git.sesse.net Git - bcachefs-tools-debian/blob - libbcachefs/clock.c

   1 #include "bcachefs.h"
   2 #include "clock.h"
   3
   4 #include <linux/freezer.h>
   5 #include <linux/kthread.h>
   6 #include <linux/preempt.h>
   7
   8 static inline long io_timer_cmp(io_timer_heap *h,
   9                                 struct io_timer *l,
  10                                 struct io_timer *r)
  11 {
  12         return l->expire - r->expire;
  13 }
  14
  15 void bch2_io_timer_add(struct io_clock *clock, struct io_timer *timer)
  16 {
  17         size_t i;
  18
  19         spin_lock(&clock->timer_lock);
  20         for (i = 0; i < clock->timers.used; i++)
  21                 if (clock->timers.data[i] == timer)
  22                         goto out;
  23
  24         BUG_ON(!heap_add(&clock->timers, timer, io_timer_cmp));
  25 out:
  26         spin_unlock(&clock->timer_lock);
  27 }
  28
  29 void bch2_io_timer_del(struct io_clock *clock, struct io_timer *timer)
  30 {
  31         size_t i;
  32
  33         spin_lock(&clock->timer_lock);
  34
  35         for (i = 0; i < clock->timers.used; i++)
  36                 if (clock->timers.data[i] == timer) {
  37                         heap_del(&clock->timers, i, io_timer_cmp);
  38                         break;
  39                 }
  40
  41         spin_unlock(&clock->timer_lock);
  42 }
  43
  44 struct io_clock_wait {
  45         struct io_timer         timer;
  46         struct task_struct      *task;
  47         int                     expired;
  48 };
  49
  50 static void io_clock_wait_fn(struct io_timer *timer)
  51 {
  52         struct io_clock_wait *wait = container_of(timer,
  53                                 struct io_clock_wait, timer);
  54
  55         wait->expired = 1;
  56         wake_up_process(wait->task);
  57 }
  58
  59 void bch2_io_clock_schedule_timeout(struct io_clock *clock, unsigned long until)
  60 {
  61         struct io_clock_wait wait;
  62
  63         /* XXX: calculate sleep time rigorously */
  64         wait.timer.expire       = until;
  65         wait.timer.fn           = io_clock_wait_fn;
  66         wait.task               = current;
  67         wait.expired            = 0;
  68         bch2_io_timer_add(clock, &wait.timer);
  69
  70         schedule();
  71
  72         bch2_io_timer_del(clock, &wait.timer);
  73 }
  74
  75 /*
  76  * _only_ to be used from a kthread
  77  */
  78 void bch2_kthread_io_clock_wait(struct io_clock *clock,
  79                                unsigned long until)
  80 {
  81         struct io_clock_wait wait;
  82
  83         /* XXX: calculate sleep time rigorously */
  84         wait.timer.expire       = until;
  85         wait.timer.fn           = io_clock_wait_fn;
  86         wait.task               = current;
  87         wait.expired            = 0;
  88         bch2_io_timer_add(clock, &wait.timer);
  89
  90         while (1) {
  91                 set_current_state(TASK_INTERRUPTIBLE);
  92                 if (kthread_should_stop())
  93                         break;
  94
  95                 if (wait.expired)
  96                         break;
  97
  98                 schedule();
  99                 try_to_freeze();
 100         }
 101
 102         __set_current_state(TASK_RUNNING);
 103         bch2_io_timer_del(clock, &wait.timer);
 104 }
 105
 106 static struct io_timer *get_expired_timer(struct io_clock *clock,
 107                                           unsigned long now)
 108 {
 109         struct io_timer *ret = NULL;
 110
 111         spin_lock(&clock->timer_lock);
 112
 113         if (clock->timers.used &&
 114             time_after_eq(now, clock->timers.data[0]->expire))
 115                 heap_pop(&clock->timers, ret, io_timer_cmp);
 116
 117         spin_unlock(&clock->timer_lock);
 118
 119         return ret;
 120 }
 121
 122 void bch2_increment_clock(struct bch_fs *c, unsigned sectors, int rw)
 123 {
 124         struct io_clock *clock = &c->io_clock[rw];
 125         struct io_timer *timer;
 126         unsigned long now;
 127
 128         /* Buffer up one megabyte worth of IO in the percpu counter */
 129         preempt_disable();
 130
 131         if (likely(this_cpu_add_return(*clock->pcpu_buf, sectors) <
 132                    IO_CLOCK_PCPU_SECTORS)) {
 133                 preempt_enable();
 134                 return;
 135         }
 136
 137         sectors = this_cpu_xchg(*clock->pcpu_buf, 0);
 138         preempt_enable();
 139         now = atomic_long_add_return(sectors, &clock->now);
 140
 141         while ((timer = get_expired_timer(clock, now)))
 142                 timer->fn(timer);
 143 }
 144
 145 void bch2_io_clock_exit(struct io_clock *clock)
 146 {
 147         free_heap(&clock->timers);
 148         free_percpu(clock->pcpu_buf);
 149 }
 150
 151 int bch2_io_clock_init(struct io_clock *clock)
 152 {
 153         atomic_long_set(&clock->now, 0);
 154         spin_lock_init(&clock->timer_lock);
 155
 156         clock->pcpu_buf = alloc_percpu(*clock->pcpu_buf);
 157         if (!clock->pcpu_buf)
 158                 return -ENOMEM;
 159
 160         if (!init_heap(&clock->timers, NR_IO_TIMERS, GFP_KERNEL))
 161                 return -ENOMEM;
 162
 163         return 0;
 164 }