bcachefs: Convert various code to printbuf

printbufs know how big the buffer is that was allocated, so we can get
rid of the random PAGE_SIZEs all over the place.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_io.c

@@ -1835,9 +1835,8 @@ void bch2_btree_verify_flushed(struct bch_fs *c)
 	rcu_read_unlock();
 }
 
-ssize_t bch2_dirty_btree_nodes_print(struct bch_fs *c, char *buf)
+void bch2_dirty_btree_nodes_to_text(struct printbuf *out, struct bch_fs *c)
 {
-	struct printbuf out = _PBUF(buf, PAGE_SIZE);
 	struct bucket_table *tbl;
 	struct rhash_head *pos;
 	struct btree *b;
@@ -1850,7 +1849,7 @@ ssize_t bch2_dirty_btree_nodes_print(struct bch_fs *c, char *buf)
 		if (!(flags & (1 << BTREE_NODE_dirty)))
 			continue;
 
-		pr_buf(&out, "%p d %u n %u l %u w %u b %u r %u:%lu\n",
+		pr_buf(out, "%p d %u n %u l %u w %u b %u r %u:%lu\n",
 		       b,
 		       (flags & (1 << BTREE_NODE_dirty)) != 0,
 		       (flags & (1 << BTREE_NODE_need_write)) != 0,
@@ -1861,6 +1860,4 @@ ssize_t bch2_dirty_btree_nodes_print(struct bch_fs *c, char *buf)
 		       b->will_make_reachable & 1);
 	}
 	rcu_read_unlock();
-
-	return out.pos - buf;
 }

fs/bcachefs/btree_io.h

@@ -140,7 +140,7 @@ do {									\
 void bch2_btree_flush_all_reads(struct bch_fs *);
 void bch2_btree_flush_all_writes(struct bch_fs *);
 void bch2_btree_verify_flushed(struct bch_fs *);
-ssize_t bch2_dirty_btree_nodes_print(struct bch_fs *, char *);
+void bch2_dirty_btree_nodes_to_text(struct printbuf *, struct bch_fs *);
 
 static inline void compat_bformat(unsigned level, enum btree_id btree_id,
 				 unsigned version, unsigned big_endian,

fs/bcachefs/btree_update_interior.c

@@ -1974,22 +1974,19 @@ void bch2_btree_root_alloc(struct bch_fs *c, enum btree_id id)
 	six_unlock_intent(&b->c.lock);
 }
 
-ssize_t bch2_btree_updates_print(struct bch_fs *c, char *buf)
+void bch2_btree_updates_to_text(struct printbuf *out, struct bch_fs *c)
 {
-	struct printbuf out = _PBUF(buf, PAGE_SIZE);
 	struct btree_update *as;
 
 	mutex_lock(&c->btree_interior_update_lock);
 	list_for_each_entry(as, &c->btree_interior_update_list, list)
-		pr_buf(&out, "%p m %u w %u r %u j %llu\n",
+		pr_buf(out, "%p m %u w %u r %u j %llu\n",
 		       as,
 		       as->mode,
 		       as->nodes_written,
 		       atomic_read(&as->cl.remaining) & CLOSURE_REMAINING_MASK,
 		       as->journal.seq);
 	mutex_unlock(&c->btree_interior_update_lock);
-
-	return out.pos - buf;
 }
 
 size_t bch2_btree_interior_updates_nr_pending(struct bch_fs *c)

fs/bcachefs/btree_update_interior.h

@@ -317,7 +317,7 @@ static inline bool bch2_btree_node_insert_fits(struct bch_fs *c,
 	return u64s <= bch_btree_keys_u64s_remaining(c, b);
 }
 
-ssize_t bch2_btree_updates_print(struct bch_fs *, char *);
+void bch2_btree_updates_to_text(struct printbuf *, struct bch_fs *);
 
 size_t bch2_btree_interior_updates_nr_pending(struct bch_fs *);
 

fs/bcachefs/clock.c

@@ -152,9 +152,8 @@ void __bch2_increment_clock(struct io_clock *clock, unsigned sectors)
 		timer->fn(timer);
 }
 
-ssize_t bch2_io_timers_show(struct io_clock *clock, char *buf)
+void bch2_io_timers_to_text(struct printbuf *out, struct io_clock *clock)
 {
-	struct printbuf out = _PBUF(buf, PAGE_SIZE);
 	unsigned long now;
 	unsigned i;
 
