From: "Michael S. Tsirkin" <mst@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: piaojun <piaojun@huawei.com>, Miklos Szeredi <miklos@szeredi.hu>,
linux-kernel@vger.kernel.org, virtio-fs@redhat.com,
linux-fsdevel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [Virtio-fs] [PATCH 00/18] virtiofs: Fix various races and cleanups round 1
Date: Mon, 9 Sep 2019 12:18:13 -0400 [thread overview]
Message-ID: <20190909121604-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20190909161455.GG20875@stefanha-x1.localdomain>
On Mon, Sep 09, 2019 at 06:14:55PM +0200, Stefan Hajnoczi wrote:
> On Sun, Sep 08, 2019 at 07:53:55PM +0800, piaojun wrote:
> >
> >
> > On 2019/9/6 19:52, Miklos Szeredi wrote:
> > > On Fri, Sep 6, 2019 at 12:36 PM Stefan Hajnoczi <stefanha@redhat.com> wrote:
> > >>
> > >> On Fri, Sep 06, 2019 at 10:15:14AM +0200, Miklos Szeredi wrote:
> > >>> On Thu, Sep 5, 2019 at 9:49 PM Vivek Goyal <vgoyal@redhat.com> wrote:
> > >>>>
> > >>>> Hi,
> > >>>>
> > >>>> Michael Tsirkin pointed out issues w.r.t various locking related TODO
> > >>>> items and races w.r.t device removal.
> > >>>>
> > >>>> In this first round of cleanups, I have taken care of most pressing
> > >>>> issues.
> > >>>>
> > >>>> These patches apply on top of following.
> > >>>>
> > >>>> git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse.git#virtiofs-v4
> > >>>>
> > >>>> I have tested these patches with mount/umount and device removal using
> > >>>> qemu monitor. For example.
> > >>>
> > >>> Is device removal mandatory? Can't this be made a non-removable
> > >>> device? Is there a good reason why removing the virtio-fs device
> > >>> makes sense?
> > >>
> > >> Hot plugging and unplugging virtio PCI adapters is common. I'd very
> > >> much like removal to work from the beginning.
> > >
> > > Can you give an example use case?
> >
> > I think VirtFS migration need hot plugging, or it may cause QEMU crash
> > or some problems.
>
> Live migration is currently unsupported. Hot unplugging the virtio-fs
> device would allow the guest to live migrate successfully, so it's a
> useful feature to work around the missing live migration support.
>
> Is this what you mean?
>
> Stefan
Exactly. That's what I also said. To add to that, hotplug can not be
negotiated, so it's not a feature we can easily add down the road if old
guests crash on unplug. Thus a driver that does not support unplug
should not claim to support removal.
--
MST
WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: virtio-fs@redhat.com, Miklos Szeredi <miklos@szeredi.hu>,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
linux-fsdevel@vger.kernel.org, Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [Virtio-fs] [PATCH 00/18] virtiofs: Fix various races and cleanups round 1
Date: Mon, 9 Sep 2019 12:18:13 -0400 [thread overview]
Message-ID: <20190909121604-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20190909161455.GG20875@stefanha-x1.localdomain>
On Mon, Sep 09, 2019 at 06:14:55PM +0200, Stefan Hajnoczi wrote:
> On Sun, Sep 08, 2019 at 07:53:55PM +0800, piaojun wrote:
> >
> >
> > On 2019/9/6 19:52, Miklos Szeredi wrote:
> > > On Fri, Sep 6, 2019 at 12:36 PM Stefan Hajnoczi <stefanha@redhat.com> wrote:
> > >>
> > >> On Fri, Sep 06, 2019 at 10:15:14AM +0200, Miklos Szeredi wrote:
> > >>> On Thu, Sep 5, 2019 at 9:49 PM Vivek Goyal <vgoyal@redhat.com> wrote:
> > >>>>
> > >>>> Hi,
> > >>>>
> > >>>> Michael Tsirkin pointed out issues w.r.t various locking related TODO
> > >>>> items and races w.r.t device removal.
> > >>>>
> > >>>> In this first round of cleanups, I have taken care of most pressing
> > >>>> issues.
> > >>>>
> > >>>> These patches apply on top of following.
> > >>>>
> > >>>> git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse.git#virtiofs-v4
> > >>>>
> > >>>> I have tested these patches with mount/umount and device removal using
> > >>>> qemu monitor. For example.
> > >>>
> > >>> Is device removal mandatory? Can't this be made a non-removable
> > >>> device? Is there a good reason why removing the virtio-fs device
> > >>> makes sense?
> > >>
> > >> Hot plugging and unplugging virtio PCI adapters is common. I'd very
> > >> much like removal to work from the beginning.
> > >
> > > Can you give an example use case?
> >
> > I think VirtFS migration need hot plugging, or it may cause QEMU crash
> > or some problems.
>
> Live migration is currently unsupported. Hot unplugging the virtio-fs
> device would allow the guest to live migrate successfully, so it's a
> useful feature to work around the missing live migration support.
