1
linux/fs/bcachefs/btree_cache.c
Kent Overstreet baefd3f849 bcachefs: btree_cache.freeable list fixes
When allocating new btree nodes, we were leaving them on the freeable
list - unlocked - allowing them to be reclaimed: ouch.

Additionally, bch2_btree_node_free_never_used() ->
bch2_btree_node_hash_remove was putting it on the freelist, while
bch2_btree_node_free_never_used() was putting it back on the btree
update reserve list - ouch.

Originally, the code was written to always keep btree nodes on a list -
live or freeable - and this worked when new nodes were kept locked.

But now with the cycle detector, we can't keep nodes locked that aren't
tracked by the cycle detector; and this is fine as long as they're not
reachable.

We also have better and more robust leak detection now, with memory
allocation profiling, so the original justification no longer applies.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-11-07 16:48:21 -05:00

1492 lines
38 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include "bcachefs.h"
#include "bbpos.h"
#include "bkey_buf.h"
#include "btree_cache.h"
#include "btree_io.h"
#include "btree_iter.h"
#include "btree_locking.h"
#include "debug.h"
#include "errcode.h"
#include "error.h"
#include "journal.h"
#include "trace.h"
#include <linux/prefetch.h>
#include <linux/sched/mm.h>
#include <linux/swap.h>
#define BTREE_CACHE_NOT_FREED_INCREMENT(counter) \
do { \
if (shrinker_counter) \
bc->not_freed[BCH_BTREE_CACHE_NOT_FREED_##counter]++; \
} while (0)
const char * const bch2_btree_node_flags[] = {
#define x(f) #f,
BTREE_FLAGS()
#undef x
NULL
};
void bch2_recalc_btree_reserve(struct bch_fs *c)
{
unsigned reserve = 16;
if (!c->btree_roots_known[0].b)
reserve += 8;
for (unsigned i = 0; i < btree_id_nr_alive(c); i++) {
struct btree_root *r = bch2_btree_id_root(c, i);
if (r->b)
reserve += min_t(unsigned, 1, r->b->c.level) * 8;
}
c->btree_cache.nr_reserve = reserve;
}
static inline size_t btree_cache_can_free(struct btree_cache_list *list)
{
struct btree_cache *bc = container_of(list, struct btree_cache, live[list->idx]);
size_t can_free = list->nr;
if (!list->idx)
can_free = max_t(ssize_t, 0, can_free - bc->nr_reserve);
return can_free;
}
static void btree_node_to_freedlist(struct btree_cache *bc, struct btree *b)
{
BUG_ON(!list_empty(&b->list));
if (b->c.lock.readers)
list_add(&b->list, &bc->freed_pcpu);
else
list_add(&b->list, &bc->freed_nonpcpu);
}
static void __bch2_btree_node_to_freelist(struct btree_cache *bc, struct btree *b)
{
BUG_ON(!list_empty(&b->list));
BUG_ON(!b->data);
bc->nr_freeable++;
list_add(&b->list, &bc->freeable);
}
void bch2_btree_node_to_freelist(struct bch_fs *c, struct btree *b)
{
struct btree_cache *bc = &c->btree_cache;
mutex_lock(&bc->lock);
__bch2_btree_node_to_freelist(bc, b);
mutex_unlock(&bc->lock);
six_unlock_write(&b->c.lock);
six_unlock_intent(&b->c.lock);
}
static void __btree_node_data_free(struct btree_cache *bc, struct btree *b)
{
BUG_ON(!list_empty(&b->list));
BUG_ON(btree_node_hashed(b));
/*
* This should really be done in slub/vmalloc, but we're using the
* kmalloc_large() path, so we're working around a slub bug by doing
* this here:
*/
if (b->data)
mm_account_reclaimed_pages(btree_buf_bytes(b) / PAGE_SIZE);
if (b->aux_data)
mm_account_reclaimed_pages(btree_aux_data_bytes(b) / PAGE_SIZE);
EBUG_ON(btree_node_write_in_flight(b));
clear_btree_node_just_written(b);
kvfree(b->data);
b->data = NULL;
#ifdef __KERNEL__
kvfree(b->aux_data);
#else
munmap(b->aux_data, btree_aux_data_bytes(b));
#endif
b->aux_data = NULL;
btree_node_to_freedlist(bc, b);
}
static void btree_node_data_free(struct btree_cache *bc, struct btree *b)
{
BUG_ON(list_empty(&b->list));
list_del_init(&b->list);
--bc->nr_freeable;
__btree_node_data_free(bc, b);
}
static int bch2_btree_cache_cmp_fn(struct rhashtable_compare_arg *arg,
const void *obj)
{
const struct btree *b = obj;
const u64 *v = arg->key;
return b->hash_val == *v ? 0 : 1;
}
static const struct rhashtable_params bch_btree_cache_params = {
.head_offset = offsetof(struct btree, hash),
.key_offset = offsetof(struct btree, hash_val),
.key_len = sizeof(u64),
.obj_cmpfn = bch2_btree_cache_cmp_fn,
.automatic_shrinking = true,
};
static int btree_node_data_alloc(struct bch_fs *c, struct btree *b, gfp_t gfp)
{
BUG_ON(b->data || b->aux_data);
gfp |= __GFP_ACCOUNT|__GFP_RECLAIMABLE;
b->data = kvmalloc(btree_buf_bytes(b), gfp);
