Messages in this thread | | | Date | Wed, 26 Jul 2023 17:33:36 +0800 | Subject | Re: [PATCH v2 28/47] bcache: dynamically allocate the md-bcache shrinker | From | Qi Zheng <> |
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On 2023/7/26 15:32, Muchun Song wrote: > > > On 2023/7/24 17:43, Qi Zheng wrote: >> In preparation for implementing lockless slab shrink, use new APIs to >> dynamically allocate the md-bcache shrinker, so that it can be freed >> asynchronously using kfree_rcu(). Then it doesn't need to wait for RCU >> read-side critical section when releasing the struct cache_set. >> >> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> >> --- >> drivers/md/bcache/bcache.h | 2 +- >> drivers/md/bcache/btree.c | 27 ++++++++++++++++----------- >> drivers/md/bcache/sysfs.c | 3 ++- >> 3 files changed, 19 insertions(+), 13 deletions(-) >> >> diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h >> index 5a79bb3c272f..c622bc50f81b 100644 >> --- a/drivers/md/bcache/bcache.h >> +++ b/drivers/md/bcache/bcache.h >> @@ -541,7 +541,7 @@ struct cache_set { >> struct bio_set bio_split; >> /* For the btree cache */ >> - struct shrinker shrink; >> + struct shrinker *shrink; >> /* For the btree cache and anything allocation related */ >> struct mutex bucket_lock; >> diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c >> index fd121a61f17c..c176c7fc77d9 100644 >> --- a/drivers/md/bcache/btree.c >> +++ b/drivers/md/bcache/btree.c >> @@ -667,7 +667,7 @@ static int mca_reap(struct btree *b, unsigned int >> min_order, bool flush) >> static unsigned long bch_mca_scan(struct shrinker *shrink, >> struct shrink_control *sc) >> { >> - struct cache_set *c = container_of(shrink, struct cache_set, >> shrink); >> + struct cache_set *c = shrink->private_data; >> struct btree *b, *t; >> unsigned long i, nr = sc->nr_to_scan; >> unsigned long freed = 0; >> @@ -734,7 +734,7 @@ static unsigned long bch_mca_scan(struct shrinker >> *shrink, >> static unsigned long bch_mca_count(struct shrinker *shrink, >> struct shrink_control *sc) >> { >> - struct cache_set *c = container_of(shrink, struct cache_set, >> shrink); >> + struct cache_set *c = shrink->private_data; >> if (c->shrinker_disabled) >> return 0; >> @@ -752,8 +752,8 @@ void bch_btree_cache_free(struct cache_set *c) >> closure_init_stack(&cl); >> - if (c->shrink.list.next) >> - unregister_shrinker(&c->shrink); >> + if (c->shrink) >> + shrinker_unregister(c->shrink); >> mutex_lock(&c->bucket_lock); >> @@ -828,14 +828,19 @@ int bch_btree_cache_alloc(struct cache_set *c) >> c->verify_data = NULL; >> #endif >> - c->shrink.count_objects = bch_mca_count; >> - c->shrink.scan_objects = bch_mca_scan; >> - c->shrink.seeks = 4; >> - c->shrink.batch = c->btree_pages * 2; >> + c->shrink = shrinker_alloc(0, "md-bcache:%pU", c->set_uuid); >> + if (!c->shrink) { >> + pr_warn("bcache: %s: could not allocate shrinker\n", __func__); >> + return -ENOMEM; > > Seems you have cheanged the semantic of this. In the past, > it is better to have a shrinker, but now it becomes a mandatory. > Right? I don't know if it is acceptable. From my point of view, > just do the cleanup, don't change any behaviour.
Oh, should return 0 here, will do.
> >> + } >> + >> + c->shrink->count_objects = bch_mca_count; >> + c->shrink->scan_objects = bch_mca_scan; >> + c->shrink->seeks = 4; >> + c->shrink->batch = c->btree_pages * 2; >> + c->shrink->private_data = c; >> - if (register_shrinker(&c->shrink, "md-bcache:%pU", c->set_uuid)) >> - pr_warn("bcache: %s: could not register shrinker\n", >> - __func__); >> + shrinker_register(c->shrink); >> return 0; >> } >> diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c >> index 0e2c1880f60b..45d8af755de6 100644 >> --- a/drivers/md/bcache/sysfs.c >> +++ b/drivers/md/bcache/sysfs.c >> @@ -866,7 +866,8 @@ STORE(__bch_cache_set) >> sc.gfp_mask = GFP_KERNEL; >> sc.nr_to_scan = strtoul_or_return(buf); >> - c->shrink.scan_objects(&c->shrink, &sc); >> + if (c->shrink) >> + c->shrink->scan_objects(c->shrink, &sc); >> } >> sysfs_strtoul_clamp(congested_read_threshold_us, >
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