[FASTFAT] Implement support for stack overflow in read operations.
[reactos.git] / drivers / filesystems / fastfat / rw.c
index 7474c5b..76ffff9 100644 (file)
@@ -1,9 +1,10 @@
 /*
  * COPYRIGHT:        See COPYING in the top level directory
  * PROJECT:          ReactOS kernel
- * FILE:             drivers/fs/vfat/rw.c
+ * FILE:             drivers/filesystems/fastfat/rw.c
  * PURPOSE:          VFAT Filesystem
  * PROGRAMMER:       Jason Filby (jasonfilby@yahoo.com)
+ *                   Pierre Schweitzer (pierre@reactos.org)
  *
  */
 
  */
 /* #define DEBUG_VERIFY_OFFSET_CACHING */
 
+/* Arbitrary, taken from MS FastFAT, should be
+ * refined given what we experience in common
+ * out of stack operations
+ */
+#define OVERFLOW_READ_THRESHHOLD 0xE00
+
 /* FUNCTIONS *****************************************************************/
 
 /*
@@ -150,12 +157,12 @@ VfatReadFileData(
     BytesPerSector = DeviceExt->FatInfo.BytesPerSector;
     BytesPerCluster = DeviceExt->FatInfo.BytesPerCluster;
 
-    ASSERT(ReadOffset.QuadPart + Length <= ROUND_UP(Fcb->RFCB.FileSize.QuadPart, BytesPerSector));
+    ASSERT(ReadOffset.QuadPart + Length <= ROUND_UP_64(Fcb->RFCB.FileSize.QuadPart, BytesPerSector));
     ASSERT(ReadOffset.u.LowPart % BytesPerSector == 0);
     ASSERT(Length % BytesPerSector == 0);
 
     /* Is this a read of the FAT? */
-    if (Fcb->Flags & FCB_IS_FAT)
+    if (BooleanFlagOn(Fcb->Flags, FCB_IS_FAT))
     {
         ReadOffset.QuadPart += DeviceExt->FatInfo.FATStart * BytesPerSector;
         Status = VfatReadDiskPartial(IrpContext, &ReadOffset, Length, 0, TRUE);
@@ -172,7 +179,7 @@ VfatReadFileData(
     }
 
     /* Is this a read of the Volume ? */
-    if (Fcb->Flags & FCB_IS_VOLUME)
+    if (BooleanFlagOn(Fcb->Flags, FCB_IS_VOLUME))
     {
         Status = VfatReadDiskPartial(IrpContext, &ReadOffset, Length, 0, TRUE);
         if (NT_SUCCESS(Status))
@@ -367,7 +374,7 @@ VfatWriteFileData(
     ASSERT(Length % BytesPerSector == 0);
 
     /* Is this a write of the volume? */
-    if (Fcb->Flags & FCB_IS_VOLUME)
+    if (BooleanFlagOn(Fcb->Flags, FCB_IS_VOLUME))
     {
         Status = VfatWriteDiskPartial(IrpContext, &WriteOffset, Length, 0, TRUE);
         if (!NT_SUCCESS(Status))
@@ -378,7 +385,7 @@ VfatWriteFileData(
     }
 
     /* Is this a write to the FAT? */
-    if (Fcb->Flags & FCB_IS_FAT)
+    if (BooleanFlagOn(Fcb->Flags, FCB_IS_FAT))
     {
         WriteOffset.u.LowPart += DeviceExt->FatInfo.FATStart * BytesPerSector;
         IrpContext->RefCount = 1;
@@ -535,6 +542,169 @@ VfatWriteFileData(
     return Status;
 }
 
