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Subject[PATCH 1/2] f2fs: fix wrong calculation of block age
Date
Currently we wrongly calculate the new block age to
old * LAST_AGE_WEIGHT / 100.

Fix it to new * (100 - LAST_AGE_WEIGHT) / 100
+ old * LAST_AGE_WEIGHT / 100.

Signed-off-by: qixiaoyu1 <qixiaoyu1@xiaomi.com>
---
fs/f2fs/extent_cache.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
index 342af24b2f8c..93a1ab186517 100644
--- a/fs/f2fs/extent_cache.c
+++ b/fs/f2fs/extent_cache.c
@@ -874,11 +874,7 @@ void f2fs_update_read_extent_tree_range_compressed(struct inode *inode,
static unsigned long long __calculate_block_age(unsigned long long new,
unsigned long long old)
{
- unsigned long long diff;
-
- diff = (new >= old) ? new - (new - old) : new + (old - new);
-
- return div_u64(diff * LAST_AGE_WEIGHT, 100);
+ return new - new / 100 * LAST_AGE_WEIGHT + old / 100 * LAST_AGE_WEIGHT;
}

/* This returns a new age and allocated blocks in ei */
--
2.36.1
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