@@ -162,12 +161,10 @@ ssize_t bch2_io_timers_show(struct io_clock *clock, char *buf)
 	now = atomic_long_read(&clock->now);
 
 	for (i = 0; i < clock->timers.used; i++)
-		pr_buf(&out, "%ps:\t%li\n",
+		pr_buf(out, "%ps:\t%li\n",
 		       clock->timers.data[i]->fn,
 		       clock->timers.data[i]->expire - now);
 	spin_unlock(&clock->timer_lock);
-
-	return out.pos - buf;
 }
 
 void bch2_io_clock_exit(struct io_clock *clock)

fs/bcachefs/clock.h

@@ -30,7 +30,7 @@ void bch2_io_clock_schedule_timeout(struct io_clock *, unsigned long);
 	__ret;								\
 })
 
-ssize_t bch2_io_timers_show(struct io_clock *, char *);
+void bch2_io_timers_to_text(struct printbuf *, struct io_clock *);
 
 void bch2_io_clock_exit(struct io_clock *);
 int bch2_io_clock_init(struct io_clock *);

fs/bcachefs/ec.c

@@ -1575,6 +1575,35 @@ void bch2_stripes_heap_to_text(struct printbuf *out, struct bch_fs *c)
 	spin_unlock(&c->ec_stripes_heap_lock);
 }
 
+void bch2_new_stripes_to_text(struct printbuf *out, struct bch_fs *c)
+{
+	struct ec_stripe_head *h;
+	struct ec_stripe_new *s;
+
+	mutex_lock(&c->ec_stripe_head_lock);
+	list_for_each_entry(h, &c->ec_stripe_head_list, list) {
+		pr_buf(out, "target %u algo %u redundancy %u:\n",
+		       h->target, h->algo, h->redundancy);
+
+		if (h->s)
+			pr_buf(out, "\tpending: blocks %u allocated %u\n",
+			       h->s->blocks.nr,
+			       bitmap_weight(h->s->blocks_allocated,
+					     h->s->blocks.nr));
+	}
+	mutex_unlock(&c->ec_stripe_head_lock);
+
+	mutex_lock(&c->ec_stripe_new_lock);
+	list_for_each_entry(h, &c->ec_stripe_new_list, list) {
+		pr_buf(out, "\tin flight: blocks %u allocated %u pin %u\n",
+		       s->blocks.nr,
+		       bitmap_weight(s->blocks_allocated,
+				     s->blocks.nr),
+		       atomic_read(&s->pin));
+	}
+	mutex_unlock(&c->ec_stripe_new_lock);
+}
+
 void bch2_fs_ec_exit(struct bch_fs *c)
 {
 	struct ec_stripe_head *h;

fs/bcachefs/ec.h

@@ -161,6 +161,7 @@ int bch2_stripes_write(struct bch_fs *, unsigned, bool *);
 int bch2_ec_mem_alloc(struct bch_fs *, bool);
 
 void bch2_stripes_heap_to_text(struct printbuf *, struct bch_fs *);
+void bch2_new_stripes_to_text(struct printbuf *, struct bch_fs *);
 
 void bch2_fs_ec_exit(struct bch_fs *);
 int bch2_fs_ec_init(struct bch_fs *);

fs/bcachefs/journal.c

@@ -1137,9 +1137,8 @@ int bch2_fs_journal_init(struct journal *j)
 
 /* debug: */
 
-ssize_t bch2_journal_print_debug(struct journal *j, char *buf)
+void bch2_journal_debug_to_text(struct printbuf *out, struct journal *j)
 {
-	struct printbuf out = _PBUF(buf, PAGE_SIZE);
 	struct bch_fs *c = container_of(j, struct bch_fs, journal);
 	union journal_res_state s;
 	struct bch_dev *ca;
@@ -1149,7 +1148,7 @@ ssize_t bch2_journal_print_debug(struct journal *j, char *buf)
 	spin_lock(&j->lock);
 	s = READ_ONCE(j->reservations);
 
