[Virtio-fs] [PATCH] virtiofsd: Show submounts

[Max Reitz]

On 29.04.20 16:57, Dr. David Alan Gilbert wrote:
> * Dr. David Alan Gilbert (dgilbert at redhat.com) wrote:
>> * Max Reitz (mreitz at 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 <mreitz at 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?

Max

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