reactos/drivers/filesystems/btrfs/cache.c

   1 /* Copyright (c) Mark Harmstone 2016
   2  *
   3  * This file is part of WinBtrfs.
   4  *
   5  * WinBtrfs is free software: you can redistribute it and/or modify
   6  * it under the terms of the GNU Lesser General Public Licence as published by
   7  * the Free Software Foundation, either version 3 of the Licence, or
   8  * (at your option) any later version.
   9  *
  10  * WinBtrfs is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU Lesser General Public Licence for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public Licence
  16  * along with WinBtrfs.  If not, see <http://www.gnu.org/licenses/>. */
  17
  18 #include "btrfs_drv.h"
  19 #include <wdm.h>
  20
  21 CACHE_MANAGER_CALLBACKS* cache_callbacks;
  22
  23 static BOOLEAN STDCALL acquire_for_lazy_write(PVOID Context, BOOLEAN Wait) {
  24     PFILE_OBJECT FileObject = Context;
  25     fcb* fcb = FileObject->FsContext;
  26
  27     TRACE("(%p, %u)\n", Context, Wait);
  28
  29     if (!fcb || FileObject->Flags & FO_CLEANUP_COMPLETE)
  30         return FALSE;
  31
  32     fcb->lazy_writer_thread = KeGetCurrentThread();
  33
  34     return TRUE;
  35 }
  36
  37 static void STDCALL release_from_lazy_write(PVOID Context) {
  38     PFILE_OBJECT FileObject = Context;
  39     fcb* fcb = FileObject->FsContext;
  40
  41     TRACE("(%p)\n", Context);
  42
  43     if (!fcb || FileObject->Flags & FO_CLEANUP_COMPLETE)
  44         return;
  45
  46     fcb->lazy_writer_thread = NULL;
  47 }
  48
  49 static BOOLEAN STDCALL acquire_for_read_ahead(PVOID Context, BOOLEAN Wait) {
  50     TRACE("(%p, %u)\n", Context, Wait);
  51
  52     return TRUE;
  53 }
  54
  55 static void STDCALL release_from_read_ahead(PVOID Context) {
  56     TRACE("(%p)\n", Context);
  57 }
  58
  59 NTSTATUS STDCALL init_cache() {
  60     cache_callbacks = ExAllocatePoolWithTag(NonPagedPool, sizeof(CACHE_MANAGER_CALLBACKS), ALLOC_TAG);
  61     if (!cache_callbacks) {
  62         ERR("out of memory\n");
  63         return STATUS_INSUFFICIENT_RESOURCES;
  64     }
  65
  66     cache_callbacks->AcquireForLazyWrite = acquire_for_lazy_write;
  67     cache_callbacks->ReleaseFromLazyWrite = release_from_lazy_write;
  68     cache_callbacks->AcquireForReadAhead = acquire_for_read_ahead;
  69     cache_callbacks->ReleaseFromReadAhead = release_from_read_ahead;
  70
  71     return STATUS_SUCCESS;
  72 }
  73
  74 void STDCALL free_cache() {
  75     ExFreePool(cache_callbacks);
  76 }