-	pr_buf(&out,
+	pr_buf(out,
 	       "active journal entries:\t%llu\n"
 	       "seq:\t\t\t%llu\n"
 	       "last_seq:\t\t%llu\n"
@@ -1167,31 +1166,31 @@ ssize_t bch2_journal_print_debug(struct journal *j, char *buf)
 
 	switch (s.cur_entry_offset) {
 	case JOURNAL_ENTRY_ERROR_VAL:
-		pr_buf(&out, "error\n");
+		pr_buf(out, "error\n");
 		break;
 	case JOURNAL_ENTRY_CLOSED_VAL:
-		pr_buf(&out, "closed\n");
+		pr_buf(out, "closed\n");
 		break;
 	default:
-		pr_buf(&out, "%u/%u\n",
+		pr_buf(out, "%u/%u\n",
 		       s.cur_entry_offset,
 		       j->cur_entry_u64s);
 		break;
 	}
 
-	pr_buf(&out,
+	pr_buf(out,
 	       "current entry refs:\t%u\n"
 	       "prev entry unwritten:\t",
 	       journal_state_count(s, s.idx));
 
 	if (s.prev_buf_unwritten)
-		pr_buf(&out, "yes, ref %u sectors %u\n",
+		pr_buf(out, "yes, ref %u sectors %u\n",
 		       journal_state_count(s, !s.idx),
 		       journal_prev_buf(j)->sectors);
 	else
-		pr_buf(&out, "no\n");
+		pr_buf(out, "no\n");
 
-	pr_buf(&out,
+	pr_buf(out,
 	       "need write:\t\t%i\n"
 	       "replay done:\t\t%i\n",
 	       test_bit(JOURNAL_NEED_WRITE,	&j->flags),
@@ -1204,7 +1203,7 @@ ssize_t bch2_journal_print_debug(struct journal *j, char *buf)
 		if (!ja->nr)
 			continue;
 
-		pr_buf(&out,
+		pr_buf(out,
 		       "dev %u:\n"
 		       "\tnr\t\t%u\n"
 		       "\tavailable\t%u:%u\n"
@@ -1223,34 +1222,29 @@ ssize_t bch2_journal_print_debug(struct journal *j, char *buf)
 
 	spin_unlock(&j->lock);
 	rcu_read_unlock();
-
-	return out.pos - buf;
 }
 
-ssize_t bch2_journal_print_pins(struct journal *j, char *buf)
+void bch2_journal_pins_to_text(struct printbuf *out, struct journal *j)
 {
-	struct printbuf out = _PBUF(buf, PAGE_SIZE);
 	struct journal_entry_pin_list *pin_list;
 	struct journal_entry_pin *pin;
 	u64 i;
 
 	spin_lock(&j->lock);
 	fifo_for_each_entry_ptr(pin_list, &j->pin, i) {
-		pr_buf(&out, "%llu: count %u\n",
+		pr_buf(out, "%llu: count %u\n",
 		       i, atomic_read(&pin_list->count));
 
 		list_for_each_entry(pin, &pin_list->list, list)
-			pr_buf(&out, "\t%px %ps\n",
+			pr_buf(out, "\t%px %ps\n",
 			       pin, pin->flush);
 
 		if (!list_empty(&pin_list->flushed))
-			pr_buf(&out, "flushed:\n");
+			pr_buf(out, "flushed:\n");
 
 		list_for_each_entry(pin, &pin_list->flushed, list)
-			pr_buf(&out, "\t%px %ps\n",
+			pr_buf(out, "\t%px %ps\n",
 			       pin, pin->flush);
 	}
 	spin_unlock(&j->lock);
-
-	return out.pos - buf;
 }

fs/bcachefs/journal.h

@@ -501,8 +501,8 @@ static inline void bch2_journal_set_replay_done(struct journal *j)
 void bch2_journal_unblock(struct journal *);
 void bch2_journal_block(struct journal *);
 
-ssize_t bch2_journal_print_debug(struct journal *, char *);
-ssize_t bch2_journal_print_pins(struct journal *, char *);
+void bch2_journal_debug_to_text(struct printbuf *, struct journal *);
+void bch2_journal_pins_to_text(struct printbuf *, struct journal *);
 
 int bch2_set_nr_journal_buckets(struct bch_fs *, struct bch_dev *,
 				unsigned nr);

fs/bcachefs/rebalance.c

@@ -249,45 +249,42 @@ static int bch2_rebalance_thread(void *arg)
 	return 0;
 }
 
-ssize_t bch2_rebalance_work_show(struct bch_fs *c, char *buf)
+void bch2_rebalance_work_to_text(struct printbuf *out, struct bch_fs *c)
 {
-	struct printbuf out = _PBUF(buf, PAGE_SIZE);
 	struct bch_fs_rebalance *r = &c->rebalance;
 	struct rebalance_work w = rebalance_work(c);
 	char h1[21], h2[21];
 
