[PATCH v3 17/17] bcachefs: Remove heap-related macros and switch to generic min_heap

Kuan-Wei Chiu
2024-04-06T16:49:02Z

Drop the heap-related macros from bcachefs and replacing them with the
generic min_heap implementation from include/linux. By doing so, code
readability is improved by using functions instead of macros. Moreover,
the min_heap implementation in include/linux adopts a bottom-up
variation compared to the textbook version currently used in bcachefs.
This bottom-up variation allows for approximately 50% reduction in the
number of comparison operations during heap siftdown, without changing
the number of swaps, thus making it more efficient.

Link: https://lkml.kernel.org/ioyfizrzq7w7mjrqcadtzsfgpuntowtjdw5pgn4qhvsdp4mqqg@nrlek5vmisbu
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Reviewed-by: Ian Rogers <irogers@google.com>
---
Changes in v3:
- Correct bugs where the parameter types in some compare functions
should have been 'type **', but were mistakenly written as 'type *'.

fs/bcachefs/clock.c | 43 ++++++++++----
fs/bcachefs/clock_types.h | 2 +-
fs/bcachefs/ec.c | 76 ++++++++++++++++--------
fs/bcachefs/ec_types.h | 2 +-
fs/bcachefs/util.h | 118 +-------------------------------------
5 files changed, 87 insertions(+), 154 deletions(-)

diff --git a/fs/bcachefs/clock.c b/fs/bcachefs/clock.c
index 363644451106..3ec64fe6a064 100644
--- a/fs/bcachefs/clock.c
+++ b/fs/bcachefs/clock.c
@@ -6,16 +6,29 @@
#include <linux/kthread.h>
#include <linux/preempt.h>

-static inline long io_timer_cmp(io_timer_heap *h,
- struct io_timer *l,
- struct io_timer *r)
+static inline bool io_timer_cmp(const void *l, const void *r, void __always_unused *args)
{
- return l->expire - r->expire;
+ struct io_timer **_l = (struct io_timer **)l;
+ struct io_timer **_r = (struct io_timer **)r;
+
+ return (*_l)->expire < (*_r)->expire;
+}
+
+static inline void io_timer_swp(void *l, void *r, void __always_unused *args)
+{
+ struct io_timer **_l = (struct io_timer **)l;
+ struct io_timer **_r = (struct io_timer **)r;
+
+ swap(*_l, *_r);
}

void bch2_io_timer_add(struct io_clock *clock, struct io_timer *timer)
{
size_t i;
+ const struct min_heap_callbacks callbacks = {
+ .less = io_timer_cmp,
+ .swp = io_timer_swp,
+ };

spin_lock(&clock->timer_lock);

@@ -26,11 +39,11 @@ void bch2_io_timer_add(struct io_clock *clock, struct io_timer *timer)
return;
}

- for (i = 0; i < clock->timers.used; i++)
+ for (i = 0; i < clock->timers.nr; i++)
if (clock->timers.data[i] == timer)
goto out;

- BUG_ON(!heap_add(&clock->timers, timer, io_timer_cmp, NULL));
+ BUG_ON(!min_heap_push(&clock->timers, &timer, &callbacks, NULL));
out:
spin_unlock(&clock->timer_lock);
}
@@ -38,12 +51,16 @@ void bch2_io_timer_add(struct io_clock *clock, struct io_timer *timer)
void bch2_io_timer_del(struct io_clock *clock, struct io_timer *timer)
{
size_t i;
+ const struct min_heap_callbacks callbacks = {
+ .less = io_timer_cmp,
+ .swp = io_timer_swp,
+ };

spin_lock(&clock->timer_lock);

- for (i = 0; i < clock->timers.used; i++)
+ for (i = 0; i < clock->timers.nr; i++)
if (clock->timers.data[i] == timer) {
- heap_del(&clock->timers, i, io_timer_cmp, NULL);
+ min_heap_del(&clock->timers, i, &callbacks, NULL);
break;
}

@@ -131,12 +148,16 @@ static struct io_timer *get_expired_timer(struct io_clock *clock,
unsigned long now)
{
struct io_timer *ret = NULL;
+ const struct min_heap_callbacks callbacks = {
+ .less = io_timer_cmp,
+ .swp = io_timer_swp,
+ };

spin_lock(&clock->timer_lock);

- if (clock->timers.used &&
+ if (clock->timers.nr &&
time_after_eq(now, clock->timers.data[0]->expire))
- heap_pop(&clock->timers, ret, io_timer_cmp, NULL);
+ min_heap_pop(&clock->timers, &callbacks, NULL);

spin_unlock(&clock->timer_lock);

