From c70089a176e5ba86a8e7fc99d760c4f707722d3e Mon Sep 17 00:00:00 2001
From: Bill Zissimopoulos <billziss@navimatics.com>
Date: Wed, 27 Sep 2017 18:01:17 -0700
Subject: [PATCH] sys: FSP_FILE_DESC: DirectoryNoMoreFiles optimization

---
 src/sys/dirctl.c | 17 +++++++++++++++++
 src/sys/driver.h |  2 +-
 src/sys/file.c   |  3 +++
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/sys/dirctl.c b/src/sys/dirctl.c
index 59e4d851..f08e1171 100644
--- a/src/sys/dirctl.c
+++ b/src/sys/dirctl.c
@@ -339,6 +339,10 @@ static NTSTATUS FspFsvolQueryDirectoryCopyCache(
             if (0 != *PDestLen)
                 FileDesc->DirectoryHasSuchFile = TRUE;
             FileDesc->DirInfoCacheHint = (ULONG)((PUINT8)DirInfo - DirInfoBgn);
+
+            if (DirInfoEnd >= (PUINT8)DirInfo + sizeof(DirInfo->Size) &&
+                sizeof(FSP_FSCTL_DIR_INFO) > DirInfo->Size)
+                FileDesc->DirectoryNoMoreFiles = TRUE;
         }
     }
     else if (STATUS_NO_MORE_FILES == Result && !FileDesc->DirectoryHasSuchFile)
@@ -361,6 +365,7 @@ static NTSTATUS FspFsvolQueryDirectoryCopyInPlace(
     BOOLEAN CaseInsensitive = !FileDesc->CaseSensitive;
     PUNICODE_STRING DirectoryPattern = &FileDesc->DirectoryPattern;
     UNICODE_STRING DirectoryMarker = FileDesc->DirectoryMarker;
+    PUINT8 DirInfoEnd = (PUINT8)DirInfo + DirInfoSize;
 
     ASSERT(DirInfo == DestBuf);
     FSP_FSCTL_STATIC_ASSERT(
@@ -381,6 +386,10 @@ static NTSTATUS FspFsvolQueryDirectoryCopyInPlace(
         {
             if (0 != *PDestLen)
                 FileDesc->DirectoryHasSuchFile = TRUE;
+
+            if (DirInfoEnd >= (PUINT8)DirInfo + sizeof(DirInfo->Size) &&
+                sizeof(FSP_FSCTL_DIR_INFO) > DirInfo->Size)
+                FileDesc->DirectoryNoMoreFiles = TRUE;
         }
     }
     else if (STATUS_NO_MORE_FILES == Result && !FileDesc->DirectoryHasSuchFile)
@@ -529,6 +538,14 @@ static NTSTATUS FspFsvolQueryDirectoryRetry(
         return Result;
     }
 
+    /* check if the FileDesc has already seen the "End Of Directory" mark */
+    if (FileDesc->DirectoryNoMoreFiles)
+    {
+        FspFileNodeRelease(FileNode, Full);
+        return !FileDesc->DirectoryHasSuchFile ?
+            STATUS_NO_SUCH_FILE : STATUS_NO_MORE_FILES;
+    }
+
     /* see if the required information is still in the cache and valid! */
     if (FspFileNodeReferenceDirInfo(FileNode, &DirInfoBuffer, &DirInfoSize))
     {
diff --git a/src/sys/driver.h b/src/sys/driver.h
index 8b37875d..c681cffb 100644
--- a/src/sys/driver.h
+++ b/src/sys/driver.h
@@ -1267,7 +1267,7 @@ typedef struct
         DidSetMetadata:1,
         DidSetFileAttributes:1, DidSetReparsePoint:1, DidSetSecurity:1,
         DidSetCreationTime:1, DidSetLastAccessTime:1, DidSetLastWriteTime:1, DidSetChangeTime:1,
-        DirectoryHasSuchFile:1;
+        DirectoryHasSuchFile:1, DirectoryNoMoreFiles:1;
     UNICODE_STRING DirectoryPattern;
     UNICODE_STRING DirectoryMarker;
     UINT64 DirInfo;
diff --git a/src/sys/file.c b/src/sys/file.c
index bc60a64a..cf1806bd 100644
--- a/src/sys/file.c
+++ b/src/sys/file.c
@@ -2121,6 +2121,7 @@ NTSTATUS FspFileDescResetDirectory(FSP_FILE_DESC *FileDesc,
 
         FileDesc->DirectoryPattern = DirectoryPattern;
         FileDesc->DirectoryHasSuchFile = FALSE;
+        FileDesc->DirectoryNoMoreFiles = FALSE;
 
         if (0 != FileDesc->DirectoryMarker.Buffer)
         {
@@ -2133,6 +2134,7 @@ NTSTATUS FspFileDescResetDirectory(FSP_FILE_DESC *FileDesc,
         ASSERT(0 == FileName || 0 == FileName->Length);
 
         FileDesc->DirectoryHasSuchFile = FALSE;
+        FileDesc->DirectoryNoMoreFiles = FALSE;
 
         if (0 != FileDesc->DirectoryMarker.Buffer)
         {
@@ -2149,6 +2151,7 @@ NTSTATUS FspFileDescResetDirectory(FSP_FILE_DESC *FileDesc,
             return Result;
 
         FileDesc->DirectoryHasSuchFile = FALSE;
+        FileDesc->DirectoryNoMoreFiles = FALSE;
     }
 
     return STATUS_SUCCESS;