 	bch2_hprint(&PBUF(h1), w.dev_most_full_work << 9);
 	bch2_hprint(&PBUF(h2), w.dev_most_full_capacity << 9);
-	pr_buf(&out, "fullest_dev (%i):\t%s/%s\n",
+	pr_buf(out, "fullest_dev (%i):\t%s/%s\n",
 	       w.dev_most_full_idx, h1, h2);
 
 	bch2_hprint(&PBUF(h1), w.total_work << 9);
 	bch2_hprint(&PBUF(h2), c->capacity << 9);
-	pr_buf(&out, "total work:\t\t%s/%s\n", h1, h2);
+	pr_buf(out, "total work:\t\t%s/%s\n", h1, h2);
 
-	pr_buf(&out, "rate:\t\t\t%u\n", r->pd.rate.rate);
+	pr_buf(out, "rate:\t\t\t%u\n", r->pd.rate.rate);
 
 	switch (r->state) {
 	case REBALANCE_WAITING:
-		pr_buf(&out, "waiting\n");
+		pr_buf(out, "waiting\n");
 		break;
 	case REBALANCE_THROTTLED:
 		bch2_hprint(&PBUF(h1),
 			    (r->throttled_until_iotime -
 			     atomic_long_read(&c->io_clock[WRITE].now)) << 9);
-		pr_buf(&out, "throttled for %lu sec or %s io\n",
+		pr_buf(out, "throttled for %lu sec or %s io\n",
 		       (r->throttled_until_cputime - jiffies) / HZ,
 		       h1);
 		break;
 	case REBALANCE_RUNNING:
-		pr_buf(&out, "running\n");
-		pr_buf(&out, "pos %llu:%llu\n",
+		pr_buf(out, "running\n");
+		pr_buf(out, "pos %llu:%llu\n",
 		       r->move_stats.pos.inode,
 		       r->move_stats.pos.offset);
 		break;
 	}
-
-	return out.pos - buf;
 }
 
 void bch2_rebalance_stop(struct bch_fs *c)

fs/bcachefs/rebalance.h

@@ -19,7 +19,7 @@ void bch2_rebalance_add_key(struct bch_fs *, struct bkey_s_c,
 			    struct bch_io_opts *);
 void bch2_rebalance_add_work(struct bch_fs *, u64);
 
-ssize_t bch2_rebalance_work_show(struct bch_fs *, char *);
+void bch2_rebalance_work_to_text(struct printbuf *, struct bch_fs *);
 
 void bch2_rebalance_stop(struct bch_fs *);
 int bch2_rebalance_start(struct bch_fs *);

fs/bcachefs/sysfs.c

@@ -75,7 +75,6 @@ do {									\
 #define sysfs_hprint(file, val)						\
 do {									\
 	if (attr == &sysfs_ ## file) {					\
-		struct printbuf out = _PBUF(buf, PAGE_SIZE);		\
 		bch2_hprint(&out, val);					\
 		pr_buf(&out, "\n");					\
 		return out.pos - buf;					\
@@ -239,24 +238,22 @@ static size_t bch2_btree_cache_size(struct bch_fs *c)
 	return ret;
 }
 
-static ssize_t show_fs_alloc_debug(struct bch_fs *c, char *buf)
+static int fs_alloc_debug_to_text(struct printbuf *out, struct bch_fs *c)
 {
-	struct printbuf out = _PBUF(buf, PAGE_SIZE);
 	struct bch_fs_usage_online *fs_usage = bch2_fs_usage_read(c);
 
 	if (!fs_usage)
 		return -ENOMEM;
 
-	bch2_fs_usage_to_text(&out, c, fs_usage);
+	bch2_fs_usage_to_text(out, c, fs_usage);
 
 	percpu_up_read(&c->mark_lock);
 
 	kfree(fs_usage);
-
-	return out.pos - buf;
+	return 0;
 }
 
-static ssize_t bch2_compression_stats(struct bch_fs *c, char *buf)
+static int bch2_compression_stats_to_text(struct printbuf *out, struct bch_fs *c)
 {
 	struct btree_trans trans;
 	struct btree_iter *iter;
@@ -299,7 +296,7 @@ static ssize_t bch2_compression_stats(struct bch_fs *c, char *buf)
 	if (ret)
 		return ret;
 
