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

[Max Reitz]

On 29.04.20 10:52, Miklos Szeredi wrote:
> On Wed, Apr 29, 2020 at 10:31 AM Max Reitz <address@hidden> wrote:
>>
>> On 28.04.20 21:15, Dr. David Alan Gilbert wrote:
> 
>>> So are you saying we need a:
>>>        if (mount(NULL, "/", NULL, MS_REC | MS_SHARED, NULL) < 0) {
>>>
>>>   and can this go straight after (1) ?
>>
>> Isn’t MS_SHARED and MS_SLAVE mutually exclusive, that is, both are just
>> different propagation types?  So shouldn’t putting this after (1) be
>> effectively the same as replacing (1)?
> 
> No, think of it more like a set of groups (mounts in a group have the
> same "shared:$ID" tag in /proc/self/mountinfo) and these groups being
> arranged into a tree, where child groups get propagation from the
> parent group (mounts have a "master:$PARENT_ID" tag), but not the
> other way round.
> 
> So if a mount is part of a shared group and this group is also the
> child of another shared group, then it will have both a "shared:$ID"
> and a "master:$PARENT_ID" tag in /proc/self/mountinfo.

Ah, OK.

Thanks a lot for the explanation!

> For the gory details see Documentation/filesystems/sharedsubtree.txt

Not sure whether I want to *cough* O:)

Max

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