+NTSTATUS
+VfatCommonRead(
+    PVFAT_IRP_CONTEXT IrpContext)
+{
+    PVFATFCB Fcb;
+    PVOID Buffer;
+    NTSTATUS Status;
+    ULONG Length = 0;
+    ULONG BytesPerSector;
+    LARGE_INTEGER ByteOffset;
+    ULONG ReturnedLength = 0;
+    BOOLEAN PagingIo, CanWait, IsVolume, NoCache;
+
+    PagingIo = BooleanFlagOn(IrpContext->Irp->Flags, IRP_PAGING_IO);
+    CanWait = BooleanFlagOn(IrpContext->Flags, IRPCONTEXT_CANWAIT);
+    NoCache = BooleanFlagOn(IrpContext->Irp->Flags, IRP_NOCACHE);
+    Fcb = IrpContext->FileObject->FsContext;
+    IsVolume = BooleanFlagOn(Fcb->Flags, FCB_IS_VOLUME);
+
+    ByteOffset = IrpContext->Stack->Parameters.Read.ByteOffset;
+    Length = IrpContext->Stack->Parameters.Read.Length;
+    BytesPerSector = IrpContext->DeviceExt->FatInfo.BytesPerSector;
+
+    if (!PagingIo &&
+        FsRtlAreThereCurrentFileLocks(&Fcb->FileLock))
+    {
+        if (!FsRtlCheckLockForReadAccess(&Fcb->FileLock, IrpContext->Irp))
+        {
+            return STATUS_FILE_LOCK_CONFLICT;
+        }
+    }
+
+    Buffer = VfatGetUserBuffer(IrpContext->Irp, PagingIo);
+
+    if (!PagingIo && !NoCache && !IsVolume)
+    {
+        // cached read
+        Status = STATUS_SUCCESS;
+        if (ByteOffset.u.LowPart + Length > Fcb->RFCB.FileSize.u.LowPart)
+        {
+            Length = Fcb->RFCB.FileSize.u.LowPart - ByteOffset.u.LowPart;
+            Status = /*STATUS_END_OF_FILE*/STATUS_SUCCESS;
+        }
+
+        vfatAddToStat(IrpContext->DeviceExt, Base.UserFileReads, 1);
+        vfatAddToStat(IrpContext->DeviceExt, Base.UserFileReadBytes, Length);
+
+        _SEH2_TRY
+        {
+            if (IrpContext->FileObject->PrivateCacheMap == NULL)
+            {
+                CcInitializeCacheMap(IrpContext->FileObject,
+                                     (PCC_FILE_SIZES)(&Fcb->RFCB.AllocationSize),
+                                     FALSE,
+                                     &(VfatGlobalData->CacheMgrCallbacks),
+                                     Fcb);
+            }
+
+            if (!CcCopyRead(IrpContext->FileObject,
+                            &ByteOffset,
+                            Length,
+                            CanWait,
+                            Buffer,
+                            &IrpContext->Irp->IoStatus))
+            {
+                ASSERT(!CanWait);
+                Status = STATUS_PENDING;
+                goto ByeBye;
+            }
+        }
+        _SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
+        {
+            Status = _SEH2_GetExceptionCode();
+            goto ByeBye;
+        }
+        _SEH2_END;
+
+        if (!NT_SUCCESS(IrpContext->Irp->IoStatus.Status))
+        {
+            Status = IrpContext->Irp->IoStatus.Status;
+        }
+    }
+    else
+    {
+        // non cached read
+        Status = VfatLockUserBuffer(IrpContext->Irp, Length, IoWriteAccess);
+        if (!NT_SUCCESS(Status))
+        {
+            goto ByeBye;
+        }
+
+        if (ByteOffset.QuadPart + Length > ROUND_UP_64(Fcb->RFCB.FileSize.QuadPart, BytesPerSector))
+        {
+            Length = (ULONG)(ROUND_UP_64(Fcb->RFCB.FileSize.QuadPart, BytesPerSector) - ByteOffset.QuadPart);
+        }
+
+        if (!IsVolume)
+        {
+            vfatAddToStat(IrpContext->DeviceExt, Fat.NonCachedReads, 1);
+            vfatAddToStat(IrpContext->DeviceExt, Fat.NonCachedReadBytes, Length);
+        }
+        else
+        {
+            vfatAddToStat(IrpContext->DeviceExt, Base.MetaDataReads, 1);
+            vfatAddToStat(IrpContext->DeviceExt, Base.MetaDataReadBytes, Length);
+        }
+
+        Status = VfatReadFileData(IrpContext, Length, ByteOffset, &ReturnedLength);
+        if (NT_SUCCESS(Status))
+        {
+            IrpContext->Irp->IoStatus.Information = ReturnedLength;
+        }
+    }
+
+ByeBye:
+    return Status;
+}
+
+VOID
+NTAPI
+VfatStackOverflowRead(
+    PVOID Context,
+    IN PKEVENT Event)
+{
+    PVFAT_IRP_CONTEXT IrpContext;
+
+    IrpContext = Context;
+    /* In a separate thread, we can wait and resources got locked */
+    SetFlag(IrpContext->Flags, IRPCONTEXT_CANWAIT);
+
+    /* Perform the read operation */
+    DPRINT1("Performing posted read\n");
+    VfatCommonRead(IrpContext);
+
+    KeSetEvent(Event, 0, FALSE);
+}
+
+VOID
+VfatPostRead(
+    PVFAT_IRP_CONTEXT IrpContext,
+    PERESOURCE Lock,
+    BOOLEAN PagingIo)
+{
+    KEVENT Event;
+
+    KeInitializeEvent(&Event, NotificationEvent, FALSE);
+
+    ExAcquireResourceSharedLite(Lock, TRUE);
+
+    /* If paging IO, call the non failing but blocking routine */
+    if (PagingIo)
+    {
+        FsRtlPostPagingFileStackOverflow(IrpContext, &Event, VfatStackOverflowRead);
+    }
+    else
+    {
+        FsRtlPostStackOverflow(IrpContext, &Event, VfatStackOverflowRead);
+    }
+
+    /* Wait till it's done */
+    KeWaitForSingleObject(&Event, Executive, KernelMode, FALSE, NULL);
+}
+
 NTSTATUS
 VfatRead(
     PVFAT_IRP_CONTEXT IrpContext)
@@ -542,11 +712,10 @@ VfatRead(
     NTSTATUS Status;
     PVFATFCB Fcb;
     ULONG Length = 0;
-    ULONG ReturnedLength = 0;
     PERESOURCE Resource = NULL;
     LARGE_INTEGER ByteOffset;
-    PVOID Buffer;
     ULONG BytesPerSector;
+    BOOLEAN PagingIo, CanWait, IsVolume, NoCache;
 
