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Re: [Virtio-fs] [PATCH] virtiofsd: Show submounts
From: |
Miklos Szeredi |
Subject: |
Re: [Virtio-fs] [PATCH] virtiofsd: Show submounts |
Date: |
Wed, 29 Apr 2020 11:26:49 +0200 |
On Wed, Apr 29, 2020 at 9:59 AM Miklos Szeredi <address@hidden> wrote:
>
> On Tue, Apr 28, 2020 at 9:15 PM Dr. David Alan Gilbert
> <address@hidden> wrote:
>
> > So our current sequence is:
> >
> > (new namespace)
> > 1) if (mount(NULL, "/", NULL, MS_REC | MS_SLAVE, NULL) < 0) {
> > 2) if (mount("proc", "/proc", "proc",
> > ....
> > 3) if (mount(source, source, NULL, MS_BIND | MS_REC, NULL) < 0) {
> > 4) (chdir newroot, pivot, chdir oldroot)
> > 5) if (mount("", ".", "", MS_SLAVE | MS_REC, NULL) < 0) {
> > 6) if (umount2(".", MNT_DETACH) < 0) {
> >
> > So are you saying we need a:
> > if (mount(NULL, "/", NULL, MS_REC | MS_SHARED, NULL) < 0) {
> >
> > and can this go straight after (1) ?
>
> Or right before (3). Important thing is that that new mount will
> only receive propagation if the type of the mount at source (before
> (3) is performed) is shared.
And seems I was wrong. Bind mounting clones the slave property, hence
no need to set MS_SHARED. I.e. if the source was a slave, the bind
mount will be a slave to the same master as well; the two slaves won't
receive propagation between each other, but both will receive
propagation from the master.
The only reason to set MS_SHARED would be if the bind mount wanted to
receive propagation from within the cloned namespace. Which is not
the case.
Didn't I tell ya it was complicated ;)
Thanks,
Miklos
- Re: [PATCH] virtiofsd: Show submounts, (continued)
Re: [PATCH] virtiofsd: Show submounts, Daniel P . Berrangé, 2020/04/28
Re: [PATCH] virtiofsd: Show submounts, Stefan Hajnoczi, 2020/04/28
- Re: [PATCH] virtiofsd: Show submounts, Daniel P . Berrangé, 2020/04/28
- Re: [Virtio-fs] [PATCH] virtiofsd: Show submounts, Miklos Szeredi, 2020/04/28
- Re: [Virtio-fs] [PATCH] virtiofsd: Show submounts, Dr. David Alan Gilbert, 2020/04/28
- Re: [Virtio-fs] [PATCH] virtiofsd: Show submounts, Miklos Szeredi, 2020/04/29
- Re: [Virtio-fs] [PATCH] virtiofsd: Show submounts,
Miklos Szeredi <=
- Re: [Virtio-fs] [PATCH] virtiofsd: Show submounts, Vivek Goyal, 2020/04/29
- Re: [Virtio-fs] [PATCH] virtiofsd: Show submounts, Vivek Goyal, 2020/04/29
Re: [Virtio-fs] [PATCH] virtiofsd: Show submounts, Max Reitz, 2020/04/29
Re: [Virtio-fs] [PATCH] virtiofsd: Show submounts, Miklos Szeredi, 2020/04/29
Re: [Virtio-fs] [PATCH] virtiofsd: Show submounts, Max Reitz, 2020/04/29
Re: [PATCH] virtiofsd: Show submounts, Dr. David Alan Gilbert, 2020/04/29