Re: [PATCH 5/8] rpdfs: add basic file data initialization

On Fri, Apr 24, 2026 at 04:05:17PM +0200, Valerie Aurora wrote:
> Initialize the file data root, plus a few simple routines to calculate
> mapping block levels. Rename the field in the inode from "data" to
> "data_root" to avoid confusion with the "data" member of struct
> rpdfs_block_handle.

> +/*
> + * Calculate the index of the block reference for this logical block
> + * within an mapping block at this level (1 = pointers to data blocks).
> + */
> +static u32 calc_ref_ind(u64 lblk, int level)
> +{
> +	u32 ind;
> +	int i;
> +
> +	BUG_ON(level < 1);
> +
> +	for (i = 1; i < level; i++)
> +		lblk >>= RPDFS_DATA_REFS_PER_BLK_SHIFT;
> +
> +	ind = lblk & (RPDFS_DATA_REFS_PER_BLK - 1ULL);

This could be a much smaller ">> ((level - 1) * shift) & mask".  And
let's have a specific _MASK define instead of the -1 by hand.

> +static u8 height_from_lblk(u64 lblk)
> +{
> +	u8 height = 2;
> +
> +	if (lblk == 0)
> +		return 1;
> +
> +	while (lblk >>= RPDFS_DATA_REFS_PER_BLK_SHIFT)
> +		height++;
> +
> +	return height;

Similarly, this could be something involving "fls() / _SHIFT" while being
careful with the various +1/-1 fenceposts.

- z