From: Amir Goldstein <amir73il@gmail.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: lsf-pc@lists.linux-foundation.org,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux MM <linux-mm@kvack.org>, Vivek Goyal <vgoyal@redhat.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: [LSF/MM TOPIC] filesystem virtualization
Date: Wed, 6 Feb 2019 22:02:40 +0200 [thread overview]
Message-ID: <CAOQ4uxgYKdCcqEu8i_+h3Cu3CPJu4v4MDusK8S8auQi=fS0vxQ@mail.gmail.com> (raw)
In-Reply-To: <CAJfpeguq60X745NnYDAKZhodLEvFRha2QTpAu6g63vJxq8SvaQ@mail.gmail.com>
On Wed, Feb 6, 2019 at 3:06 PM Miklos Szeredi <miklos@szeredi.hu> wrote:
>
> This is a joint topic proposal with Vivek Goyal.
>
> Discuss remaining issues related to exporting a filesystem from host to
> guest (see virtio-fs prototype posting[1] for more background):
>
> * How to provide strong coherency guarantees?
>
> - Fsnotify synchronous post op notification
> - Extend lease (delegation) API to userspace
There are some commonalities here with userspace networking
file servers. I am interested in samba in particular and things
that we can do to improve Linux interfaces for samba.
SMB3 directory leases for example.
Thanks,
Amir.
> - Multi-component path revalidation
>
> * Issues related to c/m/atime handling:
>
> - Clock synchronization between host and guest (not an fs issue, but fs
> has to deal with lack of it)
>
> - Could we have O_NOCMTIME open flag?
>
> * Shared access to file data:
>
> - Use DAX in guest to access host page cache (mmap/munmap sections of
> file in guest address space; happens dynamically on a need basis); is
> this design reasonable?
>
> - Avoids memory copies and cache duplication, but host page table setup
> may have high cost. Can that be improved? (E.g. fault-ahead)
>
> - Too many VMA’s on host per qemu instance?
>
> * File locking:
>
> - Host API for POSIX lock sharing?
>
> * Ideas for the future:
>
> - Buffering directory operations (e.g. "tar xfz ..." with as few
> synchronous ops as possible)
>
> [1] https://lore.kernel.org/lkml/20181210171318.16998-1-vgoyal@redhat.com/
prev parent reply other threads:[~2019-02-06 20:02 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-06 13:00 [LSF/MM TOPIC] filesystem virtualization Miklos Szeredi
2019-02-06 20:02 ` Amir Goldstein [this message]
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