     ASSERT(IrpContext);
 
@@ -554,6 +723,10 @@ VfatRead(
 
     ASSERT(IrpContext->DeviceObject);
 
+    PagingIo = BooleanFlagOn(IrpContext->Irp->Flags, IRP_PAGING_IO);
+    CanWait = BooleanFlagOn(IrpContext->Flags, IRPCONTEXT_CANWAIT);
+    NoCache = BooleanFlagOn(IrpContext->Irp->Flags, IRP_NOCACHE);
+
     // This request is not allowed on the main device object
     if (IrpContext->DeviceObject == VfatGlobalData->DeviceObject)
     {
@@ -567,14 +740,16 @@ VfatRead(
     Fcb = IrpContext->FileObject->FsContext;
     ASSERT(Fcb);
 
-    if (Fcb->Flags & FCB_IS_PAGE_FILE)
+    IsVolume = BooleanFlagOn(Fcb->Flags, FCB_IS_VOLUME);
+
+    if (BooleanFlagOn(Fcb->Flags, FCB_IS_PAGE_FILE))
     {
         PFATINFO FatInfo = &IrpContext->DeviceExt->FatInfo;
         IrpContext->Stack->Parameters.Read.ByteOffset.QuadPart += FatInfo->dataStart * FatInfo->BytesPerSector;
         IoSkipCurrentIrpStackLocation(IrpContext->Irp);
+        IrpContext->Flags &= ~IRPCONTEXT_COMPLETE;
         DPRINT("Read from page file, disk offset %I64x\n", IrpContext->Stack->Parameters.Read.ByteOffset.QuadPart);
         Status = IoCallDriver(IrpContext->DeviceExt->StorageDevice, IrpContext->Irp);
-        VfatFreeIrpContext(IrpContext);
         return Status;
     }
 
@@ -585,7 +760,7 @@ VfatRead(
     BytesPerSector = IrpContext->DeviceExt->FatInfo.BytesPerSector;
 
     /* fail if file is a directory and no paged read */
-    if (*Fcb->Attributes & FILE_ATTRIBUTE_DIRECTORY && !(IrpContext->Irp->Flags & IRP_PAGING_IO))
+    if (vfatFCBIsDirectory(Fcb) && !PagingIo)
     {
         Status = STATUS_INVALID_PARAMETER;
         goto ByeBye;
@@ -593,12 +768,19 @@ VfatRead(
 
     DPRINT("'%wZ', Offset: %u, Length %u\n", &Fcb->PathNameU, ByteOffset.u.LowPart, Length);
 
-    if (ByteOffset.u.HighPart && !(Fcb->Flags & FCB_IS_VOLUME))
+    if (ByteOffset.u.HighPart && !IsVolume)
     {
        Status = STATUS_INVALID_PARAMETER;
        goto ByeBye;
     }
 
+    if (Length == 0)
+    {
+        IrpContext->Irp->IoStatus.Information = 0;
+        Status = STATUS_SUCCESS;
+        goto ByeBye;
+    }
+
     if (ByteOffset.QuadPart >= Fcb->RFCB.FileSize.QuadPart)
     {
        IrpContext->Irp->IoStatus.Information = 0;
@@ -606,7 +788,7 @@ VfatRead(
        goto ByeBye;
     }
 
