.

wcfs/client/wcfs.cpp

@@ -411,6 +411,12 @@ pair<Mapping, error> _FileH::mmap(int64_t blk_start, int64_t blk_len, VMA *vma)
         return make_pair(nil, E(err));
     mem_stop = mem_start + blk_len*f.blksize;
 
+    bool retok = false;
+    defer([&]() {
+        if (!retok)
+            mm::unmap(mem_start, mem_stop - mem_start); // ignore error
+    });
+
     if (stop > f._headfsize) {
         uint8_t *zmem_start = mem_start + (max(f._headfsize/*XXX -1 ?*/, start) - start);
         err = mmap_zero_into_ro(zmem_start, mem_stop - zmem_start);
@@ -430,7 +436,9 @@ pair<Mapping, error> _FileH::mmap(int64_t blk_start, int64_t blk_len, VMA *vma)
         zodb::Tid  rev = _.second;
         if (!(blk_start <= blk && blk < blk_stop))
             continue;   // blk out of this mapping
-        mmap->_remmapblk(blk, rev); // XXX err?
+        err = mmap->_remmapblk(blk, rev);
+        if (err != nil)
+            return make_pair(nil, E(err));
     }
 
     f._mmaps.push_back(mmap);    // XXX keep f._mmaps ↑blk_start
@@ -439,6 +447,7 @@ pair<Mapping, error> _FileH::mmap(int64_t blk_start, int64_t blk_len, VMA *vma)
         vma->mmap_overlay_server = mmap._ptr(); // XXX +giveref
     }
 
+    retok = true;
     return make_pair(mmap, nil);
 }