@@ -161,7 +182,7 @@ void bch2_io_timers_to_text(struct printbuf *out, struct io_clock *clock)
spin_lock(&clock->timer_lock);
now = atomic64_read(&clock->now);

- for (i = 0; i < clock->timers.used; i++)
+ for (i = 0; i < clock->timers.nr; i++)
prt_printf(out, "%ps:\t%li\n",
clock->timers.data[i]->fn,
clock->timers.data[i]->expire - now);
diff --git a/fs/bcachefs/clock_types.h b/fs/bcachefs/clock_types.h
index 5fae0012d808..59716e148645 100644
--- a/fs/bcachefs/clock_types.h
+++ b/fs/bcachefs/clock_types.h
@@ -23,7 +23,7 @@ struct io_timer {
/* Amount to buffer up on a percpu counter */
#define IO_CLOCK_PCPU_SECTORS 128

-typedef HEAP(struct io_timer *) io_timer_heap;
+typedef MIN_HEAP(struct io_timer *, io_timer_heap) io_timer_heap;

struct io_clock {
atomic64_t now;
diff --git a/fs/bcachefs/ec.c b/fs/bcachefs/ec.c
index 082075244e16..f2d00dd9ca33 100644
--- a/fs/bcachefs/ec.c
+++ b/fs/bcachefs/ec.c
@@ -866,8 +866,8 @@ static int __ec_stripe_mem_alloc(struct bch_fs *c, size_t idx, gfp_t gfp)

mutex_lock(&c->ec_stripes_heap_lock);
if (n.size > h->size) {
- memcpy(n.data, h->data, h->used * sizeof(h->data[0]));
- n.used = h->used;
+ memcpy(n.data, h->data, h->nr * sizeof(h->data[0]));
+ n.nr = h->nr;
swap(*h, n);
}
mutex_unlock(&c->ec_stripes_heap_lock);
@@ -958,7 +958,7 @@ static u64 stripe_idx_to_delete(struct bch_fs *c)

lockdep_assert_held(&c->ec_stripes_heap_lock);

- if (h->used &&
+ if (h->nr &&
h->data[0].blocks_nonempty == 0 &&
!bch2_stripe_is_open(c, h->data[0].idx))
return h->data[0].idx;
@@ -966,14 +966,6 @@ static u64 stripe_idx_to_delete(struct bch_fs *c)
return 0;
}

-static inline int ec_stripes_heap_cmp(ec_stripes_heap *h,
- struct ec_stripe_heap_entry l,
- struct ec_stripe_heap_entry r)
-{
- return ((l.blocks_nonempty > r.blocks_nonempty) -
- (l.blocks_nonempty < r.blocks_nonempty));
-}
-
static inline void ec_stripes_heap_set_backpointer(ec_stripes_heap *h,
size_t i)
{
@@ -982,39 +974,71 @@ static inline void ec_stripes_heap_set_backpointer(ec_stripes_heap *h,
genradix_ptr(&c->stripes, h->data[i].idx)->heap_idx = i;
}

+static inline bool ec_stripes_heap_cmp(const void *l, const void *r, void __always_unused *args)
+{
+ struct ec_stripe_heap_entry *_l = (struct ec_stripe_heap_entry *)l;
+ struct ec_stripe_heap_entry *_r = (struct ec_stripe_heap_entry *)r;
+
+ return ((_l->blocks_nonempty > _r->blocks_nonempty) <
+ (_l->blocks_nonempty < _r->blocks_nonempty));
+}
+
+static inline void ec_stripes_heap_swap(void *l, void *r, void *h)
+{
+ struct ec_stripe_heap_entry *_l = (struct ec_stripe_heap_entry *)l;
+ struct ec_stripe_heap_entry *_r = (struct ec_stripe_heap_entry *)r;
+ ec_stripes_heap *_h = (ec_stripes_heap *)h;
+ size_t i = _l - _h->data;
+ size_t j = _r - _h->data;
+
+ ec_stripes_heap_set_backpointer(_h, i);
+ ec_stripes_heap_set_backpointer(_h, j);
+
+ swap(*_l, *_r);
+}
+
static void heap_verify_backpointer(struct bch_fs *c, size_t idx)
{
ec_stripes_heap *h = &c->ec_stripes_heap;
struct stripe *m = genradix_ptr(&c->stripes, idx);

- BUG_ON(m->heap_idx >= h->used);
+ BUG_ON(m->heap_idx >= h->nr);
BUG_ON(h->data[m->heap_idx].idx != idx);
}

void bch2_stripes_heap_del(struct bch_fs *c,
struct stripe *m, size_t idx)
{
+ const struct min_heap_callbacks callbacks = {
+ .less = ec_stripes_heap_cmp,
+ .swp = ec_stripes_heap_swap,
+ };
+
mutex_lock(&c->ec_stripes_heap_lock);
heap_verify_backpointer(c, idx);