-    if (IrpContext->Irp->Flags & (IRP_PAGING_IO | IRP_NOCACHE) || (Fcb->Flags & FCB_IS_VOLUME))
+    if (NoCache || PagingIo || IsVolume)
     {
         if (ByteOffset.u.LowPart % BytesPerSector != 0 || Length % BytesPerSector != 0)
         {
@@ -617,18 +799,11 @@ VfatRead(
         }
     }
 
-    if (Length == 0)
-    {
-        IrpContext->Irp->IoStatus.Information = 0;
-        Status = STATUS_SUCCESS;
-        goto ByeBye;
-    }
-
-    if (Fcb->Flags & FCB_IS_VOLUME)
+    if (IsVolume)
     {
         Resource = &IrpContext->DeviceExt->DirResource;
     }
-    else if (IrpContext->Irp->Flags & IRP_PAGING_IO)
+    else if (PagingIo)
     {
         Resource = &Fcb->PagingIoResource;
     }
@@ -637,84 +812,31 @@ VfatRead(
         Resource = &Fcb->MainResource;
     }
 
-    if (!ExAcquireResourceSharedLite(Resource,
-                                     IrpContext->Flags & IRPCONTEXT_CANWAIT ? TRUE : FALSE))
+    /* Are we out of stack for the rest of the operation? */
+    if (IoGetRemainingStackSize() < OVERFLOW_READ_THRESHHOLD)
     {
-        Resource = NULL;
-        Status = STATUS_PENDING;
-        goto ByeBye;
-    }
-
-    if (!(IrpContext->Irp->Flags & IRP_PAGING_IO) &&
-        FsRtlAreThereCurrentFileLocks(&Fcb->FileLock))
-    {
-        if (!FsRtlCheckLockForReadAccess(&Fcb->FileLock, IrpContext->Irp))
+        /* Lock the buffer */
+        Status = VfatLockUserBuffer(IrpContext->Irp, Length, IoWriteAccess);
+        if (!NT_SUCCESS(Status))
         {
-            Status = STATUS_FILE_LOCK_CONFLICT;
-            goto ByeBye;
+            return Status;
         }
-    }
 
-    Buffer = VfatGetUserBuffer(IrpContext->Irp);
-    if (!Buffer)
-    {
-        Status = STATUS_INVALID_USER_BUFFER;
-        goto ByeBye;
+        /* And post the read to the overflow thread */
+        VfatPostRead(IrpContext, Resource, PagingIo);
+
+        /* Return the appropriate status */
+        return IrpContext->Irp->IoStatus.Status;
     }
 
-    if (!(IrpContext->Irp->Flags & (IRP_NOCACHE|IRP_PAGING_IO)) &&
-        !(Fcb->Flags & (FCB_IS_PAGE_FILE|FCB_IS_VOLUME)))
+    if (!ExAcquireResourceSharedLite(Resource, CanWait))
     {
-        // cached read
-        Status = STATUS_SUCCESS;
-        if (ByteOffset.u.LowPart + Length > Fcb->RFCB.FileSize.u.LowPart)
-        {
-            Length = Fcb->RFCB.FileSize.u.LowPart - ByteOffset.u.LowPart;
-            Status = /*STATUS_END_OF_FILE*/STATUS_SUCCESS;
-        }
-
-        if (IrpContext->FileObject->PrivateCacheMap == NULL)
-        {
-            CcInitializeCacheMap(IrpContext->FileObject,
-                                 (PCC_FILE_SIZES)(&Fcb->RFCB.AllocationSize),
-                                 FALSE,
-                                 &(VfatGlobalData->CacheMgrCallbacks),
-                                 Fcb);
-        }
-
-        if (!CcCopyRead(IrpContext->FileObject, &ByteOffset, Length,
-                        (BOOLEAN)(IrpContext->Flags & IRPCONTEXT_CANWAIT), Buffer,
-                        &IrpContext->Irp->IoStatus))
-        {
-            Status = STATUS_PENDING;
-            goto ByeBye;
-        }
-
-        if (!NT_SUCCESS(IrpContext->Irp->IoStatus.Status))
-        {
-            Status = IrpContext->Irp->IoStatus.Status;
-        }
+        Resource = NULL;
+        Status = STATUS_PENDING;
+        goto ByeBye;
     }
-    else
-    {
-        // non cached read
-        if (ByteOffset.QuadPart + Length > ROUND_UP(Fcb->RFCB.FileSize.QuadPart, BytesPerSector))
-        {
-            Length = (ULONG)(ROUND_UP(Fcb->RFCB.FileSize.QuadPart, BytesPerSector) - ByteOffset.QuadPart);
-        }
-
-        Status = VfatLockUserBuffer(IrpContext->Irp, Length, IoWriteAccess);
-        if (!NT_SUCCESS(Status))
-        {
-            goto ByeBye;
-        }
 
