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Commit Graph

579 Commits

Author SHA1 Message Date
Martin Schwenke
0b5dd07604 ctdb-recoverd: Add function node_flags() and use it in elections
Indexing a node map by PNN is suboptimal.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-07-22 16:09:31 +00:00
Martin Schwenke
90a96f06a9 ctdb-recoverd: Do not ban on unknown error when taking cluster lock
If the cluster filesystem is unavailable then I/O errors may occur.
This is no worse than contention, so don't ban.  This avoids having
services unavailable for longer than necessary.

Update the associated test to simply confirm that this results in a
leaderless cluster, and leadership is restored when the lock can once
again be taken.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-05-31 05:06:29 +00:00
Martin Schwenke
0e74e03c9c ctdb-recoverd: Consistently log start of election
Elections should now be quite rare, so always log when one begins.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14958

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-02-14 01:47:31 +00:00
Martin Schwenke
bf55a0117d ctdb-recoverd: Always send unknown leader broadcast when starting election
This is currently missed when the cluster lock is lost.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14958

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-02-14 01:47:31 +00:00
Martin Schwenke
9b3fab052b ctdb-recoverd: Consistently have caller set election-in-progress
The problem here is that election-in-progress must be set to
potentially avoid restarting the election broadcast timeout in
main_loop(), so this is already done by leader_handler().

Have force_election() set election-in-progress for all election types
and do not bother setting it in cluster_lock_election().

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14958

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-02-14 01:47:31 +00:00
Martin Schwenke
188a902156 ctdb-recoverd: Always cancel election in progress
Election-in-progress is set by unknown leader broadcast, so needs to
be cleared in all cases when election completes.

This was seen in a case where the leader node stalled, so didn't send
leader broadcasts for some time.  The node continued to hold the
cluster lock, so another node could not become leader.  However, after
the node returned to normal it still did not send leader broadcasts
because election-in-progress was never cleared.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14958

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-02-14 01:47:31 +00:00
Martin Schwenke
34d2ca0ae6 ctdb-config: Add configuration option [cluster] leader timeout
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:33 +00:00
Martin Schwenke
73555e8248 ctdb-recoverd: Use race for cluster lock as election when lock is enabled
If the cluster is partitioned then nodes in one partition can not take
the lock anyway, so election is pointless.  It just introduces
unnecessary corner cases.

Instead just race for the lock.

When a node notices a lack of leader and notifies other nodes of an
election via an unknown leader broadcast, the cluster lock election is
hooked into this broadcast.

The test needs to be updated because losing the cluster lock can now
result in a leadership change.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:33 +00:00
Martin Schwenke
c68267b2a6 ctdb-recoverd: Drop calls to ctdb_ctrl_setrecmaster()
Nothing fetches this value anymore.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:33 +00:00
Martin Schwenke
58d7fcdf7c ctdb-recoverd: Drop recovery master verification
This doesn't make sense if leader broadcasts are used.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:33 +00:00
Martin Schwenke
958746f947 ctdb-recoverd: Simplify some stopped/banned checks to inactive checks
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:33 +00:00
Martin Schwenke
358c59f51a ctdb-recoverd: No longer take cluster lock during recovery
Confirm instead that it is already held.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:33 +00:00
Martin Schwenke
36ffaaa691 ctdb-recoverd: Add and use function cluster_lock_enabled()
Now all references to ctdb->recovery_lock are encapsulated in the
cluster lock code.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:33 +00:00
Martin Schwenke
5ee664ee17 ctdb-recoverd: Terminology change: recovery lock -> cluster lock
No functional changes, just name changes for clarity.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:33 +00:00
Martin Schwenke
0f2250f4f9 ctdb-recoverd: Take cluster lock when election completes
It is no longer just a recovery lock but is always held by the cluster
leader.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:33 +00:00
Martin Schwenke
011e880002 ctdb-recoverd: Factor out function cluster_lock_take()
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:33 +00:00
Martin Schwenke
b029ca4d51 ctdb-recoverd: Drop leader validation
The introduction of the leader broadcast timeout provides an
alternative to the current leader validation.  Using the leader
broadcast may not be as fast but it is more correct.

When the leader node is stopped or banned, the only way of triggering
an election is currently to fetch the leader's node map to check
whether the it is still active.  This is because the leader will no
longer push the node map to other nodes.  However, having all nodes
fetch the node map from an inactive leader may be unreliable.

Most of the other cases are also handled more reliably by the leader
broadcast timeout.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
7e53fab0a3 ctdb-recoverd: Drop special case for elected-before-connected
This no longer occurs at startup due to the leader broadcast timeout.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
ef4b8c13c0 ctdb-recoverd: Handle leader broadcast timeout
If no leader broadcasts have been received from the leader for more
than 5s then trigger an election.

Apart from being sane behaviour, this avoids elected-before-connected
bugs at startup, where a node elects itself leader before it is
connected to other nodes.

