I think this comment may have been disingenuous on their part. The reason is that this problem more than likely still exists in WSL2 for the /mnt/c, /mnt/d file systems (i.e. what they used to call "DrvFs" in WSL1).

WSL1 comes with (at least) 2 file systems. "VolFs" which is the file system that they use for the Linux root file system and "DrvFs" which is the file system that they use to access Windows drives (C:, D:, ...).

In WSL1 VolFs was implemented as a layer on top of NTFS, so it comes with all the Windows file system and NTFS baggage. In WSL2 they will replace this file system with a native ext4 formatted partition on a VHD file, thus eliminating the Windows I/O stack (except for READ/WRITE I/O to the VHD file).

My contention is that they could have instead replaced VolFs with a native WSL1 file system that uses a disk partition or VHD as its backend storage, thus eliminating the Windows I/O stack in the same way. They could then have implemented proper Linux file system semantics without any baggage.

> I think they found the boundary of OS research in this case

Unlikely. It would not surprise me if the changes we are seeing are less technical and more political.