diff options
| -rw-r--r-- | drivers/block/drbd/drbd_req.c | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c index 8323449fbbab..a9111b68fe2d 100644 --- a/drivers/block/drbd/drbd_req.c +++ b/drivers/block/drbd/drbd_req.c @@ -935,6 +935,20 @@ static int drbd_process_write_request(struct drbd_request *req) send_oos = drbd_should_send_out_of_sync(mdev->state); rcu_read_unlock(); + /* Need to replicate writes. Unless it is an empty flush, + * which is better mapped to a DRBD P_BARRIER packet, + * also for drbd wire protocol compatibility reasons. + * If this was a flush, just start a new epoch. + * Unless the current epoch was empty anyways, or we are not currently + * replicating, in which case there is no point. */ + if (unlikely(req->i.size == 0)) { + /* The only size==0 bios we expect are empty flushes. */ + D_ASSERT(req->master_bio->bi_rw & REQ_FLUSH); + if (remote && mdev->tconn->current_tle_writes) + start_new_tl_epoch(mdev->tconn); + return 0; + } + if (!remote && !send_oos) return 0; @@ -1004,8 +1018,10 @@ void __drbd_make_request(struct drbd_conf *mdev, struct bio *bio, unsigned long * extent. This waits for any resync activity in the corresponding * resync extent to finish, and, if necessary, pulls in the target * extent into the activity log, which involves further disk io because - * of transactional on-disk meta data updates. */ - if (rw == WRITE && req->private_bio + * of transactional on-disk meta data updates. + * Empty flushes don't need to go into the activity log, they can only + * flush data for pending writes which are already in there. */ + if (rw == WRITE && req->private_bio && req->i.size && !test_bit(AL_SUSPENDED, &mdev->flags)) { req->rq_state |= RQ_IN_ACT_LOG; drbd_al_begin_io(mdev, &req->i); @@ -1047,7 +1063,10 @@ void __drbd_make_request(struct drbd_conf *mdev, struct bio *bio, unsigned long if (rw == WRITE) mdev->tconn->current_tle_writes++; - list_add_tail(&req->tl_requests, &mdev->tconn->transfer_log); + /* no point in adding empty flushes to the transfer log, + * they are mapped to drbd barriers already. */ + if (likely(req->i.size!=0)) + list_add_tail(&req->tl_requests, &mdev->tconn->transfer_log); if (rw == WRITE) { if (!drbd_process_write_request(req)) |