.

wcfs/client/wcfs.cpp

@@ -117,7 +117,7 @@
 //
 // XXX locking -> explain atMu + slaves and refer to "Locking" in wcfs.go
 //
-// Conn.atMu > Conn.filehMu > FileH.mu
+// Conn.atMu > Conn.filehMu > FileH.mmapMu
 //
 // Several locks are RWMutex instead of just Mutex not only to allow more
 // concurrency, but, in the first place for correctness: pinner thread being
@@ -150,7 +150,7 @@
 //
 //      - wconn.atMu.R
 //      - wconn.filehMu.R
-//      - fileh.mu (R:.mmaps W:.pinned)
+//      - fileh.mmapMu (R:.mmaps W:.pinned)
 //
 //      - virt_lock
 //
@@ -442,12 +442,12 @@ error _Conn::__pin1(PinReq *req) {
     // Mapping.remmap_blk and Mapping.unmap under virt_lock locked. In those
     // functions the order of locks is
     //
-    //      virt_lock, wconn.atMu.R, fileh.mu
+    //      virt_lock, wconn.atMu.R, fileh.mmapMu
     //
     // So if we take virt_lock right around mmap._remmapblk(), the order of
     // locks in pinner would be
     //
-    //      wconn.atMu.R, wconn.filehMu.R, fileh.mu, virt_lock
+    //      wconn.atMu.R, wconn.filehMu.R, fileh.mmapMu, virt_lock
     //
     // which means there is AB-BA deadlock possibility.
     //
@@ -489,9 +489,9 @@ error _Conn::__pin1(PinReq *req) {
     // our view to requested @at, and "closing" - due to other clients
     // accessing wcfs/head/f simultaneously.
 
-    f->_mu.lock();
+    f->_mmapMu.lock();
     defer([&]() {
-        f->_mu.unlock();
+        f->_mmapMu.unlock();
     });
 
     for (auto mmap : f->_mmaps) {   // TODO use ↑blk_start for binary search
@@ -635,7 +635,7 @@ error _Conn::resync(zodb::Tid at) {
             return E(fmt::errorf("wcfs bug: head/file size %% blksize != 0"));
 
         // replace zero regions in f mappings in accordance to adjusted f._headfsize.
-        // NOTE it is ok to access f._mmaps without locking f._mu because we hold wconn.atMu.W
+        // NOTE it is ok to access f._mmaps without locking f._mmapMu because we hold wconn.atMu.W
         for (auto mmap : f->_mmaps) {
             //printf("  resync -> %s: unzero [%lu:%lu)", v(at), f->_headfsize/f->blksize, headfsize/f->blksize);
             uint8_t *mem_unzero_start = min(mmap->mem_stop,
@@ -789,7 +789,7 @@ retry:
     });
 
     // do the actuall open.
-    // we hold only wconn.atMu.R, but niether wconn.filehMu, nor f.mu .
+    // we hold only wconn.atMu.R, but niether wconn.filehMu, nor f.mmapMu .
     f->_openErr = f->_open();
     if (f->_openErr != nil)
         return make_pair(nil, E(f->_openErr));
@@ -815,7 +815,7 @@ retry:
 // Called with:
 // - wconn.atMu     held
 // - wconn.filehMu  not locked
-// - f.mu           not locked
+// - f.mmapMu       not locked
 error _FileH::_open() {
     _FileH* f = this;
     Conn    wconn = f->wconn;
@@ -843,7 +843,7 @@ error _FileH::_open() {
                         v(f->_headf->name()), f->_headfsize, f->blksize);
 
     // start watching f
-    // NOTE we are _not_ holding wconn.filehMu nor f.mu - only wconn.atMu to rely on wconn.at being stable.
+    // NOTE we are _not_ holding wconn.filehMu nor f.mmapMu - only wconn.atMu to rely on wconn.at being stable.
     // NOTE wcfs will reply "ok" only after wcfs/head/at ≥ wconn.at
     string ack;
     tie(ack, err) = wconn->_wlink->sendReq(context::background(),
@@ -941,9 +941,9 @@ error _FileH::_closeLocked(bool force) {
     reterr1(fileh._headf->close());
 
     // change all fileh.mmaps to cause EFAULT on any access after fileh.close
-    fileh._mu.lock();
+    fileh._mmapMu.lock();
     defer([&]() {
-        fileh._mu.unlock();
+        fileh._mmapMu.unlock();
     });
 
     for (auto mmap : fileh._mmaps) {
@@ -969,9 +969,9 @@ pair<Mapping, error> _FileH::mmap(int64_t blk_start, int64_t blk_len, VMA *vma)
     // NOTE virtmem lock is held by virtmem caller
     // XXX locking ok?
     f.wconn->_atMu.RLock(); // e.g. f._headfsize
-    f._mu.lock();           // f._pinned, f._mmaps
+    f._mmapMu.lock();       // f._pinned, f._mmaps
     defer([&]() {
-        f._mu.unlock();
+        f._mmapMu.unlock();
         f.wconn->_atMu.RUnlock();
     });
 
@@ -1066,9 +1066,9 @@ error _Mapping::unmap() {
 
     // NOTE virtmem lock is held by virtmem caller
     f->wconn->_atMu.RLock();
-    f->_mu.lock();          // f._mmaps
+    f->_mmapMu.lock();
     defer([&]() {
-        f->_mu.unlock();
+        f->_mmapMu.unlock();
         f->wconn->_atMu.RUnlock();
     });
 
@@ -1091,7 +1091,7 @@ error _Mapping::unmap() {
     // XXX clear other fields?
 
     // XXX do it first? (to avoid pinner going through f.mmaps and hitting unmapped memory)
-    //     -> no need: both pinner and unmap lock on f.mu
+    //     -> no need: both pinner and unmap lock on f.mmapMu
     //f->_mmaps.remove(mmap);
     f->_mmaps.erase(
         std::remove(f->_mmaps.begin(), f->_mmaps.end(), mmap),
@@ -1107,7 +1107,7 @@ error _Mapping::unmap() {
 //
 // The following locks must be held by caller:
 // - f.wconn.atMu
-// - f._mu          XXX not needed? (f._mmaps and f._pinned are not used)
+// - f._mmapMu          XXX not needed? (f._mmaps and f._pinned are not used)
 error _Mapping::_remmapblk(int64_t blk, zodb::Tid at) {
     // XXX must not be called after Mapping is switched to efault?
 
@@ -1172,9 +1172,9 @@ error _Mapping::remmap_blk(int64_t blk) {
 
     // NOTE virtmem lock is held by virtmem caller
     f->wconn->_atMu.RLock();
-    f->_mu.lock();
+    f->_mmapMu.lock();
     defer([&]() {
-        f->_mu.unlock();
+        f->_mmapMu.unlock();
         f->wconn->_atMu.RUnlock();
     });
 

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   XXX -> mmapMu ?
+    sync::Mutex               _mmapMu; // atMu.W  |  atMu.R + _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