-	return scnprintf(buf, PAGE_SIZE,
+	pr_buf(out,
 	       "uncompressed data:\n"
 	       "	nr extents:			%llu\n"
 	       "	size (bytes):			%llu\n"
@@ -312,46 +309,13 @@ static ssize_t bch2_compression_stats(struct bch_fs *c, char *buf)
 	       nr_compressed_extents,
 	       compressed_sectors_compressed << 9,
 	       compressed_sectors_uncompressed << 9);
-}
-
-static ssize_t bch2_new_stripes(struct bch_fs *c, char *buf)
-{
-	char *out = buf, *end = buf + PAGE_SIZE;
-	struct ec_stripe_head *h;
-	struct ec_stripe_new *s;
-
-	mutex_lock(&c->ec_stripe_head_lock);
-	list_for_each_entry(h, &c->ec_stripe_head_list, list) {
-		out += scnprintf(out, end - out,
-				 "target %u algo %u redundancy %u:\n",
-				 h->target, h->algo, h->redundancy);
-
-		if (h->s)
-			out += scnprintf(out, end - out,
-					 "\tpending: blocks %u allocated %u\n",
-					 h->s->blocks.nr,
-					 bitmap_weight(h->s->blocks_allocated,
-						       h->s->blocks.nr));
-	}
-	mutex_unlock(&c->ec_stripe_head_lock);
-
-	mutex_lock(&c->ec_stripe_new_lock);
-	list_for_each_entry(h, &c->ec_stripe_new_list, list) {
-		out += scnprintf(out, end - out,
-				 "\tin flight: blocks %u allocated %u pin %u\n",
-				 s->blocks.nr,
-				 bitmap_weight(s->blocks_allocated,
-					       s->blocks.nr),
-				 atomic_read(&s->pin));
-	}
-	mutex_unlock(&c->ec_stripe_new_lock);
-
-	return out - buf;
+	return 0;
 }
 
 SHOW(bch2_fs)
 {
 	struct bch_fs *c = container_of(kobj, struct bch_fs, kobj);
+	struct printbuf out = _PBUF(buf, PAGE_SIZE);
 
 	sysfs_print(minor,			c->minor);
 	sysfs_printf(internal_uuid, "%pU",	c->sb.uuid.b);
@@ -381,8 +345,10 @@ SHOW(bch2_fs)
 	sysfs_pd_controller_show(rebalance,	&c->rebalance.pd); /* XXX */
 	sysfs_pd_controller_show(copy_gc,	&c->copygc_pd);
 
-	if (attr == &sysfs_rebalance_work)
-		return bch2_rebalance_work_show(c, buf);
+	if (attr == &sysfs_rebalance_work) {
+		bch2_rebalance_work_to_text(&out, c);
+		return out.pos - buf;
+	}
 
 	sysfs_print(promote_whole_extents,	c->promote_whole_extents);
 
@@ -392,51 +358,61 @@ SHOW(bch2_fs)
 	/* Debugging: */
 
 	if (attr == &sysfs_alloc_debug)
-		return show_fs_alloc_debug(c, buf);
+		return fs_alloc_debug_to_text(&out, c) ?: out.pos - buf;
 
-	if (attr == &sysfs_journal_debug)
-		return bch2_journal_print_debug(&c->journal, buf);
+	if (attr == &sysfs_journal_debug) {
+		bch2_journal_debug_to_text(&out, &c->journal);
+		return out.pos - buf;
+	}
 
-	if (attr == &sysfs_journal_pins)
-		return bch2_journal_print_pins(&c->journal, buf);
+	if (attr == &sysfs_journal_pins) {
+		bch2_journal_pins_to_text(&out, &c->journal);
+		return out.pos - buf;
+	}
 
-	if (attr == &sysfs_btree_updates)
-		return bch2_btree_updates_print(c, buf);
+	if (attr == &sysfs_btree_updates) {
+		bch2_btree_updates_to_text(&out, c);
+		return out.pos - buf;
+	}
 
