From: Greg Kurz <groug@kaod.org>
To: Max Reitz <mreitz@redhat.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
linux-fsdevel@vger.kernel.org, virtio-fs@redhat.com,
linux-kernel@vger.kernel.org, Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [Virtio-fs] [PATCH 3/4] fuse: Call vfs_get_tree() for submounts
Date: Thu, 3 Jun 2021 09:34:17 +0200 [thread overview]
Message-ID: <20210603093333.154c23ac@bahia.lan> (raw)
In-Reply-To: <7b4a3379-3004-98f2-841c-386ce62c888a@redhat.com>
On Thu, 27 May 2021 15:24:40 +0200
Max Reitz <mreitz@redhat.com> wrote:
> On 25.05.21 17:02, Greg Kurz wrote:
> > We recently fixed an infinite loop by setting the SB_BORN flag on
> > submounts along with the write barrier needed by super_cache_count().
> > This is the job of vfs_get_tree() and FUSE shouldn't have to care
> > about the barrier at all.
> >
> > Split out some code from fuse_dentry_automount() to a new dedicated
> > fuse_get_tree_submount() handler for submounts and call vfs_get_tree().
> >
> > The fs_private field of the filesystem context isn't used with
> > submounts : hijack it to pass the FUSE inode of the mount point
> > down to fuse_get_tree_submount().
>
> What exactly do you mean by “isn’t used”? virtio_fs_init_fs_context()
> still sets it (it is non-NULL in fuse_dentry_automount() after
> fs_context_for_submount()). It does appear like it is never read, but
> one thing that definitely would need to be done is for it to be freed
> before putting mp_fi there.
>
Oops... yes it should. Thanks for the catch !
> So I think it may technically be fine to use this field, but then
> virtio_fs_init_fs_context() shouldn’t set it for submounts (should be
> discernible with fsc->purpose), and perhaps that should be a separate patch.
>
Yes, I'll do just that.
> (Apart from that, this patch looks good to me, though.)
>
> Max
>
> > Finally, adapt virtiofs to use this.
> >
> > Signed-off-by: Greg Kurz <groug@kaod.org>
> > ---
> > fs/fuse/dir.c | 58 +++++++--------------------------------------
> > fs/fuse/fuse_i.h | 6 +++++
> > fs/fuse/inode.c | 44 ++++++++++++++++++++++++++++++++++
> > fs/fuse/virtio_fs.c | 3 +++
> > 4 files changed, 62 insertions(+), 49 deletions(-)
>
next prev parent reply other threads:[~2021-06-03 7:34 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-25 15:02 [PATCH 0/4] fuse: Some fixes for submounts Greg Kurz
2021-05-25 15:02 ` [PATCH 1/4] fuse: Fix crash in fuse_dentry_automount() error path Greg Kurz
2021-05-27 9:51 ` [Virtio-fs] " Max Reitz
2021-05-25 15:02 ` [PATCH 2/4] fuse: Fix infinite loop in sget_fc() Greg Kurz
2021-05-27 10:08 ` [Virtio-fs] " Max Reitz
2021-05-27 12:31 ` Greg Kurz
2021-05-25 15:02 ` [PATCH 3/4] fuse: Call vfs_get_tree() for submounts Greg Kurz
2021-05-27 13:24 ` [Virtio-fs] " Max Reitz
2021-06-03 7:34 ` Greg Kurz [this message]
2021-05-25 15:02 ` [PATCH 4/4] fuse: Make fuse_fill_super_submount() static Greg Kurz
2021-05-27 13:28 ` [Virtio-fs] " Max Reitz
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