On 11/29/23 18:39, Amir Goldstein wrote:
On Wed, Nov 29, 2023 at 6:55 PM Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
On Wed, 29 Nov 2023 at 16:52, Amir Goldstein <amir73il@xxxxxxxxx> wrote:
direct I/O read()/write() is never a problem.
The question is whether mmap() on a file opened with FOPEN_DIRECT_IO
when the inode is in passthrough mode, also uses fuse_passthrough_mmap()?
I think it should.
or denied, similar to how mmap with ff->open_flags & FOPEN_DIRECT_IO &&
vma->vm_flags & VM_MAYSHARE) && !fc->direct_io_relax
is denied?
What would be the use case for FOPEN_DIRECT_IO with passthrough mmap?
I don't have a use case. That's why I was wondering if we should
support it at all, but will try to make it work.
What is actually the use case for FOPEN_DIRECT_IO and passthrough?
Avoiding double page cache?
A bit more challenging, because we will need to track unmounts, or at
least track
"was_cached_mmaped" state per file, but doable.
Tracking unmaps via fuse_vma_close() should not be difficult.
OK. so any existing mmap, whether on FOPEN_DIRECT_IO or not
always prevents an inode from being "neutral".
Thanks,
Bernd
