On 12/14/2011 06:29 AM, Li Zefan wrote:
Tejun Heo wrote:
On Sun, Dec 11, 2011 at 03:45:37PM +0100, Glauber Costa wrote:
There is no reason to have a flags field, and then a separate
bool field just to indicate if the clone_children flag is set.
Make it a flag

Signed-off-by: Glauber Costa<glom...@parallels.com>

Doesn't this change how remount conditions are checked?


Well, I was thinking it wouldn't, because I patched all callers. But I forget life is not always that simple: After you mentioned, I checked and we do test for changes in the flag field explicitly on remount. So I missed that, indeed.

Right. Currently we can do this:

        # mount -t cgroup xxx /mnt
        # mount -o remount,clone_children /mnt

with this patch, the above remount will fail.

But..the current bevaiour of remount is a bit confusing in that remount
with/without "clone_children" has no effect on anything:

        # mount -t cgroup -o clone_children xxx /mnt
        # cat /mnt/cgroup.clone_children
        1
        # mount -o remount xxx /mnt
        # mount | grep cgroup
        xxx on /mnt type cgroup (rw,clone_children)
        # cat /mnt/cgroup.clone_children
        1

That's indeed confusing, and it comes from the fact that we always inherit clone_children from the parent - which is sane, IMHO. So this flag only has any value in establishing the initial behaviour of the top root cgroup. I wonder then if it wouldn't better to just be explicit and fail in this case ?

_______________________________________________
Devel mailing list
Devel@openvz.org
https://openvz.org/mailman/listinfo/devel

Reply via email to