From: Lars Ellenberg <lars.ellenb...@linbit.com>
There may have been more incoming requests while we where preparing
the current transaction. Try to consolidate more updates into this
transaction until we make no more progres.
Signed-off-by: Philipp Reisner <philipp.reis...@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenb...@linbit.com>
---
drivers/block/drbd/drbd_req.c | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index d72f2fe..9f7ff1c 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -1226,6 +1226,37 @@ void do_submit(struct work_struct *ws)
break;
wait_event(mdev->al_wait, prepare_al_transaction_nonblock(mdev,
&incoming, &pending));
+ /* Maybe more was queued, while we prepared the transaction?
+ * Try to stuff them into this transaction as well.
+ * Be strictly non-blocking here, no wait_event, we already
+ * have something to commit.
+ * Stop if we don't make any more progres.
+ */
+ for (;;) {
+ LIST_HEAD(more_pending);
+ LIST_HEAD(more_incoming);
+ bool made_progress;
+
+ /* It is ok to look outside the lock,
+ * it's only an optimization anyways */
+ if (list_empty(&mdev->submit.writes))
+ break;
+
+ spin_lock(&mdev->submit.lock);
+ list_splice_tail_init(&mdev->submit.writes,
&more_incoming);
+ spin_unlock(&mdev->submit.lock);
+
+ if (list_empty(&more_incoming))
+ break;
+
+ made_progress = prepare_al_transaction_nonblock(mdev,
&more_incoming, &more_pending);
+
+ list_splice_tail_init(&more_pending, &pending);
+ list_splice_tail_init(&more_incoming, &incoming);
+
+ if (!made_progress)
+ break;
+ }
drbd_al_begin_io_commit(mdev, false);
list_for_each_entry_safe(req, tmp, &pending, tl_requests) {
--
1.7.9.5
--
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