- heap_del(&c->ec_stripes_heap, m->heap_idx,
- ec_stripes_heap_cmp,
- ec_stripes_heap_set_backpointer);
+ min_heap_del(&c->ec_stripes_heap, m->heap_idx, &callbacks, &c->ec_stripes_heap);
mutex_unlock(&c->ec_stripes_heap_lock);
}

void bch2_stripes_heap_insert(struct bch_fs *c,
struct stripe *m, size_t idx)
{
+ const struct min_heap_callbacks callbacks = {
+ .less = ec_stripes_heap_cmp,
+ .swp = ec_stripes_heap_swap,
+ };
+
mutex_lock(&c->ec_stripes_heap_lock);
- BUG_ON(heap_full(&c->ec_stripes_heap));
+ BUG_ON(min_heap_full(&c->ec_stripes_heap));

- heap_add(&c->ec_stripes_heap, ((struct ec_stripe_heap_entry) {
+ genradix_ptr(&c->stripes, idx)->heap_idx = c->ec_stripes_heap.nr;
+ min_heap_push(&c->ec_stripes_heap, &((struct ec_stripe_heap_entry) {
.idx = idx,
.blocks_nonempty = m->blocks_nonempty,
}),
- ec_stripes_heap_cmp,
- ec_stripes_heap_set_backpointer);
+ &callbacks,
+ &c->ec_stripes_heap);

heap_verify_backpointer(c, idx);
mutex_unlock(&c->ec_stripes_heap_lock);
@@ -1023,6 +1047,10 @@ void bch2_stripes_heap_insert(struct bch_fs *c,
void bch2_stripes_heap_update(struct bch_fs *c,
struct stripe *m, size_t idx)
{
+ const struct min_heap_callbacks callbacks = {
+ .less = ec_stripes_heap_cmp,
+ .swp = ec_stripes_heap_swap,
+ };
ec_stripes_heap *h = &c->ec_stripes_heap;
bool do_deletes;
size_t i;
@@ -1033,10 +1061,8 @@ void bch2_stripes_heap_update(struct bch_fs *c,
h->data[m->heap_idx].blocks_nonempty = m->blocks_nonempty;

i = m->heap_idx;
- heap_sift_up(h, i, ec_stripes_heap_cmp,
- ec_stripes_heap_set_backpointer);
- heap_sift_down(h, i, ec_stripes_heap_cmp,
- ec_stripes_heap_set_backpointer);
+ min_heap_sift_up(h, i, &callbacks, &c->ec_stripes_heap);
+ min_heap_sift_down(h, i, &callbacks, &c->ec_stripes_heap);

heap_verify_backpointer(c, idx);

@@ -1828,7 +1854,7 @@ static s64 get_existing_stripe(struct bch_fs *c,
return -1;

mutex_lock(&c->ec_stripes_heap_lock);
- for (heap_idx = 0; heap_idx < h->used; heap_idx++) {
+ for (heap_idx = 0; heap_idx < h->nr; heap_idx++) {
/* No blocks worth reusing, stripe will just be deleted: */
if (!h->data[heap_idx].blocks_nonempty)
continue;
@@ -2159,7 +2185,7 @@ void bch2_stripes_heap_to_text(struct printbuf *out, struct bch_fs *c)
size_t i;

mutex_lock(&c->ec_stripes_heap_lock);
- for (i = 0; i < min_t(size_t, h->used, 50); i++) {
+ for (i = 0; i < min_t(size_t, h->nr, 50); i++) {
m = genradix_ptr(&c->stripes, h->data[i].idx);

prt_printf(out, "%zu %u/%u+%u", h->data[i].idx,
diff --git a/fs/bcachefs/ec_types.h b/fs/bcachefs/ec_types.h
index 976426da3a12..2ed67431a81c 100644
--- a/fs/bcachefs/ec_types.h
+++ b/fs/bcachefs/ec_types.h
@@ -36,6 +36,6 @@ struct ec_stripe_heap_entry {
unsigned blocks_nonempty;
};

-typedef HEAP(struct ec_stripe_heap_entry) ec_stripes_heap;
+typedef MIN_HEAP(struct ec_stripe_heap_entry, ec_stripes_heap) ec_stripes_heap;

#endif /* _BCACHEFS_EC_TYPES_H */
diff --git a/fs/bcachefs/util.h b/fs/bcachefs/util.h
index b7e7c29278fc..9757c2c1218e 100644
--- a/fs/bcachefs/util.h
+++ b/fs/bcachefs/util.h
@@ -8,6 +8,7 @@
#include <linux/errno.h>
#include <linux/freezer.h>
#include <linux/kernel.h>
+#include <linux/min_heap.h>
#include <linux/sched/clock.h>
#include <linux/llist.h>
#include <linux/log2.h>
@@ -54,17 +55,9 @@ static inline size_t buf_pages(void *p, size_t len)
PAGE_SIZE);
}

