Changeset 78608 in vbox for trunk/src/VBox/Additions/WINNT/SharedFolders/driver/file.cpp

Timestamp:

May 20, 2019 11:04:08 PM (6 years ago)

Author:

vboxsync

Message:

winnt/vboxsf: Don't flush and purge the cache twice on newer systems, instead do a library trick to redirect relevant imports from write.obj and read.obj to our wrappers that uses CcCoherencyFlushAndPurgeCache when possible to get better coherency between mmap regions and file content when writing and reading normally. This comes at a cost when the file has been mmapped at some point previously (or currently) and we may need to purge stuff. bugref:9172

File:

• trunk/src/VBox/Additions/WINNT/SharedFolders/driver/file.cpp (modified) (5 diffs)

trunk/src/VBox/Additions/WINNT/SharedFolders/driver/file.cpp

@@ -30 +30 @@
 /** How many pages we should try transfer in one I/O request (read/write). */
 #define VBSF_MAX_IO_PAGES   RT_MIN(_16K / sizeof(RTGCPHYS64) /* => 8MB buffer */, VMMDEV_MAX_HGCM_DATA_SIZE >> PAGE_SHIFT)
+
+
+
+
+/** @name Hacks for using the better CcCoherencyFlushAndPurgeCache when
+ *        available (>= Windows 7) and avoid flushing+puring twice.
+ *
+ * We change the cache flushing and purging related imports from  the write.obj
+ * and read.obj files in the rdbsslib.lib to import so these gets redirected
+ * here instead of going directly to ntoskrnl.  We will use
+ * CcCoherencyFlushAndPurgeCache when present, and on older systems there will
+ * be no change.  This does however save us from doing double flushing and
+ * purging on newer systems.
+ *
+ * See VBoxEditCoffLib and the Makefile.kmk for the rest of the puzzle.
+ *
+ * @{
+ */
+
+static VOID NTAPI vbsfNtReadCcFlushCache(PSECTION_OBJECT_POINTERS pSectObjPtrs, PLARGE_INTEGER poffFlush, ULONG cbFlush,
+                                         PIO_STATUS_BLOCK pIos)
+{
+    if (g_pfnCcCoherencyFlushAndPurgeCache)
+        g_pfnCcCoherencyFlushAndPurgeCache(pSectObjPtrs, poffFlush, cbFlush, pIos, CC_FLUSH_AND_PURGE_NO_PURGE);
+    else
+        CcFlushCache(pSectObjPtrs, poffFlush, cbFlush, pIos);
+}
+
+static VOID NTAPI vbsfNtWriteCcFlushCache(PSECTION_OBJECT_POINTERS pSectObjPtrs, PLARGE_INTEGER poffFlush, ULONG cbFlush,
+                                          PIO_STATUS_BLOCK pIos)
+{
+    if (g_pfnCcCoherencyFlushAndPurgeCache)
+        g_pfnCcCoherencyFlushAndPurgeCache(pSectObjPtrs, poffFlush, cbFlush, pIos, 0 /*fFlags*/);
+    else
+        CcFlushCache(pSectObjPtrs, poffFlush, cbFlush, pIos);
+}
+
+
+static BOOLEAN NTAPI vbsfNtWriteCcPurgeCacheSection(PSECTION_OBJECT_POINTERS pSectObjPtrs, PLARGE_INTEGER poffPurge,ULONG cbPurge,
+#if (NTDDI_VERSION >= NTDDI_VISTA)
+                                                    ULONG fUninitializeCacheMaps)
+#else
+                                                    BOOLEAN fUninitializeCacheMaps)
+#endif
+{
+#if (NTDDI_VERSION >= NTDDI_VISTA)
+    fUninitializeCacheMaps &= 0xff; /* Used to be BOOLEAN before Vista. */
+#endif
+    Assert(fUninitializeCacheMaps == 0);
+    BOOLEAN fRet;
+    if (g_pfnCcCoherencyFlushAndPurgeCache)
+        fRet = TRUE;
+    else
+        fRet = CcPurgeCacheSection(pSectObjPtrs, poffPurge, cbPurge, fUninitializeCacheMaps);
+    return fRet;
+}
+
+extern "C" {
+decltype(CcFlushCache)        *g_pfnRdFlushCache        = vbsfNtReadCcFlushCache;
+decltype(CcFlushCache)        *g_pfnWrFlushCache        = vbsfNtWriteCcFlushCache;
+decltype(CcPurgeCacheSection) *g_pfnWrPurgeCacheSection = vbsfNtWriteCcPurgeCacheSection;
+}
+
+/** @} */
+
 
 
@@ -115 +180 @@
             pReq->PgLst.offFirstPage = offPage;
 
+#if 0 /* Instead we hook into read.obj's import function pointers to do this more efficiently. */
             /*
              * Flush dirty cache content before we try read it from the host.  RDBSS calls
@@ -135 +201 @@
                 {   RxReleasePagingIoResource(NULL, capFcb); /* requires {} */ }
             }
+#endif
 
             /*
@@ -377 +444 @@
             pReq->PgLst.offFirstPage = offPage;
 
+#if 0 /* Instead we hook into write.obj's import function pointers to do this more efficiently. */
             /*
              * Flush and purge the cache range we're touching upon now, provided we can and
@@ -395 +463 @@
                 {   RxReleasePagingIoResource(NULL, capFcb); /* requires {} */ }
             }
+#endif
 
             /*