drbd: allow resync requests to be larger than max_segment_size

this should allow for better background resync performance.

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

diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index d771b1e..91085c1 100644 (file)
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -462,7 +462,7 @@ int w_make_resync_request(struct drbd_conf *mdev,
        unsigned long bit;
        sector_t sector;
        const sector_t capacity = drbd_get_capacity(mdev->this_bdev);
-       int max_segment_size = queue_max_segment_size(mdev->rq_queue);
+       int max_segment_size;
        int number, i, size, pe, mx;
        int align, queued, sndbuf;
 
@@ -488,6 +488,11 @@ int w_make_resync_request(struct drbd_conf *mdev,
                return 1;
        }
 
+       /* starting with drbd 8.3.8, we can handle multi-bio EEs,
+        * if it should be necessary */
+       max_segment_size = mdev->agreed_pro_version < 94 ?
+               queue_max_segment_size(mdev->rq_queue) : DRBD_MAX_SEGMENT_SIZE;
+
        mdev->c_sync_rate = calc_resync_rate(mdev);
        number = SLEEP_TIME * mdev->c_sync_rate  / ((BM_BLOCK_SIZE / 1024) * HZ);
        pe = atomic_read(&mdev->rs_pending_cnt);
@@ -552,12 +557,6 @@ next_sector:
                 *
                 * Additionally always align bigger requests, in order to
                 * be prepared for all stripe sizes of software RAIDs.
-                *
-                * we _do_ care about the agreed-upon q->max_segment_size
-                * here, as splitting up the requests on the other side is more
-                * difficult.  the consequence is, that on lvm and md and other
-                * "indirect" devices, this is dead code, since
-                * q->max_segment_size will be PAGE_SIZE.
                 */
                align = 1;
                for (;;) {