FUSE_COPY_FILE_RANGE instructs the server to write data to a file.
fusefs must invalidate any cached data within the written range.
Also,
fusefs: inline fuse_io_dispatch
This function was always confusing, because it created an H-shaped
callgraph: two functions called in and left via different paths based on
which which called.
MFC after: 2 weeks
PR: 260242
MFC after: 2 weeks