On Wed, Dec 13, 2023 at 5:07 PM Bernd Schubert <bschubert@xxxxxxx> 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 save to call
typo: safe to call...
> invalidate_inode_pages2 for MAP_PRIVATE and MAP_SHARED as well.
>
> Cc: Hao Xu <howeyxu@xxxxxxxxxxx>
> Cc: Miklos Szeredi <miklos@xxxxxxxxxx>
> Cc: Dharmendra Singh <dsingh@xxxxxxx>
> Cc: Amir Goldstein <amir73il@xxxxxxxxx>
> Cc: linux-fsdevel@xxxxxxxxxxxxxxx
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: e78662e818f9 ("fuse: add a new fuse init flag to relax restrictions in no cache mode")
> Signed-off-by: Bernd Schubert <bschubert@xxxxxxx>
> ---
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
Thanks,
Amir.
> fs/fuse/file.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> index a660f1f21540..174aa16407c4 100644
> --- a/fs/fuse/file.c
> +++ b/fs/fuse/file.c
> @@ -2475,7 +2475,10 @@ static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
>
> invalidate_inode_pages2(file->f_mapping);
>
> - return generic_file_mmap(file, vma);
> + if (!(vma->vm_flags & VM_MAYSHARE)) {
> + /* MAP_PRIVATE */
> + return generic_file_mmap(file, vma);
> + }
> }
>
> if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
> --
> 2.40.1
>
