linux/fs/bcachefs/btree_key_cache.c
Kent Overstreet be9e782df3 bcachefs: Don't downgrade locks on transaction restart
We should only be downgrading locks on success - otherwise, our
transaction restarts won't be getting the correct locks and we'll
livelock.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-11-01 21:11:08 -04:00

1073 lines
26 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include "bcachefs.h"
#include "btree_cache.h"
#include "btree_iter.h"
#include "btree_key_cache.h"
#include "btree_locking.h"
#include "btree_update.h"
#include "errcode.h"
#include "error.h"
#include "journal.h"
#include "journal_reclaim.h"
#include "trace.h"
#include <linux/sched/mm.h>
static inline bool btree_uses_pcpu_readers(enum btree_id id)
{
return id == BTREE_ID_subvolumes;
}
static struct kmem_cache *bch2_key_cache;
static int bch2_btree_key_cache_cmp_fn(struct rhashtable_compare_arg *arg,
const void *obj)
{
const struct bkey_cached *ck = obj;
const struct bkey_cached_key *key = arg->key;
return ck->key.btree_id != key->btree_id ||
!bpos_eq(ck->key.pos, key->pos);
}
static const struct rhashtable_params bch2_btree_key_cache_params = {
.head_offset = offsetof(struct bkey_cached, hash),
.key_offset = offsetof(struct bkey_cached, key),
.key_len = sizeof(struct bkey_cached_key),
.obj_cmpfn = bch2_btree_key_cache_cmp_fn,
};
__flatten
inline struct bkey_cached *
bch2_btree_key_cache_find(struct bch_fs *c, enum btree_id btree_id, struct bpos pos)
{
struct bkey_cached_key key = {
.btree_id = btree_id,
.pos = pos,
};
return rhashtable_lookup_fast(&c->btree_key_cache.table, &key,
bch2_btree_key_cache_params);
}
static bool bkey_cached_lock_for_evict(struct bkey_cached *ck)
{
if (!six_trylock_intent(&ck->c.lock))
return false;
if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
six_unlock_intent(&ck->c.lock);
return false;
}
if (!six_trylock_write(&ck->c.lock)) {
six_unlock_intent(&ck->c.lock);
return false;
}
return true;
}
static void bkey_cached_evict(struct btree_key_cache *c,
struct bkey_cached *ck)
{
BUG_ON(rhashtable_remove_fast(&c->table, &ck->hash,
bch2_btree_key_cache_params));
memset(&ck->key, ~0, sizeof(ck->key));
atomic_long_dec(&c->nr_keys);
}
static void bkey_cached_free(struct btree_key_cache *bc,
struct bkey_cached *ck)
{
struct bch_fs *c = container_of(bc, struct bch_fs, btree_key_cache);
BUG_ON(test_bit(BKEY_CACHED_DIRTY, &ck->flags));
ck->btree_trans_barrier_seq =
start_poll_synchronize_srcu(&c->btree_trans_barrier);
if (ck->c.lock.readers)
list_move_tail(&ck->list, &bc->freed_pcpu);
else
list_move_tail(&ck->list, &bc->freed_nonpcpu);
atomic_long_inc(&bc->nr_freed);
kfree(ck->k);
ck->k = NULL;
ck->u64s = 0;
six_unlock_write(&ck->c.lock);
six_unlock_intent(&ck->c.lock);
}
#ifdef __KERNEL__
static void __bkey_cached_move_to_freelist_ordered(struct btree_key_cache *bc,
struct bkey_cached *ck)
{
struct bkey_cached *pos;
list_for_each_entry_reverse(pos, &bc->freed_nonpcpu, list) {
if (ULONG_CMP_GE(ck->btree_trans_barrier_seq,
pos->btree_trans_barrier_seq)) {
list_move(&ck->list, &pos->list);
return;
}
}
list_move(&ck->list, &bc->freed_nonpcpu);
}
#endif
