drbd: factor out drbd_rs_number_requests

Preparation patch to be able to use the auto-throttling resync controller
for online-verify requests as well.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

1 files changed, 29 insertions, 32 deletions

diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index 971e9b3b13b..6d111c8515f 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -492,6 +492,32 @@ int drbd_rs_controller(struct drbd_conf *mdev)
         return req_sect;
 }
 
+int drbd_rs_number_requests(struct drbd_conf *mdev)
+{
+        int number;
+        if (mdev->rs_plan_s.size) { /* mdev->sync_conf.c_plan_ahead */
+                number = drbd_rs_controller(mdev) >> (BM_BLOCK_SHIFT - 9);
+                mdev->c_sync_rate = number * HZ * (BM_BLOCK_SIZE / 1024) / SLEEP_TIME;
+        } else {
+                mdev->c_sync_rate = mdev->sync_conf.rate;
+                number = SLEEP_TIME * mdev->c_sync_rate  / ((BM_BLOCK_SIZE / 1024) * HZ);
+        }
+
+        /* Throttle resync on lower level disk activity, which may also be
+         * caused by application IO on Primary/SyncTarget.
+         * Keep this after the call to drbd_rs_controller, as that assumes
+         * to be called as precisely as possible every SLEEP_TIME,
+         * and would be confused otherwise. */
+        if (number && drbd_rs_should_slow_down(mdev)) {
+                mdev->c_sync_rate = 1;
+                number = 0;
+        }
+
+        /* ignore the amount of pending requests, the resync controller should
+         * throttle down to incoming reply rate soon enough anyways. */
+        return number;
+}
+
 int w_make_resync_request(struct drbd_conf *mdev,
                 struct drbd_work *w, int cancel)
 {
@@ -499,7 +525,7 @@ int w_make_resync_request(struct drbd_conf *mdev,
         sector_t sector;
         const sector_t capacity = drbd_get_capacity(mdev->this_bdev);
         int max_segment_size;
-        int number, rollback_i, size, pe, mx;
+        int number, rollback_i, size;
         int align, queued, sndbuf;
         int i = 0;
 
@@ -537,39 +563,10 @@ int w_make_resync_request(struct drbd_conf *mdev,
                 mdev->agreed_pro_version < 94 ? queue_max_segment_size(mdev->rq_queue) :
                 mdev->agreed_pro_version < 95 ? DRBD_MAX_SIZE_H80_PACKET : DRBD_MAX_SEGMENT_SIZE;
 
-        if (mdev->rs_plan_s.size) { /* mdev->sync_conf.c_plan_ahead */
-                number = drbd_rs_controller(mdev) >> (BM_BLOCK_SHIFT - 9);
-                mdev->c_sync_rate = number * HZ * (BM_BLOCK_SIZE / 1024) / SLEEP_TIME;
-        } else {
-                mdev->c_sync_rate = mdev->sync_conf.rate;
-                number = SLEEP_TIME * mdev->c_sync_rate  / ((BM_BLOCK_SIZE / 1024) * HZ);
-        }
-
-        /* Throttle resync on lower level disk activity, which may also be
-         * caused by application IO on Primary/SyncTarget.
-         * Keep this after the call to drbd_rs_controller, as that assumes
-         * to be called as precisely as possible every SLEEP_TIME,
-         * and would be confused otherwise. */
-        if (drbd_rs_should_slow_down(mdev))
+        number = drbd_rs_number_requests(mdev);
+        if (number == 0)
                 goto requeue;
 
-        mutex_lock(&mdev->data.mutex);
-        if (mdev->data.socket)
-                mx = mdev->data.socket->sk->sk_rcvbuf / sizeof(struct p_block_req);
-        else
-                mx = 1;
-        mutex_unlock(&mdev->data.mutex);
-
-        /* For resync rates >160MB/sec, allow more pending RS requests */
-        if (number > mx)
-                mx = number;
-
-        /* Limit the number of pending RS requests to no more than the peer's receive buffer */
-        pe = atomic_read(&mdev->rs_pending_cnt);
-        if ((pe + number) > mx) {
-                number = mx - pe;
-        }
-
         for (i = 0; i < number; i++) {
                 /* Stop generating RS requests, when half of the send buffer is filled */
                 mutex_lock(&mdev->data.mutex);