diff mbox

xfs: avoid harmless gcc-7 warnings

Message ID 20170511124932.226016-1-arnd@arndb.de
State Superseded
Headers show

Commit Message

Arnd Bergmann May 11, 2017, 12:49 p.m. UTC 
gcc-7 flags the use of integer math inside of a condition
as a potential bug:

fs/xfs/xfs_bmap_util.c: In function 'xfs_swap_extents_check_format':
fs/xfs/xfs_bmap_util.c:1619:8: error: '<<' in boolean context, did you mean '<' ? [-Werror=int-in-bool-context]
fs/xfs/xfs_bmap_util.c:1629:8: error: '<<' in boolean context, did you mean '<' ? [-Werror=int-in-bool-context]

This one is clearly fine, and we can add a comparison to zero
to shut up the warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
 fs/xfs/xfs_bmap_util.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

-- 
2.9.0

Comments

Eric Sandeen May 11, 2017, 1:33 p.m. UTC | #1 
On 5/11/17 7:49 AM, Arnd Bergmann wrote:
> gcc-7 flags the use of integer math inside of a condition

> as a potential bug:

> 

> fs/xfs/xfs_bmap_util.c: In function 'xfs_swap_extents_check_format':

> fs/xfs/xfs_bmap_util.c:1619:8: error: '<<' in boolean context, did you mean '<' ? [-Werror=int-in-bool-context]

> fs/xfs/xfs_bmap_util.c:1629:8: error: '<<' in boolean context, did you mean '<' ? [-Werror=int-in-bool-context]

> 

> This one is clearly fine, and we can add a comparison to zero

> to shut up the warning.

> 

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>


Thanks Arnd -

Reviewed-by: Eric Sandeen <sandeen@redhat.com>


> ---

>  fs/xfs/xfs_bmap_util.c | 4 ++--

>  1 file changed, 2 insertions(+), 2 deletions(-)

> 

> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c

> index 2b954308a1d6..cbd3ffe42f39 100644

> --- a/fs/xfs/xfs_bmap_util.c

> +++ b/fs/xfs/xfs_bmap_util.c

> @@ -1613,7 +1613,7 @@ xfs_swap_extents_check_format(

>  	 * extent format...

>  	 */

>  	if (tip->i_d.di_format == XFS_DINODE_FMT_BTREE) {

> -		if (XFS_IFORK_BOFF(ip) &&

> +		if ((XFS_IFORK_BOFF(ip) != 0) &&

>  		    XFS_BMAP_BMDR_SPACE(tip->i_df.if_broot) > XFS_IFORK_BOFF(ip))

>  			return -EINVAL;

>  		if (XFS_IFORK_NEXTENTS(tip, XFS_DATA_FORK) <=

> @@ -1623,7 +1623,7 @@ xfs_swap_extents_check_format(

>  

>  	/* Reciprocal target->temp btree format checks */

>  	if (ip->i_d.di_format == XFS_DINODE_FMT_BTREE) {

> -		if (XFS_IFORK_BOFF(tip) &&

> +		if ((XFS_IFORK_BOFF(tip) != 0) &&

>  		    XFS_BMAP_BMDR_SPACE(ip->i_df.if_broot) > XFS_IFORK_BOFF(tip))

>  			return -EINVAL;

>  		if (XFS_IFORK_NEXTENTS(ip, XFS_DATA_FORK) <=

>
'Christoph Hellwig' May 11, 2017, 2:02 p.m. UTC | #2 
On Thu, May 11, 2017 at 02:49:21PM +0200, Arnd Bergmann wrote:
> gcc-7 flags the use of integer math inside of a condition

> as a potential bug:

> 

> fs/xfs/xfs_bmap_util.c: In function 'xfs_swap_extents_check_format':

> fs/xfs/xfs_bmap_util.c:1619:8: error: '<<' in boolean context, did you mean '<' ? [-Werror=int-in-bool-context]

> fs/xfs/xfs_bmap_util.c:1629:8: error: '<<' in boolean context, did you mean '<' ? [-Werror=int-in-bool-context]

> 

> This one is clearly fine, and we can add a comparison to zero

> to shut up the warning.

> 

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

> ---

>  fs/xfs/xfs_bmap_util.c | 4 ++--

>  1 file changed, 2 insertions(+), 2 deletions(-)

> 

> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c

> index 2b954308a1d6..cbd3ffe42f39 100644

> --- a/fs/xfs/xfs_bmap_util.c

> +++ b/fs/xfs/xfs_bmap_util.c

> @@ -1613,7 +1613,7 @@ xfs_swap_extents_check_format(

>  	 * extent format...

