* Max Reitz (mre...@redhat.com) wrote:
> On 29.04.20 16:57, Dr. David Alan Gilbert wrote:
> > * Dr. David Alan Gilbert (dgilb...@redhat.com) wrote:
> >> * Max Reitz (mre...@redhat.com) wrote:
> >>> Currently, setup_mounts() bind-mounts the shared directory without
> >>> MS_REC. This makes all submounts disappear.
> >>>
> >>> Pass MS_REC so that the guest can see submounts again.
> >>
> >> Thanks!
> >>
> >>> Fixes: 3ca8a2b1c83eb185c232a4e87abbb65495263756
> >>
> >> Should this actually be 5baa3b8e95064c2434bd9e2f312edd5e9ae275dc ?
> >>
> >>> Signed-off-by: Max Reitz <mre...@redhat.com>
> >>> ---
> >>> tools/virtiofsd/passthrough_ll.c | 2 +-
> >>> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/tools/virtiofsd/passthrough_ll.c
> >>> b/tools/virtiofsd/passthrough_ll.c
> >>> index 4c35c95b25..9d7f863e66 100644
> >>> --- a/tools/virtiofsd/passthrough_ll.c
> >>> +++ b/tools/virtiofsd/passthrough_ll.c
> >>> @@ -2643,7 +2643,7 @@ static void setup_mounts(const char *source)
> >>> int oldroot;
> >>> int newroot;
> >>>
> >>> - if (mount(source, source, NULL, MS_BIND, NULL) < 0) {
> >>> + if (mount(source, source, NULL, MS_BIND | MS_REC, NULL) < 0) {
> >>> fuse_log(FUSE_LOG_ERR, "mount(%s, %s, MS_BIND): %m\n", source,
> >>> source);
> >>> exit(1);
> >>> }
> >>
> >> Do we want MS_SLAVE to pick up future mounts that might happenf rom the
> >> host?
> >> What's the interaction between this and the MS_REC|MS_SLAVE that we have
> >> a few lines above for / ?
> >
> > Just to confirm something from vgoyal, and what had confused me about
> > why we hadn't spotted this earlier.
> >
> > Even without this patch, the SLAVE stuff worked so if you start the
> > daemon and *then* mount under the shared directory, the guest sees it
> > with or without this patch.
>
> Hm, I don’t. Do you really?
Yes! With your patch reverted:
Start virtiofsd, mount in the guest:
host:
# ./virtiofsd --socket-path=/tmp/vhostqemu -o
source=/home/dgilbert/virtio-fs/fs -o log_level=warn -o no_writeback
guest:
# mount -t virtiofs myfs /sysroot
host:
# findmnt -o +PROPAGATION -N 6100
TARGET SOURCE
FSTYPE OPTIONS PROPAGATION
/ /dev/mapper/fedora_dgilbert--t580-root[/home/dgilbert/virtio-fs/fs] xfs
rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,no private,slave
# mount -t tmpfs /dev/null /home/dgilbert/virtio-fs/fs/tmp
# findmnt -o +PROPAGATION -N 6100
TARGET SOURCE
FSTYPE OPTIONS PROPAGATION
/ /dev/mapper/fedora_dgilbert--t580-root[/home/dgilbert/virtio-fs/fs] xfs
rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,no private,slave
└─/tmp /dev/null
tmpfs rw,relatime,seclabel
private,slave
# touch /home/dgilbert/virtio-fs/fs/tmp/hello
guest:
# ls -l /sysroot/tmp
total 0
-rw-r--r-- 1 root root 0 Apr 30 08:50 hello
Maybe this is related to what Vivek said about default behaviours on
systemd's, what does:
# findmnt -o +PROPAGATION
TARGET SOURCE FSTYPE OPTIONS
PROPAGATION
/ /dev/mapper/fedora_dgilbert--t580-root
│ xfs
rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota
shared
say for your source= directory?
Dave
> Max
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
