.

wcfs/client/wcfs.cpp

@@ -627,13 +627,29 @@ pair<FileH, error> _Conn::open(zodb::Oid foid) {
         return make_pair(nil, E(err));
     }
 
+retry:
     FileH f; bool ok;
     tie(f, ok) = wconn._filehTab.get_(foid);
     if (ok) {
+        bool closing;
+
+        if (f->_state <= _FileHOpened) {
             f->_nopen++; // XXX lock by f.mu ?
+            closing = false;
+        } else {
+            closing = true;
+        }
         wconn._mu.Unlock();
 
-        // wait for: "opening" -> opened
+        // if the file was closing|closed, we should wait for the close to
+        // complete and retry the open.
+        if (closing) {
+            f->_closedq.recv();
+            goto retry;
+        }
+
+        // the file was opening|opened. wait for it to be opened and return the result.
+        // we can be sure there won't be last Close simultaneous to us as we did ._nopen++
         f->_openReady.recv();
         if (f->_openErr != nil) {
             // don't care about f->_nopen-- since f is not returned anywhere
@@ -649,10 +665,12 @@ pair<FileH, error> _Conn::open(zodb::Oid foid) {
     f->wconn      = newref(&wconn);
     f->foid       = foid;
     f->_openReady = makechan<structZ>();
+    f->_closedq   = makechan<structZ>();
     f->_openErr   = nil;
     f->_headf     = nil;
     f->blksize    = 0;
     f->_headfsize = 0;
+    f->_state     = _FileHOpening;
     f->_nopen     = 1;
     f->_closed    = false;
 

wcfs/client/wcfs.h

@@ -233,6 +233,7 @@ struct _FileH : object {
 
     chan<structZ> _openReady; // in-flight open completed
     error         _openErr;   // error result from open
+    chan<structZ> _closedq;   // in-flight close completed
 
     os::File      _headf;     // file object of head/file
     size_t        blksize;    // block size of this file (does not change after fileh open)