On Thu, Oct 12, 2023 at 07:17:13AM +0200, Christoph Hellwig wrote:
> On Wed, Oct 11, 2023 at 11:05:27AM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@xxxxxxxxxx>
> >
> > Create helpers to do unit conversions of rt block numbers to rt extent
> > numbers. There are two variations -- the suffix "t" denotes the one
> > that returns only the truncated extent number; the other one also
> > returns the misalignment. Convert all the div_u64_rem users; we'll do
> > the do_div users in the next patch.
>
> When trying to work with thee helpers I found the t prefix here a bit
> weird, as it works different than the T in say XFS_B_TO_FSB
> vs XFS_B_TO_FSBT which give you different results for the two versions.
> Here we get the same returned result, just with the additional
> return for the remainder.
>
> Maybe have xfs_rtb_to_rtx and xfs_rtb_to_rtx_rem for the version with
> the modulo?
<nod> I've decided to go with:
/* Convert an rt block number into an rt extent number. */
static inline xfs_rtxnum_t
xfs_rtb_to_rtx(
struct xfs_mount *mp,
xfs_rtblock_t rtbno)
{
return div_u64(rtbno, mp->m_sb.sb_rextsize);
}
/* Return the offset of an rt block number within an rt extent. */
static inline xfs_extlen_t
xfs_rtb_to_rtxoff(
struct xfs_mount *mp,
xfs_rtblock_t rtbno)
{
return do_div(rtbno, mp->m_sb.sb_rextsize);
}
/*
* Crack an rt block number into an rt extent number and an offset within that
* rt extent. Returns the rt extent number directly and the offset in @off.
*/
static inline xfs_rtxnum_t
xfs_rtb_to_rtxrem(
struct xfs_mount *mp,
xfs_rtblock_t rtbno,
xfs_extlen_t *off)
{
return div_u64_rem(rtbno, mp->m_sb.sb_rextsize, off);
}
> We also have quite a few places that only care about the mod,
> so an additƣonal xfs_rtb_rem/mod might be useful as well.
Agreed, I had noticed that there were a fair number of places where
we're really only checking for rtx alignment. xfs_rtb_to_rtxoff is
the new helper.
--D