static void bkey_cached_move_to_freelist(struct btree_key_cache *bc,
struct bkey_cached *ck)
{
BUG_ON(test_bit(BKEY_CACHED_DIRTY, &ck->flags));
if (!ck->c.lock.readers) {
#ifdef __KERNEL__
struct btree_key_cache_freelist *f;
bool freed = false;
preempt_disable();
f = this_cpu_ptr(bc->pcpu_freed);
if (f->nr < ARRAY_SIZE(f->objs)) {
f->objs[f->nr++] = ck;
freed = true;
}
preempt_enable();
if (!freed) {
mutex_lock(&bc->lock);
preempt_disable();
f = this_cpu_ptr(bc->pcpu_freed);
while (f->nr > ARRAY_SIZE(f->objs) / 2) {
struct bkey_cached *ck2 = f->objs[--f->nr];
__bkey_cached_move_to_freelist_ordered(bc, ck2);
}
preempt_enable();
__bkey_cached_move_to_freelist_ordered(bc, ck);
mutex_unlock(&bc->lock);
}
#else
mutex_lock(&bc->lock);
list_move_tail(&ck->list, &bc->freed_nonpcpu);
mutex_unlock(&bc->lock);
#endif
} else {
mutex_lock(&bc->lock);
list_move_tail(&ck->list, &bc->freed_pcpu);
mutex_unlock(&bc->lock);
}
}
static void bkey_cached_free_fast(struct btree_key_cache *bc,
struct bkey_cached *ck)
{
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_del_init(&ck->list);
atomic_long_inc(&bc->nr_freed);
kfree(ck->k);
ck->k = NULL;
ck->u64s = 0;
bkey_cached_move_to_freelist(bc, ck);
six_unlock_write(&ck->c.lock);
six_unlock_intent(&ck->c.lock);
}
static struct bkey_cached *
bkey_cached_alloc(struct btree_trans *trans, struct btree_path *path,
bool *was_new)
{
struct bch_fs *c = trans->c;
struct btree_key_cache *bc = &c->btree_key_cache;
struct bkey_cached *ck = NULL;
bool pcpu_readers = btree_uses_pcpu_readers(path->btree_id);
int ret;
if (!pcpu_readers) {
#ifdef __KERNEL__
struct btree_key_cache_freelist *f;
preempt_disable();
f = this_cpu_ptr(bc->pcpu_freed);
if (f->nr)
ck = f->objs[--f->nr];
preempt_enable();
if (!ck) {
mutex_lock(&bc->lock);
preempt_disable();
f = this_cpu_ptr(bc->pcpu_freed);
while (!list_empty(&bc->freed_nonpcpu) &&
f->nr < ARRAY_SIZE(f->objs) / 2) {
ck = list_last_entry(&bc->freed_nonpcpu, struct bkey_cached, list);
list_del_init(&ck->list);
f->objs[f->nr++] = ck;
}
ck = f->nr ? f->objs[--f->nr] : NULL;
preempt_enable();
mutex_unlock(&bc->lock);
}
#else
mutex_lock(&bc->lock);
if (!list_empty(&bc->freed_nonpcpu)) {
ck = list_last_entry(&bc->freed_nonpcpu, struct bkey_cached, list);
list_del_init(&ck->list);
}
mutex_unlock(&bc->lock);
#endif
} else {
mutex_lock(&bc->lock);
if (!list_empty(&bc->freed_pcpu)) {
ck = list_last_entry(&bc->freed_pcpu, struct bkey_cached, list);
list_del_init(&ck->list);
}
mutex_unlock(&bc->lock);
}
if (ck) {
ret = btree_node_lock_nopath(trans, &ck->c, SIX_LOCK_intent, _THIS_IP_);
if (unlikely(ret)) {
bkey_cached_move_to_freelist(bc, ck);
return ERR_PTR(ret);
}
path->l[0].b = (void *) ck;
path->l[0].lock_seq = six_lock_seq(&ck->c.lock);
mark_btree_node_locked(trans, path, 0, BTREE_NODE_INTENT_LOCKED);
ret = bch2_btree_node_lock_write(trans, path, &ck->c);
if (unlikely(ret)) {
btree_node_unlock(trans, path, 0);
bkey_cached_move_to_freelist(bc, ck);
return ERR_PTR(ret);
}
return ck;
}
ck = allocate_dropping_locks(trans, ret,
kmem_cache_zalloc(bch2_key_cache, _gfp));
if (ret) {
kmem_cache_free(bch2_key_cache, ck);
return ERR_PTR(ret);
}
if (!ck)
return NULL;