-	if (attr == &sysfs_dirty_btree_nodes)
-		return bch2_dirty_btree_nodes_print(c, buf);
+	if (attr == &sysfs_dirty_btree_nodes) {
+		bch2_dirty_btree_nodes_to_text(&out, c);
+		return out.pos - buf;
+	}
 
 	if (attr == &sysfs_btree_key_cache) {
-		struct printbuf out = _PBUF(buf, PAGE_SIZE);
-
 		bch2_btree_key_cache_to_text(&out, &c->btree_key_cache);
 		return out.pos - buf;
 	}
 
 	if (attr == &sysfs_btree_transactions) {
-		struct printbuf out = _PBUF(buf, PAGE_SIZE);
-
 		bch2_btree_trans_to_text(&out, c);
 		return out.pos - buf;
 	}
 
 	if (attr == &sysfs_stripes_heap) {
-		struct printbuf out = _PBUF(buf, PAGE_SIZE);
-
 		bch2_stripes_heap_to_text(&out, c);
 		return out.pos - buf;
 	}
 
-	if (attr == &sysfs_compression_stats)
-		return bch2_compression_stats(c, buf);
+	if (attr == &sysfs_compression_stats) {
+		bch2_compression_stats_to_text(&out, c);
+		return out.pos - buf;
+	}
 
-	if (attr == &sysfs_new_stripes)
-		return bch2_new_stripes(c, buf);
+	if (attr == &sysfs_new_stripes) {
+		bch2_new_stripes_to_text(&out, c);
+		return out.pos - buf;
+	}
 
-	if (attr == &sysfs_io_timers_read)
-		return bch2_io_timers_show(&c->io_clock[READ], buf);
-	if (attr == &sysfs_io_timers_write)
-		return bch2_io_timers_show(&c->io_clock[WRITE], buf);
+	if (attr == &sysfs_io_timers_read) {
+		bch2_io_timers_to_text(&out, &c->io_clock[READ]);
+		return out.pos - buf;
+	}
+	if (attr == &sysfs_io_timers_write) {
+		bch2_io_timers_to_text(&out, &c->io_clock[WRITE]);
+		return out.pos - buf;
+	}
 
 #define BCH_DEBUG_PARAM(name, description) sysfs_print(name, c->name);
 	BCH_DEBUG_PARAMS()
@@ -705,11 +681,13 @@ int bch2_opts_create_sysfs_files(struct kobject *kobj)
 SHOW(bch2_fs_time_stats)
 {
 	struct bch_fs *c = container_of(kobj, struct bch_fs, time_stats);
+	struct printbuf out = _PBUF(buf, PAGE_SIZE);
 
 #define x(name)								\
-	if (attr == &sysfs_time_stat_##name)				\
-		return bch2_time_stats_print(&c->times[BCH_TIME_##name],\
-					     buf, PAGE_SIZE);
+	if (attr == &sysfs_time_stat_##name) {				\
+		bch2_time_stats_to_text(&out, &c->times[BCH_TIME_##name]);\
+		return out.pos - buf;					\
+	}
 	BCH_TIME_STATS()
 #undef x
 
@@ -762,13 +740,13 @@ static int unsigned_cmp(const void *_l, const void *_r)
 	return cmp_int(*l, *r);
 }
 
-static ssize_t show_quantiles(struct bch_fs *c, struct bch_dev *ca,
-			      char *buf, bucket_map_fn *fn, void *private)
+static int quantiles_to_text(struct printbuf *out,
+			     struct bch_fs *c, struct bch_dev *ca,
+			     bucket_map_fn *fn, void *private)
 {
 	size_t i, n;
 	/* Compute 31 quantiles */
 	unsigned q[31], *p;
-	ssize_t ret = 0;
 
 	down_read(&ca->bucket_lock);
 	n = ca->mi.nbuckets;
@@ -795,35 +773,30 @@ static ssize_t show_quantiles(struct bch_fs *c, struct bch_dev *ca,
 	vfree(p);
 
 	for (i = 0; i < ARRAY_SIZE(q); i++)
-		ret += scnprintf(buf + ret, PAGE_SIZE - ret,
-				 "%u ", q[i]);
-	buf[ret - 1] = '\n';
-
-	return ret;
+		pr_buf(out, "%u ", q[i]);
+	pr_buf(out, "\n");
+	return 0;
 }
 
-static ssize_t show_reserve_stats(struct bch_dev *ca, char *buf)
+static void reserve_stats_to_text(struct printbuf *out, struct bch_dev *ca)
 {
-	struct printbuf out = _PBUF(buf, PAGE_SIZE);
 	enum alloc_reserve i;
 
 	spin_lock(&ca->fs->freelist_lock);
 
