Re: [PATCH v2 1/5] fuse: Fix VM_MAYSHARE and direct_io_allow_mmap

[Miklos Szeredi <miklos@szeredi.hu>]

On Thu, 1 Feb 2024 at 00:09, Bernd Schubert <bschubert@ddn.com> wrote:
>
> There were multiple issues with direct_io_allow_mmap:
> - fuse_link_write_file() was missing, resulting in warnings in
>   fuse_write_file_get() and EIO from msync()
> - "vma->vm_ops = &fuse_file_vm_ops" was not set, but especially
>   fuse_page_mkwrite is needed.
>
> The semantics of invalidate_inode_pages2() is so far not clearly defined
> in fuse_file_mmap. It dates back to
> commit 3121bfe76311 ("fuse: fix "direct_io" private mmap")
> Though, as direct_io_allow_mmap is a new feature, that was for MAP_PRIVATE
> only. As invalidate_inode_pages2() is calling into fuse_launder_folio()
> and writes out dirty pages, it should be safe to call
> invalidate_inode_pages2 for MAP_PRIVATE and MAP_SHARED as well.

Did you test with fsx (various versions can be found in LTP/xfstests)?
 It's very good at finding  mapped vs. non-mapped bugs.

Thanks,
Miklos