INIT_LIST_HEAD(&ck->list);
bch2_btree_lock_init(&ck->c, pcpu_readers ? SIX_LOCK_INIT_PCPU : 0);
ck->c.cached = true;
BUG_ON(!six_trylock_intent(&ck->c.lock));
BUG_ON(!six_trylock_write(&ck->c.lock));
*was_new = true;
return ck;
}
static struct bkey_cached *
bkey_cached_reuse(struct btree_key_cache *c)
{
struct bucket_table *tbl;
struct rhash_head *pos;
struct bkey_cached *ck;
unsigned i;
mutex_lock(&c->lock);
rcu_read_lock();
tbl = rht_dereference_rcu(c->table.tbl, &c->table);
for (i = 0; i < tbl->size; i++)
rht_for_each_entry_rcu(ck, pos, tbl, i, hash) {
if (!test_bit(BKEY_CACHED_DIRTY, &ck->flags) &&
bkey_cached_lock_for_evict(ck)) {
bkey_cached_evict(c, ck);
goto out;
}
}
ck = NULL;
out:
rcu_read_unlock();
mutex_unlock(&c->lock);
return ck;
}
static struct bkey_cached *
btree_key_cache_create(struct btree_trans *trans, struct btree_path *path)
{
struct bch_fs *c = trans->c;
struct btree_key_cache *bc = &c->btree_key_cache;
struct bkey_cached *ck;
bool was_new = false;
ck = bkey_cached_alloc(trans, path, &was_new);
if (IS_ERR(ck))
return ck;
if (unlikely(!ck)) {
ck = bkey_cached_reuse(bc);
if (unlikely(!ck)) {
bch_err(c, "error allocating memory for key cache item, btree %s",
bch2_btree_id_str(path->btree_id));
return ERR_PTR(-BCH_ERR_ENOMEM_btree_key_cache_create);
}
mark_btree_node_locked(trans, path, 0, BTREE_NODE_INTENT_LOCKED);
}
ck->c.level = 0;
ck->c.btree_id = path->btree_id;
ck->key.btree_id = path->btree_id;
ck->key.pos = path->pos;
ck->valid = false;
ck->flags = 1U << BKEY_CACHED_ACCESSED;
if (unlikely(rhashtable_lookup_insert_fast(&bc->table,
&ck->hash,
bch2_btree_key_cache_params))) {
/* We raced with another fill: */
if (likely(was_new)) {
six_unlock_write(&ck->c.lock);
six_unlock_intent(&ck->c.lock);
kfree(ck);
} else {
bkey_cached_free_fast(bc, ck);
}
mark_btree_node_locked(trans, path, 0, BTREE_NODE_UNLOCKED);
return NULL;
}
atomic_long_inc(&bc->nr_keys);
six_unlock_write(&ck->c.lock);
return ck;
}
static int btree_key_cache_fill(struct btree_trans *trans,
struct btree_path *ck_path,
struct bkey_cached *ck)
{
struct btree_iter iter;
struct bkey_s_c k;
unsigned new_u64s = 0;
struct bkey_i *new_k = NULL;
int ret;
k = bch2_bkey_get_iter(trans, &iter, ck->key.btree_id, ck->key.pos,
BTREE_ITER_KEY_CACHE_FILL|
BTREE_ITER_CACHED_NOFILL);
ret = bkey_err(k);
if (ret)
goto err;
if (!bch2_btree_node_relock(trans, ck_path, 0)) {
trace_and_count(trans->c, trans_restart_relock_key_cache_fill, trans, _THIS_IP_, ck_path);
ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_key_cache_fill);
goto err;
}
/*
* bch2_varint_decode can read past the end of the buffer by at
* most 7 bytes (it won't be used):
*/
new_u64s = k.k->u64s + 1;
/*
* Allocate some extra space so that the transaction commit path is less
* likely to have to reallocate, since that requires a transaction
* restart:
*/
new_u64s = min(256U, (new_u64s * 3) / 2);
if (new_u64s > ck->u64s) {
new_u64s = roundup_pow_of_two(new_u64s);
new_k = kmalloc(new_u64s * sizeof(u64), GFP_NOWAIT|__GFP_NOWARN);
if (!new_k) {
bch2_trans_unlock(trans);
new_k = kmalloc(new_u64s * sizeof(u64), GFP_KERNEL);
if (!new_k) {
