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>

1 files changed, 6 insertions, 7 deletions

diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index d771b1e0424b..91085c1ab52f 100644
--- 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 (;;) {