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authorTang Junhui <tang.junhui@zte.com.cn>2018-03-18 17:36:22 -0700
committerJens Axboe <axboe@kernel.dk>2018-03-18 20:15:20 -0600
commitca71df31661a0518ed58a1a59cf1993962153ebb (patch)
treeb1804803052dbad87886ce0284a93369fa915f7a /drivers/md
parentf3641c3abd1da978ee969b0203b71b86ec1bfa93 (diff)
downloadlinux-ca71df31661a0518ed58a1a59cf1993962153ebb.tar.bz2
bcache: fix using of loop variable in memory shrink
In bch_mca_scan(), There are some confusion and logical error in the use of loop variables. In this patch, we clarify them as: 1) nr: the number of btree nodes needs to scan, which will decrease after we scan a btree node, and should not be less than 0; 2) i: the number of btree nodes have scanned, includes both btree_cache_freeable and btree_cache, which should not be bigger than btree_cache_used; 3) freed: the number of btree nodes have freed. Signed-off-by: Tang Junhui <tang.junhui@zte.com.cn> Reviewed-by: Michael Lyle <mlyle@lyle.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/bcache/btree.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index b2d4899f48d5..d64aff0b8abc 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -665,6 +665,7 @@ static unsigned long bch_mca_scan(struct shrinker *shrink,
struct btree *b, *t;
unsigned long i, nr = sc->nr_to_scan;
unsigned long freed = 0;
+ unsigned int btree_cache_used;
if (c->shrinker_disabled)
return SHRINK_STOP;
@@ -689,9 +690,10 @@ static unsigned long bch_mca_scan(struct shrinker *shrink,
nr = min_t(unsigned long, nr, mca_can_free(c));
i = 0;
+ btree_cache_used = c->btree_cache_used;
list_for_each_entry_safe(b, t, &c->btree_cache_freeable, list) {
- if (freed >= nr)
- break;
+ if (nr <= 0)
+ goto out;
if (++i > 3 &&
!mca_reap(b, 0, false)) {
@@ -699,9 +701,10 @@ static unsigned long bch_mca_scan(struct shrinker *shrink,
rw_unlock(true, b);
freed++;
}
+ nr--;
}
- for (i = 0; (nr--) && i < c->btree_cache_used; i++) {
+ for (; (nr--) && i < btree_cache_used; i++) {
if (list_empty(&c->btree_cache))
goto out;