-        Status = VfatReadFileData(IrpContext, Length, ByteOffset, &ReturnedLength);
-        if (NT_SUCCESS(Status))
-        {
-            IrpContext->Irp->IoStatus.Information = ReturnedLength;
-        }
-    }
+    Status = VfatCommonRead(IrpContext);
 
 ByeBye:
     if (Resource)
@@ -727,29 +849,22 @@ ByeBye:
         Status = VfatLockUserBuffer(IrpContext->Irp, Length, IoWriteAccess);
         if (NT_SUCCESS(Status))
         {
-            Status = VfatQueueRequest(IrpContext);
-        }
-        else
-        {
-            IrpContext->Irp->IoStatus.Status = Status;
-            IoCompleteRequest(IrpContext->Irp, IO_NO_INCREMENT);
-            VfatFreeIrpContext(IrpContext);
+            Status = VfatMarkIrpContextForQueue(IrpContext);
         }
     }
     else
     {
         IrpContext->Irp->IoStatus.Status = Status;
-        if (IrpContext->FileObject->Flags & FO_SYNCHRONOUS_IO &&
-            !(IrpContext->Irp->Flags & IRP_PAGING_IO) &&
+        if (BooleanFlagOn(IrpContext->FileObject->Flags, FO_SYNCHRONOUS_IO) &&
+            !PagingIo &&
             (NT_SUCCESS(Status) || Status == STATUS_END_OF_FILE))
         {
             IrpContext->FileObject->CurrentByteOffset.QuadPart =
                 ByteOffset.QuadPart + IrpContext->Irp->IoStatus.Information;
         }
 
-        IoCompleteRequest(IrpContext->Irp,
-                          (CCHAR)(NT_SUCCESS(Status) ? IO_DISK_INCREMENT : IO_NO_INCREMENT));
-        VfatFreeIrpContext(IrpContext);
+        if (NT_SUCCESS(Status))
+            IrpContext->PriorityBoost = IO_DISK_INCREMENT;
     }
     DPRINT("%x\n", Status);
     return Status;
@@ -767,6 +882,7 @@ VfatWrite(
     ULONG Length = 0;
     PVOID Buffer;
     ULONG BytesPerSector;
+    BOOLEAN PagingIo, CanWait, IsVolume, IsFAT, NoCache;
 
     ASSERT(IrpContext);
 
@@ -774,6 +890,10 @@ VfatWrite(
 
     ASSERT(IrpContext->DeviceObject);
 
+    PagingIo = BooleanFlagOn(IrpContext->Irp->Flags, IRP_PAGING_IO);
+    CanWait = BooleanFlagOn(IrpContext->Flags, IRPCONTEXT_CANWAIT);
+    NoCache = BooleanFlagOn(IrpContext->Irp->Flags, IRP_NOCACHE);
+
     // This request is not allowed on the main device object
     if (IrpContext->DeviceObject == VfatGlobalData->DeviceObject)
     {
@@ -787,21 +907,24 @@ VfatWrite(
     Fcb = IrpContext->FileObject->FsContext;
     ASSERT(Fcb);
 
-    if (Fcb->Flags & FCB_IS_PAGE_FILE)
+    IsVolume = BooleanFlagOn(Fcb->Flags, FCB_IS_VOLUME);
+    IsFAT = BooleanFlagOn(Fcb->Flags, FCB_IS_FAT);
+
+    if (BooleanFlagOn(Fcb->Flags, FCB_IS_PAGE_FILE))
     {
         PFATINFO FatInfo = &IrpContext->DeviceExt->FatInfo;
         IrpContext->Stack->Parameters.Write.ByteOffset.QuadPart += FatInfo->dataStart * FatInfo->BytesPerSector;
         IoSkipCurrentIrpStackLocation(IrpContext->Irp);
+        IrpContext->Flags &= ~IRPCONTEXT_COMPLETE;
         DPRINT("Write to page file, disk offset %I64x\n", IrpContext->Stack->Parameters.Write.ByteOffset.QuadPart);
         Status = IoCallDriver(IrpContext->DeviceExt->StorageDevice, IrpContext->Irp);
-        VfatFreeIrpContext(IrpContext);
         return Status;
     }
 
     DPRINT("<%wZ>\n", &Fcb->PathNameU);
 
