In dlm_assert_master_handler, spinlock is released little sooner which creates
a window for two nodes to race during mastery.
In a scenario where node A had a head start during lock mastery and dlm
spinlock is just released on node B in dlm_assert_master_handler. Right then
a process on node B started to master the resource. It finds the mle but
doesn't find lockres. Since mle *master* is not set it creates a lockres and
waits for the mastery and doesn't send a master request.
dlm_assert_master_handler doesn't know about this and doesn't set
have_lockres_ref(doesn't set DLM_ASSERT_RESPONSE_MASTERY_REF) which creates a
hole that results in loss of refmap bit on the master node.
Signed-off-by: Srinivas Eeda <srinivas.e...@oracle.com>
---
fs/ocfs2/dlm/dlmmaster.c | 4 +---
1 files changed, 1 insertions(+), 3 deletions(-)
diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index 83bcaf2..6e694b6 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -1875,7 +1875,6 @@ int dlm_assert_master_handler(struct o2net_msg *msg, u32
len, void *data,
ok:
spin_unlock(&res->spinlock);
}
- spin_unlock(&dlm->spinlock);
// mlog(0, "woo! got an assert_master from node %u!\n",
// assert->node_idx);
@@ -1926,7 +1925,6 @@ ok:
/* master is known, detach if not already detached.
* ensures that only one assert_master call will happen
* on this mle. */
- spin_lock(&dlm->spinlock);
spin_lock(&dlm->master_lock);
rr = atomic_read(&mle->mle_refs.refcount);
@@ -1959,7 +1957,6 @@ ok:
__dlm_put_mle(mle);
}
spin_unlock(&dlm->master_lock);
- spin_unlock(&dlm->spinlock);
} else if (res) {
if (res->owner != assert->node_idx) {
mlog(0, "assert_master from %u, but current "
@@ -1967,6 +1964,7 @@ ok:
res->owner, namelen, name);
}
}
+ spin_unlock(&dlm->spinlock);
done:
ret = 0;
--
1.5.6.5
_______________________________________________
Ocfs2-devel mailing list
Ocfs2-devel@oss.oracle.com
http://oss.oracle.com/mailman/listinfo/ocfs2-devel
