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Commit 70df7092 authored by Lars Ellenberg's avatar Lars Ellenberg Committed by Philipp Reisner
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drbd: allow write-ordering policy to be bumped up again 



Previously, once you disabled flushes as a means of enforcing
write-ordering, you'd need to detach/re-attach to enable them again.

Allow drbdsetup disk-options to re-enable previously disabled
write-ordering policy options at runtime.

While at it fix RCU in drbd_bump_write_ordering()
max_allowed_wo() uses rcu_dereference, therefore it must
be called within rcu_read_lock()/rcu_read_unlock()

Signed-off-by: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
parent 44a4d551

drivers/block/drbd/drbd_nl.c

+9 −1
Original line number Diff line number Diff line
@@ -1294,6 +1294,13 @@ static unsigned int drbd_al_extents_max(struct drbd_backing_dev *bdev) 
	return (al_size_4k - 1) * AL_CONTEXT_PER_TRANSACTION;

}



static bool write_ordering_changed(struct disk_conf *a, struct disk_conf *b)

{

	return	a->disk_barrier != b->disk_barrier ||

		a->disk_flushes != b->disk_flushes ||

		a->disk_drain != b->disk_drain;

}



int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info)

{

	struct drbd_config_context adm_ctx;
@@ -1400,6 +1407,7 @@ int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info) 
	else

		set_bit(MD_NO_FUA, &device->flags);



	if (write_ordering_changed(old_disk_conf, new_disk_conf))

		drbd_bump_write_ordering(device->resource, NULL, WO_bdev_flush);



	drbd_md_sync(device);

drivers/block/drbd/drbd_receiver.c

+4 −2
Original line number Diff line number Diff line
@@ -1290,6 +1290,7 @@ void drbd_bump_write_ordering(struct drbd_resource *resource, struct drbd_backin 
	};



	pwo = resource->write_ordering;

	if (wo != WO_bdev_flush)

		wo = min(pwo, wo);

	rcu_read_lock();

	idr_for_each_entry(&resource->devices, device, vnr) {
@@ -1300,11 +1301,12 @@ void drbd_bump_write_ordering(struct drbd_resource *resource, struct drbd_backin 
			put_ldev(device);

		}

	}

	rcu_read_unlock();



	if (bdev)

		wo = max_allowed_wo(bdev, wo);



	rcu_read_unlock();



	resource->write_ordering = wo;

	if (pwo != resource->write_ordering || wo == WO_bdev_flush)

		drbd_info(resource, "Method to ensure write ordering: %s\n", write_ordering_str[resource->write_ordering]);