if (!b->data)
return -BCH_ERR_ENOMEM_btree_node_mem_alloc;
#ifdef __KERNEL__
b->aux_data = kvmalloc(btree_aux_data_bytes(b), gfp);
#else
b->aux_data = mmap(NULL, btree_aux_data_bytes(b),
PROT_READ|PROT_WRITE|PROT_EXEC,
MAP_PRIVATE|MAP_ANONYMOUS, 0, 0);
if (b->aux_data == MAP_FAILED)
b->aux_data = NULL;
#endif
if (!b->aux_data) {
kvfree(b->data);
b->data = NULL;
return -BCH_ERR_ENOMEM_btree_node_mem_alloc;
}
return 0;
}
static struct btree *__btree_node_mem_alloc(struct bch_fs *c, gfp_t gfp)
{
struct btree *b;
b = kzalloc(sizeof(struct btree), gfp);
if (!b)
return NULL;
bkey_btree_ptr_init(&b->key);
INIT_LIST_HEAD(&b->list);
INIT_LIST_HEAD(&b->write_blocked);
b->byte_order = ilog2(c->opts.btree_node_size);
return b;
}
struct btree *__bch2_btree_node_mem_alloc(struct bch_fs *c)
{
struct btree_cache *bc = &c->btree_cache;
struct btree *b;
b = __btree_node_mem_alloc(c, GFP_KERNEL);
if (!b)
return NULL;
if (btree_node_data_alloc(c, b, GFP_KERNEL)) {
kfree(b);
return NULL;
}
bch2_btree_lock_init(&b->c, 0);
__bch2_btree_node_to_freelist(bc, b);
return b;
}
static inline bool __btree_node_pinned(struct btree_cache *bc, struct btree *b)
{
struct bbpos pos = BBPOS(b->c.btree_id, b->key.k.p);
u64 mask = bc->pinned_nodes_mask[!!b->c.level];
return ((mask & BIT_ULL(b->c.btree_id)) &&
bbpos_cmp(bc->pinned_nodes_start, pos) < 0 &&
bbpos_cmp(bc->pinned_nodes_end, pos) >= 0);
}
void bch2_node_pin(struct bch_fs *c, struct btree *b)
{
struct btree_cache *bc = &c->btree_cache;
mutex_lock(&bc->lock);
BUG_ON(!__btree_node_pinned(bc, b));
if (b != btree_node_root(c, b) && !btree_node_pinned(b)) {
set_btree_node_pinned(b);
list_move(&b->list, &bc->live[1].list);
bc->live[0].nr--;
bc->live[1].nr++;
}
mutex_unlock(&bc->lock);
}
void bch2_btree_cache_unpin(struct bch_fs *c)
{
struct btree_cache *bc = &c->btree_cache;
struct btree *b, *n;
mutex_lock(&bc->lock);
c->btree_cache.pinned_nodes_mask[0] = 0;
c->btree_cache.pinned_nodes_mask[1] = 0;
list_for_each_entry_safe(b, n, &bc->live[1].list, list) {
clear_btree_node_pinned(b);
list_move(&b->list, &bc->live[0].list);
bc->live[0].nr++;
bc->live[1].nr--;
}
mutex_unlock(&bc->lock);
}
/* Btree in memory cache - hash table */
void __bch2_btree_node_hash_remove(struct btree_cache *bc, struct btree *b)
{
lockdep_assert_held(&bc->lock);
int ret = rhashtable_remove_fast(&bc->table, &b->hash, bch_btree_cache_params);
BUG_ON(ret);
/* Cause future lookups for this node to fail: */
b->hash_val = 0;
if (b->c.btree_id < BTREE_ID_NR)
--bc->nr_by_btree[b->c.btree_id];
--bc->live[btree_node_pinned(b)].nr;
list_del_init(&b->list);
}
void bch2_btree_node_hash_remove(struct btree_cache *bc, struct btree *b)
{
__bch2_btree_node_hash_remove(bc, b);
__bch2_btree_node_to_freelist(bc, b);
}
int __bch2_btree_node_hash_insert(struct btree_cache *bc, struct btree *b)
{
BUG_ON(!list_empty(&b->list));
BUG_ON(b->hash_val);
b->hash_val = btree_ptr_hash_val(&b->key);
int ret = rhashtable_lookup_insert_fast(&bc->table, &b->hash,
bch_btree_cache_params);
if (ret)
return ret;
if (b->c.btree_id < BTREE_ID_NR)
bc->nr_by_btree[b->c.btree_id]++;
bool p = __btree_node_pinned(bc, b);
mod_bit(BTREE_NODE_pinned, &b->flags, p);
list_add_tail(&b->list, &bc->live[p].list);
bc->live[p].nr++;
return 0;
}
int bch2_btree_node_hash_insert(struct btree_cache *bc, struct btree *b,
unsigned level, enum btree_id id)
{
b->c.level = level;
b->c.btree_id = id;
mutex_lock(&bc->lock);
int ret = __bch2_btree_node_hash_insert(bc, b);
mutex_unlock(&bc->lock);
return ret;
}
void bch2_btree_node_update_key_early(struct btree_trans *trans,
enum btree_id btree, unsigned level,
struct bkey_s_c old, struct bkey_i *new)
{
struct bch_fs *c = trans->c;
struct btree *b;
struct bkey_buf tmp;
int ret;
bch2_bkey_buf_init(&tmp);
bch2_bkey_buf_reassemble(&tmp, c, old);
b = bch2_btree_node_get_noiter(trans, tmp.k, btree, level, true);
if (!IS_ERR_OR_NULL(b)) {
mutex_lock(&c->btree_cache.lock);
bch2_btree_node_hash_remove(&c->btree_cache, b);
bkey_copy(&b->key, new);
ret = __bch2_btree_node_hash_insert(&c->btree_cache, b);
BUG_ON(ret);
mutex_unlock(&c->btree_cache.lock);
six_unlock_read(&b->c.lock);
}
bch2_bkey_buf_exit(&tmp, c);
}
__flatten
static inline struct btree *btree_cache_find(struct btree_cache *bc,
const struct bkey_i *k)
{
u64 v = btree_ptr_hash_val(k);
return rhashtable_lookup_fast(&bc->table, &v, bch_btree_cache_params);
}
/*