When a node processes a leader broadcast timeout it sends an unknown
leader broadcast to all nodes.  That causes cancellation of the leader
broadcast timeout across the cluster.  This is particular important at
startup, since nodes may be started in a staggered fashion.  Without
this cluster-wide cancellation, a node might notice the lack of
leader, win an election and complete a recovery before other nodes
notice the lack of leader.  When the leader broadcast timeout finally
occurs on the other nodes then they'll put the cluster back into an
unnecessary recovery.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
5c7f6da0f0 ctdb-recoverd: Send leader broadcasts
These are triggered on 1 second timer, but are only sent if the node
is the current leader and there is no election underway.

If this node can not be the leader then ensure it releases the
recovery lock.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
789a75abfa ctdb-recoverd: Process leader broadcasts
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
c2cfd9c21a ctdb-recoverd: Add an explicit flag for election in progress
An alternate election method will be added that doesn't use the
election timeout, so this provides a common way for recognising when
an election is in progress.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
ac5a3ca063 ctdb-recoverd: Only start election if node can be leader
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
7baadfe27e ctdb-recoverd: Add and use function this_node_can_be_leader()
This makes the code self-documenting.

In ctdb_election_data() there is a slight behaviour change.  An
inactive node will now try to lose an election.  This case should not happen
because:

* An inactive node can't win an election round and then send a reply.

* Any inactive node should never start an election.  There are
  currently places where this happens and they will be fixed later.

There is an instance where this could be used in
validate_recovery_master() but this involves a more serious logic
change.  Overhaul this function later.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
94b546c268 ctdb-recoverd: Logging/comments: recovery master -> leader
There are some remaining instances in this file but they will be
removed in subsequent commits.

Modernise debug macros as appropriate.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
dd79e9bd14 ctdb-recoverd: Rename recmaster field to leader
Recovery master is being renamed to leader.  This follows clustering
best practice (e.g. RAFT).

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
2ee6763c7d ctdb-recoverd: Use rec->pnn everywhere
This is currently referenced in a number of inconsistent
ways, including:

* pnn
* rec->ctdb->pnn
* ctdb->pnn
* ctdb_get_pnn(ctdb)
* ctdb_get_pnn(rec->ctdb)

The first of these always requires some thought about the context - is
this the node PNN or some other PNN (e.g. argument to function)?

rec->pnn is now always used when referring to the recovery daemon's
PNN.

Doing this also reduces reliance on struct ctdb_context internals.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
4af3b10a37 ctdb-recoverd: Change argument to srvid_disable_and_reply()
Reduce dependency on struct ctdb_context internals, enable a
subsequent change.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
b7c138ca99 ctdb-recoverd: Simplify arguments to ctdb_ban_node()
ban_time argument is always ctdb->tunable.recovery_ban_period, so
build this in and make the calling code more readable.

ctdb_ban_node() already logs how long a node is banned for, so don't
repeatedly log this.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
a5e0ddac62 ctdb-recoverd: Simplify arguments to verify_local_ip_allocation()
All other arguments are available via rec, so simplify.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
67b5191640 ctdb-recoverd: Simplify arguments to do_recovery()
pnn and nodemap are both available via the rec context, so simplify.
vnnmap is unused.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
57882beb16 ctdb-recoverd: Simplify arguments to some election functions
The pnn and nodemap arguments to force_election() and
send_election_request() are always effectively rec->pnn and
rec->nodemap, so simplify.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
9dbe7cc85e ctdb-recoverd: Add PNN to recovery daemon context
This is currently referenced in a number of inconsistent
ways, including:

* pnn
* rec->ctdb->pnn
* ctdb->pnn
* ctdb_get_pnn(ctdb)
* ctdb_get_pnn(rec->ctdb)

The first of these always requires some thought about the context - is
this the node PNN or some other PNN (e.g. argument to function)?

The intention is to always use rec->pnn when referring to the recovery
daemon's PNN.

Doing this also reduces reliance on struct ctdb_context internals.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
ff0140e470 ctdb-recoverd: Use this_node_is_leader() in an extra context
This is arguably clearer.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
c8721d01c6 ctdb-recoverd: Factor out and use function this_node_is_leader()
Make the code self-documenting.