     /* fail if file is a directory and no paged read */
-    if (*Fcb->Attributes & FILE_ATTRIBUTE_DIRECTORY && !(IrpContext->Irp->Flags & IRP_PAGING_IO))
+    if (vfatFCBIsDirectory(Fcb) && !PagingIo)
     {
         Status = STATUS_INVALID_PARAMETER;
         goto ByeBye;
@@ -816,13 +939,13 @@ VfatWrite(
     Length = IrpContext->Stack->Parameters.Write.Length;
     BytesPerSector = IrpContext->DeviceExt->FatInfo.BytesPerSector;
 
-    if (ByteOffset.u.HighPart && !(Fcb->Flags & FCB_IS_VOLUME))
+    if (ByteOffset.u.HighPart && !IsVolume)
     {
         Status = STATUS_INVALID_PARAMETER;
         goto ByeBye;
     }
 
-    if (Fcb->Flags & (FCB_IS_FAT | FCB_IS_VOLUME) ||
+    if (IsFAT || IsVolume ||
         vfatDirEntryGetFirstCluster(IrpContext->DeviceExt, &Fcb->entry) == 1)
     {
         if (ByteOffset.QuadPart + Length > Fcb->RFCB.FileSize.QuadPart)
@@ -833,7 +956,7 @@ VfatWrite(
         }
     }
 
-    if (IrpContext->Irp->Flags & (IRP_PAGING_IO|IRP_NOCACHE) || (Fcb->Flags & FCB_IS_VOLUME))
+    if (PagingIo || NoCache || IsVolume)
     {
         if (ByteOffset.u.LowPart % BytesPerSector != 0 || Length % BytesPerSector != 0)
         {
@@ -843,15 +966,17 @@ VfatWrite(
         }
     }
 
+    OldFileSize = Fcb->RFCB.FileSize;
+
     if (Length == 0)
     {
-        /* FIXME: Update last write time */
+        /* Update last write time */
         IrpContext->Irp->IoStatus.Information = 0;
         Status = STATUS_SUCCESS;
-        goto ByeBye;
+        goto Metadata;
     }
 
-    if (IrpContext->Irp->Flags & IRP_PAGING_IO)
+    if (PagingIo)
     {
         if (ByteOffset.u.LowPart + Length > Fcb->RFCB.AllocationSize.u.LowPart)
         {
@@ -865,11 +990,28 @@ VfatWrite(
         }
     }
 
-    if (Fcb->Flags & FCB_IS_VOLUME)
+    if (!NoCache && !CcCanIWrite(IrpContext->FileObject, Length, CanWait,
+                                 BooleanFlagOn(IrpContext->Flags, IRPCONTEXT_DEFERRED_WRITE)))
+    {
+        BOOLEAN Retrying;
+
+        Retrying = BooleanFlagOn(IrpContext->Flags, IRPCONTEXT_DEFERRED_WRITE);
+        SetFlag(IrpContext->Flags, IRPCONTEXT_DEFERRED_WRITE);
+
+        Status = STATUS_PENDING;
+        CcDeferWrite(IrpContext->FileObject, VfatHandleDeferredWrite,
+                     IrpContext, NULL, Length, Retrying);
+
+        DPRINT1("Dererring write!\n");
+
+        goto ByeBye;
+    }
+
+    if (IsVolume)
     {
         Resource = &IrpContext->DeviceExt->DirResource;
     }
-    else if (IrpContext->Irp->Flags & IRP_PAGING_IO)
+    else if (PagingIo)
     {
         Resource = &Fcb->PagingIoResource;
     }
@@ -878,10 +1020,9 @@ VfatWrite(
         Resource = &Fcb->MainResource;
     }
 
-    if (Fcb->Flags & FCB_IS_PAGE_FILE)
+    if (PagingIo)
     {
-        if (!ExAcquireResourceSharedLite(Resource,
-                                         (BOOLEAN)(IrpContext->Flags & IRPCONTEXT_CANWAIT)))
+        if (!ExAcquireResourceSharedLite(Resource, CanWait))
         {
             Resource = NULL;
             Status = STATUS_PENDING;
@@ -890,8 +1031,7 @@ VfatWrite(
     }
     else
     {
-        if (!ExAcquireResourceExclusiveLite(Resource,
-                                            (BOOLEAN)(IrpContext->Flags & IRPCONTEXT_CANWAIT)))
+        if (!ExAcquireResourceExclusiveLite(Resource, CanWait))
         {
             Resource = NULL;
             Status = STATUS_PENDING;
@@ -899,7 +1039,7 @@ VfatWrite(
         }
     }
 
