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drbd: allow write-ordering policy to be bumped up again

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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: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
This commit is contained in:
Lars Ellenberg 2013-12-20 11:17:02 +01:00 committed by Philipp Reisner
parent 44a4d55184
commit 70df70927b
2 changed files with 13 additions and 3 deletions
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10
drivers/block/drbd/drbd_nl.c
View File

@ -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;
@ -1400,7 +1407,8 @@ int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info)
else
set_bit(MD_NO_FUA, &device->flags);
drbd_bump_write_ordering(device->resource, NULL, WO_bdev_flush);
if (write_ordering_changed(old_disk_conf, new_disk_conf))
drbd_bump_write_ordering(device->resource, NULL, WO_bdev_flush);
drbd_md_sync(device);

6
drivers/block/drbd/drbd_receiver.c
View File

@ -1290,7 +1290,8 @@ void drbd_bump_write_ordering(struct drbd_resource *resource, struct drbd_backin
};
pwo = resource->write_ordering;
wo = min(pwo, wo);
if (wo != WO_bdev_flush)
wo = min(pwo, wo);
rcu_read_lock();
idr_for_each_entry(&resource->devices, device, vnr) {
if (get_ldev(device)) {
@ -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]);