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| author |   Chen Wandun <chenwandun@huawei.com> | 2022-04-28 23:15:57 -0700 |
|---|---|---|
| committer |   akpm <akpm@linux-foundation.org> | 2022-04-28 23:15:57 -0700 |
| commit | 21f0dd88f23dc9dc46b781f8ec9acf975dca4e6e (patch) | |
| tree | 8c9d6dc292a5720ebf79856a45db17059901148b | |
| parent | tools/vm/page_owner_sort.c: avoid repeated judgments (diff) | |
| download | linux-dev-21f0dd88f23dc9dc46b781f8ec9acf975dca4e6e.tar.xz linux-dev-21f0dd88f23dc9dc46b781f8ec9acf975dca4e6e.zip | |
mm: rework calculation of bdi_min_ratio in bdi_set_min_ratio
In function bdi_set_min_ratio, min_ratio is unsigned int, it will
result underflow when setting min_ratio below bdi->min_ratio, it
is confusing. Rework it, no functional change.
Link: https://lkml.kernel.org/r/20220422095159.2858305-1-chenwandun@huawei.com
Signed-off-by: Chen Wandun <chenwandun@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | mm/page-writeback.c | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 7e2da284e427..9f459f7f8f83 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -650,18 +650,25 @@ static unsigned int bdi_min_ratio; int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) { + unsigned int delta; int ret = 0; spin_lock_bh(&bdi_lock); if (min_ratio > bdi->max_ratio) { ret = -EINVAL; } else { - min_ratio -= bdi->min_ratio; - if (bdi_min_ratio + min_ratio < 100) { - bdi_min_ratio += min_ratio; - bdi->min_ratio += min_ratio; + if (min_ratio < bdi->min_ratio) { + delta = bdi->min_ratio - min_ratio; + bdi_min_ratio -= delta; + bdi->min_ratio = min_ratio; } else { - ret = -EINVAL; + delta = min_ratio - bdi->min_ratio; + if (bdi_min_ratio + delta < 100) { + bdi_min_ratio += delta; + bdi->min_ratio = min_ratio; + } else { + ret = -EINVAL; + } } } spin_unlock_bh(&bdi_lock); |