* this version is for btree nodes that have already been freed (we're not
* reaping a real btree node)
*/
static int __btree_node_reclaim(struct bch_fs *c, struct btree *b, bool flush, bool shrinker_counter)
{
struct btree_cache *bc = &c->btree_cache;
int ret = 0;
lockdep_assert_held(&bc->lock);
wait_on_io:
if (b->flags & ((1U << BTREE_NODE_dirty)|
(1U << BTREE_NODE_read_in_flight)|
(1U << BTREE_NODE_write_in_flight))) {
if (!flush) {
if (btree_node_dirty(b))
BTREE_CACHE_NOT_FREED_INCREMENT(dirty);
else if (btree_node_read_in_flight(b))
BTREE_CACHE_NOT_FREED_INCREMENT(read_in_flight);
else if (btree_node_write_in_flight(b))
BTREE_CACHE_NOT_FREED_INCREMENT(write_in_flight);
return -BCH_ERR_ENOMEM_btree_node_reclaim;
}
/* XXX: waiting on IO with btree cache lock held */
bch2_btree_node_wait_on_read(b);
bch2_btree_node_wait_on_write(b);
}
if (!six_trylock_intent(&b->c.lock)) {
BTREE_CACHE_NOT_FREED_INCREMENT(lock_intent);
return -BCH_ERR_ENOMEM_btree_node_reclaim;
}
if (!six_trylock_write(&b->c.lock)) {
BTREE_CACHE_NOT_FREED_INCREMENT(lock_write);
goto out_unlock_intent;
}
/* recheck under lock */
if (b->flags & ((1U << BTREE_NODE_read_in_flight)|
(1U << BTREE_NODE_write_in_flight))) {
if (!flush) {
if (btree_node_read_in_flight(b))
BTREE_CACHE_NOT_FREED_INCREMENT(read_in_flight);
else if (btree_node_write_in_flight(b))
BTREE_CACHE_NOT_FREED_INCREMENT(write_in_flight);
goto out_unlock;
}
six_unlock_write(&b->c.lock);
six_unlock_intent(&b->c.lock);
goto wait_on_io;
}
if (btree_node_noevict(b)) {
BTREE_CACHE_NOT_FREED_INCREMENT(noevict);
goto out_unlock;
}
if (btree_node_write_blocked(b)) {
BTREE_CACHE_NOT_FREED_INCREMENT(write_blocked);
goto out_unlock;
}
if (btree_node_will_make_reachable(b)) {
BTREE_CACHE_NOT_FREED_INCREMENT(will_make_reachable);
goto out_unlock;
}
if (btree_node_dirty(b)) {
if (!flush) {
BTREE_CACHE_NOT_FREED_INCREMENT(dirty);
goto out_unlock;
}
/*
* Using the underscore version because we don't want to compact
* bsets after the write, since this node is about to be evicted
* - unless btree verify mode is enabled, since it runs out of
* the post write cleanup:
*/
if (bch2_verify_btree_ondisk)
bch2_btree_node_write(c, b, SIX_LOCK_intent,
BTREE_WRITE_cache_reclaim);
else
__bch2_btree_node_write(c, b,
BTREE_WRITE_cache_reclaim);
six_unlock_write(&b->c.lock);
six_unlock_intent(&b->c.lock);
goto wait_on_io;
}
out:
if (b->hash_val && !ret)
trace_and_count(c, btree_cache_reap, c, b);
return ret;
out_unlock:
six_unlock_write(&b->c.lock);
out_unlock_intent:
six_unlock_intent(&b->c.lock);
ret = -BCH_ERR_ENOMEM_btree_node_reclaim;
goto out;
}
static int btree_node_reclaim(struct bch_fs *c, struct btree *b, bool shrinker_counter)
{
return __btree_node_reclaim(c, b, false, shrinker_counter);
}
static int btree_node_write_and_reclaim(struct bch_fs *c, struct btree *b)
{
return __btree_node_reclaim(c, b, true, false);
}
static unsigned long bch2_btree_cache_scan(struct shrinker *shrink,
struct shrink_control *sc)
{
struct btree_cache_list *list = shrink->private_data;
struct btree_cache *bc = container_of(list, struct btree_cache, live[list->idx]);
struct bch_fs *c = container_of(bc, struct bch_fs, btree_cache);
struct btree *b, *t;
unsigned long nr = sc->nr_to_scan;
unsigned long can_free = 0;
unsigned long freed = 0;
unsigned long touched = 0;
unsigned i, flags;
unsigned long ret = SHRINK_STOP;
bool trigger_writes = atomic_long_read(&bc->nr_dirty) + nr >= list->nr * 3 / 4;
if (bch2_btree_shrinker_disabled)
return SHRINK_STOP;
mutex_lock(&bc->lock);
flags = memalloc_nofs_save();
/*
* It's _really_ critical that we don't free too many btree nodes - we
* have to always leave ourselves a reserve. The reserve is how we
* guarantee that allocating memory for a new btree node can always
* succeed, so that inserting keys into the btree can always succeed and
* IO can always make forward progress:
*/
can_free = btree_cache_can_free(list);
nr = min_t(unsigned long, nr, can_free);
i = 0;
list_for_each_entry_safe(b, t, &bc->freeable, list) {
/*
* Leave a few nodes on the freeable list, so that a btree split
* won't have to hit the system allocator:
*/
if (++i <= 3)
continue;
touched++;
if (touched >= nr)
goto out;
if (!btree_node_reclaim(c, b, true)) {
btree_node_data_free(bc, b);
six_unlock_write(&b->c.lock);
six_unlock_intent(&b->c.lock);
freed++;
bc->nr_freed++;
}
}
restart:
list_for_each_entry_safe(b, t, &list->list, list) {