This preempts an upcoming change to terminology but doing it now saves
a lot of churn.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 10:21:32 +00:00
Martin Schwenke
57a32cebdd ctdb-recoverd: Pass SIGHUP to running helper
The recovery and takeover helpers can run for a while and generate
non-trivial logs, so have them reopen their logs to support log
rotation.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>

Autobuild-User(master): Amitay Isaacs <amitay@samba.org>
Autobuild-Date(master): Mon Jan 17 04:36:30 UTC 2022 on sn-devel-184
2022-01-17 04:36:30 +00:00
Martin Schwenke
8e949a6082 ctdb-recoverd: Record helper PID in recovery daemon context
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 03:43:30 +00:00
Martin Schwenke
4acfefed61 ctdb-recoverd: Add basic log reopening
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2022-01-17 03:43:30 +00:00
Martin Schwenke
916c5ee131 ctdb-recoverd: Mark CTDB_SRVID_SET_NODE_FLAGS obsolete
CTDB_SRVID_SET_NODE_FLAGS is no longer sent so drop monitor_handler()
and replace with srvid_not_implemented().  Mark the SRVID obsolete in
its comment.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14784
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2021-09-09 01:46:49 +00:00
Martin Schwenke
8305f6a7f1 ctdb-recoverd: Push flags for a node if any remote node disagrees
This will usually happen if flags on the node in question change, so
keeping the code simple and pushing to all nodes won't hurt.  When all
nodes come up there might be differences in connected nodes, causing
such "fix ups".  Receiving nodes will ignore no-op pushes.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14784
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2021-09-09 01:46:49 +00:00
Martin Schwenke
620d078714 ctdb-recoverd: Update the local node map before pushing out flags
The resulting code structure looks a little weird.  However, there is
another condition that requires the flags to be pushed that will be
inserted before the continue statement in a subsequent commit..

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14784
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2021-09-09 01:46:49 +00:00
Martin Schwenke
82a075d4d7 ctdb-recoverd: Add a helper variable
Improves readability and simplifies subsequent changes.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14784
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2021-09-09 01:46:49 +00:00
Martin Schwenke
4b01f54041 ctdb-recoverd: Drop unnecessary and broken code
update_flags() has already updated the recovery master's canonical
node map, based on the flags from each remote node, and pushed out
these flags to all nodes.

If i == j then the node map has already been updated from this remote
node's flags, so simply drop this case.

Although update_flags() has updated flags for all nodes, it did not
update each node map in remote_nodemaps[] to reflect this.  This means
that remote_nodemaps[] may contain inconsistent flags for some nodes
so it should not be used to check consistency when i != j.

Further, a meaningful difference in flags can only really occur if
update_flags() failed.  In that case this code is never reached.

These observations combine to imply that this whole loop should be
dropped.

This leaves potential sub-second inconsistencies due to out-of-band
healthy/unhealthy flag changes pushed via CTDB_SRVID_PUSH_NODE_FLAGS.
These updates could be dropped (takeover run asks each node for
available IPs rather than making centralised decisions based on node
flags) but for now they will be fixed in the next iteration of
main_loop().

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14513
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2020-10-06 03:12:35 +00:00
Martin Schwenke
3ab52b5286 ctdb-recoverd: Drop unnecessary code
This has already been done in update_flags().

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14513
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2020-10-06 03:12:35 +00:00
Martin Schwenke
8bb6a6607d ctdb-recoverd: Broadcast takeover run message when verifying IPs
This makes it consistent with the monitoring code.  If the master has
changed then this means the master will always get the message.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>

Autobuild-User(master): Amitay Isaacs <amitay@samba.org>
Autobuild-Date(master): Tue Aug 18 06:24:11 UTC 2020 on sn-devel-184
2020-08-18 06:24:11 +00:00
Martin Schwenke
4aa8e72d60 ctdb-recoverd: Rename update_local_flags() -> update_flags()
This also updates remote flags so the name is misleading.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14466
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2020-08-18 05:02:25 +00:00
Martin Schwenke
702c7c4934 ctdb-recoverd: Change update_local_flags() to use already retrieved nodemaps
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14466
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2020-08-18 05:02:25 +00:00
Martin Schwenke
910a0b3b74 ctdb-recoverd: Get remote nodemaps earlier
update_local_flags() will be changed to use these nodemaps.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14466
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2020-08-18 05:02:25 +00:00
Martin Schwenke
d50919b0cb ctdb-recoverd: Do not fetch the nodemap from the recovery master
The nodemap has already been fetched from the local node and is
actually passed to this function.  Care must be taken to avoid
referencing the "remote" nodemap for the recovery master.  It also
isn't useful to do so, since it would be the same nodemap.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14466
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2020-08-18 05:02:25 +00:00
Martin Schwenke
762d1d8a96 ctdb-recoverd: Change get_remote_nodemaps() to use connected nodes
The plan here is to use the nodemaps retrieved by get_remote_nodes()
in update_local_flags().  This will improve efficiency, since
get_remote_nodes() fetches flags from nodes in parallel.  It also
means that get_remote_nodes() can be used exactly once early on in
main_loop() to retrieve remote nodemaps.  Retrieving nodemaps multiple
times is unnecessary and racy - a single monitoring iteration should
not fetch flags multiple times and compare them.

This introduces a temporary behaviour change but it will be of no
consequence when the above changes are made.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14466
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2020-08-18 05:02:25 +00:00