-    if (!(IrpContext->Irp->Flags & IRP_PAGING_IO) &&
+    if (!PagingIo &&
         FsRtlAreThereCurrentFileLocks(&Fcb->FileLock))
     {
         if (!FsRtlCheckLockForWriteAccess(&Fcb->FileLock, IrpContext->Irp))
@@ -909,7 +1049,7 @@ VfatWrite(
         }
     }
 
-    if (!(IrpContext->Flags & IRPCONTEXT_CANWAIT) && !(Fcb->Flags & FCB_IS_VOLUME))
+    if (!CanWait && !IsVolume)
     {
         if (ByteOffset.u.LowPart + Length > Fcb->RFCB.AllocationSize.u.LowPart)
         {
@@ -918,18 +1058,9 @@ VfatWrite(
         }
     }
 
-    OldFileSize = Fcb->RFCB.FileSize;
-
-    Buffer = VfatGetUserBuffer(IrpContext->Irp);
-    if (!Buffer)
-    {
-        Status = STATUS_INVALID_USER_BUFFER;
-        goto ByeBye;
-    }
-
+    Buffer = VfatGetUserBuffer(IrpContext->Irp, PagingIo);
 
-    if (!(Fcb->Flags & (FCB_IS_FAT|FCB_IS_VOLUME)) &&
-        !(IrpContext->Irp->Flags & IRP_PAGING_IO) &&
+    if (!IsFAT && !IsVolume && !PagingIo &&
         ByteOffset.u.LowPart + Length > Fcb->RFCB.FileSize.u.LowPart)
     {
         LARGE_INTEGER AllocationSize;
@@ -942,49 +1073,74 @@ VfatWrite(
         }
     }
 
-    if (!(IrpContext->Irp->Flags & (IRP_NOCACHE|IRP_PAGING_IO)) &&
-        !(Fcb->Flags & (FCB_IS_PAGE_FILE|FCB_IS_VOLUME)))
+    if (!NoCache && !PagingIo && !IsVolume)
     {
         // cached write
 
-        if (IrpContext->FileObject->PrivateCacheMap == NULL)
-        {
-            CcInitializeCacheMap(IrpContext->FileObject,
-                                 (PCC_FILE_SIZES)(&Fcb->RFCB.AllocationSize),
-                                 FALSE,
-                                 &VfatGlobalData->CacheMgrCallbacks,
-                                 Fcb);
-        }
+        vfatAddToStat(IrpContext->DeviceExt, Base.UserFileWrites, 1);
+        vfatAddToStat(IrpContext->DeviceExt, Base.UserFileWriteBytes, Length);
 
-        if (ByteOffset.QuadPart > OldFileSize.QuadPart)
+        _SEH2_TRY
         {
-            CcZeroData(IrpContext->FileObject, &OldFileSize, &ByteOffset, TRUE);
-        }
+            if (IrpContext->FileObject->PrivateCacheMap == NULL)
+            {
+                CcInitializeCacheMap(IrpContext->FileObject,
+                                     (PCC_FILE_SIZES)(&Fcb->RFCB.AllocationSize),
+                                     FALSE,
+                                     &VfatGlobalData->CacheMgrCallbacks,
+                                     Fcb);
+            }
 
-        if (CcCopyWrite(IrpContext->FileObject, &ByteOffset, Length,
-                        1 /*IrpContext->Flags & IRPCONTEXT_CANWAIT*/, Buffer))
-        {
-            IrpContext->Irp->IoStatus.Information = Length;
-            Status = STATUS_SUCCESS;
+            if (ByteOffset.QuadPart > OldFileSize.QuadPart)
+            {
+                CcZeroData(IrpContext->FileObject, &OldFileSize, &ByteOffset, TRUE);
+            }
+
+            if (CcCopyWrite(IrpContext->FileObject,
+                            &ByteOffset,
+                            Length,
+                            TRUE /*CanWait*/,
+                            Buffer))
+            {
+                IrpContext->Irp->IoStatus.Information = Length;
+                Status = STATUS_SUCCESS;
+            }
+            else
+            {
+                ASSERT(FALSE /*!CanWait*/);
+                Status = STATUS_UNSUCCESSFUL;
+            }
         }
-        else
+        _SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
         {
-            Status = STATUS_UNSUCCESSFUL;
+            Status = _SEH2_GetExceptionCode();
         }
+        _SEH2_END;
     }
     else
     {
         // non cached write
+        Status = VfatLockUserBuffer(IrpContext->Irp, Length, IoReadAccess);
+        if (!NT_SUCCESS(Status))
+        {
+            Status = STATUS_INVALID_USER_BUFFER;
+            goto ByeBye;
+        }
 
         if (ByteOffset.QuadPart > OldFileSize.QuadPart)
         {
             CcZeroData(IrpContext->FileObject, &OldFileSize, &ByteOffset, TRUE);
         }
 
