On Wed, Dec 13, 2023 at 5:07 PM 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 save to call

typo: safe to call...

invalidate_inode_pages2 for MAP_PRIVATE and MAP_SHARED as well.

Cc: Hao Xu howeyxu@tencent.com Cc: Miklos Szeredi miklos@szeredi.hu Cc: Dharmendra Singh dsingh@ddn.com Cc: Amir Goldstein amir73il@gmail.com Cc: linux-fsdevel@vger.kernel.org Cc: stable@vger.kernel.org Fixes: e78662e818f9 ("fuse: add a new fuse init flag to relax restrictions in no cache mode") Signed-off-by: Bernd Schubert bschubert@ddn.com

---

Reviewed-by: Amir Goldstein amir73il@gmail.com

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