1 files changed, 180 insertions, 0 deletions
diff --git a/fs/bcachefs/clock.c b/fs/bcachefs/clock.c
new file mode 100644
index 000000000000..96f8030384fa
--- /dev/null
+++ b/fs/bcachefs/clock.c
@@ -0,0 +1,180 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "bcachefs.h"
+#include "clock.h"
+
+#include <linux/freezer.h>
+#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)
+{
+	return l->expire - r->expire;
+}
+
+void bch2_io_timer_add(struct io_clock *clock, struct io_timer *timer)
+{
+	size_t i;
+
+	spin_lock(&clock->timer_lock);
+	for (i = 0; i < clock->timers.used; i++)
+		if (clock->timers.data[i] == timer)
+			goto out;
+
+	BUG_ON(!heap_add(&clock->timers, timer, io_timer_cmp));
+out:
+	spin_unlock(&clock->timer_lock);
+}
+
+void bch2_io_timer_del(struct io_clock *clock, struct io_timer *timer)
+{
+	size_t i;
+
+	spin_lock(&clock->timer_lock);
+
+	for (i = 0; i < clock->timers.used; i++)
+		if (clock->timers.data[i] == timer) {
+			heap_del(&clock->timers, i, io_timer_cmp);
+			break;
+		}
+
+	spin_unlock(&clock->timer_lock);
+}
+
+struct io_clock_wait {
+	struct io_timer		io_timer;
+	struct timer_list	cpu_timer;
+	struct task_struct	*task;
+	int			expired;
+};
+
+static void io_clock_wait_fn(struct io_timer *timer)
+{
+	struct io_clock_wait *wait = container_of(timer,
+				struct io_clock_wait, io_timer);
+
+	wait->expired = 1;
+	wake_up_process(wait->task);
+}
+
+static void io_clock_cpu_timeout(struct timer_list *timer)
+{
+	struct io_clock_wait *wait = container_of(timer,
+				struct io_clock_wait, cpu_timer);
+
+	wait->expired = 1;
+	wake_up_process(wait->task);
+}
+
+void bch2_io_clock_schedule_timeout(struct io_clock *clock, unsigned long until)
+{
+	struct io_clock_wait wait;
+
+	/* XXX: calculate sleep time rigorously */
+	wait.io_timer.expire	= until;
+	wait.io_timer.fn	= io_clock_wait_fn;
+	wait.task		= current;
+	wait.expired		= 0;
+	bch2_io_timer_add(clock, &wait.io_timer);
+
+	schedule();
+
+	bch2_io_timer_del(clock, &wait.io_timer);
+}
+
+void bch2_kthread_io_clock_wait(struct io_clock *clock,
+				unsigned long io_until,
+				unsigned long cpu_timeout)
+{
+	bool kthread = (current->flags & PF_KTHREAD) != 0;
+	struct io_clock_wait wait;
+
+	wait.io_timer.expire	= io_until;
+	wait.io_timer.fn	= io_clock_wait_fn;
+	wait.task		= current;
+	wait.expired		= 0;
+	bch2_io_timer_add(clock, &wait.io_timer);
+
+	timer_setup_on_stack(&wait.cpu_timer, io_clock_cpu_timeout, 0);
+
+	if (cpu_timeout != MAX_SCHEDULE_TIMEOUT)
+		mod_timer(&wait.cpu_timer, cpu_timeout + jiffies);
+
+	while (1) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (kthread && kthread_should_stop())
+			break;
+
+		if (wait.expired)
+			break;
+
+		schedule();
+		try_to_freeze();
+	}
+
+	__set_current_state(TASK_RUNNING);
+	del_timer_sync(&wait.cpu_timer);
+	destroy_timer_on_stack(&wait.cpu_timer);
+	bch2_io_timer_del(clock, &wait.io_timer);
+}
+
+static struct io_timer *get_expired_timer(struct io_clock *clock,
+					  unsigned long now)
+{
+	struct io_timer *ret = NULL;
+
+	spin_lock(&clock->timer_lock);
+
+	if (clock->timers.used &&
+	    time_after_eq(now, clock->timers.data[0]->expire))
+		heap_pop(&clock->timers, ret, io_timer_cmp);
+
+	spin_unlock(&clock->timer_lock);
+
+	return ret;
+}
+
+void bch2_increment_clock(struct bch_fs *c, unsigned sectors, int rw)
+{
+	struct io_clock *clock = &c->io_clock[rw];
+	struct io_timer *timer;
+	unsigned long now;
+
+	/* Buffer up one megabyte worth of IO in the percpu counter */
+	preempt_disable();
+
+	if (likely(this_cpu_add_return(*clock->pcpu_buf, sectors) <
+		   IO_CLOCK_PCPU_SECTORS)) {
+		preempt_enable();
+		return;
+	}
+
+	sectors = this_cpu_xchg(*clock->pcpu_buf, 0);
+	preempt_enable();
+	now = atomic_long_add_return(sectors, &clock->now);
+
+	while ((timer = get_expired_timer(clock, now)))
+		timer->fn(timer);
+}
+
+void bch2_io_clock_exit(struct io_clock *clock)
+{
+	free_heap(&clock->timers);
+	free_percpu(clock->pcpu_buf);
+}
+
+int bch2_io_clock_init(struct io_clock *clock)
+{
+	atomic_long_set(&clock->now, 0);
+	spin_lock_init(&clock->timer_lock);
+
+	clock->pcpu_buf = alloc_percpu(*clock->pcpu_buf);
+	if (!clock->pcpu_buf)
+		return -ENOMEM;
+
+	if (!init_heap(&clock->timers, NR_IO_TIMERS, GFP_KERNEL))
+		return -ENOMEM;
+
+	return 0;
+}