>
> Is this what you mean?
>
> Stefan
Exactly. That's what I also said. To add to that, hotplug can not be
negotiated, so it's not a feature we can easily add down the road if old
guests crash on unplug. Thus a driver that does not support unplug
should not claim to support removal.
--
MST
next prev parent reply other threads:[~2019-09-09 16:18 UTC|newest]
Thread overview: 176+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-05 19:48 [PATCH 00/18] virtiofs: Fix various races and cleanups round 1 Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-05 19:48 ` [PATCH 01/18] virtiofs: Remove request from processing list before calling end Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-05 19:48 ` Vivek Goyal
2019-09-06 10:40 ` Stefan Hajnoczi
2019-09-06 10:40 ` Stefan Hajnoczi
2019-09-06 10:40 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 02/18] virtiofs: Check whether hiprio queue is connected at submission time Vivek Goyal
2019-09-05 19:48 ` Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-06 10:43 ` Stefan Hajnoczi
2019-09-06 10:43 ` Stefan Hajnoczi
2019-09-06 10:43 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 03/18] virtiofs: Pass fsvq instead of vq as parameter to virtio_fs_enqueue_req Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-05 19:48 ` Vivek Goyal
2019-09-06 10:44 ` Stefan Hajnoczi
2019-09-06 10:44 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-06 10:44 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 04/18] virtiofs: Check connected state for VQ_REQUEST queue as well Vivek Goyal
2019-09-05 19:48 ` Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-06 10:45 ` Stefan Hajnoczi
2019-09-06 10:45 ` Stefan Hajnoczi
2019-09-06 10:45 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 05/18] Maintain count of in flight requests for VQ_REQUEST queue Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-06 10:46 ` Stefan Hajnoczi
2019-09-06 10:46 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-06 10:46 ` Stefan Hajnoczi
2019-09-05 19:48 ` Vivek Goyal
2019-09-05 19:48 ` [PATCH 06/18] virtiofs: ->remove should not clean virtiofs fuse devices Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-06 10:47 ` Stefan Hajnoczi
2019-09-06 10:47 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-06 10:47 ` Stefan Hajnoczi
2019-09-05 19:48 ` Vivek Goyal
2019-09-05 19:48 ` [PATCH 07/18] virtiofs: Stop virtiofs queues when device is being removed Vivek Goyal
2019-09-05 19:48 ` Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-06 10:47 ` Stefan Hajnoczi
2019-09-06 10:47 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-06 10:47 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 08/18] virtiofs: Drain all pending requests during ->remove time Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-05 19:48 ` Vivek Goyal
2019-09-06 10:52 ` Stefan Hajnoczi
2019-09-06 10:52 ` Stefan Hajnoczi
2019-09-06 10:52 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-06 14:17 ` Vivek Goyal
2019-09-06 14:17 ` Vivek Goyal
2019-09-06 14:17 ` [Virtio-fs] " Vivek Goyal
2019-09-06 14:18 ` Michael S. Tsirkin
2019-09-06 14:18 ` Michael S. Tsirkin
2019-09-06 14:18 ` [Virtio-fs] " Michael S. Tsirkin
2019-09-09 16:10 ` Stefan Hajnoczi
2019-09-09 16:10 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-09 16:10 ` Stefan Hajnoczi
2019-09-08 10:11 ` [Virtio-fs] " piaojun
2019-09-08 10:11 ` piaojun
2019-09-05 19:48 ` [PATCH 09/18] virtiofs: Add an helper to start all the queues Vivek Goyal
2019-09-05 19:48 ` Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-06 10:54 ` Stefan Hajnoczi
2019-09-06 10:54 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-06 10:54 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 10/18] virtiofs: Do not use device managed mem for virtio_fs and virtio_fs_vq Vivek Goyal
2019-09-05 19:48 ` Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-06 10:56 ` Stefan Hajnoczi
2019-09-06 10:56 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-06 10:56 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 11/18] virtiofs: stop and drain queues after sending DESTROY Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-06 11:50 ` Stefan Hajnoczi
2019-09-06 11:50 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-06 11:50 ` Stefan Hajnoczi
2019-09-05 19:48 ` Vivek Goyal