-#define HEAP(type) \
-struct { \
- size_t size, used; \
- type *data; \
-}
-
-#define DECLARE_HEAP(type, name) HEAP(type) name
-
#define init_heap(heap, _size, gfp) \
({ \
- (heap)->used = 0; \
+ (heap)->nr = 0; \
(heap)->size = (_size); \
(heap)->data = kvmalloc((heap)->size * sizeof((heap)->data[0]),\
(gfp)); \
@@ -76,113 +69,6 @@ do { \
(heap)->data = NULL; \
} while (0)

-#define heap_set_backpointer(h, i, _fn) \
-do { \
- void (*fn)(typeof(h), size_t) = _fn; \
- if (fn) \
- fn(h, i); \
-} while (0)
-
-#define heap_swap(h, i, j, set_backpointer) \
-do { \
- swap((h)->data[i], (h)->data[j]); \
- heap_set_backpointer(h, i, set_backpointer); \
- heap_set_backpointer(h, j, set_backpointer); \
-} while (0)
-
-#define heap_peek(h) \
-({ \
- EBUG_ON(!(h)->used); \
- (h)->data[0]; \
-})
-
-#define heap_full(h) ((h)->used == (h)->size)
-
-#define heap_sift_down(h, i, cmp, set_backpointer) \
-do { \
- size_t _c, _j = i; \
- \
- for (; _j * 2 + 1 < (h)->used; _j = _c) { \
- _c = _j * 2 + 1; \
- if (_c + 1 < (h)->used && \
- cmp(h, (h)->data[_c], (h)->data[_c + 1]) >= 0) \
- _c++; \
- \
- if (cmp(h, (h)->data[_c], (h)->data[_j]) >= 0) \
- break; \
- heap_swap(h, _c, _j, set_backpointer); \
- } \
-} while (0)
-
-#define heap_sift_up(h, i, cmp, set_backpointer) \
-do { \
- while (i) { \
- size_t p = (i - 1) / 2; \
- if (cmp(h, (h)->data[i], (h)->data[p]) >= 0) \
- break; \
- heap_swap(h, i, p, set_backpointer); \
- i = p; \
- } \
-} while (0)
-
-#define __heap_add(h, d, cmp, set_backpointer) \
-({ \
- size_t _i = (h)->used++; \
- (h)->data[_i] = d; \
- heap_set_backpointer(h, _i, set_backpointer); \
- \
- heap_sift_up(h, _i, cmp, set_backpointer); \
- _i; \
-})
-
-#define heap_add(h, d, cmp, set_backpointer) \
-({ \
- bool _r = !heap_full(h); \
- if (_r) \
- __heap_add(h, d, cmp, set_backpointer); \
- _r; \
-})
-
-#define heap_add_or_replace(h, new, cmp, set_backpointer) \
-do { \
- if (!heap_add(h, new, cmp, set_backpointer) && \
- cmp(h, new, heap_peek(h)) >= 0) { \
- (h)->data[0] = new; \
- heap_set_backpointer(h, 0, set_backpointer); \
- heap_sift_down(h, 0, cmp, set_backpointer); \
- } \
-} while (0)
-
-#define heap_del(h, i, cmp, set_backpointer) \
-do { \
- size_t _i = (i); \
- \
- BUG_ON(_i >= (h)->used); \
- (h)->used--; \
- if ((_i) < (h)->used) { \
- heap_swap(h, _i, (h)->used, set_backpointer); \
- heap_sift_up(h, _i, cmp, set_backpointer); \
- heap_sift_down(h, _i, cmp, set_backpointer); \
- } \
-} while (0)
-
-#define heap_pop(h, d, cmp, set_backpointer) \
-({ \
- bool _r = (h)->used; \
- if (_r) { \
- (d) = (h)->data[0]; \
- heap_del(h, 0, cmp, set_backpointer); \
- } \
- _r; \
-})
-
-#define heap_resort(heap, cmp, set_backpointer) \
-do { \
- ssize_t _i; \
- for (_i = (ssize_t) (heap)->used / 2 - 1; _i >= 0; --_i) \
- heap_sift_down(heap, _i, cmp, set_backpointer); \
-} while (0)
-
#define ANYSINT_MAX(t) \
((((t) 1 << (sizeof(t) * 8 - 2)) - (t) 1) * (t) 2 + (t) 1)

--
2.34.1