btrfs: simplify percent calculation helpers, rename div_factor

The div_factor* helpers calculate fraction or percentage fraction. The
name is a bit confusing, we use it only for percentage calculations and
there are two helpers.

There's a helper mult_frac that's for general fractions, that tries to
be accurate but we multiply and divide by small numbers so we can use
the div_u64 helper.

Rename the div_factor* helpers and use 1..100 percentage range, also drop
the case checking for percentage == 100, it's never hit.

The conversions:

* div_factor calculates tenths and the numbers need to be adjusted
* div_factor_fine is direct replacement

Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 11e5b5a1eb5a..d28ee4e36f3d 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -859,7 +859,7 @@ static bool need_preemptive_reclaim(struct btrfs_fs_info *fs_info,
 	u64 thresh;
 	u64 used;
 
-	thresh = div_factor_fine(total, 90);
+	thresh = mult_perc(total, 90);
 
 	lockdep_assert_held(&space_info->lock);
 
@@ -977,7 +977,7 @@ static bool steal_from_global_rsv(struct btrfs_fs_info *fs_info,
 		return false;
 
 	spin_lock(&global_rsv->lock);
-	min_bytes = div_factor(global_rsv->size, 1);
+	min_bytes = mult_perc(global_rsv->size, 10);
 	if (global_rsv->reserved < min_bytes + ticket->bytes) {
 		spin_unlock(&global_rsv->lock);
 		return false;