+static void fifo_set(struct fifo_buffer *fb, int value)
+{
+ int i;
+
+ for (i = 0; i < fb->size; i++)
+ fb->values[i] = value;
+}
+
+static int fifo_push(struct fifo_buffer *fb, int value)
+{
+ int ov;
+
+ ov = fb->values[fb->head_index];
+ fb->values[fb->head_index++] = value;
+
+ if (fb->head_index >= fb->size)
+ fb->head_index = 0;
+
+ return ov;
+}
+
+static void fifo_add_val(struct fifo_buffer *fb, int value)
+{
+ int i;
+
+ for (i = 0; i < fb->size; i++)
+ fb->values[i] += value;
+}
+
+int drbd_rs_controller(struct drbd_conf *mdev)
+{
+ unsigned int sect_in; /* Number of sectors that came in since the last turn */
+ unsigned int want; /* The number of sectors we want in the proxy */
+ int req_sect; /* Number of sectors to request in this turn */
+ int correction; /* Number of sectors more we need in the proxy*/
+ int cps; /* correction per invocation of drbd_rs_controller() */
+ int steps; /* Number of time steps to plan ahead */
+ int curr_corr;
+ int max_sect;
+
+ sect_in = atomic_xchg(&mdev->rs_sect_in, 0); /* Number of sectors that came in */
+ mdev->rs_in_flight -= sect_in;
+
+ spin_lock(&mdev->peer_seq_lock); /* get an atomic view on mdev->rs_plan_s */
+
+ steps = mdev->rs_plan_s.size; /* (mdev->sync_conf.c_plan_ahead * 10 * SLEEP_TIME) / HZ; */
+
+ if (mdev->rs_in_flight + sect_in == 0) { /* At start of resync */
+ want = ((mdev->sync_conf.rate * 2 * SLEEP_TIME) / HZ) * steps;
+ } else { /* normal path */
+ want = mdev->sync_conf.c_fill_target ? mdev->sync_conf.c_fill_target :
+ sect_in * mdev->sync_conf.c_delay_target * HZ / (SLEEP_TIME * 10);
+ }
+
+ correction = want - mdev->rs_in_flight - mdev->rs_planed;
+
+ /* Plan ahead */
+ cps = correction / steps;
+ fifo_add_val(&mdev->rs_plan_s, cps);
+ mdev->rs_planed += cps * steps;
+
+ /* What we do in this step */
+ curr_corr = fifo_push(&mdev->rs_plan_s, 0);
+ spin_unlock(&mdev->peer_seq_lock);
+ mdev->rs_planed -= curr_corr;
+
+ req_sect = sect_in + curr_corr;
+ if (req_sect < 0)
+ req_sect = 0;
+
+ max_sect = (mdev->sync_conf.c_max_rate * 2 * SLEEP_TIME) / HZ;
+ if (req_sect > max_sect)
+ req_sect = max_sect;
+
+ /*
+ dev_warn(DEV, "si=%u if=%d wa=%u co=%d st=%d cps=%d pl=%d cc=%d rs=%d\n",
+ sect_in, mdev->rs_in_flight, want, correction,
+ steps, cps, mdev->rs_planed, curr_corr, req_sect);
+ */
+
+ return req_sect;
+}
+