bch_err(trans->c, "error allocating memory for key cache key, btree %s u64s %u",
bch2_btree_id_str(ck->key.btree_id), new_u64s);
ret = -BCH_ERR_ENOMEM_btree_key_cache_fill;
goto err;
}
if (!bch2_btree_node_relock(trans, ck_path, 0)) {
kfree(new_k);
trace_and_count(trans->c, trans_restart_relock_key_cache_fill, trans, _THIS_IP_, ck_path);
ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_key_cache_fill);
goto err;
}
ret = bch2_trans_relock(trans);
if (ret) {
kfree(new_k);
goto err;
}
}
}
ret = bch2_btree_node_lock_write(trans, ck_path, &ck_path->l[0].b->c);
if (ret) {
kfree(new_k);
goto err;
}
if (new_k) {
kfree(ck->k);
ck->u64s = new_u64s;
ck->k = new_k;
}
bkey_reassemble(ck->k, k);
ck->valid = true;
bch2_btree_node_unlock_write(trans, ck_path, ck_path->l[0].b);
/* We're not likely to need this iterator again: */
set_btree_iter_dontneed(&iter);
err:
bch2_trans_iter_exit(trans, &iter);
return ret;
}
static noinline int
bch2_btree_path_traverse_cached_slowpath(struct btree_trans *trans, struct btree_path *path,
unsigned flags)
{
struct bch_fs *c = trans->c;
struct bkey_cached *ck;
int ret = 0;
BUG_ON(path->level);
path->l[1].b = NULL;
if (bch2_btree_node_relock_notrace(trans, path, 0)) {
ck = (void *) path->l[0].b;
goto fill;
}
retry:
ck = bch2_btree_key_cache_find(c, path->btree_id, path->pos);
if (!ck) {
ck = btree_key_cache_create(trans, path);
ret = PTR_ERR_OR_ZERO(ck);
if (ret)
goto err;
if (!ck)
goto retry;
mark_btree_node_locked(trans, path, 0, BTREE_NODE_INTENT_LOCKED);
path->locks_want = 1;
} else {
enum six_lock_type lock_want = __btree_lock_want(path, 0);
ret = btree_node_lock(trans, path, (void *) ck, 0,
lock_want, _THIS_IP_);
if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
goto err;
BUG_ON(ret);
if (ck->key.btree_id != path->btree_id ||
!bpos_eq(ck->key.pos, path->pos)) {
six_unlock_type(&ck->c.lock, lock_want);
goto retry;
}
mark_btree_node_locked(trans, path, 0,
(enum btree_node_locked_type) lock_want);
}
path->l[0].lock_seq = six_lock_seq(&ck->c.lock);
path->l[0].b = (void *) ck;
fill:
path->uptodate = BTREE_ITER_UPTODATE;
if (!ck->valid && !(flags & BTREE_ITER_CACHED_NOFILL)) {
/*
* Using the underscore version because we haven't set
* path->uptodate yet:
*/
if (!path->locks_want &&
!__bch2_btree_path_upgrade(trans, path, 1, NULL)) {
trace_and_count(trans->c, trans_restart_key_cache_upgrade, trans, _THIS_IP_);
ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_key_cache_upgrade);
goto err;
}
ret = btree_key_cache_fill(trans, path, ck);
if (ret)
goto err;
ret = bch2_btree_path_relock(trans, path, _THIS_IP_);
if (ret)
goto err;
path->uptodate = BTREE_ITER_UPTODATE;
}
if (!test_bit(BKEY_CACHED_ACCESSED, &ck->flags))
set_bit(BKEY_CACHED_ACCESSED, &ck->flags);
BUG_ON(btree_node_locked_type(path, 0) != btree_lock_want(path, 0));
BUG_ON(path->uptodate);
return ret;
err:
path->uptodate = BTREE_ITER_NEED_TRAVERSE;
if (!bch2_err_matches(ret, BCH_ERR_transaction_restart)) {
btree_node_unlock(trans, path, 0);
path->l[0].b = ERR_PTR(ret);
}
return ret;
}
int bch2_btree_path_traverse_cached(struct btree_trans *trans, struct btree_path *path,
unsigned flags)
{
struct bch_fs *c = trans->c;
struct bkey_cached *ck;
