[PATCH] fs: Replace offsetof() with struct_size() in ioctl_file_dedupe_range()

[PATCH] fs: Replace offsetof() with struct_size() in ioctl_file_dedupe_range()

[Xichao Zhao]

When dealing with structures containing flexible arrays, struct_size()
provides additional compile-time checks compared to offsetof(). This
enhances code robustness and reduces the risk of potential errors.

Signed-off-by: Xichao Zhao <zhao.xichao@vivo.com>
---
 fs/ioctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ioctl.c b/fs/ioctl.c
index 0248cb8db2d3..83d07218b6cd 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -426,7 +426,7 @@ static int ioctl_file_dedupe_range(struct file *file,
 		goto out;
 	}
 
-	size = offsetof(struct file_dedupe_range, info[count]);
+	size = struct_size(same, info, count);
 	if (size > PAGE_SIZE) {
 		ret = -ENOMEM;
 		goto out;
-- 
2.34.1

Re: [PATCH] fs: Replace offsetof() with struct_size() in ioctl_file_dedupe_range()

[Jan Kara]

On Fri 29-08-25 17:15:10, Xichao Zhao wrote:
> When dealing with structures containing flexible arrays, struct_size()
> provides additional compile-time checks compared to offsetof(). This
> enhances code robustness and reduces the risk of potential errors.
> 
> Signed-off-by: Xichao Zhao <zhao.xichao@vivo.com>

Indeed. Also with struct_size() it is more obvious what was the intention.
Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/ioctl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ioctl.c b/fs/ioctl.c
> index 0248cb8db2d3..83d07218b6cd 100644
> --- a/fs/ioctl.c
> +++ b/fs/ioctl.c
> @@ -426,7 +426,7 @@ static int ioctl_file_dedupe_range(struct file *file,
>  		goto out;
>  	}
>  
> -	size = offsetof(struct file_dedupe_range, info[count]);
> +	size = struct_size(same, info, count);
>  	if (size > PAGE_SIZE) {
>  		ret = -ENOMEM;
>  		goto out;
> -- 
> 2.34.1
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH] fs: Replace offsetof() with struct_size() in ioctl_file_dedupe_range()

[Christian Brauner]

On Fri, 29 Aug 2025 17:15:10 +0800, Xichao Zhao wrote:
> When dealing with structures containing flexible arrays, struct_size()
> provides additional compile-time checks compared to offsetof(). This
> enhances code robustness and reduces the risk of potential errors.
> 
> 

Applied to the vfs-6.18.misc branch of the vfs/vfs.git tree.
Patches in the vfs-6.18.misc branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs-6.18.misc

[1/1] fs: Replace offsetof() with struct_size() in ioctl_file_dedupe_range()
      https://git.kernel.org/vfs/vfs/c/38d1227fa71d