From: "Yan, Zheng" <zheng.z.yan@xxxxxxxxx>
Migrator::export_dir() only check if it can lock the export lock set
but not take the lock set. So someone else can change the path to
the exporting dir and confuse Migrator::handle_export_discover().
Signed-off-by: Yan, Zheng <zheng.z.yan@xxxxxxxxx>
---
src/mds/Migrator.cc | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/src/mds/Migrator.cc b/src/mds/Migrator.cc
index c157279..5db21cd 100644
--- a/src/mds/Migrator.cc
+++ b/src/mds/Migrator.cc
@@ -236,6 +236,8 @@ void Migrator::handle_mds_failure_or_stop(int who)
dir->unfreeze_tree(); // cancel the freeze
dir->auth_unpin(this);
export_state.erase(dir); // clean up
+ export_unlock(dir);
+ export_locks.erase(dir);
dir->state_clear(CDir::STATE_EXPORTING);
if (export_peer[dir] != who) // tell them.
mds->send_message_mds(new MExportDirCancel(dir->dirfrag()), export_peer[dir]);
@@ -663,6 +665,8 @@ void Migrator::export_dir(CDir *dir, int dest)
dout(7) << "export_dir can't rdlock needed locks, failing." << dendl;
return;
}
+ mds->locker->rdlock_take_set(locks);
+ export_locks[dir].swap(locks);
// ok.
assert(export_state.count(dir) == 0);
@@ -705,6 +709,9 @@ void Migrator::handle_export_discover_ack(MExportDirDiscoverAck *m)
export_peer[dir] != m->get_source().num()) {
dout(7) << "must have aborted" << dendl;
} else {
+ // release locks to avoid deadlock
+ export_unlock(dir);
+ export_locks.erase(dir);
// freeze the subtree
export_state[dir] = EXPORT_FREEZING;
dir->auth_unpin(this);
--
1.7.11.7
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