>  	 */

>  	if (tip->i_d.di_format == XFS_DINODE_FMT_BTREE) {

> -		if (XFS_IFORK_BOFF(ip) &&

> +		if ((XFS_IFORK_BOFF(ip) != 0) &&


Even if we were fine with fixing this odd warning the additional braces
are simply bogus.
Arnd Bergmann May 11, 2017, 2:56 p.m. UTC | #3 
On Thu, May 11, 2017 at 4:02 PM, Christoph Hellwig <hch@infradead.org> wrote:
> On Thu, May 11, 2017 at 02:49:21PM +0200, Arnd Bergmann wrote:

>> gcc-7 flags the use of integer math inside of a condition

>> as a potential bug:

>>

>> fs/xfs/xfs_bmap_util.c: In function 'xfs_swap_extents_check_format':

>> fs/xfs/xfs_bmap_util.c:1619:8: error: '<<' in boolean context, did you mean '<' ? [-Werror=int-in-bool-context]

>> fs/xfs/xfs_bmap_util.c:1629:8: error: '<<' in boolean context, did you mean '<' ? [-Werror=int-in-bool-context]

>>

>> This one is clearly fine, and we can add a comparison to zero

>> to shut up the warning.

>>

>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

>> ---

>>  fs/xfs/xfs_bmap_util.c | 4 ++--

>>  1 file changed, 2 insertions(+), 2 deletions(-)

>>

>> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c

>> index 2b954308a1d6..cbd3ffe42f39 100644

>> --- a/fs/xfs/xfs_bmap_util.c

>> +++ b/fs/xfs/xfs_bmap_util.c

>> @@ -1613,7 +1613,7 @@ xfs_swap_extents_check_format(

>>        * extent format...

>>        */

>>       if (tip->i_d.di_format == XFS_DINODE_FMT_BTREE) {

>> -             if (XFS_IFORK_BOFF(ip) &&

>> +             if ((XFS_IFORK_BOFF(ip) != 0) &&

>

> Even if we were fine with fixing this odd warning the additional braces

> are simply bogus.


The warning seems generally useful and is enabled by default in gcc-7.
An example of a real bug it found is
https://patchwork.kernel.org/patch/9431813/, so I'd prefer to leave it
enabled and fix the few instances in the kernel.

I found a better way to rework the code to avoid the warning, sending
out v2 now.

    Arnd
Joe Perches May 12, 2017, 2:18 p.m. UTC | #4 
On Thu, 2017-05-11 at 14:49 +0200, Arnd Bergmann wrote:
> gcc-7 flags the use of integer math inside of a condition

> as a potential bug:

> 

> fs/xfs/xfs_bmap_util.c: In function 'xfs_swap_extents_check_format':

> fs/xfs/xfs_bmap_util.c:1619:8: error: '<<' in boolean context, did you mean '<' ? [-Werror=int-in-bool-context]

> fs/xfs/xfs_bmap_util.c:1629:8: error: '<<' in boolean context, did you mean '<' ? [-Werror=int-in-bool-context]

> 

> This one is clearly fine, and we can add a comparison to zero

> to shut up the warning.

[]
> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c

[]
> @@ -1613,7 +1613,7 @@ xfs_swap_extents_check_format(

>  	 * extent format...

>  	 */

>  	if (tip->i_d.di_format == XFS_DINODE_FMT_BTREE) {

> -		if (XFS_IFORK_BOFF(ip) &&

> +		if ((XFS_IFORK_BOFF(ip) != 0) &&


As far as I can tell, this suggestion makes no sense.

$ git grep -E "define\s+XFS_IFORK_BOFF"
fs/xfs/libxfs/xfs_inode_fork.h:#define XFS_IFORK_BOFF(ip)               ((int)((ip)->i_d.di_forkoff << 3))

$ git grep -w di_forkoff|grep -P "\w+\s+di_forkoff\s*;"
fs/xfs/libxfs/xfs_format.h:	__u8		di_forkoff;	/* attr fork offs, <<3 for 64b align */
fs/xfs/libxfs/xfs_inode_buf.h:	__uint8_t	di_forkoff;	/* attr fork offs, <<3 for 64b align */
fs/xfs/libxfs/xfs_log_format.h:	__uint8_t	di_forkoff;	/* attr fork offs, <<3 for 64b align */
diff mbox

Patch

diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 2b954308a1d6..cbd3ffe42f39 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -1613,7 +1613,7 @@  xfs_swap_extents_check_format(
 	 * extent format...
 	 */
 	if (tip->i_d.di_format == XFS_DINODE_FMT_BTREE) {
-		if (XFS_IFORK_BOFF(ip) &&
+		if ((XFS_IFORK_BOFF(ip) != 0) &&
 		    XFS_BMAP_BMDR_SPACE(tip->i_df.if_broot) > XFS_IFORK_BOFF(ip))
 			return -EINVAL;
 		if (XFS_IFORK_NEXTENTS(tip, XFS_DATA_FORK) <=
@@ -1623,7 +1623,7 @@  xfs_swap_extents_check_format(
 
 	/* Reciprocal target->temp btree format checks */
 	if (ip->i_d.di_format == XFS_DINODE_FMT_BTREE) {
-		if (XFS_IFORK_BOFF(tip) &&
+		if ((XFS_IFORK_BOFF(tip) != 0) &&
 		    XFS_BMAP_BMDR_SPACE(ip->i_df.if_broot) > XFS_IFORK_BOFF(tip))
 			return -EINVAL;
 		if (XFS_IFORK_NEXTENTS(ip, XFS_DATA_FORK) <=