int ret = 0;
EBUG_ON(path->level);
path->l[1].b = NULL;
if (bch2_btree_node_relock_notrace(trans, path, 0)) {
ck = (void *) path->l[0].b;
goto fill;
}
retry:
ck = bch2_btree_key_cache_find(c, path->btree_id, path->pos);
if (!ck) {
return bch2_btree_path_traverse_cached_slowpath(trans, path, flags);
} else {
enum six_lock_type lock_want = __btree_lock_want(path, 0);
ret = btree_node_lock(trans, path, (void *) ck, 0,
lock_want, _THIS_IP_);
EBUG_ON(ret && !bch2_err_matches(ret, BCH_ERR_transaction_restart));
if (ret)
return ret;
if (ck->key.btree_id != path->btree_id ||
!bpos_eq(ck->key.pos, path->pos)) {
six_unlock_type(&ck->c.lock, lock_want);
goto retry;
}
mark_btree_node_locked(trans, path, 0,
(enum btree_node_locked_type) lock_want);
}
path->l[0].lock_seq = six_lock_seq(&ck->c.lock);
path->l[0].b = (void *) ck;
fill:
if (!ck->valid)
return bch2_btree_path_traverse_cached_slowpath(trans, path, flags);
if (!test_bit(BKEY_CACHED_ACCESSED, &ck->flags))
set_bit(BKEY_CACHED_ACCESSED, &ck->flags);
path->uptodate = BTREE_ITER_UPTODATE;
EBUG_ON(!ck->valid);
EBUG_ON(btree_node_locked_type(path, 0) != btree_lock_want(path, 0));
return ret;
}
static int btree_key_cache_flush_pos(struct btree_trans *trans,
struct bkey_cached_key key,
u64 journal_seq,
unsigned commit_flags,
bool evict)
{
struct bch_fs *c = trans->c;
struct journal *j = &c->journal;
struct btree_iter c_iter, b_iter;
struct bkey_cached *ck = NULL;
int ret;
bch2_trans_iter_init(trans, &b_iter, key.btree_id, key.pos,
BTREE_ITER_SLOTS|
BTREE_ITER_INTENT|
BTREE_ITER_ALL_SNAPSHOTS);
bch2_trans_iter_init(trans, &c_iter, key.btree_id, key.pos,
BTREE_ITER_CACHED|
BTREE_ITER_INTENT);
b_iter.flags &= ~BTREE_ITER_WITH_KEY_CACHE;
ret = bch2_btree_iter_traverse(&c_iter);
if (ret)
goto out;
ck = (void *) c_iter.path->l[0].b;
if (!ck)
goto out;
if (!test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
if (evict)
goto evict;
goto out;
}
BUG_ON(!ck->valid);
if (journal_seq && ck->journal.seq != journal_seq)
goto out;
/*
* Since journal reclaim depends on us making progress here, and the
* allocator/copygc depend on journal reclaim making progress, we need
* to be using alloc reserves:
*/
ret = bch2_btree_iter_traverse(&b_iter) ?:
bch2_trans_update(trans, &b_iter, ck->k,
BTREE_UPDATE_KEY_CACHE_RECLAIM|
BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|
BTREE_TRIGGER_NORUN) ?:
bch2_trans_commit(trans, NULL, NULL,
BTREE_INSERT_NOCHECK_RW|
BTREE_INSERT_NOFAIL|
(ck->journal.seq == journal_last_seq(j)
? BCH_WATERMARK_reclaim
: 0)|
commit_flags);
bch2_fs_fatal_err_on(ret &&
!bch2_err_matches(ret, BCH_ERR_transaction_restart) &&
!bch2_err_matches(ret, BCH_ERR_journal_reclaim_would_deadlock) &&
!bch2_journal_error(j), c,
"error flushing key cache: %s", bch2_err_str(ret));
if (ret)
goto out;
bch2_journal_pin_drop(j, &ck->journal);
bch2_journal_preres_put(j, &ck->res);
BUG_ON(!btree_node_locked(c_iter.path, 0));
if (!evict) {
if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
clear_bit(BKEY_CACHED_DIRTY, &ck->flags);
atomic_long_dec(&c->btree_key_cache.nr_dirty);
}
} else {
struct btree_path *path2;
evict:
trans_for_each_path(trans, path2)
