Messages in this thread | | | Date | Wed, 26 Jul 2023 15:32:10 +0800 | Subject | Re: [PATCH v2 28/47] bcache: dynamically allocate the md-bcache shrinker | From | Muchun Song <> |
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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.
> + } > + > + 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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