.

wcfs/client/wcfs.cpp

@@ -832,7 +832,7 @@ error _FileH::close() {
         return nil;
 
     // last open went away - real close.
-    xerr::Contextf E("%s: close f<%s>", v(wconn), v(fileh.foid));
+    xerr::Contextf E("%s: %s: close", v(wconn), v(fileh));
     etrace("");
 
     ASSERT(fileh._state == _FileHOpened); // there can be no open-in-progress, because
@@ -849,9 +849,6 @@ error _FileH::close() {
             eret = err;
     };
 
-    // XXX do something with f.mu ?
-    // XXX change all fileh.mmaps to cause EFAULT on any access after fileh.close
-
     // stop watching f
     string ack;
     tie(ack, err) = wconn->_wlink->sendReq(context::background(),
@@ -870,6 +867,19 @@ error _FileH::close() {
 
     reterr1(fileh._headf->close());
 
+    // change all fileh.mmaps to cause EFAULT on any access after fileh.close
+    fileh._mu.lock();
+    defer([&]() {
+        fileh._mu.unlock();
+    });
+
+    for (auto mmap : fileh._mmaps) {
+        err = mmap->__remmapAsEfault();
+        if (err != nil)
+            reterr1(err);
+    }
+
+    // fileh close complete
     fileh._state = _FileHClosed;
     fileh._closedq.close();
 
@@ -892,7 +902,7 @@ pair<Mapping, error> _FileH::mmap(int64_t blk_start, int64_t blk_len, VMA *vma)
         f.wconn->_atMu.RUnlock();
     });
 
-    xerr::Contextf E("%s: mmap f<%s> [blk%ld +blk%ld)", v(f.wconn), v(f.foid), blk_start, blk_len);
+    xerr::Contextf E("%s: %s: mmap [#%ld +%ld)", v(f.wconn), v(f), blk_start, blk_len);
     etrace("");
 
     if (f._state >= _FileHClosing)  // XXX locking
@@ -989,7 +999,7 @@ error _Mapping::unmap() {
         f->wconn->_atMu.RUnlock();
     });
 
-    xerr::Contextf E("%s: f<%s>: unmap", v(f->wconn), v(f->foid));
+    xerr::Contextf E("%s: %s: %s: unmap", v(f->wconn), v(f), v(mmap));
     etrace("");
 
     if (mmap->vma != nil) {
@@ -1030,7 +1040,7 @@ error _Mapping::_remmapblk(int64_t blk, zodb::Tid at) {
 
     _Mapping *mmap = this;
     FileH f = mmap->fileh;
-    xerr::Contextf E("%s: f<%s>: remmapblk #%ld @%s", v(f->wconn), v(f->foid), blk, v(at));
+    xerr::Contextf E("%s: %s: %s: remmapblk #%ld @%s", v(f->wconn), v(f), v(mmap), blk, v(at));
     etrace("");
 
     ASSERT(mmap->blk_start <= blk && blk < mmap->blk_stop());
@@ -1113,6 +1123,26 @@ error _Mapping::remmap_blk(int64_t blk) {
     return nil;
 }
 
+// __remmapEfault remmaps Mapping memory to cause SIGSEGV on access.
+//
+// It is used on FileH shutdown to turn all fileh mappings into incorrect ones,
+// because after fileh is down, it is not possible to continue to provide
+// correct f@at data view.
+//
+// Must be called with the following locks held by caller:
+// - virt_lock
+// XXX more?
+error _Mapping::__remmapAsEfault() {
+    _Mapping& mmap = *this;
+    FileH f = mmap.fileh;
+
+    xerr::Contextf E("%s: remmap as efault", v(mmap)); // XXX +wconn, +f ?
+    etrace("");
+
+    error err = mmap_efault_into(mmap.mem_start, mmap.mem_stop - mmap.mem_start);
+    return E(err);
+}
+
 // ---- WCFS raw file access ----
 
 // _path returns path for object on wcfs.
@@ -1216,6 +1246,18 @@ string _Conn::String() const {
     return fmt::sprintf("%s: conn%d @%s", v(wconn._wc), wconn._wlink->fd(), v(wconn.at));
 }
 
+string _FileH::String() const {
+    const _FileH& f = *this;
+    return fmt::sprintf("f<%s>", v(f.foid));
+}
+
+string _Mapping::String() const {
+    const _Mapping& mmap = *this;
+    return fmt::sprintf("m[#%ld +%ld) v[%p +%lx)",
+                mmap.blk_start, mmap.blk_stop() - mmap.blk_start,
+                mmap.mem_start, mmap.mem_stop   - mmap.mem_start);
+}
+
 _Conn::_Conn()  {}
 _Conn::~_Conn() {}
 void _Conn::decref() {

wcfs/client/wcfs.h

@@ -246,7 +246,7 @@ struct _FileH : object {
     // protected by .wconn._atMu
     off_t       _headfsize;
 
-    sync::Mutex               _mu;     // atMu.W  |  atMu.R + _mu
+    sync::Mutex               _mu;     // atMu.W  |  atMu.R + _mu   XXX -> mmapMu ?
     dict<int64_t, zodb::Tid>  _pinned; // {} blk -> rev   that wcfs already sent us for this file
     vector<Mapping>           _mmaps;  // []Mapping ↑blk_start    mappings of this file
 
@@ -263,6 +263,7 @@ public:
     pair<Mapping, error> mmap(int64_t blk_start, int64_t blk_len, VMA *vma=nil);
 
     error _open();
+    string String() const;
 };
 
 // Mapping represents one memory mapping of FileH.
@@ -286,11 +287,13 @@ struct _Mapping : object {
         return blk_start + (mem_stop - mem_start) / fileh->blksize;
     }
 
-    void  _assertVMAOk();
-    error _remmapblk(int64_t blk, zodb::Tid at);
     error remmap_blk(int64_t blk); // for virtmem-only
     error unmap();
 
+    void  _assertVMAOk();
+    error _remmapblk(int64_t blk, zodb::Tid at);
+    error __remmapAsEfault();
+
     // don't new - create via FileH.mmap
 private:
     _Mapping();
@@ -298,6 +301,8 @@ private:
     friend pair<Mapping, error> _FileH::mmap(int64_t blk_start, int64_t blk_len, VMA *vma);
 public:
     void decref();
+
+    string String() const;
 };