drbd: Improve compatibility with drbd's older than 8.3.7
Regression introduced with 8.3.11 commit:
drbd: Take a more conservative approach when deciding max_bio_size
Never ever tell an older drbd, that we support more than 32KiB
in a single data request (packet).
Never believe an older drbd, that is supports more than 32KiB
in a single data request (packet)
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_nl.c b/drivers/block/drbd/drbd_nl.c
index f7b5f7e..cabad39 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -845,9 +845,10 @@
Because new from 8.3.8 onwards the peer can use multiple
BIOs for a single peer_request */
if (mdev->state.conn >= C_CONNECTED) {
- if (mdev->agreed_pro_version < 94)
- peer = mdev->peer_max_bio_size;
- else if (mdev->agreed_pro_version == 94)
+ if (mdev->agreed_pro_version < 94) {
+ peer = min_t(int, mdev->peer_max_bio_size, DRBD_MAX_SIZE_H80_PACKET);
+ /* Correct old drbd (up to 8.3.7) if it believes it can do more than 32KiB */
+ } else if (mdev->agreed_pro_version == 94)
peer = DRBD_MAX_SIZE_H80_PACKET;
else /* drbd 8.3.8 onwards */
peer = DRBD_MAX_BIO_SIZE;