touched++;
if (btree_node_accessed(b)) {
clear_btree_node_accessed(b);
bc->not_freed[BCH_BTREE_CACHE_NOT_FREED_access_bit]++;
--touched;;
} else if (!btree_node_reclaim(c, b, true)) {
__bch2_btree_node_hash_remove(bc, b);
__btree_node_data_free(bc, b);
freed++;
bc->nr_freed++;
six_unlock_write(&b->c.lock);
six_unlock_intent(&b->c.lock);
if (freed == nr)
goto out_rotate;
} else if (trigger_writes &&
btree_node_dirty(b) &&
!btree_node_will_make_reachable(b) &&
!btree_node_write_blocked(b) &&
six_trylock_read(&b->c.lock)) {
list_move(&list->list, &b->list);
mutex_unlock(&bc->lock);
__bch2_btree_node_write(c, b, BTREE_WRITE_cache_reclaim);
six_unlock_read(&b->c.lock);
if (touched >= nr)
goto out_nounlock;
mutex_lock(&bc->lock);
goto restart;
}
if (touched >= nr)
break;
}
out_rotate:
if (&t->list != &list->list)
list_move_tail(&list->list, &t->list);
out:
mutex_unlock(&bc->lock);
out_nounlock:
ret = freed;
memalloc_nofs_restore(flags);
trace_and_count(c, btree_cache_scan, sc->nr_to_scan, can_free, ret);
return ret;
}
static unsigned long bch2_btree_cache_count(struct shrinker *shrink,
struct shrink_control *sc)
{
struct btree_cache_list *list = shrink->private_data;
if (bch2_btree_shrinker_disabled)
return 0;
return btree_cache_can_free(list);
}
void bch2_fs_btree_cache_exit(struct bch_fs *c)
{
struct btree_cache *bc = &c->btree_cache;
struct btree *b, *t;
unsigned long flags;
shrinker_free(bc->live[1].shrink);
shrinker_free(bc->live[0].shrink);
/* vfree() can allocate memory: */
flags = memalloc_nofs_save();
mutex_lock(&bc->lock);
if (c->verify_data)
list_move(&c->verify_data->list, &bc->live[0].list);
kvfree(c->verify_ondisk);
for (unsigned i = 0; i < btree_id_nr_alive(c); i++) {
struct btree_root *r = bch2_btree_id_root(c, i);
if (r->b)
list_add(&r->b->list, &bc->live[0].list);
}
list_for_each_entry_safe(b, t, &bc->live[1].list, list)
bch2_btree_node_hash_remove(bc, b);
list_for_each_entry_safe(b, t, &bc->live[0].list, list)
bch2_btree_node_hash_remove(bc, b);
list_for_each_entry_safe(b, t, &bc->freeable, list) {
BUG_ON(btree_node_read_in_flight(b) ||
btree_node_write_in_flight(b));
btree_node_data_free(bc, b);
}
BUG_ON(!bch2_journal_error(&c->journal) &&
atomic_long_read(&c->btree_cache.nr_dirty));
list_splice(&bc->freed_pcpu, &bc->freed_nonpcpu);
list_for_each_entry_safe(b, t, &bc->freed_nonpcpu, list) {
list_del(&b->list);
six_lock_exit(&b->c.lock);
kfree(b);
}
mutex_unlock(&bc->lock);
memalloc_nofs_restore(flags);
for (unsigned i = 0; i < ARRAY_SIZE(bc->nr_by_btree); i++)
BUG_ON(bc->nr_by_btree[i]);
BUG_ON(bc->live[0].nr);
BUG_ON(bc->live[1].nr);
BUG_ON(bc->nr_freeable);
if (bc->table_init_done)
rhashtable_destroy(&bc->table);
}
int bch2_fs_btree_cache_init(struct bch_fs *c)
{
struct btree_cache *bc = &c->btree_cache;
struct shrinker *shrink;
unsigned i;
int ret = 0;
ret = rhashtable_init(&bc->table, &bch_btree_cache_params);
if (ret)
goto err;
bc->table_init_done = true;
bch2_recalc_btree_reserve(c);
for (i = 0; i < bc->nr_reserve; i++)
if (!__bch2_btree_node_mem_alloc(c))
goto err;
list_splice_init(&bc->live[0].list, &bc->freeable);
mutex_init(&c->verify_lock);
shrink = shrinker_alloc(0, "%s-btree_cache", c->name);
if (!shrink)
goto err;
bc->live[0].shrink = shrink;
shrink->count_objects = bch2_btree_cache_count;
shrink->scan_objects = bch2_btree_cache_scan;
shrink->seeks = 2;
shrink->private_data = &bc->live[0];
shrinker_register(shrink);
shrink = shrinker_alloc(0, "%s-btree_cache-pinned", c->name);
if (!shrink)
goto err;
bc->live[1].shrink = shrink;
shrink->count_objects = bch2_btree_cache_count;
shrink->scan_objects = bch2_btree_cache_scan;
shrink->seeks = 8;
shrink->private_data = &bc->live[1];
shrinker_register(shrink);
return 0;
err:
return -BCH_ERR_ENOMEM_fs_btree_cache_init;
}
void bch2_fs_btree_cache_init_early(struct btree_cache *bc)
{
mutex_init(&bc->lock);
for (unsigned i = 0; i < ARRAY_SIZE(bc->live); i++) {
bc->live[i].idx = i;
INIT_LIST_HEAD(&bc->live[i].list);
}
INIT_LIST_HEAD(&bc->freeable);
INIT_LIST_HEAD(&bc->freed_pcpu);
INIT_LIST_HEAD(&bc->freed_nonpcpu);
}
/*
* We can only have one thread cannibalizing other cached btree nodes at a time,
* or we'll deadlock. We use an open coded mutex to ensure that, which a
* cannibalize_bucket() will take. This means every time we unlock the root of
* the btree, we need to release this lock if we have it held.