-	pr_buf(&out, "free_inc:\t%zu\t%zu\n",
+	pr_buf(out, "free_inc:\t%zu\t%zu\n",
 	       fifo_used(&ca->free_inc),
 	       ca->free_inc.size);
 
 	for (i = 0; i < RESERVE_NR; i++)
-		pr_buf(&out, "free[%u]:\t%zu\t%zu\n", i,
+		pr_buf(out, "free[%u]:\t%zu\t%zu\n", i,
 		       fifo_used(&ca->free[i]),
 		       ca->free[i].size);
 
 	spin_unlock(&ca->fs->freelist_lock);
-
-	return out.pos - buf;
 }
 
-static ssize_t show_dev_alloc_debug(struct bch_dev *ca, char *buf)
+static void dev_alloc_debug_to_text(struct printbuf *out, struct bch_dev *ca)
 {
 	struct bch_fs *c = ca->fs;
 	struct bch_dev_usage stats = bch2_dev_usage_read(ca);
@@ -834,7 +807,7 @@ static ssize_t show_dev_alloc_debug(struct bch_dev *ca, char *buf)
 	for (i = 0; i < ARRAY_SIZE(c->open_buckets); i++)
 		nr[c->open_buckets[i].type]++;
 
-	return scnprintf(buf, PAGE_SIZE,
+	pr_buf(out,
 		"free_inc:               %zu/%zu\n"
 		"free[RESERVE_BTREE]:    %zu/%zu\n"
 		"free[RESERVE_MOVINGGC]: %zu/%zu\n"
@@ -898,21 +871,18 @@ static const char * const bch2_rw[] = {
 	NULL
 };
 
-static ssize_t show_dev_iodone(struct bch_dev *ca, char *buf)
+static void dev_iodone_to_text(struct printbuf *out, struct bch_dev *ca)
 {
-	struct printbuf out = _PBUF(buf, PAGE_SIZE);
 	int rw, i;
 
 	for (rw = 0; rw < 2; rw++) {
-		pr_buf(&out, "%s:\n", bch2_rw[rw]);
+		pr_buf(out, "%s:\n", bch2_rw[rw]);
 
 		for (i = 1; i < BCH_DATA_NR; i++)
-			pr_buf(&out, "%-12s:%12llu\n",
+			pr_buf(out, "%-12s:%12llu\n",
 			       bch2_data_types[i],
 			       percpu_u64_get(&ca->io_done->sectors[rw][i]) << 9);
 	}
-
-	return out.pos - buf;
 }
 
 SHOW(bch2_dev)
@@ -964,34 +934,44 @@ SHOW(bch2_dev)
 		return out.pos - buf;
 	}
 
-	if (attr == &sysfs_iodone)
-		return show_dev_iodone(ca, buf);
+	if (attr == &sysfs_iodone) {
+		dev_iodone_to_text(&out, ca);
+		return out.pos - buf;
+	}
 
 	sysfs_print(io_latency_read,		atomic64_read(&ca->cur_latency[READ]));
 	sysfs_print(io_latency_write,		atomic64_read(&ca->cur_latency[WRITE]));
 
-	if (attr == &sysfs_io_latency_stats_read)
-		return bch2_time_stats_print(&ca->io_latency[READ], buf, PAGE_SIZE);
-	if (attr == &sysfs_io_latency_stats_write)
-		return bch2_time_stats_print(&ca->io_latency[WRITE], buf, PAGE_SIZE);
+	if (attr == &sysfs_io_latency_stats_read) {
+		bch2_time_stats_to_text(&out, &ca->io_latency[READ]);
+		return out.pos - buf;
+	}
+	if (attr == &sysfs_io_latency_stats_write) {
+		bch2_time_stats_to_text(&out, &ca->io_latency[WRITE]);
+		return out.pos - buf;
+	}
 
 	sysfs_printf(congested,			"%u%%",
 		     clamp(atomic_read(&ca->congested), 0, CONGESTED_MAX)
 		     * 100 / CONGESTED_MAX);
 
