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authorLars Ellenberg <lars.ellenberg@linbit.com>2011-11-28 15:04:49 +0100
committerPhilipp Reisner <philipp.reisner@linbit.com>2012-11-08 16:58:35 +0100
commitb6dd1a89767bc33e9c98b3195f8925b46c5c95f3 (patch)
treee82371062171f5cade79cb0c4a6cd22486b5f082 /drivers/block/drbd/drbd_nl.c
parentd5b27b01f17ef1f0badc45f9eea521be3457c9cb (diff)
downloadvexpress-lsk-b6dd1a89767bc33e9c98b3195f8925b46c5c95f3.tar.gz
drbd: remove struct drbd_tl_epoch objects (barrier works)
cherry-picked and adapted from drbd 9 devel branch DRBD requests (struct drbd_request) are already on the per resource transfer log list, and carry their epoch number. We do not need to additionally link them on other ring lists in other structs. The drbd sender thread can recognize itself when to send a P_BARRIER, by tracking the currently processed epoch, and how many writes have been processed for that epoch. If the epoch of the request to be processed does not match the currently processed epoch, any writes have been processed in it, a P_BARRIER for this last processed epoch is send out first. The new epoch then becomes the currently processed epoch. To not get stuck in drbd_al_begin_io() waiting for P_BARRIER_ACK, the sender thread also needs to handle the case when the current epoch was closed already, but no new requests are queued yet, and send out P_BARRIER as soon as possible. This is done by comparing the per resource "current transfer log epoch" (tconn->current_tle_nr) with the per connection "currently processed epoch number" (tconn->send.current_epoch_nr), while waiting for new requests to be processed in wait_for_work(). Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com> Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Diffstat (limited to 'drivers/block/drbd/drbd_nl.c')
-rw-r--r--drivers/block/drbd/drbd_nl.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index c5d4fac1a11..bbc5c2f4a9b 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -622,6 +622,8 @@ drbd_set_role(struct drbd_conf *mdev, enum drbd_role new_role, int force)
/* Wait until nothing is on the fly :) */
wait_event(mdev->misc_wait, atomic_read(&mdev->ap_pending_cnt) == 0);
+ /* FIXME also wait for all pending P_BARRIER_ACK? */
+
if (new_role == R_SECONDARY) {
set_disk_ro(mdev->vdisk, true);
if (get_ldev(mdev)) {
@@ -1436,6 +1438,12 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
drbd_suspend_io(mdev);
/* also wait for the last barrier ack. */
+ /* FIXME see also https://daiquiri.linbit/cgi-bin/bugzilla/show_bug.cgi?id=171
+ * We need a way to either ignore barrier acks for barriers sent before a device
+ * was attached, or a way to wait for all pending barrier acks to come in.
+ * As barriers are counted per resource,
+ * we'd need to suspend io on all devices of a resource.
+ */
wait_event(mdev->misc_wait, !atomic_read(&mdev->ap_pending_cnt) || drbd_suspended(mdev));
/* and for any other previously queued work */
drbd_flush_workqueue(mdev);