diff mbox series

[f2fs-dev] f2fs: Fix type of single bit bitfield in f2fs_io_info

Message ID 20230201-f2fs-fix-single-length-bitfields-v1-1-e386f7916b94@kernel.org (mailing list archive)
State New
Headers show
Series [f2fs-dev] f2fs: Fix type of single bit bitfield in f2fs_io_info | expand

Commit Message

Nathan Chancellor Feb. 1, 2023, 4:40 p.m. UTC 
Clang warns:

  ../fs/f2fs/data.c:995:17: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
          fio->submitted = 1;
                         ^ ~
  ../fs/f2fs/data.c:1011:15: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
                          fio->retry = 1;
                                     ^ ~

  ../fs/f2fs/segment.c:3320:16: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
                  fio->in_list = 1;
                               ^ ~

There is not a bug here because the value of these fields is never
explicitly compared against (just whether it is zero or non-zero) but
it is easy to silence the warning by using an unsigned type to allow
an assignment of 0 or 1 without implicit conversion.

Fixes: 998863dadd2c ("f2fs: reduce stack memory cost by using bitfield in struct f2fs_io_info")
Link: https://github.com/ClangBuiltLinux/linux/issues/1796
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 fs/f2fs/f2fs.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)


---
base-commit: de6b3a5e09b29c014bd04044b023896107cfa2ee
change-id: 20230201-f2fs-fix-single-length-bitfields-df8cc78e880a

Best regards,

Comments

Chao Yu Feb. 2, 2023, 6:13 a.m. UTC | #1 
On 2023/2/2 0:40, Nathan Chancellor wrote:
> Clang warns:
> 
>    ../fs/f2fs/data.c:995:17: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
>            fio->submitted = 1;
>                           ^ ~
>    ../fs/f2fs/data.c:1011:15: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
>                            fio->retry = 1;
>                                       ^ ~
> 
>    ../fs/f2fs/segment.c:3320:16: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
>                    fio->in_list = 1;
>                                 ^ ~
> 
> There is not a bug here because the value of these fields is never
> explicitly compared against (just whether it is zero or non-zero) but
> it is easy to silence the warning by using an unsigned type to allow
> an assignment of 0 or 1 without implicit conversion.

Nathan, thanks a lot for catching this, do you mind letting I merge this fix
into original patch? as the original patch has not been upstreamed yet.

Thanks,
Nathan Chancellor Feb. 2, 2023, 6:15 a.m. UTC | #2 
On Thu, Feb 02, 2023 at 02:13:18PM +0800, Chao Yu wrote:
> On 2023/2/2 0:40, Nathan Chancellor wrote:
> > Clang warns:
> > 
> >    ../fs/f2fs/data.c:995:17: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
> >            fio->submitted = 1;
> >                           ^ ~
> >    ../fs/f2fs/data.c:1011:15: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
> >                            fio->retry = 1;
> >                                       ^ ~
> > 
> >    ../fs/f2fs/segment.c:3320:16: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
> >                    fio->in_list = 1;
> >                                 ^ ~
> > 
> > There is not a bug here because the value of these fields is never
> > explicitly compared against (just whether it is zero or non-zero) but
> > it is easy to silence the warning by using an unsigned type to allow
> > an assignment of 0 or 1 without implicit conversion.
> 
> Nathan, thanks a lot for catching this, do you mind letting I merge this fix
> into original patch? as the original patch has not been upstreamed yet.

No worries, do whatever you need to! I just care that the problem gets
resolved one way or another :)

Cheers,
Nathan
Chao Yu Feb. 2, 2023, 7:11 a.m. UTC | #3 
On 2023/2/2 14:15, Nathan Chancellor wrote:
> On Thu, Feb 02, 2023 at 02:13:18PM +0800, Chao Yu wrote:
>> On 2023/2/2 0:40, Nathan Chancellor wrote:
>>> Clang warns:
>>>
>>>     ../fs/f2fs/data.c:995:17: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
>>>             fio->submitted = 1;
>>>                            ^ ~
>>>     ../fs/f2fs/data.c:1011:15: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
>>>                             fio->retry = 1;
>>>                                        ^ ~
>>>
>>>     ../fs/f2fs/segment.c:3320:16: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
>>>                     fio->in_list = 1;
>>>                                  ^ ~
>>>
>>> There is not a bug here because the value of these fields is never
>>> explicitly compared against (just whether it is zero or non-zero) but
>>> it is easy to silence the warning by using an unsigned type to allow
>>> an assignment of 0 or 1 without implicit conversion.
>>
>> Nathan, thanks a lot for catching this, do you mind letting I merge this fix
>> into original patch? as the original patch has not been upstreamed yet.
> 
> No worries, do whatever you need to! I just care that the problem gets
> resolved one way or another :)

Thank you! Updated a v3 patch. :)

Thanks,

> 
> Cheers,
> Nathan
diff mbox series

Patch

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 08dc64c5050e..89f6fdfeed19 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1213,12 +1213,12 @@  struct f2fs_io_info {
 	int compr_blocks;	/* # of compressed block addresses */
 	int need_lock:8;	/* indicate we need to lock cp_rwsem */
 	int version:8;		/* version of the node */
-	int submitted:1;	/* indicate IO submission */
-	int in_list:1;		/* indicate fio is in io_list */
-	int is_por:1;		/* indicate IO is from recovery or not */
-	int retry:1;		/* need to reallocate block address */
-	int encrypted:1;	/* indicate file is encrypted */
-	int post_read:1;	/* require post read */
+	unsigned int submitted:1;	/* indicate IO submission */
+	unsigned int in_list:1;		/* indicate fio is in io_list */
+	unsigned int is_por:1;		/* indicate IO is from recovery or not */
+	unsigned int retry:1;		/* need to reallocate block address */
+	unsigned int encrypted:1;	/* indicate file is encrypted */
+	unsigned int post_read:1;	/* require post read */
 	enum iostat_type io_type;	/* io type */
 	struct writeback_control *io_wbc; /* writeback control */
 	struct bio **bio;		/* bio for ipu */