 	if (attr == &sysfs_bucket_quantiles_last_read)
-		return show_quantiles(c, ca, buf, bucket_last_io_fn, (void *) 0);
+		return quantiles_to_text(&out, c, ca, bucket_last_io_fn, (void *) 0) ?: out.pos - buf;
 	if (attr == &sysfs_bucket_quantiles_last_write)
-		return show_quantiles(c, ca, buf, bucket_last_io_fn, (void *) 1);
+		return quantiles_to_text(&out, c, ca, bucket_last_io_fn, (void *) 1) ?: out.pos - buf;
 	if (attr == &sysfs_bucket_quantiles_fragmentation)
-		return show_quantiles(c, ca, buf, bucket_sectors_used_fn, NULL);
+		return quantiles_to_text(&out, c, ca, bucket_sectors_used_fn, NULL)  ?: out.pos - buf;
 	if (attr == &sysfs_bucket_quantiles_oldest_gen)
-		return show_quantiles(c, ca, buf, bucket_oldest_gen_fn, NULL);
+		return quantiles_to_text(&out, c, ca, bucket_oldest_gen_fn, NULL)    ?: out.pos - buf;
 
-	if (attr == &sysfs_reserve_stats)
-		return show_reserve_stats(ca, buf);
-	if (attr == &sysfs_alloc_debug)
-		return show_dev_alloc_debug(ca, buf);
+	if (attr == &sysfs_reserve_stats) {
+		reserve_stats_to_text(&out, ca);
+		return out.pos - buf;
+	}
+	if (attr == &sysfs_alloc_debug) {
+		dev_alloc_debug_to_text(&out, ca);
+		return out.pos - buf;
+	}
 
 	return 0;
 }

fs/bcachefs/util.c

@@ -320,43 +320,40 @@ static void pr_time_units(struct printbuf *out, u64 ns)
 	pr_buf(out, "%llu %s", div_u64(ns, u->nsecs), u->name);
 }
 
-size_t bch2_time_stats_print(struct bch2_time_stats *stats, char *buf, size_t len)
+void bch2_time_stats_to_text(struct printbuf *out, struct bch2_time_stats *stats)
 {
-	struct printbuf out = _PBUF(buf, len);
 	const struct time_unit *u;
 	u64 freq = READ_ONCE(stats->average_frequency);
 	u64 q, last_q = 0;
 	int i;
 
-	pr_buf(&out, "count:\t\t%llu\n",
+	pr_buf(out, "count:\t\t%llu\n",
 			 stats->count);
-	pr_buf(&out, "rate:\t\t%llu/sec\n",
+	pr_buf(out, "rate:\t\t%llu/sec\n",
 	       freq ?  div64_u64(NSEC_PER_SEC, freq) : 0);
 
-	pr_buf(&out, "frequency:\t");
-	pr_time_units(&out, freq);
+	pr_buf(out, "frequency:\t");
+	pr_time_units(out, freq);
 
-	pr_buf(&out, "\navg duration:\t");
-	pr_time_units(&out, stats->average_duration);
+	pr_buf(out, "\navg duration:\t");
+	pr_time_units(out, stats->average_duration);
 
-	pr_buf(&out, "\nmax duration:\t");
-	pr_time_units(&out, stats->max_duration);
+	pr_buf(out, "\nmax duration:\t");
+	pr_time_units(out, stats->max_duration);
 
 	i = eytzinger0_first(NR_QUANTILES);
 	u = pick_time_units(stats->quantiles.entries[i].m);
 
-	pr_buf(&out, "\nquantiles (%s):\t", u->name);
+	pr_buf(out, "\nquantiles (%s):\t", u->name);
 	eytzinger0_for_each(i, NR_QUANTILES) {
 		bool is_last = eytzinger0_next(i, NR_QUANTILES) == -1;
 
 		q = max(stats->quantiles.entries[i].m, last_q);
-		pr_buf(&out, "%llu%s",
+		pr_buf(out, "%llu%s",
 		       div_u64(q, u->nsecs),
 		       is_last ? "\n" : " ");
 		last_q = q;
 	}
-
-	return out.pos - buf;
 }
 
 void bch2_time_stats_exit(struct bch2_time_stats *stats)

fs/bcachefs/util.h

@@ -390,7 +390,7 @@ static inline void bch2_time_stats_update(struct bch2_time_stats *stats, u64 sta
 	__bch2_time_stats_update(stats, start, local_clock());
 }
 
-size_t bch2_time_stats_print(struct bch2_time_stats *, char *, size_t);
+void bch2_time_stats_to_text(struct printbuf *, struct bch2_time_stats *);
 
 void bch2_time_stats_exit(struct bch2_time_stats *);
 void bch2_time_stats_init(struct bch2_time_stats *);