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bcachefs: Add a shrinker for the btree key cache

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Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2020-11-12 17:19:47 -05:00 committed by Kent Overstreet
parent 876c7af3a6
commit 628a3ad2c2
2 changed files with 90 additions and 5 deletions
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93
fs/bcachefs/btree_key_cache.c
View file

@ -10,6 +10,8 @@
#include "journal_reclaim.h"
#include "trace.h"
#include <linux/sched/mm.h>
static int bch2_btree_key_cache_cmp_fn(struct rhashtable_compare_arg *arg,
const void *obj)
{
@ -69,10 +71,15 @@ static void bkey_cached_evict(struct btree_key_cache *c,
c->nr_keys--;
}
static void bkey_cached_free(struct btree_key_cache *c,
static void bkey_cached_free(struct btree_key_cache *bc,
struct bkey_cached *ck)
{
list_move(&ck->list, &c->freed);
struct bch_fs *c = container_of(bc, struct bch_fs, btree_key_cache);
ck->btree_trans_barrier_seq =
start_poll_synchronize_srcu(&c->btree_trans_barrier);
list_move(&ck->list, &bc->freed);
kfree(ck->k);
ck->k = NULL;
@ -404,19 +411,23 @@ static void btree_key_cache_journal_flush(struct journal *j,
struct bkey_cached_key key;
struct btree_trans trans;
int srcu_idx = srcu_read_lock(&c->btree_trans_barrier);
six_lock_read(&ck->c.lock, NULL, NULL);
key = ck->key;
if (ck->journal.seq != seq ||
!test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
six_unlock_read(&ck->c.lock);
return;
goto unlock;
}
six_unlock_read(&ck->c.lock);
bch2_trans_init(&trans, c, 0, 0);
btree_key_cache_flush_pos(&trans, key, seq, false);
bch2_trans_exit(&trans);
unlock:
srcu_read_unlock(&c->btree_trans_barrier, srcu_idx);
}
/*
@ -481,11 +492,77 @@ void bch2_btree_key_cache_verify_clean(struct btree_trans *trans,
}
#endif
static unsigned long bch2_btree_key_cache_scan(struct shrinker *shrink,
struct shrink_control *sc)
{
struct bch_fs *c = container_of(shrink, struct bch_fs,
btree_key_cache.shrink);
struct btree_key_cache *bc = &c->btree_key_cache;
struct bkey_cached *ck, *t;
size_t scanned = 0, freed = 0, nr = sc->nr_to_scan;
unsigned flags;
/* Return -1 if we can't do anything right now */
if (sc->gfp_mask & __GFP_FS)
mutex_lock(&bc->lock);
else if (!mutex_trylock(&bc->lock))
return -1;
flags = memalloc_nofs_save();
list_for_each_entry_safe(ck, t, &bc->freed, list) {
scanned++;
if (poll_state_synchronize_srcu(&c->btree_trans_barrier,
ck->btree_trans_barrier_seq)) {
list_del(&ck->list);
kfree(ck);
freed++;
}
if (scanned >= nr)
goto out;
}
list_for_each_entry_safe(ck, t, &bc->clean, list) {
scanned++;
if (bkey_cached_lock_for_evict(ck)) {
bkey_cached_evict(bc, ck);
bkey_cached_free(bc, ck);
}
if (scanned >= nr) {
if (&t->list != &bc->clean)
list_move_tail(&bc->clean, &t->list);
goto out;
}
}
out:
memalloc_nofs_restore(flags);
mutex_unlock(&bc->lock);
return freed;
}
static unsigned long bch2_btree_key_cache_count(struct shrinker *shrink,
struct shrink_control *sc)
{
struct bch_fs *c = container_of(shrink, struct bch_fs,
btree_key_cache.shrink);
struct btree_key_cache *bc = &c->btree_key_cache;
return bc->nr_keys;
}
void bch2_fs_btree_key_cache_exit(struct btree_key_cache *bc)
{
struct bch_fs *c = container_of(bc, struct bch_fs, btree_key_cache);
struct bkey_cached *ck, *n;
if (bc->shrink.list.next)
unregister_shrinker(&bc->shrink);
mutex_lock(&bc->lock);
list_splice(&bc->dirty, &bc->clean);
@ -516,9 +593,15 @@ void bch2_fs_btree_key_cache_init_early(struct btree_key_cache *c)
INIT_LIST_HEAD(&c->dirty);
}
int bch2_fs_btree_key_cache_init(struct btree_key_cache *c)
int bch2_fs_btree_key_cache_init(struct btree_key_cache *bc)
{
return rhashtable_init(&c->table, &bch2_btree_key_cache_params);
struct bch_fs *c = container_of(bc, struct bch_fs, btree_key_cache);
bc->shrink.count_objects = bch2_btree_key_cache_count;
bc->shrink.scan_objects = bch2_btree_key_cache_scan;
return register_shrinker(&bc->shrink, "%s/btree_key_cache", c->name) ?:
rhashtable_init(&bc->table, &bch2_btree_key_cache_params);
}
void bch2_btree_key_cache_to_text(struct printbuf *out, struct btree_key_cache *c)

2
fs/bcachefs/btree_types.h
View file

@ -296,6 +296,7 @@ struct btree_key_cache {
struct list_head freed;
struct list_head clean;
struct list_head dirty;
struct shrinker shrink;
size_t nr_keys;
size_t nr_dirty;
@ -314,6 +315,7 @@ struct bkey_cached {
unsigned long flags;
u8 u64s;
bool valid;
u32 btree_trans_barrier_seq;
struct bkey_cached_key key;
struct rhash_head hash;