FuseDaemon: Rework inode tracking.

This change contains two related fixes :

(a) Clean up a couple of places where nodes were being Released but
not tracked. To do this in non-brittle way, the calls to NodeCreated
and NodeDeleted have been moved to the point of creation and deletion
(i.e, the calls to new and delete).

(b) Move  node::Create+NodeCreated to the same critical section,
and the same for node::Release+NodeReleased. Otherwise it's possible to
hit the following race conition:

T1: p1->Release()
T2: p1 = node::Create()
T2: NodeCreated(p1)
T1: NodeDeleted(p1)
T?: Lookup(p1)

(c) This change also tightens up inode tracking by making sure we never
insert a duplicate element into set of known inodes. This would have
made this problem a little more obvious.

(d) Also fix up fuse_node_test to reflect this new API, and fix a bug
in node::DeleteTree that was made very obvious by this fix, given the
extra work we do during deletion.

Test: atest FuseDaemonHostTest
Test: adb shell /data/local/fsstress-run.sh
Bug: 148709965

Change-Id: I6eea19020007eb56e6111f60cc9e5a4924b592a4
(cherry picked from commit fc867dd040ddee561f97d1bf9c1552a0d79153df)

1 files changed, 6 insertions, 4 deletions

diff --git a/jni/node.cpp b/jni/node.cpp
index 618777442..e17a9e88a 100644
--- a/jni/node.cpp
+++ b/jni/node.cpp
@@ -97,13 +97,15 @@ void node::DeleteTree(node* tree) {
     std::lock_guard<std::recursive_mutex> guard(*tree->lock_);
 
     if (tree) {
-        for (node* child : tree->children_) {
+        // Make a copy of the list of children because calling Delete tree
+        // will modify the list of children, which will cause issues while
+        // iterating over them.
+        std::vector<node*> children(tree->children_.begin(), tree->children_.end());
+        for (node* child : children) {
             DeleteTree(child);
         }
-        tree->children_.clear();
 
-        LOG(DEBUG) << "DELETE node " << tree->GetName();
-        tree->RemoveFromParent();
+        CHECK(tree->children_.empty());
         delete tree;
     }
 }