Re: [PATCH] xfs: use kmalloc_array() instead of kmalloc() for map allocation

[Nirjhar Roy (IBM)]

On Sat, 2025-10-18 at 19:45 +0000, Kriish Sharma wrote:
> Using kmalloc_array() better reflects the intent to allocate an array of
> map entries, and improves consistency with similar allocations across the
> kernel.
> 
> No functional change intended.
> 
> Signed-off-by: Kriish Sharma <kriish.sharma2006@xxxxxxxxx>
> ---
>  fs/xfs/xfs_qm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
> index 23ba84ec919a..34ec61e455ff 100644
> --- a/fs/xfs/xfs_qm.c
> +++ b/fs/xfs/xfs_qm.c
> @@ -1218,7 +1218,7 @@ xfs_qm_reset_dqcounts_buf(
>  	if (qip->i_nblocks == 0)
>  		return 0;
>  
> -	map = kmalloc(XFS_DQITER_MAP_SIZE * sizeof(*map),
> +	map = kmalloc_array(XFS_DQITER_MAP_SIZE, sizeof(*map),
>  			GFP_KERNEL | __GFP_NOFAIL);
I think kmalloc_array is more useful when the size of memory to be allocated is dynamic with
kmalloc_array doing some additional checks on the size that is being passed. In this case, both
XFS_QUITER_MAP_SIZE  and sizeof(*map) are constant i.e, we are allocating constant size memory, so
maybe this isn't quite necessary?

Definition of kmalloc_array()

static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
{
	if (size != 0 && n > SIZE_MAX / size)
		return NULL;
	return kmalloc(n * size, flags);
}


--NR
>  
>  	lblkno = 0;