f2fs] Error 2
>>> make: *** [Makefile:1819: fs] Error 2
>>>
>>> [1] https://en.wikipedia.org/wiki/Flexible_array_member
>>> [2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and-one-element-arrays
>>>
>>> Link: https://github.com/KSPP/linux/issues/79
>>> Build-tested-by: kernel test robot <[email protected]>
>>> Link: https://lore.kernel.org/lkml/603647e4.DeEFbl4eqljuwAUe%[email protected]/
>>> Signed-off-by: Gustavo A. R. Silva <[email protected]>
>>> ---
>>> fs/f2fs/f2fs.h | 5 +++--
>>> include/linux/f2fs_fs.h | 2 +-
>>> 2 files changed, 4 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>> index e2d302ae3a46..3f5cb097c30f 100644
>>> --- a/fs/f2fs/f2fs.h
>>> +++ b/fs/f2fs/f2fs.h
>>> @@ -2215,6 +2215,7 @@ static inline block_t __cp_payload(struct f2fs_sb_info *sbi)
>>> static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
>>> {
>>> struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
>>> + void *tmp_ptr = &ckpt->sit_nat_version_bitmap;
>>> int offset;
>>> if (is_set_ckpt_flags(sbi, CP_LARGE_NAT_BITMAP_FLAG)) {
>>> @@ -2224,7 +2225,7 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
>>> * if large_nat_bitmap feature is enabled, leave checksum
>>> * protection for all nat/sit bitmaps.
>>> */
>>> - return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32);
>>> + return tmp_ptr + offset + sizeof(__le32);
>>> }
>>> if (__cp_payload(sbi) > 0) {
>>> @@ -2235,7 +2236,7 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
>>> } else {
>>> offset = (flag == NAT_BITMAP) ?
>>> le32_to_cpu(ckpt->sit_ver_bitmap_bytesize) : 0;
>>> - return &ckpt->sit_nat_version_bitmap + offset;
>>> + return tmp_ptr + offset;
>>> }
>>> }
>>> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
>>> index c6cc0a566ef5..5487a80617a3 100644
>>> --- a/include/linux/f2fs_fs.h
>>> +++ b/include/linux/f2fs_fs.h
>>> @@ -168,7 +168,7 @@ 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;
>>> #define CP_CHKSUM_OFFSET 4092 /* default chksum offset in checkpoint */
>>>
> .
>