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WinFsp 2023

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@billziss-gh billziss-gh released this 16 Mar 11:27
· 12 commits to master since this release

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This release is a major version change for WinFsp (from 1.x to 2.x). There are no backwards incompatible API changes in this release, but nevertheless enough things change that warrant a version change.

The major new feature of this release is that it allows uninstallation and reinstallation of WinFsp without reboot. Going forward installers named winfsp-2.x.y.msi can be uninstalled and reinstalled without reboot. Furthermore a later version winfsp-2.x.y.msi installer can be used to upgrade over an earlier version winfsp-2.x.y.msi installer. However note that a winfsp-2.x.y.msi installer cannot be used to upgrade over a legacy winfsp-1.x.y.msi installer; you will still need to uninstall the old winfsp-1.x.y.msi installer, potentially reboot and then install the new winfsp-2.x.y.msi installer.

Changes visible to file system developers are listed below:

  • WinFsp executable files are now installed by default in the directory C:\Program Files (x86)\WinFsp\SxS\sxs.<InstanceID>\bin. The previous directory C:\Program Files (x86)\WinFsp\bin is now a junction that points to the above directory.

  • The WinFsp driver name is no longer winfsp, but rather a name such as winfsp+<InstanceID>. This means that managing the driver using the sc.exe utility is no longer as easy.

  • The fsptool utility has been updated with new commands lsdrv, load, unload and ver. The lsdrv, load and unload commands can be used to manage the driver from the command line. This is rarely necessary, but may be useful for troubleshooting purposes.

  • Prior to this release the WinFsp driver would never unmount a file system volume unless the user mode file system requested the unmount. From this release onward it is possible for the WinFsp driver to unmount a file system volume, without a user mode file system request. This is to allow for the driver to be unloaded.

    A new operation DispatcherStopped has been added to FSP_FILE_SYSTEM_INTERFACE, which is sent after the file system volume has been unmounted and the file system dispatcher has been stopped. This can happen because of a user mode file system request via FspFileSystemStopDispatcher or because of driver unload. The DispatcherStopped operation includes a Normally parameter, which is TRUE for normal file system shutdown via FspFileSystemStopDispatcher and FALSE otherwise.

    Native file systems that use the FspService infrastructure can use the FspFileSystemStopServiceIfNecessary API to handle the DispatcherStopped operation (see the MEMFS and NTPTFS samples). FUSE file systems get this functionality for free. .NET file systems that use the Service class infrastructure also get this functionality for free.

  • WinFsp now offers a .NET library that targets .NET Framework 3.5 (as before) and one that targets .NET Standard 2.0. This is due to work by @Noire001 in PR #451.

  • FUSE now supports path components up to 255 characters long (previously it was 255 bytes). This is due to work by @zeho11 in PR #474.

    • The FUSE passthrough file systems have been updated to support long paths. This is also due to work by @zeho11.
  • In some rare circumstances WinFsp file systems could report duplicate directory entries. This problem has been fixed. (GitHub issue #475.)

  • The WinFsp symbols directory has been removed. If you are looking for WinFsp symbols you can find them at


  • winfsp-2.0.23075.msi: 6324DC81194A6A08F97B6AECA303CF5C2325C53EDE153BAE9FC4378F0838C101
  • AEECDAC2BE9684C4FF9D977C41853B0DE9E065C230DBA755E86C3F8130BBC816