ocfs2: Avoid -Wflex-array-member-not-at-end warning

[PATCH][next] ocfs2: Avoid -Wflex-array-member-not-at-end warning

Posted by Gustavo A. R. Silva 2 months, 4 weeks ago

-Wflex-array-member-not-at-end was introduced in GCC-14, and we are
getting ready to enable it, globally.

Use the new TRAILING_OVERLAP() helper to fix the following warning:

fs/ocfs2/xattr.c:52:41: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

This helper creates a union between a flexible-array member (FAM) and a
set of MEMBERS that would otherwise follow it.

This overlays the trailing MEMBER struct ocfs2_extent_rec er; onto the
FAM struct ocfs2_xattr_value_root::xr_list.l_recs[], while keeping the
FAM and the start of MEMBER aligned.

The static_assert() ensures this alignment remains, and it's
intentionally placed inmediately after the related structure --no
blank line in between.

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 fs/ocfs2/xattr.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index d70a20d29e3e..09069defd7e1 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -49,9 +49,13 @@
 #include "ocfs2_trace.h"
 
 struct ocfs2_xattr_def_value_root {
-	struct ocfs2_xattr_value_root	xv;
-	struct ocfs2_extent_rec		er;
+	/* Must be last as it ends in a flexible-array member. */
+	TRAILING_OVERLAP(struct ocfs2_xattr_value_root, xv, xr_list.l_recs,
+		struct ocfs2_extent_rec		er;
+	);
 };
+static_assert(offsetof(struct ocfs2_xattr_def_value_root, xv.xr_list.l_recs) ==
+	      offsetof(struct ocfs2_xattr_def_value_root, er));
 
 struct ocfs2_xattr_bucket {
 	/* The inode these xattrs are associated with */
-- 
2.43.0

Re: [PATCH][next] ocfs2: Avoid -Wflex-array-member-not-at-end warning

Posted by Heming Zhao 2 months, 3 weeks ago

On Tue, Nov 11, 2025 at 12:01:19PM +0900, Gustavo A. R. Silva wrote:
> -Wflex-array-member-not-at-end was introduced in GCC-14, and we are
> getting ready to enable it, globally.
> 
> Use the new TRAILING_OVERLAP() helper to fix the following warning:
> 
> fs/ocfs2/xattr.c:52:41: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
> 
> This helper creates a union between a flexible-array member (FAM) and a
> set of MEMBERS that would otherwise follow it.
> 
> This overlays the trailing MEMBER struct ocfs2_extent_rec er; onto the
> FAM struct ocfs2_xattr_value_root::xr_list.l_recs[], while keeping the
> FAM and the start of MEMBER aligned.
> 
> The static_assert() ensures this alignment remains, and it's
> intentionally placed inmediately after the related structure --no
> blank line in between.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

LGTM.
Reviewed-by: Heming Zhao <heming.zhao@suse.com>

> ---
>  fs/ocfs2/xattr.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
> index d70a20d29e3e..09069defd7e1 100644
> --- a/fs/ocfs2/xattr.c
> +++ b/fs/ocfs2/xattr.c
> @@ -49,9 +49,13 @@
>  #include "ocfs2_trace.h"
>  
>  struct ocfs2_xattr_def_value_root {
> -	struct ocfs2_xattr_value_root	xv;
> -	struct ocfs2_extent_rec		er;
> +	/* Must be last as it ends in a flexible-array member. */
> +	TRAILING_OVERLAP(struct ocfs2_xattr_value_root, xv, xr_list.l_recs,
> +		struct ocfs2_extent_rec		er;
> +	);
>  };
> +static_assert(offsetof(struct ocfs2_xattr_def_value_root, xv.xr_list.l_recs) ==
> +	      offsetof(struct ocfs2_xattr_def_value_root, er));
>  
>  struct ocfs2_xattr_bucket {
>  	/* The inode these xattrs are associated with */
> -- 
> 2.43.0
> 
>

Re: [PATCH][next] ocfs2: Avoid -Wflex-array-member-not-at-end warning

Posted by Joseph Qi 2 months ago


On 2025/11/17 13:32, Heming Zhao wrote:
> On Tue, Nov 11, 2025 at 12:01:19PM +0900, Gustavo A. R. Silva wrote:
>> -Wflex-array-member-not-at-end was introduced in GCC-14, and we are
>> getting ready to enable it, globally.
>>
>> Use the new TRAILING_OVERLAP() helper to fix the following warning:
>>
>> fs/ocfs2/xattr.c:52:41: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
>>
>> This helper creates a union between a flexible-array member (FAM) and a
>> set of MEMBERS that would otherwise follow it.
>>
>> This overlays the trailing MEMBER struct ocfs2_extent_rec er; onto the
>> FAM struct ocfs2_xattr_value_root::xr_list.l_recs[], while keeping the
>> FAM and the start of MEMBER aligned.
>>
>> The static_assert() ensures this alignment remains, and it's
>> intentionally placed inmediately after the related structure --no
>> blank line in between.
>>
>> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> 
> LGTM.
> Reviewed-by: Heming Zhao <heming.zhao@suse.com>
> 

