4:32 p.m.
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teigland pushed a commit to branch testing3
in repository sanlock.
commit 735781d683e99cccb3be7ffe8b4fff1392a2a4c8
Author: David Teigland <teigland(a)redhat.com>
Date: Wed Nov 29 13:30:51 2017 -0600
sanlock: fix incorrect error from release
In paxos release, check for different write_id first, rather
than checking for different lver or owner first, because the
different lver or owner is possible with a different write_id.
When there is a write_id other than our own, setting the released
flag in our dblock allows others to acquire the lease, and when
we read the leader record, we can find that it's already held
by another host. This fix avoids returning an error from paxos
release in this case.
---
src/paxos_lease.c | 78 ++++++++++++++++++++++++++++++++-----------------------
1 file changed, 45 insertions(+), 33 deletions(-)
diff --git a/src/paxos_lease.c b/src/paxos_lease.c
index c13c5a2..49fdff2 100644
--- a/src/paxos_lease.c
+++ b/src/paxos_lease.c
@@ -1955,6 +1955,50 @@ int paxos_lease_release(struct task *task,
else
last = leader_last;
+ /*
+ * This will happen when two hosts finish the same ballot
+ * successfully, the second commiting the same inp values
+ * that the first did, as it should. But the second will
+ * write it's own write_id/gen/timestap, which will differ
+ * from what the first host wrote. So when the first host
+ * rereads here in the release, it will find different
+ * write_id/gen/timestamp from what it wrote. This is
+ * perfectly fine (use log warn since it's interesting
+ * to see when this happens.)
+ *
+ * If another host was the writer and committed us as the
+ * owner, then we don't zero the leader record when we release,
+ * we just release our dblock (by setting the release flag,
+ * already done prior to calling paxos_lease_release). This is
+ * because other hosts will ignore our leader record if we were
+ * not the writer once we release our dblock. Those other
+ * hosts will then run a ballot and commit/write a new leader.
+ * If we are also zeroing the leader, that can race with
+ * another host writing a new leader, and we could clobber the
+ * new leader.
+ */
+ if (leader.write_id != token->host_id) {
+ log_level(0, token->token_id, NULL, LOG_WARNING,
+ "paxos_release skip write "
+ "last lver %llu owner %llu %llu %llu writer %llu %llu %llu "
+ "disk lver %llu owner %llu %llu %llu writer %llu %llu %llu",
+ (unsigned long long)last->lver,
+ (unsigned long long)last->owner_id,
+ (unsigned long long)last->owner_generation,
+ (unsigned long long)last->timestamp,
+ (unsigned long long)last->write_id,
+ (unsigned long long)last->write_generation,
+ (unsigned long long)last->write_timestamp,
+ (unsigned long long)leader.lver,
+ (unsigned long long)leader.owner_id,
+ (unsigned long long)leader.owner_generation,
+ (unsigned long long)leader.timestamp,
+ (unsigned long long)leader.write_id,
+ (unsigned long long)leader.write_generation,
+ (unsigned long long)leader.write_timestamp);
+ return 0;
+ }
+
if (leader.lver != last->lver) {
log_errot(token, "paxos_release other lver "
"last lver %llu owner %llu %llu %llu writer %llu %llu %llu "
@@ -2022,17 +2066,6 @@ int paxos_lease_release(struct task *task,
}
if (memcmp(&leader, last, sizeof(struct leader_record))) {
- /*
- * This will happen when two hosts finish the same ballot
- * successfully, the second commiting the same inp values
- * that the first did, as it should. But the second will
- * write it's own write_id/gen/timestap, which will differ
- * from what the first host wrote. So when the first host
- * rereads here in the release, it will find different
- * write_id/gen/timestamp from what it wrote. This is
- * perfectly fine (use log_error since it's interesting
- * to see when this happens.)
- */
log_errot(token, "paxos_release different vals "
"last lver %llu owner %llu %llu %llu writer %llu %llu %llu "
"disk lver %llu owner %llu %llu %llu writer %llu %llu %llu",
@@ -2050,28 +2083,7 @@ int paxos_lease_release(struct task *task,
(unsigned long long)leader.write_id,
(unsigned long long)leader.write_generation,
(unsigned long long)leader.write_timestamp);
-
- /*
- log_leader_error(0, token, &token->disks[0], last, "paxos_release");
- log_leader_error(0, token, &token->disks[0], &leader,
"paxos_release");
- */
-
- /*
- * If another host was the writer and committed us as the
- * owner, then we don't zero the leader record when we release,
- * we just release our dblock (by setting the release flag,
- * already done prior to calling paxos_lease_release). This is
- * because other hosts will ignore our leader record if we were
- * not the writer once we release our dblock. Those other
- * hosts will then run a ballot and commit/write a new leader.
- * If we are also zeroing the leader, that can race with
- * another host writing a new leader, and we could clobber the
- * new leader.
- */
- if (leader.write_id != token->host_id) {
- log_token(token, "paxos_release %llu skip leader write", (unsigned long
long)last->lver);
- return 0;
- }
+ return SANLK_RELEASE_OWNER;
}
if (resrename)
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