On 22/04/2025 13:42, cem@xxxxxxxxxx wrote:
> From: Carlos Maiolino <cem@xxxxxxxxxx>
>
> xfs_zoned_need_gc makes use of mult_frac() to calculate the threshold
> for triggering the zoned garbage collector, but, turns out mult_frac()
> doesn't properly work with 64-bit data types and this caused build
> failures on some 32-bit architectures.
>
> Fix this by essentially open coding mult_frac() in a 64-bit friendly
> way.
>
> Notice we don't need to bother with counters underflow here because
> xfs_estimate_freecounter() will always return a positive value, as it
> leverages percpu_counter_read_positive to read such counters.
>
> Fixes: 845abeb1f06a ("xfs: add tunable threshold parameter for triggering zone GC")
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Closes: https://lore.kernel.org/oe-kbuild-all/202504181233.F7D9Atra-lkp@xxxxxxxxx/
> Signed-off-by: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
> ---
>
> fs/xfs/xfs_zone_gc.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_zone_gc.c b/fs/xfs/xfs_zone_gc.c
> index 8c541ca71872..b0e8915ef733 100644
> --- a/fs/xfs/xfs_zone_gc.c
> +++ b/fs/xfs/xfs_zone_gc.c
> @@ -171,6 +171,7 @@ xfs_zoned_need_gc(
> struct xfs_mount *mp)
> {
> s64 available, free;
> + s32 threshold, remainder;
>
> if (!xfs_group_marked(mp, XG_TYPE_RTG, XFS_RTG_RECLAIMABLE))
> return false;
> @@ -183,7 +184,12 @@ xfs_zoned_need_gc(
> return true;
>
> free = xfs_estimate_freecounter(mp, XC_FREE_RTEXTENTS);
> - if (available < mult_frac(free, mp->m_zonegc_low_space, 100))
> +
> + threshold = div_s64_rem(free, 100, &remainder);
Hmm, shouldn't threshold be a s64?
> + threshold = threshold * mp->m_zonegc_low_space +
> + remainder * div_s64(mp->m_zonegc_low_space, 100);
> +
> + if (available < threshold)
> return true;
>
> return false;