2019-09-05 19:48 ` [PATCH 12/18] virtiofs: Use virtio_fs_free_devs() in error path Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-06 11:51 ` Stefan Hajnoczi
2019-09-06 11:51 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-06 11:51 ` Stefan Hajnoczi
2019-09-05 19:48 ` Vivek Goyal
2019-09-05 19:48 ` [PATCH 13/18] virtiofs: Do not access virtqueue in request submission path Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-06 11:52 ` Stefan Hajnoczi
2019-09-06 11:52 ` Stefan Hajnoczi
2019-09-06 11:52 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-05 19:48 ` Vivek Goyal
2019-09-05 19:48 ` [PATCH 14/18] virtiofs: Add a fuse_iqueue operation to put() reference Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-06 12:00 ` Stefan Hajnoczi
2019-09-06 12:00 ` Stefan Hajnoczi
2019-09-06 12:00 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-06 13:35 ` Vivek Goyal
2019-09-06 13:35 ` Vivek Goyal
2019-09-06 13:35 ` [Virtio-fs] " Vivek Goyal
2019-09-05 19:48 ` Vivek Goyal
2019-09-05 19:48 ` [PATCH 15/18] virtiofs: Make virtio_fs object refcounted Vivek Goyal
2019-09-05 19:48 ` Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-06 12:03 ` Stefan Hajnoczi
2019-09-06 12:03 ` Stefan Hajnoczi
2019-09-06 12:03 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-06 13:50 ` Vivek Goyal
2019-09-06 13:50 ` Vivek Goyal
2019-09-06 13:50 ` [Virtio-fs] " Vivek Goyal
2019-09-09 16:12 ` Stefan Hajnoczi
2019-09-09 16:12 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-09 16:12 ` Stefan Hajnoczi
2019-09-08 11:10 ` [Virtio-fs] " piaojun
2019-09-08 11:10 ` piaojun
2019-09-09 15:35 ` Vivek Goyal
2019-09-09 15:35 ` Vivek Goyal
2019-09-09 15:35 ` Vivek Goyal
2019-09-05 19:48 ` [PATCH 16/18] virtiofs: Use virtio_fs_mutex for races w.r.t ->remove and mount path Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-06 12:05 ` Stefan Hajnoczi
2019-09-06 12:05 ` Stefan Hajnoczi
2019-09-06 12:05 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-06 13:51 ` Vivek Goyal
2019-09-06 13:51 ` [Virtio-fs] " Vivek Goyal
2019-09-09 16:13 ` Stefan Hajnoczi
2019-09-09 16:13 ` Stefan Hajnoczi
2019-09-09 16:13 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-06 13:51 ` Vivek Goyal
2019-09-08 11:19 ` [Virtio-fs] " piaojun
2019-09-08 11:19 ` piaojun
2019-09-05 19:48 ` Vivek Goyal
2019-09-05 19:48 ` [PATCH 17/18] virtiofs: Remove TODO to quiesce/end_requests Vivek Goyal
2019-09-05 19:48 ` Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-06 12:06 ` Stefan Hajnoczi
2019-09-06 12:06 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-06 12:06 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 18/18] virtiofs: Remove TODO item from virtio_fs_free_devs() Vivek Goyal
2019-09-05 19:48 ` [Virtio-fs] " Vivek Goyal
2019-09-06 12:06 ` Stefan Hajnoczi
2019-09-06 12:06 ` Stefan Hajnoczi
2019-09-06 12:06 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-05 19:48 ` Vivek Goyal
2019-09-06 8:15 ` [PATCH 00/18] virtiofs: Fix various races and cleanups round 1 Miklos Szeredi
2019-09-06 8:15 ` [Virtio-fs] " Miklos Szeredi
2019-09-06 10:36 ` Stefan Hajnoczi
2019-09-06 10:36 ` [Virtio-fs] " Stefan Hajnoczi
2019-09-06 11:52 ` Miklos Szeredi
2019-09-06 11:52 ` [Virtio-fs] " Miklos Szeredi
2019-09-06 12:08 ` Vivek Goyal
2019-09-06 12:08 ` Vivek Goyal
2019-09-06 12:08 ` [Virtio-fs] " Vivek Goyal
2019-09-06 13:55 ` Miklos Szeredi
2019-09-06 13:55 ` [Virtio-fs] " Miklos Szeredi
2019-09-06 13:57 ` Michael S. Tsirkin
2019-09-06 13:57 ` [Virtio-fs] " Michael S. Tsirkin
2019-09-06 13:57 ` Michael S. Tsirkin
2019-09-06 14:11 ` Miklos Szeredi
2019-09-06 14:11 ` [Virtio-fs] " Miklos Szeredi
2019-09-06 14:17 ` Michael S. Tsirkin
2019-09-06 14:17 ` Michael S. Tsirkin
2019-09-06 14:17 ` [Virtio-fs] " Michael S. Tsirkin
2019-09-08 11:53 ` piaojun
2019-09-08 11:53 ` piaojun
2019-09-09 16:14 ` Stefan Hajnoczi
2019-09-09 16:14 ` Stefan Hajnoczi
2019-09-09 16:14 ` Stefan Hajnoczi
2019-09-09 16:18 ` Michael S. Tsirkin [this message]
2019-09-09 16:18 ` Michael S. Tsirkin
2019-09-09 16:18 ` Michael S. Tsirkin
2019-09-09 23:52 ` piaojun
2019-09-09 23:52 ` piaojun
2019-09-06 10:36 ` Stefan Hajnoczi
2019-09-06 13:37 ` Michael S. Tsirkin
2019-09-06 13:37 ` Michael S. Tsirkin
2019-09-06 13:37 ` [Virtio-fs] " Michael S. Tsirkin
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