*/
void bch2_btree_cache_cannibalize_unlock(struct btree_trans *trans)
{
struct bch_fs *c = trans->c;
struct btree_cache *bc = &c->btree_cache;
if (bc->alloc_lock == current) {
trace_and_count(c, btree_cache_cannibalize_unlock, trans);
bc->alloc_lock = NULL;
closure_wake_up(&bc->alloc_wait);
}
}
int bch2_btree_cache_cannibalize_lock(struct btree_trans *trans, struct closure *cl)
{
struct bch_fs *c = trans->c;
struct btree_cache *bc = &c->btree_cache;
struct task_struct *old;
old = NULL;
if (try_cmpxchg(&bc->alloc_lock, &old, current) || old == current)
goto success;
if (!cl) {
trace_and_count(c, btree_cache_cannibalize_lock_fail, trans);
return -BCH_ERR_ENOMEM_btree_cache_cannibalize_lock;
}
closure_wait(&bc->alloc_wait, cl);
/* Try again, after adding ourselves to waitlist */
old = NULL;
if (try_cmpxchg(&bc->alloc_lock, &old, current) || old == current) {
/* We raced */
closure_wake_up(&bc->alloc_wait);
goto success;
}
trace_and_count(c, btree_cache_cannibalize_lock_fail, trans);
return -BCH_ERR_btree_cache_cannibalize_lock_blocked;
success:
trace_and_count(c, btree_cache_cannibalize_lock, trans);
return 0;
}
static struct btree *btree_node_cannibalize(struct bch_fs *c)
{
struct btree_cache *bc = &c->btree_cache;
struct btree *b;
for (unsigned i = 0; i < ARRAY_SIZE(bc->live); i++)
list_for_each_entry_reverse(b, &bc->live[i].list, list)
if (!btree_node_reclaim(c, b, false))
return b;
while (1) {
for (unsigned i = 0; i < ARRAY_SIZE(bc->live); i++)
list_for_each_entry_reverse(b, &bc->live[i].list, list)
if (!btree_node_write_and_reclaim(c, b))
return b;
/*
* Rare case: all nodes were intent-locked.
* Just busy-wait.
*/
WARN_ONCE(1, "btree cache cannibalize failed\n");
cond_resched();
}
}
struct btree *bch2_btree_node_mem_alloc(struct btree_trans *trans, bool pcpu_read_locks)
{
struct bch_fs *c = trans->c;
struct btree_cache *bc = &c->btree_cache;
struct list_head *freed = pcpu_read_locks
? &bc->freed_pcpu
: &bc->freed_nonpcpu;
struct btree *b, *b2;
u64 start_time = local_clock();
mutex_lock(&bc->lock);
/*
* We never free struct btree itself, just the memory that holds the on
* disk node. Check the freed list before allocating a new one:
*/
list_for_each_entry(b, freed, list)
if (!btree_node_reclaim(c, b, false)) {
list_del_init(&b->list);
goto got_node;
}
b = __btree_node_mem_alloc(c, GFP_NOWAIT|__GFP_NOWARN);
if (!b) {
mutex_unlock(&bc->lock);
bch2_trans_unlock(trans);
b = __btree_node_mem_alloc(c, GFP_KERNEL);
if (!b)
goto err;
mutex_lock(&bc->lock);
}
bch2_btree_lock_init(&b->c, pcpu_read_locks ? SIX_LOCK_INIT_PCPU : 0);
BUG_ON(!six_trylock_intent(&b->c.lock));
BUG_ON(!six_trylock_write(&b->c.lock));
got_node:
/*
* btree_free() doesn't free memory; it sticks the node on the end of
* the list. Check if there's any freed nodes there:
*/
list_for_each_entry(b2, &bc->freeable, list)
if (!btree_node_reclaim(c, b2, false)) {
swap(b->data, b2->data);
swap(b->aux_data, b2->aux_data);
list_del_init(&b2->list);
--bc->nr_freeable;
btree_node_to_freedlist(bc, b2);
mutex_unlock(&bc->lock);
six_unlock_write(&b2->c.lock);
six_unlock_intent(&b2->c.lock);
goto got_mem;
}
mutex_unlock(&bc->lock);
if (btree_node_data_alloc(c, b, GFP_NOWAIT|__GFP_NOWARN)) {
bch2_trans_unlock(trans);
if (btree_node_data_alloc(c, b, GFP_KERNEL|__GFP_NOWARN))
goto err;
}
got_mem:
BUG_ON(!list_empty(&b->list));
BUG_ON(btree_node_hashed(b));
BUG_ON(btree_node_dirty(b));
BUG_ON(btree_node_write_in_flight(b));
out:
b->flags = 0;
b->written = 0;
b->nsets = 0;
b->sib_u64s[0] = 0;
b->sib_u64s[1] = 0;
b->whiteout_u64s = 0;
bch2_btree_keys_init(b);
set_btree_node_accessed(b);
bch2_time_stats_update(&c->times[BCH_TIME_btree_node_mem_alloc],
start_time);
int ret = bch2_trans_relock(trans);
if (unlikely(ret)) {
bch2_btree_node_to_freelist(c, b);
return ERR_PTR(ret);
}
return b;
err:
mutex_lock(&bc->lock);
/* Try to cannibalize another cached btree node: */
if (bc->alloc_lock == current) {
b2 = btree_node_cannibalize(c);
clear_btree_node_just_written(b2);
__bch2_btree_node_hash_remove(bc, b2);
if (b) {
swap(b->data, b2->data);
swap(b->aux_data, b2->aux_data);
btree_node_to_freedlist(bc, b2);
six_unlock_write(&b2->c.lock);
six_unlock_intent(&b2->c.lock);
} else {
b = b2;
}
BUG_ON(!list_empty(&b->list));
mutex_unlock(&bc->lock);
trace_and_count(c, btree_cache_cannibalize, trans);
goto out;
}
mutex_unlock(&bc->lock);
return ERR_PTR(-BCH_ERR_ENOMEM_btree_node_mem_alloc);
}
/* Slowpath, don't want it inlined into btree_iter_traverse() */
static noinline struct btree *bch2_btree_node_fill(struct btree_trans *trans,
struct btree_path *path,
const struct bkey_i *k,
enum btree_id btree_id,
unsigned level,
enum six_lock_type lock_type,
bool sync)
{
struct bch_fs *c = trans->c;
struct btree_cache *bc = &c->btree_cache;
struct btree *b;
if (unlikely(level >= BTREE_MAX_DEPTH)) {
int ret = bch2_fs_topology_error(c, "attempting to get btree node at level %u, >= max depth %u",
level, BTREE_MAX_DEPTH);
return ERR_PTR(ret);
}
if (unlikely(!bkey_is_btree_ptr(&k->k))) {
struct printbuf buf = PRINTBUF;
bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(k));
int ret = bch2_fs_topology_error(c, "attempting to get btree node with non-btree key %s", buf.buf);
printbuf_exit(&buf);
return ERR_PTR(ret);
}
if (unlikely(k->k.u64s > BKEY_BTREE_PTR_U64s_MAX)) {
struct printbuf buf = PRINTBUF;
bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(k));