if (path2 != c_iter.path)
__bch2_btree_path_unlock(trans, path2);
bch2_btree_node_lock_write_nofail(trans, c_iter.path, &ck->c);
if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
clear_bit(BKEY_CACHED_DIRTY, &ck->flags);
atomic_long_dec(&c->btree_key_cache.nr_dirty);
}
mark_btree_node_locked_noreset(c_iter.path, 0, BTREE_NODE_UNLOCKED);
bkey_cached_evict(&c->btree_key_cache, ck);
bkey_cached_free_fast(&c->btree_key_cache, ck);
}
out:
bch2_trans_iter_exit(trans, &b_iter);
bch2_trans_iter_exit(trans, &c_iter);
return ret;
}
int bch2_btree_key_cache_journal_flush(struct journal *j,
struct journal_entry_pin *pin, u64 seq)
{
struct bch_fs *c = container_of(j, struct bch_fs, journal);
struct bkey_cached *ck =
container_of(pin, struct bkey_cached, journal);
struct bkey_cached_key key;
struct btree_trans *trans = bch2_trans_get(c);
int srcu_idx = srcu_read_lock(&c->btree_trans_barrier);
int ret = 0;
btree_node_lock_nopath_nofail(trans, &ck->c, SIX_LOCK_read);
key = ck->key;
if (ck->journal.seq != seq ||
!test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
six_unlock_read(&ck->c.lock);
goto unlock;
}
if (ck->seq != seq) {
bch2_journal_pin_update(&c->journal, ck->seq, &ck->journal,
bch2_btree_key_cache_journal_flush);
six_unlock_read(&ck->c.lock);
goto unlock;
}
six_unlock_read(&ck->c.lock);
ret = commit_do(trans, NULL, NULL, 0,
btree_key_cache_flush_pos(trans, key, seq,
BTREE_INSERT_JOURNAL_RECLAIM, false));
unlock:
srcu_read_unlock(&c->btree_trans_barrier, srcu_idx);
bch2_trans_put(trans);
return ret;
}
/*
* Flush and evict a key from the key cache:
*/
int bch2_btree_key_cache_flush(struct btree_trans *trans,
enum btree_id id, struct bpos pos)
{
struct bch_fs *c = trans->c;
struct bkey_cached_key key = { id, pos };
/* Fastpath - assume it won't be found: */
if (!bch2_btree_key_cache_find(c, id, pos))
return 0;
return btree_key_cache_flush_pos(trans, key, 0, 0, true);
}
bool bch2_btree_insert_key_cached(struct btree_trans *trans,
unsigned flags,
struct btree_insert_entry *insert_entry)
{
struct bch_fs *c = trans->c;
struct bkey_cached *ck = (void *) insert_entry->path->l[0].b;
struct bkey_i *insert = insert_entry->k;
bool kick_reclaim = false;
BUG_ON(insert->k.u64s > ck->u64s);
if (likely(!(flags & BTREE_INSERT_JOURNAL_REPLAY))) {
int difference;
BUG_ON(jset_u64s(insert->k.u64s) > trans->journal_preres.u64s);
difference = jset_u64s(insert->k.u64s) - ck->res.u64s;
if (difference > 0) {
trans->journal_preres.u64s -= difference;
ck->res.u64s += difference;
}
}
bkey_copy(ck->k, insert);
ck->valid = true;
if (!test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
EBUG_ON(test_bit(BCH_FS_CLEAN_SHUTDOWN, &c->flags));
set_bit(BKEY_CACHED_DIRTY, &ck->flags);
atomic_long_inc(&c->btree_key_cache.nr_dirty);
if (bch2_nr_btree_keys_need_flush(c))
kick_reclaim = true;
}
/*
* To minimize lock contention, we only add the journal pin here and
* defer pin updates to the flush callback via ->seq. Be careful not to
* update ->seq on nojournal commits because we don't want to update the
* pin to a seq that doesn't include journal updates on disk. Otherwise
* we risk losing the update after a crash.
