sys: IRP_MJ_READ, IRP_MJ_WRITE: fix paging I/O sizes

inc/winfsp/fsctl.h

@@ -206,6 +206,7 @@ typedef struct
             UINT64 Offset;
             UINT32 Length;
             UINT32 Key;
+            UINT32 ConstrainedIo:1;
         } Write;
         struct
         {

inc/winfsp/winfsp.h

@@ -70,7 +70,8 @@ typedef struct _FSP_FILE_SYSTEM_INTERFACE
         PULONG PBytesTransferred, FSP_FSCTL_FILE_INFO *FileInfo);
     NTSTATUS (*Write)(FSP_FILE_SYSTEM *FileSystem,
         FSP_FSCTL_TRANSACT_REQ *Request,
-        PVOID FileNode, PVOID Buffer, UINT64 Offset, ULONG Length, BOOLEAN WriteToEndOfFile,
+        PVOID FileNode, PVOID Buffer, UINT64 Offset, ULONG Length,
+        BOOLEAN WriteToEndOfFile, BOOLEAN ConstrainedIo,
         PULONG PBytesTransferred, FSP_FSCTL_FILE_INFO *FileInfo);
     NTSTATUS (*Flush)(FSP_FILE_SYSTEM *FileSystem,
         FSP_FSCTL_TRANSACT_REQ *Request,

src/dll/fsop.c

@@ -449,6 +449,7 @@ FSP_API NTSTATUS FspFileSystemOpWrite(FSP_FILE_SYSTEM *FileSystem,
         Request->Req.Write.Offset,
         Request->Req.Write.Length,
         (UINT64)-1LL == Request->Req.Write.Offset,
+        0 != Request->Req.Write.ConstrainedIo,
         &BytesTransferred,
         &FileInfo);
     if (!NT_SUCCESS(Result))

src/sys/read.c

@@ -220,8 +220,9 @@ static NTSTATUS FspFsvolReadNonCached(
     if (FlagOn(IrpSp->MinorFunction, IRP_MN_MDL))
         return STATUS_INVALID_PARAMETER;
 
-    /* if this is a recursive read (cache) see if we can optimize it away! */
+    /* if this is a Paging I/O see if we can optimize it away! */
-    if (FlagOn(FspIrpTopFlags(Irp), FspFileNodeAcquireMain) &&  /* if TopLevelIrp has acquired Main */
+    if (PagingIo &&                                             /* if this is Paging I/O             */
+        FlagOn(FspIrpTopFlags(Irp), FspFileNodeAcquireMain) &&  /* and TopLevelIrp has acquired Main */
         FspFileNodeTryGetFileInfo(FileNode, &FileInfo) &&       /* and the cached FileSize is valid  */
         (UINT64)ReadOffset.QuadPart >= FileInfo.FileSize)       /* and the ReadOffset is past EOF    */
         return STATUS_END_OF_FILE;

src/sys/write.c

@@ -276,23 +276,13 @@ static NTSTATUS FspFsvolWriteNonCached(
     if (FspIoqStopped(FspFsvolDeviceExtension(FsvolDeviceObject)->Ioq))
         return FspFsvolDeviceStoppedStatus(FsvolDeviceObject);
 
-    /* if we are called by the lazy writer we must constrain writes */
+    /* if this is a Paging I/O see if we can optimize it away! */
-    if (FlagOn(FspIrpTopFlags(Irp), FspFileNodeAcquireMain) &&  /* if TopLevelIrp has acquired Main */
+    if (PagingIo &&                                             /* if this is Paging I/O             */
-        FileNode->Tls.LazyWriteThread == PsGetCurrentThread())  /* and this is a lazy writer thread */
+        FlagOn(FspIrpTopFlags(Irp), FspFileNodeAcquireMain) &&  /* and TopLevelIrp has acquired Main */
-    {
+        FspFileNodeTryGetFileInfo(FileNode, &FileInfo) &&       /* and the cached FileSize is valid  */
-        ASSERT(PagingIo);
+        (UINT64)WriteOffset.QuadPart >= FileInfo.FileSize)      /* and the WriteOffset is past EOF   */
-        ASSERT(FspTimeoutInfinity32 ==
-            FspFsvolDeviceExtension(FsvolDeviceObject)->VolumeParams.FileInfoTimeout);
-
-        FspFileNodeGetFileInfo(FileNode, &FileInfo);
-
-        if ((UINT64)WriteOffset.QuadPart >= FileInfo.FileSize)
         return STATUS_SUCCESS;
 
-        if (WriteLength > (ULONG)(FileInfo.FileSize - WriteOffset.QuadPart))
-            WriteLength = (ULONG)(FileInfo.FileSize - WriteOffset.QuadPart);
-    }
-
     /* probe and lock the user buffer */
     Result = FspLockUserBuffer(Irp, WriteLength, IoReadAccess);
     if (!NT_SUCCESS(Result))
@@ -348,6 +338,7 @@ static NTSTATUS FspFsvolWriteNonCached(
     Request->Req.Write.Offset = WriteOffset.QuadPart;
     Request->Req.Write.Length = WriteLength;
     Request->Req.Write.Key = WriteKey;
+    Request->Req.Write.ConstrainedIo = !!PagingIo;
 
     FspFileNodeSetOwner(FileNode, Full, Request);
     FspIopRequestContext(Request, RequestIrp) = Irp;

tst/memfs/memfs.cpp

@@ -482,17 +482,29 @@ static NTSTATUS Read(FSP_FILE_SYSTEM *FileSystem,
 
 static NTSTATUS Write(FSP_FILE_SYSTEM *FileSystem,
     FSP_FSCTL_TRANSACT_REQ *Request,
-    PVOID FileNode0, PVOID Buffer, UINT64 Offset, ULONG Length, BOOLEAN WriteToEndOfFile,
+    PVOID FileNode0, PVOID Buffer, UINT64 Offset, ULONG Length,
+    BOOLEAN WriteToEndOfFile, BOOLEAN ConstrainedIo,
     PULONG PBytesTransferred, FSP_FSCTL_FILE_INFO *FileInfo)
 {
     MEMFS_FILE_NODE *FileNode = (MEMFS_FILE_NODE *)FileNode0;
     UINT64 EndOffset;
 
+    if (ConstrainedIo)
+    {
+        if (Offset >= FileNode->FileInfo.FileSize)
+            return STATUS_SUCCESS;
+        EndOffset = Offset + Length;
+        if (EndOffset > FileNode->FileInfo.FileSize)
+            EndOffset = FileNode->FileInfo.FileSize;
+    }
+    else
+    {
         if (WriteToEndOfFile)
             Offset = FileNode->FileInfo.FileSize;
         EndOffset = Offset + Length;
         if (EndOffset > FileNode->FileInfo.FileSize)
             SetFileSize(FileSystem, Request, FileNode, EndOffset, FileInfo);
+    }
 
     memcpy((PUINT8)FileNode->FileData + Offset, Buffer, EndOffset - Offset);