libfuse: fix crash in unlock_path()

Patch by Ratna Manoj.

queue_element_unlock() should set ->first_locked and ->second_locked to false.

Discovered with 'fs_racer'.  The assert(wnode->treelock == TREELOCK_WRITE) in
unlock_path() was hit within minutes.

Miklos: simplified patch

2 files changed, 6 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index dbd10e8..076bcaf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2013-02-04  Miklos Szeredi <miklos@szeredi.hu>
+
+	* libfuse: fix crash in unlock_path().  Patch by Ratna Manoj
+
 2012-10-01  Miklos Szeredi <miklos@szeredi.hu>
 
 	* Released 2.9.2
diff --git a/lib/fuse.c b/lib/fuse.c
index 599a587..1917346 100644
--- a/lib/fuse.c
+++ b/lib/fuse.c
@@ -1021,10 +1021,12 @@ static void queue_element_unlock(struct fuse *f, struct lock_queue_element *qe)
 	if (qe->first_locked) {
 		wnode = qe->wnode1 ? *qe->wnode1 : NULL;
 		unlock_path(f, qe->nodeid1, wnode, NULL);
+		qe->first_locked = false;
 	}
 	if (qe->second_locked) {
 		wnode = qe->wnode2 ? *qe->wnode2 : NULL;
 		unlock_path(f, qe->nodeid2, wnode, NULL);
+		qe->second_locked = false;
 	}
 }