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dll,sys: fix issue #369

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The original WinFsp protocol for shutting down a file system was to issue
an FSP_FSCTL_STOP control code to the fsctl device. This would set the IOQ
to the "stopped" state and would also cancel all active IRP's. Cancelation
of IRP's would sometimes free buffers that may have still been in use by
the user mode file system threads; hence access violation.

To fix this problem a new control code FSP_FSCTL_STOP0 is introduced. The
new file system shutdown protocol is backwards compatible with the original
one and works as follows:

- First the file system process issues an FSP_FSCTL_STOP0 control code which
sets the IOQ to the "stopped" state but does NOT cancel IRP's.

- Then the file system process waits for its dispatcher threads to complete
(see FspFileSystemStopDispatcher).

- Finally the file system process issues an FSP_FSCTL_STOP control code
which stops the (already stopped) IOQ and cancels all IRP's.
This commit is contained in:
Bill Zissimopoulos
2021-05-18 12:30:17 -07:00
parent 23e401e312
commit ca832988ed
7 changed files with 81 additions and 17 deletions
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3
inc/winfsp/fsctl.h
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@ -85,6 +85,8 @@ extern const __declspec(selectany) GUID FspFsvrtDeviceClassGuid =
CTL_CODE(FILE_DEVICE_FILE_SYSTEM, 0x800 + 't', METHOD_OUT_DIRECT, FILE_ANY_ACCESS)
#define FSP_FSCTL_STOP \
CTL_CODE(FILE_DEVICE_FILE_SYSTEM, 0x800 + 'S', METHOD_BUFFERED, FILE_ANY_ACCESS)
#define FSP_FSCTL_STOP0 \
CTL_CODE(FILE_DEVICE_FILE_SYSTEM, 0x800 + 's', METHOD_BUFFERED, FILE_ANY_ACCESS)
#define FSP_FSCTL_NOTIFY \
CTL_CODE(FILE_DEVICE_FILE_SYSTEM, 0x800 + 'n', METHOD_NEITHER, FILE_ANY_ACCESS)
@ -647,6 +649,7 @@ FSP_API NTSTATUS FspFsctlTransact(HANDLE VolumeHandle,
PVOID RequestBuf, SIZE_T *PRequestBufSize,
BOOLEAN Batch);
FSP_API NTSTATUS FspFsctlStop(HANDLE VolumeHandle);
FSP_API NTSTATUS FspFsctlStop0(HANDLE VolumeHandle);
FSP_API NTSTATUS FspFsctlNotify(HANDLE VolumeHandle,
FSP_FSCTL_NOTIFY_INFO *NotifyInfo, SIZE_T Size);
FSP_API NTSTATUS FspFsctlGetVolumeList(PWSTR DevicePath,