int ret = bch2_fs_topology_error(c, "attempting to get btree node with too big key %s", buf.buf);
printbuf_exit(&buf);
return ERR_PTR(ret);
}
/*
* Parent node must be locked, else we could read in a btree node that's
* been freed:
*/
if (path && !bch2_btree_node_relock(trans, path, level + 1)) {
trace_and_count(c, trans_restart_relock_parent_for_fill, trans, _THIS_IP_, path);
return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_fill_relock));
}
b = bch2_btree_node_mem_alloc(trans, level != 0);
if (bch2_err_matches(PTR_ERR_OR_ZERO(b), ENOMEM)) {
if (!path)
return b;
trans->memory_allocation_failure = true;
trace_and_count(c, trans_restart_memory_allocation_failure, trans, _THIS_IP_, path);
return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_fill_mem_alloc_fail));
}
if (IS_ERR(b))
return b;
bkey_copy(&b->key, k);
if (bch2_btree_node_hash_insert(bc, b, level, btree_id)) {
/* raced with another fill: */
/* mark as unhashed... */
b->hash_val = 0;
mutex_lock(&bc->lock);
__bch2_btree_node_to_freelist(bc, b);
mutex_unlock(&bc->lock);
six_unlock_write(&b->c.lock);
six_unlock_intent(&b->c.lock);
return NULL;
}
set_btree_node_read_in_flight(b);
six_unlock_write(&b->c.lock);
if (path) {
u32 seq = six_lock_seq(&b->c.lock);
/* Unlock before doing IO: */
six_unlock_intent(&b->c.lock);
bch2_trans_unlock_noassert(trans);
bch2_btree_node_read(trans, b, sync);
int ret = bch2_trans_relock(trans);
if (ret)
return ERR_PTR(ret);
if (!sync)
return NULL;
if (!six_relock_type(&b->c.lock, lock_type, seq))
b = NULL;
} else {
bch2_btree_node_read(trans, b, sync);
if (lock_type == SIX_LOCK_read)
six_lock_downgrade(&b->c.lock);
}
return b;
}
static noinline void btree_bad_header(struct bch_fs *c, struct btree *b)
{
struct printbuf buf = PRINTBUF;
if (c->curr_recovery_pass <= BCH_RECOVERY_PASS_check_allocations)
return;
prt_printf(&buf,
"btree node header doesn't match ptr\n"
"btree %s level %u\n"
"ptr: ",
bch2_btree_id_str(b->c.btree_id), b->c.level);
bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&b->key));
prt_printf(&buf, "\nheader: btree %s level %llu\n"
"min ",
bch2_btree_id_str(BTREE_NODE_ID(b->data)),
BTREE_NODE_LEVEL(b->data));
bch2_bpos_to_text(&buf, b->data->min_key);
prt_printf(&buf, "\nmax ");
bch2_bpos_to_text(&buf, b->data->max_key);
bch2_fs_topology_error(c, "%s", buf.buf);
printbuf_exit(&buf);
}
static inline void btree_check_header(struct bch_fs *c, struct btree *b)
{
if (b->c.btree_id != BTREE_NODE_ID(b->data) ||
b->c.level != BTREE_NODE_LEVEL(b->data) ||
!bpos_eq(b->data->max_key, b->key.k.p) ||
(b->key.k.type == KEY_TYPE_btree_ptr_v2 &&
!bpos_eq(b->data->min_key,
bkey_i_to_btree_ptr_v2(&b->key)->v.min_key)))
btree_bad_header(c, b);
}
static struct btree *__bch2_btree_node_get(struct btree_trans *trans, struct btree_path *path,
const struct bkey_i *k, unsigned level,
enum six_lock_type lock_type,
unsigned long trace_ip)
{
struct bch_fs *c = trans->c;
struct btree_cache *bc = &c->btree_cache;
struct btree *b;
bool need_relock = false;
int ret;
EBUG_ON(level >= BTREE_MAX_DEPTH);
retry:
b = btree_cache_find(bc, k);
if (unlikely(!b)) {
/*
* We must have the parent locked to call bch2_btree_node_fill(),
* else we could read in a btree node from disk that's been
* freed:
*/
b = bch2_btree_node_fill(trans, path, k, path->btree_id,
level, lock_type, true);
need_relock = true;
/* We raced and found the btree node in the cache */
if (!b)
goto retry;
if (IS_ERR(b))
return b;
} else {
if (btree_node_read_locked(path, level + 1))
btree_node_unlock(trans, path, level + 1);
ret = btree_node_lock(trans, path, &b->c, level, lock_type, trace_ip);
if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
return ERR_PTR(ret);
BUG_ON(ret);
if (unlikely(b->hash_val != btree_ptr_hash_val(k) ||
b->c.level != level ||
race_fault())) {
six_unlock_type(&b->c.lock, lock_type);
if (bch2_btree_node_relock(trans, path, level + 1))
goto retry;
trace_and_count(c, trans_restart_btree_node_reused, trans, trace_ip, path);
return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_lock_node_reused));
}
/* avoid atomic set bit if it's not needed: */
if (!btree_node_accessed(b))
set_btree_node_accessed(b);
}
if (unlikely(btree_node_read_in_flight(b))) {
u32 seq = six_lock_seq(&b->c.lock);
six_unlock_type(&b->c.lock, lock_type);
bch2_trans_unlock(trans);
need_relock = true;
bch2_btree_node_wait_on_read(b);
ret = bch2_trans_relock(trans);
if (ret)
return ERR_PTR(ret);
/*
* should_be_locked is not set on this path yet, so we need to
* relock it specifically:
*/
if (!six_relock_type(&b->c.lock, lock_type, seq))
goto retry;
}
if (unlikely(need_relock)) {
ret = bch2_trans_relock(trans) ?:
bch2_btree_path_relock_intent(trans, path);
if (ret) {
six_unlock_type(&b->c.lock, lock_type);
return ERR_PTR(ret);
}
}
prefetch(b->aux_data);
for_each_bset(b, t) {
void *p = (u64 *) b->aux_data + t->aux_data_offset;
prefetch(p + L1_CACHE_BYTES * 0);
prefetch(p + L1_CACHE_BYTES * 1);
prefetch(p + L1_CACHE_BYTES * 2);
}
if (unlikely(btree_node_read_error(b))) {
six_unlock_type(&b->c.lock, lock_type);
return ERR_PTR(-BCH_ERR_btree_node_read_error);
}
EBUG_ON(b->c.btree_id != path->btree_id);
EBUG_ON(BTREE_NODE_LEVEL(b->data) != level);
btree_check_header(c, b);
return b;
}
/**
* bch2_btree_node_get - find a btree node in the cache and lock it, reading it
* in from disk if necessary.
