.

wcfs/client/wcfs.cpp

@@ -120,6 +120,7 @@ error _Conn::close() {
     _Conn& wconn = *this;
     xerr::Contextf E("wcfs %s: close conn @%s", v(wconn._wc->mountpoint), v(wconn.at));
     // XXX + conn # e.g. from wconn._wlink.id? or wlink.close should include its id itself?
+    //       (or ._wlink._f.fd() ?)
 
     error err, eret;
     auto reterr1 = [&eret](error err) {
@@ -241,6 +242,7 @@ error _Conn::__pin1(PinReq *req) {
 
     FileH f;
     bool  ok;
+    // XXX deadlock wrt Conn.open which locks wconn.filehmu and starts initial "watch"
     wconn._filehmu.lock();
     // XXX +incref f, so that simultaneous close does not remove f from wconn.filehTab ?
     tie(f, ok) = wconn._filehtab.get_(req->foid);
@@ -252,7 +254,7 @@ error _Conn::__pin1(PinReq *req) {
 
     // XXX relock wconn -> f
 
-    for (auto mmap : f->_mmaps) {    // XXX use ↑blk_start for binary search
+    for (auto mmap : f->_mmaps) {   // TODO use ↑blk_start for binary search
         if (!(mmap->blk_start <= req->blk && req->blk < mmap->blk_stop()))
             continue;   // blk ∉ mmap
 
@@ -365,6 +367,8 @@ pair<FileH, error> _Conn::open(zodb::Oid foid) {
     });
 
     // start watching f
+    // XXX if we start watching with holding either wconn.filehMu or f.Mu, then
+    // the pinner will deadlock, trying to take wconn.filehMu or f.Mu
     string ack;
     tie(ack, err) = wconn._wlink->sendReq(context::background(), fmt::sprintf("watch %s @%s", v(foid), v(wconn.at)));
     if (err != nil)
@@ -385,6 +389,8 @@ error _FileH::close() {
     Conn    wconn = fileh.wconn;
     xerr::Contextf E("wcfs %s: conn @%s: close f<%s>", v(wconn->_wc->mountpoint), v(wconn->at), v(fileh.foid));
 
+    // XXX change all fileh.mmaps to cause EFAULT on any access after fileh.close
+
     // remove fileh from wconn._filehtab
     // fileh.close can be called several times and after first call another
     // fileh could be opened for the same foid. Be careful not to erase it.

wcfs/client/wcfs.h

@@ -224,6 +224,7 @@ struct _FileH : object {
     zodb::Oid   foid;       // ZBigFile root object ID (does not change after fileh open)
     size_t      blksize;    // block size of this file (does not change after fileh open)
     os::File    _headf;     // file object of head/file
+
     off_t       _headfsize; // head/file size is known to be at least headfsize (size ↑=)
 
     dict<int64_t, zodb::Tid>  _pinned; // {} blk -> rev   that wcfs already sent us for this file