-        Status = VfatLockUserBuffer(IrpContext->Irp, Length, IoReadAccess);
-        if (!NT_SUCCESS(Status))
+        if (!IsVolume)
         {
-            goto ByeBye;
+            vfatAddToStat(IrpContext->DeviceExt, Fat.NonCachedWrites, 1);
+            vfatAddToStat(IrpContext->DeviceExt, Fat.NonCachedWriteBytes, Length);
+        }
+        else
+        {
+            vfatAddToStat(IrpContext->DeviceExt, Base.MetaDataWrites, 1);
+            vfatAddToStat(IrpContext->DeviceExt, Base.MetaDataWriteBytes, Length);
         }
 
         Status = VfatWriteFileData(IrpContext, Length, ByteOffset);
@@ -994,17 +1150,17 @@ VfatWrite(
         }
     }
 
-    if (!(IrpContext->Irp->Flags & IRP_PAGING_IO) &&
-        !(Fcb->Flags & (FCB_IS_FAT|FCB_IS_VOLUME)))
+Metadata:
+    if (!PagingIo && !IsFAT && !IsVolume)
     {
-        if(!(*Fcb->Attributes & FILE_ATTRIBUTE_DIRECTORY))
+        if(!vfatFCBIsDirectory(Fcb))
         {
             LARGE_INTEGER SystemTime;
             ULONG Filter;
 
             // set dates and times
             KeQuerySystemTime (&SystemTime);
-            if (Fcb->Flags & FCB_IS_FATX_ENTRY)
+            if (vfatVolumeIsFatX(IrpContext->DeviceExt))
             {
                 FsdSystemTimeToDosDateTime(IrpContext->DeviceExt,
                                            &SystemTime, &Fcb->entry.FatX.UpdateDate,
@@ -1026,15 +1182,7 @@ VfatWrite(
             Filter = FILE_NOTIFY_CHANGE_LAST_WRITE | FILE_NOTIFY_CHANGE_ATTRIBUTES;
             if (ByteOffset.QuadPart != OldFileSize.QuadPart) Filter |= FILE_NOTIFY_CHANGE_SIZE;
 
-            FsRtlNotifyFullReportChange(IrpContext->DeviceExt->NotifySync,
-                                        &(IrpContext->DeviceExt->NotifyList),
-                                        (PSTRING)&Fcb->PathNameU,
-                                        Fcb->PathNameU.Length - Fcb->LongNameU.Length,
-                                        NULL,
-                                        NULL,
-                                        Filter,
-                                        FILE_ACTION_MODIFIED,
-                                        NULL);
+            vfatReportChange(IrpContext->DeviceExt, Fcb, Filter, FILE_ACTION_MODIFIED);
         }
     }
 
@@ -1049,28 +1197,21 @@ ByeBye:
         Status = VfatLockUserBuffer(IrpContext->Irp, Length, IoReadAccess);
         if (NT_SUCCESS(Status))
         {
-            Status = VfatQueueRequest(IrpContext);
-        }
-        else
-        {
-            IrpContext->Irp->IoStatus.Status = Status;
-            IoCompleteRequest(IrpContext->Irp, IO_NO_INCREMENT);
-            VfatFreeIrpContext(IrpContext);
+            Status = VfatMarkIrpContextForQueue(IrpContext);
         }
     }
     else
     {
         IrpContext->Irp->IoStatus.Status = Status;
-        if (IrpContext->FileObject->Flags & FO_SYNCHRONOUS_IO &&
-            !(IrpContext->Irp->Flags & IRP_PAGING_IO) && NT_SUCCESS(Status))
+        if (BooleanFlagOn(IrpContext->FileObject->Flags, FO_SYNCHRONOUS_IO) &&
+            !PagingIo && NT_SUCCESS(Status))
         {
             IrpContext->FileObject->CurrentByteOffset.QuadPart =
                 ByteOffset.QuadPart + IrpContext->Irp->IoStatus.Information;
         }
 
-        IoCompleteRequest(IrpContext->Irp,
-                          (CCHAR)(NT_SUCCESS(Status) ? IO_DISK_INCREMENT : IO_NO_INCREMENT));
-        VfatFreeIrpContext(IrpContext);
+        if (NT_SUCCESS(Status))
+            IrpContext->PriorityBoost = IO_DISK_INCREMENT;
     }
     DPRINT("%x\n", Status);
     return Status;