*
* @trans: btree transaction object
* @path: btree_path being traversed
* @k: pointer to btree node (generally KEY_TYPE_btree_ptr_v2)
* @level: level of btree node being looked up (0 == leaf node)
* @lock_type: SIX_LOCK_read or SIX_LOCK_intent
* @trace_ip: ip of caller of btree iterator code (i.e. caller of bch2_btree_iter_peek())
*
* The btree node will have either a read or a write lock held, depending on
* the @write parameter.
*
* Returns: btree node or ERR_PTR()
*/
struct btree *bch2_btree_node_get(struct btree_trans *trans, struct btree_path *path,
const struct bkey_i *k, unsigned level,
enum six_lock_type lock_type,
unsigned long trace_ip)
{
struct bch_fs *c = trans->c;
struct btree *b;
int ret;
EBUG_ON(level >= BTREE_MAX_DEPTH);
b = btree_node_mem_ptr(k);
/*
* Check b->hash_val _before_ calling btree_node_lock() - this might not
* be the node we want anymore, and trying to lock the wrong node could
* cause an unneccessary transaction restart:
*/
if (unlikely(!c->opts.btree_node_mem_ptr_optimization ||
!b ||
b->hash_val != btree_ptr_hash_val(k)))
return __bch2_btree_node_get(trans, path, k, level, lock_type, trace_ip);
if (btree_node_read_locked(path, level + 1))
btree_node_unlock(trans, path, level + 1);
ret = btree_node_lock(trans, path, &b->c, level, lock_type, trace_ip);
if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
return ERR_PTR(ret);
BUG_ON(ret);
if (unlikely(b->hash_val != btree_ptr_hash_val(k) ||
b->c.level != level ||
race_fault())) {
six_unlock_type(&b->c.lock, lock_type);
if (bch2_btree_node_relock(trans, path, level + 1))
return __bch2_btree_node_get(trans, path, k, level, lock_type, trace_ip);
trace_and_count(c, trans_restart_btree_node_reused, trans, trace_ip, path);
return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_lock_node_reused));
}
if (unlikely(btree_node_read_in_flight(b))) {
six_unlock_type(&b->c.lock, lock_type);
return __bch2_btree_node_get(trans, path, k, level, lock_type, trace_ip);
}
prefetch(b->aux_data);
for_each_bset(b, t) {
void *p = (u64 *) b->aux_data + t->aux_data_offset;
prefetch(p + L1_CACHE_BYTES * 0);
prefetch(p + L1_CACHE_BYTES * 1);
prefetch(p + L1_CACHE_BYTES * 2);
}
/* avoid atomic set bit if it's not needed: */
if (!btree_node_accessed(b))
set_btree_node_accessed(b);
if (unlikely(btree_node_read_error(b))) {
six_unlock_type(&b->c.lock, lock_type);
return ERR_PTR(-BCH_ERR_btree_node_read_error);
}
EBUG_ON(b->c.btree_id != path->btree_id);
EBUG_ON(BTREE_NODE_LEVEL(b->data) != level);
btree_check_header(c, b);
return b;
}
struct btree *bch2_btree_node_get_noiter(struct btree_trans *trans,
const struct bkey_i *k,
enum btree_id btree_id,
unsigned level,
bool nofill)
{
struct bch_fs *c = trans->c;
struct btree_cache *bc = &c->btree_cache;
struct btree *b;
int ret;
EBUG_ON(level >= BTREE_MAX_DEPTH);
if (c->opts.btree_node_mem_ptr_optimization) {
b = btree_node_mem_ptr(k);
if (b)
goto lock_node;
}
retry:
b = btree_cache_find(bc, k);
if (unlikely(!b)) {
if (nofill)
goto out;
b = bch2_btree_node_fill(trans, NULL, k, btree_id,
level, SIX_LOCK_read, true);
/* We raced and found the btree node in the cache */
if (!b)
goto retry;
if (IS_ERR(b) &&
!bch2_btree_cache_cannibalize_lock(trans, NULL))
goto retry;
if (IS_ERR(b))
goto out;
} else {
lock_node:
ret = btree_node_lock_nopath(trans, &b->c, SIX_LOCK_read, _THIS_IP_);
if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
return ERR_PTR(ret);
BUG_ON(ret);
if (unlikely(b->hash_val != btree_ptr_hash_val(k) ||
b->c.btree_id != btree_id ||
b->c.level != level)) {
six_unlock_read(&b->c.lock);
goto retry;
}
}
/* XXX: waiting on IO with btree locks held: */
__bch2_btree_node_wait_on_read(b);
prefetch(b->aux_data);
for_each_bset(b, t) {
void *p = (u64 *) b->aux_data + t->aux_data_offset;
prefetch(p + L1_CACHE_BYTES * 0);
prefetch(p + L1_CACHE_BYTES * 1);
prefetch(p + L1_CACHE_BYTES * 2);
}
/* avoid atomic set bit if it's not needed: */
if (!btree_node_accessed(b))
set_btree_node_accessed(b);
if (unlikely(btree_node_read_error(b))) {
six_unlock_read(&b->c.lock);
b = ERR_PTR(-BCH_ERR_btree_node_read_error);
goto out;
}
EBUG_ON(b->c.btree_id != btree_id);
EBUG_ON(BTREE_NODE_LEVEL(b->data) != level);
btree_check_header(c, b);
out:
bch2_btree_cache_cannibalize_unlock(trans);
return b;
}
int bch2_btree_node_prefetch(struct btree_trans *trans,
struct btree_path *path,
const struct bkey_i *k,
