bcache: fix using of loop variable in memory shrink (ca71df31) · Commits · 戴 / test

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>

drivers/md/bcache/btree.c

+6 −3

Original line number	Diff line number	Diff line
		@@ -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;

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