linux-kernel - Re: [PATCH v2] btrfs: Refactor allocation size calculation in kzalloc()

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Message-ID: <7d0f9cd6-77a5-41e1-82fd-4641d149bfda@gmx.com>
Date: Tue, 30 Sep 2025 19:39:49 +0930
From: Qu Wenruo <quwenruo.btrfs@....com>
To: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@...il.com>, clm@...com,
 dsterba@...e.com
Cc: linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-kernel-mentees@...ts.linuxfoundation.org, skhan@...uxfoundation.org,
 david.hunter.linux@...il.com
Subject: Re: [PATCH v2] btrfs: Refactor allocation size calculation in
 kzalloc()



在 2025/9/30 19:33, Mehdi Ben Hadj Khelifa 写道:
> Wrap allocation size calculation in struct_size() to
> avoid potential overflows.

I don't think it's really about overflow or whatever, just pure code 
refactor to make it more structured/easier to read.

You don't need to send out a v3, we can handle it at merge time.

> 
> Signed-off-by: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@...il.com>

Otherwise it looks good to me.

Reviewed-by: Qu Wenruo <wqu@...e.com>

Thanks,
Qu
> ---
> Changelog:
> 
> Changes since v1:
> 
> -Use of struct_size() instead of size_add() and size_mul()
> Link:https://lore.kernel.org/linux-btrfs/342929a3-ac5f-4953-a763-b81c60e66554@gmail.com/T/#mbe2932fec1a56e7db21bc8a3d1f1271a2c1422d7
> 
>   fs/btrfs/volumes.c | 7 +------
>   1 file changed, 1 insertion(+), 6 deletions(-)
> 
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index c6e3efd6f602..d349d0b180ac 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -6076,12 +6076,7 @@ struct btrfs_io_context *alloc_btrfs_io_context(struct btrfs_fs_info *fs_info,
>   {
>   	struct btrfs_io_context *bioc;
>   
> -	bioc = kzalloc(
> -		 /* The size of btrfs_io_context */
> -		sizeof(struct btrfs_io_context) +
> -		/* Plus the variable array for the stripes */
> -		sizeof(struct btrfs_io_stripe) * (total_stripes),
> -		GFP_NOFS);
> +	bioc = kzalloc(struct_size(bioc, stripes, total_stripes), GFP_NOFS);
>   
>   	if (!bioc)
>   		return NULL;