OvmfPkg/VirtioFsDxe/FuseForget.c

   1 /** @file
   2   FUSE_FORGET wrapper for the Virtio Filesystem device.
   3
   4   Copyright (C) 2020, Red Hat, Inc.
   5
   6   SPDX-License-Identifier: BSD-2-Clause-Patent
   7 **/
   8
   9 #include "VirtioFsDxe.h"
  10
  11 /**
  12   Make the Virtio Filesysem device drop one reference count from a NodeId that
  13   the driver looked up by filename.
  14
  15   Send the FUSE_FORGET request to the Virtio Filesysem device for this. Unlike
  16   most other FUSE requests, FUSE_FORGET doesn't elicit a response, not even the
  17   common VIRTIO_FS_FUSE_RESPONSE header.
  18
  19   The function may only be called after VirtioFsFuseInitSession() returns
  20   successfully and before VirtioFsUninit() is called.
  21
  22   @param[in,out] VirtioFs  The Virtio Filesystem device to send the FUSE_FORGET
  23                            request to. On output, the FUSE request counter
  24                            "VirtioFs->RequestId" will have been incremented.
  25
  26   @param[in] NodeId        The inode number that the client learned by way of
  27                            lookup, and that the server should now un-reference
  28                            exactly once.
  29
  30   @retval EFI_SUCCESS  The FUSE_FORGET request has been submitted.
  31
  32   @return              Error codes propagated from VirtioFsSgListsValidate(),
  33                        VirtioFsFuseNewRequest(), VirtioFsSgListsSubmit().
  34 **/
  35 EFI_STATUS
  36 VirtioFsFuseForget (
  37   IN OUT VIRTIO_FS  *VirtioFs,
  38   IN     UINT64     NodeId
  39   )
  40 {
  41   VIRTIO_FS_FUSE_REQUEST         CommonReq;
  42   VIRTIO_FS_FUSE_FORGET_REQUEST  ForgetReq;
  43   VIRTIO_FS_IO_VECTOR            ReqIoVec[2];
  44   VIRTIO_FS_SCATTER_GATHER_LIST  ReqSgList;
  45   EFI_STATUS                     Status;
  46
  47   //
  48   // Set up the scatter-gather list (note: only request).
  49   //
  50   ReqIoVec[0].Buffer = &CommonReq;
  51   ReqIoVec[0].Size   = sizeof CommonReq;
  52   ReqIoVec[1].Buffer = &ForgetReq;
  53   ReqIoVec[1].Size   = sizeof ForgetReq;
  54   ReqSgList.IoVec    = ReqIoVec;
  55   ReqSgList.NumVec   = ARRAY_SIZE (ReqIoVec);
  56
  57   //
  58   // Validate the scatter-gather list (request only); calculate the total
  59   // transfer size.
  60   //
  61   Status = VirtioFsSgListsValidate (VirtioFs, &ReqSgList, NULL);
  62   if (EFI_ERROR (Status)) {
  63     return Status;
  64   }
  65
  66   //
  67   // Populate the common request header.
  68   //
  69   Status = VirtioFsFuseNewRequest (
  70              VirtioFs,
  71              &CommonReq,
  72              ReqSgList.TotalSize,
  73              VirtioFsFuseOpForget,
  74              NodeId
  75              );
  76   if (EFI_ERROR (Status)) {
  77     return Status;
  78   }
  79
  80   //
  81   // Populate the FUSE_FORGET-specific fields.
  82   //
  83   ForgetReq.NumberOfLookups = 1;
  84
  85   //
  86   // Submit the request. There's not going to be a response.
  87   //
  88   Status = VirtioFsSgListsSubmit (VirtioFs, &ReqSgList, NULL);
  89   return Status;
  90 }