*
* The only exception is if the pin is not active in the first place. We
* have to add the pin because journal reclaim drives key cache
* flushing. The flush callback will not proceed unless ->seq matches
* the latest pin, so make sure it starts with a consistent value.
*/
if (!(insert_entry->flags & BTREE_UPDATE_NOJOURNAL) ||
!journal_pin_active(&ck->journal)) {
ck->seq = trans->journal_res.seq;
}
bch2_journal_pin_add(&c->journal, trans->journal_res.seq,
&ck->journal, bch2_btree_key_cache_journal_flush);
if (kick_reclaim)
journal_reclaim_kick(&c->journal);
return true;
}
void bch2_btree_key_cache_drop(struct btree_trans *trans,
struct btree_path *path)
{
struct bch_fs *c = trans->c;
struct bkey_cached *ck = (void *) path->l[0].b;
BUG_ON(!ck->valid);
/*
* We just did an update to the btree, bypassing the key cache: the key
* cache key is now stale and must be dropped, even if dirty:
*/
if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
clear_bit(BKEY_CACHED_DIRTY, &ck->flags);
atomic_long_dec(&c->btree_key_cache.nr_dirty);
bch2_journal_pin_drop(&c->journal, &ck->journal);
}
ck->valid = false;
}
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 bucket_table *tbl;
struct bkey_cached *ck, *t;
size_t scanned = 0, freed = 0, nr = sc->nr_to_scan;
unsigned start, flags;
int srcu_idx;
mutex_lock(&bc->lock);
srcu_idx = srcu_read_lock(&c->btree_trans_barrier);
flags = memalloc_nofs_save();
/*
* Newest freed entries are at the end of the list - once we hit one
* that's too new to be freed, we can bail out:
*/
list_for_each_entry_safe(ck, t, &bc->freed_nonpcpu, list) {
if (!poll_state_synchronize_srcu(&c->btree_trans_barrier,
ck->btree_trans_barrier_seq))
break;
list_del(&ck->list);
six_lock_exit(&ck->c.lock);
kmem_cache_free(bch2_key_cache, ck);
atomic_long_dec(&bc->nr_freed);
scanned++;
freed++;
}
if (scanned >= nr)
goto out;
list_for_each_entry_safe(ck, t, &bc->freed_pcpu, list) {
if (!poll_state_synchronize_srcu(&c->btree_trans_barrier,
ck->btree_trans_barrier_seq))
break;
list_del(&ck->list);
six_lock_exit(&ck->c.lock);
kmem_cache_free(bch2_key_cache, ck);
atomic_long_dec(&bc->nr_freed);
scanned++;
freed++;
}
if (scanned >= nr)
goto out;
rcu_read_lock();
tbl = rht_dereference_rcu(bc->table.tbl, &bc->table);
if (bc->shrink_iter >= tbl->size)
bc->shrink_iter = 0;
start = bc->shrink_iter;
do {
struct rhash_head *pos, *next;
pos = rht_ptr_rcu(rht_bucket(tbl, bc->shrink_iter));
while (!rht_is_a_nulls(pos)) {
next = rht_dereference_bucket_rcu(pos->next, tbl, bc->shrink_iter);
ck = container_of(pos, struct bkey_cached, hash);
if (test_bit(BKEY_CACHED_DIRTY, &ck->flags))
goto next;
if (test_bit(BKEY_CACHED_ACCESSED, &ck->flags))
clear_bit(BKEY_CACHED_ACCESSED, &ck->flags);
else if (bkey_cached_lock_for_evict(ck)) {
bkey_cached_evict(bc, ck);
bkey_cached_free(bc, ck);
}
scanned++;
if (scanned >= nr)
break;
next:
pos = next;
}
bc->shrink_iter++;
if (bc->shrink_iter >= tbl->size)
bc->shrink_iter = 0;
} while (scanned < nr && bc->shrink_iter != start);
rcu_read_unlock();
out:
memalloc_nofs_restore(flags);
srcu_read_unlock(&c->btree_trans_barrier, srcu_idx);