Acked-by: Joseph Qi <joseph.qi@linux.alibaba.com>
>> ---
>>  fs/ocfs2/xattr.c | 8 ++++++--
>>  1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
>> index d70a20d29e3e..09069defd7e1 100644
>> --- a/fs/ocfs2/xattr.c
>> +++ b/fs/ocfs2/xattr.c
>> @@ -49,9 +49,13 @@
>>  #include "ocfs2_trace.h"
>>  
>>  struct ocfs2_xattr_def_value_root {
>> -	struct ocfs2_xattr_value_root	xv;
>> -	struct ocfs2_extent_rec		er;
>> +	/* Must be last as it ends in a flexible-array member. */
>> +	TRAILING_OVERLAP(struct ocfs2_xattr_value_root, xv, xr_list.l_recs,
>> +		struct ocfs2_extent_rec		er;
>> +	);
>>  };
>> +static_assert(offsetof(struct ocfs2_xattr_def_value_root, xv.xr_list.l_recs) ==
>> +	      offsetof(struct ocfs2_xattr_def_value_root, er));
>>  
>>  struct ocfs2_xattr_bucket {
>>  	/* The inode these xattrs are associated with */
>> -- 
>> 2.43.0
>>
>>

Re: [PATCH][next] ocfs2: Avoid -Wflex-array-member-not-at-end warning

Posted by Gustavo A. R. Silva 2 months ago

Hi all,

Friendly ping: who can take this, please? 🙂

Thanks!
-Gustavo

On 11/17/25 14:32, Heming Zhao wrote:
> On Tue, Nov 11, 2025 at 12:01:19PM +0900, Gustavo A. R. Silva wrote:
>> -Wflex-array-member-not-at-end was introduced in GCC-14, and we are
>> getting ready to enable it, globally.
>>
>> Use the new TRAILING_OVERLAP() helper to fix the following warning:
>>
>> fs/ocfs2/xattr.c:52:41: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
>>
>> This helper creates a union between a flexible-array member (FAM) and a
>> set of MEMBERS that would otherwise follow it.
>>
>> This overlays the trailing MEMBER struct ocfs2_extent_rec er; onto the
>> FAM struct ocfs2_xattr_value_root::xr_list.l_recs[], while keeping the
>> FAM and the start of MEMBER aligned.
>>
>> The static_assert() ensures this alignment remains, and it's
>> intentionally placed inmediately after the related structure --no
>> blank line in between.
>>
>> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> 
> LGTM.
> Reviewed-by: Heming Zhao <heming.zhao@suse.com>
> 
>> ---
>>   fs/ocfs2/xattr.c | 8 ++++++--
>>   1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
>> index d70a20d29e3e..09069defd7e1 100644
>> --- a/fs/ocfs2/xattr.c
>> +++ b/fs/ocfs2/xattr.c
>> @@ -49,9 +49,13 @@
>>   #include "ocfs2_trace.h"
>>   
>>   struct ocfs2_xattr_def_value_root {
>> -	struct ocfs2_xattr_value_root	xv;
>> -	struct ocfs2_extent_rec		er;
>> +	/* Must be last as it ends in a flexible-array member. */
>> +	TRAILING_OVERLAP(struct ocfs2_xattr_value_root, xv, xr_list.l_recs,
>> +		struct ocfs2_extent_rec		er;
>> +	);
>>   };
>> +static_assert(offsetof(struct ocfs2_xattr_def_value_root, xv.xr_list.l_recs) ==
>> +	      offsetof(struct ocfs2_xattr_def_value_root, er));
>>   
>>   struct ocfs2_xattr_bucket {
>>   	/* The inode these xattrs are associated with */
>> -- 
>> 2.43.0
>>
>>
>

Re: [PATCH][next] ocfs2: Avoid -Wflex-array-member-not-at-end warning

Posted by Gustavo A. R. Silva 2 months, 3 weeks ago


On 11/17/25 14:32, Heming Zhao wrote:
> On Tue, Nov 11, 2025 at 12:01:19PM +0900, Gustavo A. R. Silva wrote:
>> -Wflex-array-member-not-at-end was introduced in GCC-14, and we are
>> getting ready to enable it, globally.
>>
>> Use the new TRAILING_OVERLAP() helper to fix the following warning:
>>
>> fs/ocfs2/xattr.c:52:41: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
>>
>> This helper creates a union between a flexible-array member (FAM) and a
>> set of MEMBERS that would otherwise follow it.
>>
>> This overlays the trailing MEMBER struct ocfs2_extent_rec er; onto the
>> FAM struct ocfs2_xattr_value_root::xr_list.l_recs[], while keeping the
>> FAM and the start of MEMBER aligned.
>>
>> The static_assert() ensures this alignment remains, and it's
>> intentionally placed inmediately after the related structure --no
>> blank line in between.
>>
>> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> 
> LGTM.
> Reviewed-by: Heming Zhao <heming.zhao@suse.com>

Thanks, Heming.

-Gustavo