The previous algorithm for dealing with overlapping concurrent writes
was generating unnecessary warnings for scenarios which could be
legitimate, and did not always handle partially overlapping requests
correctly. Improve it algorithm as follows:
* While local or remote write requests are in progress, conflicting new
local write requests will be delayed (commit 82172f7).
* When a conflict between a local and remote write request is detected,
the node with the discard flag decides how to resolve the conflict: It
will ask its peer to discard conflicting requests which are fully
contained in the local request and retry requests which overlap only
partially. This involves a protocol change.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
When the node with the discard flag resolves write conflicts in
dual-primary mode, it may determine that its peer has sent ack packets
on the metadata socket which did not arrive, yet. Wait for the next ack
with ping-timeout instead of a hard-coded 30 seconds.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Commit 9b1e63e changed the concurrent write detection algorithm to only insert
peer requests into write_requests tree after determining that there is no
conflict. With this change, new conflicting local requests could be added
while the algorithm runs, but this case was not handled correctly. Instead of
making the algorithm deal with this case, switch back to adding peer requests
to the write_requests tree immediately: this improves fairness.
When a peer request is discarded, remove that request from the write_requests
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
In compatibility mode with old DRBDs, use that as the state_mutex
as well.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
The lock they constructed is only taken when the state_mutex
was already taken. It is superficial.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
No longer work callbacks must operate on a mdev. From now on they
can also operate on a tconn.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
The drbd_md_sync(mdev) happens in the after state change anyways...
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Make it more clear that update_peer_seq() is supposed to wake up the
seq_wait queue whenever the sequence number changes.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Instead of keeping a separate tree for local and remote write requests
for finding requests and for conflict detection, use the same tree for
both purposes. Introduce a flag to allow distinguishing the two
possible types of entries in this tree.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
This flag is set when a processes puts itself to sleep to wait for a
conflicting request to complete.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
These things are only used there.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