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;
long nr = atomic_long_read(&bc->nr_keys) -
atomic_long_read(&bc->nr_dirty);
return max(0L, nr);
}
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 bucket_table *tbl;
struct bkey_cached *ck, *n;
struct rhash_head *pos;
LIST_HEAD(items);
unsigned i;
#ifdef __KERNEL__
int cpu;
#endif
unregister_shrinker(&bc->shrink);
mutex_lock(&bc->lock);
/*
* The loop is needed to guard against racing with rehash:
*/
while (atomic_long_read(&bc->nr_keys)) {
rcu_read_lock();
tbl = rht_dereference_rcu(bc->table.tbl, &bc->table);
if (tbl)
for (i = 0; i < tbl->size; i++)
rht_for_each_entry_rcu(ck, pos, tbl, i, hash) {
bkey_cached_evict(bc, ck);
list_add(&ck->list, &items);
}
rcu_read_unlock();
}
#ifdef __KERNEL__
for_each_possible_cpu(cpu) {
struct btree_key_cache_freelist *f =
per_cpu_ptr(bc->pcpu_freed, cpu);
for (i = 0; i < f->nr; i++) {
ck = f->objs[i];
list_add(&ck->list, &items);
}
}
#endif
list_splice(&bc->freed_pcpu, &items);
list_splice(&bc->freed_nonpcpu, &items);
mutex_unlock(&bc->lock);
list_for_each_entry_safe(ck, n, &items, list) {
cond_resched();
bch2_journal_pin_drop(&c->journal, &ck->journal);
bch2_journal_preres_put(&c->journal, &ck->res);
list_del(&ck->list);
kfree(ck->k);
six_lock_exit(&ck->c.lock);
kmem_cache_free(bch2_key_cache, ck);
}
if (atomic_long_read(&bc->nr_dirty) &&
!bch2_journal_error(&c->journal) &&
test_bit(BCH_FS_WAS_RW, &c->flags))
panic("btree key cache shutdown error: nr_dirty nonzero (%li)\n",
atomic_long_read(&bc->nr_dirty));
if (atomic_long_read(&bc->nr_keys))
panic("btree key cache shutdown error: nr_keys nonzero (%li)\n",
atomic_long_read(&bc->nr_keys));
if (bc->table_init_done)
rhashtable_destroy(&bc->table);
free_percpu(bc->pcpu_freed);
}
void bch2_fs_btree_key_cache_init_early(struct btree_key_cache *c)
{
mutex_init(&c->lock);
INIT_LIST_HEAD(&c->freed_pcpu);
INIT_LIST_HEAD(&c->freed_nonpcpu);
}
int bch2_fs_btree_key_cache_init(struct btree_key_cache *bc)
{
struct bch_fs *c = container_of(bc, struct bch_fs, btree_key_cache);
#ifdef __KERNEL__
bc->pcpu_freed = alloc_percpu(struct btree_key_cache_freelist);
if (!bc->pcpu_freed)
return -BCH_ERR_ENOMEM_fs_btree_cache_init;
#endif
if (rhashtable_init(&bc->table, &bch2_btree_key_cache_params))
return -BCH_ERR_ENOMEM_fs_btree_cache_init;
bc->table_init_done = true;
bc->shrink.seeks = 0;
bc->shrink.count_objects = bch2_btree_key_cache_count;
bc->shrink.scan_objects = bch2_btree_key_cache_scan;
if (register_shrinker(&bc->shrink, "%s-btree_key_cache", c->name))
return -BCH_ERR_ENOMEM_fs_btree_cache_init;
return 0;
}
void bch2_btree_key_cache_to_text(struct printbuf *out, struct btree_key_cache *c)
{
prt_printf(out, "nr_freed:\t%lu", atomic_long_read(&c->nr_freed));
prt_newline(out);
prt_printf(out, "nr_keys:\t%lu", atomic_long_read(&c->nr_keys));
prt_newline(out);
prt_printf(out, "nr_dirty:\t%lu", atomic_long_read(&c->nr_dirty));
prt_newline(out);
}
void bch2_btree_key_cache_exit(void)
{
kmem_cache_destroy(bch2_key_cache);
}
int __init bch2_btree_key_cache_init(void)
{
bch2_key_cache = KMEM_CACHE(bkey_cached, SLAB_RECLAIM_ACCOUNT);
if (!bch2_key_cache)
return -ENOMEM;
return 0;
}