On Sat, May 25, 2013 at 12:03:12AM +0800, Jeff Liu wrote: > From: Jie Liu <jeff.liu@xxxxxxxxxx> > > If the root cgroup is alive without xattr, set extended > attributes on a new cgroup with xattr enabled will failed > with ENOTSUPP. e.g. > > # mount -t cgroup -o cpu none /cgroup1 > # mount -t cgroup -o cpu,xattr none /cgroup2 > # mkdir /cgroup2/test > # setfattr -n trusted.name -v test /cgroup2/test > setfattr: /cgroup2/test: Operation not supported > > This patch fix it by checking ROOT_XATTR against the new > mount and turn it up on the existing root hierarchy if needed. > > With this fix: > # mount | grep cgroup > none on /cgroup1 type cgroup (rw,cpu) > none on /cgroup2 type cgroup (rw,xattr,cpu) > > # mkdir /cgroup2/test > # setfattr -n trusted.name -v test /cgroup2/test > # getfattr -d -m - /cgroup2/test > getfattr: Removing leading '/' from absolute path names > trusted.name="test" > > Signed-off-by: Jie Liu <jeff.liu@xxxxxxxxxx> > Reported-by: Alexey Kodanev <alexey.kodanev@xxxxxxxxxx> > --- > kernel/cgroup.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/kernel/cgroup.c b/kernel/cgroup.c > index a32f943..46e8cbb 100644 > --- a/kernel/cgroup.c > +++ b/kernel/cgroup.c > @@ -1687,6 +1687,13 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, > cgroup_drop_root(opts.new_root); > /* no subsys rebinding, so refcounts don't change */ > drop_parsed_module_refcounts(opts.subsys_mask); > + > + /* > + * Enable xattr on the existing root hierarchy if it is > + * specified on new mount. > + */ > + if (test_bit(ROOT_XATTR, &opts.flags)) > + test_and_set_bit(ROOT_XATTR, &root->flags); So, while I recognize that this is broken. This is a part of larger breakage - cgroup silently ignores mount option changes when remounted. That's why when sane_behavior is specified, mount is rejected if it doesn't match the existing mount options. I don't think fixing only this part is meaningful. Maybe what we can do is adding a warning message if the mount options mismatch? Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
