Re: [PATCH v7 10/11] xfs: make the calculation generic in xfs_sb_validate_fsb_count()

[Christoph Hellwig]

> +	uint64_t		max_index;
> +	uint64_t		max_bytes;
> +
>  	ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
>  	ASSERT(sbp->sb_blocklog >= BBSHIFT);
>  
> +	if (check_shl_overflow(nblocks, sbp->sb_blocklog, &max_bytes))
> +		return -EFBIG;
> +
>  	/* Limited by ULONG_MAX of page cache index */
> -	if (nblocks >> (PAGE_SHIFT - sbp->sb_blocklog) > ULONG_MAX)
> +	max_index = max_bytes >> PAGE_SHIFT;
> +
> +	if (max_index > ULONG_MAX)

Do we really need the max_index variable for a single user here?
Or do you plan to add more uses of it later (can't really think of one
though)?