enum btree_id btree_id, unsigned level)
{
struct bch_fs *c = trans->c;
struct btree_cache *bc = &c->btree_cache;
BUG_ON(path && !btree_node_locked(path, level + 1));
BUG_ON(level >= BTREE_MAX_DEPTH);
struct btree *b = btree_cache_find(bc, k);
if (b)
return 0;
b = bch2_btree_node_fill(trans, path, k, btree_id,
level, SIX_LOCK_read, false);
int ret = PTR_ERR_OR_ZERO(b);
if (ret)
return ret;
if (b)
six_unlock_read(&b->c.lock);
return 0;
}
void bch2_btree_node_evict(struct btree_trans *trans, const struct bkey_i *k)
{
struct bch_fs *c = trans->c;
struct btree_cache *bc = &c->btree_cache;
struct btree *b;
b = btree_cache_find(bc, k);
if (!b)
return;
BUG_ON(b == btree_node_root(trans->c, b));
wait_on_io:
/* not allowed to wait on io with btree locks held: */
/* XXX we're called from btree_gc which will be holding other btree
* nodes locked
*/
__bch2_btree_node_wait_on_read(b);
__bch2_btree_node_wait_on_write(b);
btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_intent);
btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_write);
if (unlikely(b->hash_val != btree_ptr_hash_val(k)))
goto out;
if (btree_node_dirty(b)) {
__bch2_btree_node_write(c, b, BTREE_WRITE_cache_reclaim);
six_unlock_write(&b->c.lock);
six_unlock_intent(&b->c.lock);
goto wait_on_io;
}
BUG_ON(btree_node_dirty(b));
mutex_lock(&bc->lock);
bch2_btree_node_hash_remove(bc, b);
btree_node_data_free(bc, b);
mutex_unlock(&bc->lock);
out:
six_unlock_write(&b->c.lock);
six_unlock_intent(&b->c.lock);
}
const char *bch2_btree_id_str(enum btree_id btree)
{
return btree < BTREE_ID_NR ? __bch2_btree_ids[btree] : "(unknown)";
}
void bch2_btree_id_to_text(struct printbuf *out, enum btree_id btree)
{
if (btree < BTREE_ID_NR)
prt_str(out, __bch2_btree_ids[btree]);
else
prt_printf(out, "(unknown btree %u)", btree);
}
void bch2_btree_pos_to_text(struct printbuf *out, struct bch_fs *c, const struct btree *b)
{
prt_printf(out, "%s level %u/%u\n ",
bch2_btree_id_str(b->c.btree_id),
b->c.level,
bch2_btree_id_root(c, b->c.btree_id)->level);
bch2_bkey_val_to_text(out, c, bkey_i_to_s_c(&b->key));
}
void bch2_btree_node_to_text(struct printbuf *out, struct bch_fs *c, const struct btree *b)
{
struct bset_stats stats;
memset(&stats, 0, sizeof(stats));
bch2_btree_keys_stats(b, &stats);
prt_printf(out, "l %u ", b->c.level);
bch2_bpos_to_text(out, b->data->min_key);
prt_printf(out, " - ");
bch2_bpos_to_text(out, b->data->max_key);
prt_printf(out, ":\n"
" ptrs: ");
bch2_val_to_text(out, c, bkey_i_to_s_c(&b->key));
prt_newline(out);
prt_printf(out,
" format: ");
bch2_bkey_format_to_text(out, &b->format);
prt_printf(out,
" unpack fn len: %u\n"
" bytes used %zu/%zu (%zu%% full)\n"
" sib u64s: %u, %u (merge threshold %u)\n"
" nr packed keys %u\n"
" nr unpacked keys %u\n"
" floats %zu\n"
" failed unpacked %zu\n",
b->unpack_fn_len,
b->nr.live_u64s * sizeof(u64),
btree_buf_bytes(b) - sizeof(struct btree_node),
b->nr.live_u64s * 100 / btree_max_u64s(c),
b->sib_u64s[0],
b->sib_u64s[1],
c->btree_foreground_merge_threshold,
b->nr.packed_keys,
b->nr.unpacked_keys,
stats.floats,
stats.failed);
}
static void prt_btree_cache_line(struct printbuf *out, const struct bch_fs *c,
const char *label, size_t nr)
{
prt_printf(out, "%s\t", label);
prt_human_readable_u64(out, nr * c->opts.btree_node_size);
prt_printf(out, " (%zu)\n", nr);
}
static const char * const bch2_btree_cache_not_freed_reasons_strs[] = {
#define x(n) #n,
BCH_BTREE_CACHE_NOT_FREED_REASONS()
#undef x
NULL
};
void bch2_btree_cache_to_text(struct printbuf *out, const struct btree_cache *bc)
{
struct bch_fs *c = container_of(bc, struct bch_fs, btree_cache);
if (!out->nr_tabstops)
printbuf_tabstop_push(out, 32);
prt_btree_cache_line(out, c, "live:", bc->live[0].nr);
prt_btree_cache_line(out, c, "pinned:", bc->live[1].nr);
prt_btree_cache_line(out, c, "freeable:", bc->nr_freeable);
prt_btree_cache_line(out, c, "dirty:", atomic_long_read(&bc->nr_dirty));
prt_printf(out, "cannibalize lock:\t%p\n", bc->alloc_lock);
prt_newline(out);
for (unsigned i = 0; i < ARRAY_SIZE(bc->nr_by_btree); i++)
prt_btree_cache_line(out, c, bch2_btree_id_str(i), bc->nr_by_btree[i]);
prt_newline(out);
prt_printf(out, "freed:\t%zu\n", bc->nr_freed);
prt_printf(out, "not freed:\n");
for (unsigned i = 0; i < ARRAY_SIZE(bc->not_freed); i++)
prt_printf(out, " %s\t%llu\n",
bch2_btree_cache_not_freed_reasons_strs[i], bc->not_freed[i]);
}