The commit is pushed to "branch-rh7-3.10.0-123.1.2-ovz" and will appear at
https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-123.1.2.vz7.5.7
------>
commit e5f41176c3b8653ff237f1fd695d608a176aa46b
Author: Cyrill Gorcunov <gorcu...@odin.com>
Date: Fri May 29 16:50:55 2015 +0400
cgroup: Mangle cgroups root from inside of VE view
We're bindmounting cgroups for container so if say a container
is having CTID=200 then @cgroups and @mountinfo output will
contain /200 as a root. Which makes Docker to lookup for
appropriate directory inside /sys/fs/cgroup/<controller>
which of course not present because of been bindmounted
from the node (note we can't bindmount into
<controller>/<container> here because it confuses container's
systemd instance and it stuck on boot).
Thus we simply mangle root here so when one is accessing
@cgroups or @mountinfo kernel shows '/' instead of $ctid
which makes both docker and systemd happy.
https://jira.sw.ru/browse/PSBM-33757
Signed-off-by: Cyrill Gorcunov <gorcu...@virtuozzo.com>
Reviewed-by: Vladimir Davydov <vdavy...@parallels.com>
CC: Konstantin Khorenko <khore...@virtuozzo.com>
CC: Pavel Emelyanov <xe...@virtuozzo.com>
CC: Andrey Vagin <ava...@virtuozzo.com>
kgorkunov@: we have 2 variants:
1) don't hide top-level, then
- if we mount as /sys/fs/cgroup/memory/200, then systemd
hangs on start
- if we mount as /sys/fs/cgroup/memory/, then systemd starts,
but Docker inside a CT starts blaiming becase paths /200
present in /proc/pid/cgroups and /proc/pid/mountinfo,
while /sys/fs/cgroup/memory does not show them.
2) Hide top-level, then in cgroups|mountinfo output we'll see only "/",
and both systemd and Docker works fine.
---
kernel/cgroup.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 2e40430..6c87800 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1386,10 +1386,24 @@ static int cgroup_remount(struct super_block *sb, int
*flags, char *data)
return ret;
}
+#ifdef CONFIG_VE
+int cgroup_show_path(struct seq_file *m, struct dentry *dentry)
+{
+ if (!ve_is_super(get_exec_env()))
+ seq_puts(m, "/");
+ else
+ seq_dentry(m, dentry, " \t\n\\");
+ return 0;
+}
+#endif
+
static const struct super_operations cgroup_ops = {
.statfs = simple_statfs,
.drop_inode = generic_delete_inode,
.show_options = cgroup_show_options,
+#ifdef CONFIG_VE
+ .show_path = cgroup_show_path,
+#endif
.remount_fs = cgroup_remount,
};
@@ -1807,6 +1821,21 @@ int cgroup_path(const struct cgroup *cgrp, char *buf,
int buflen)
return 0;
}
+#ifdef CONFIG_VE
+ /*
+ * Containers cgroups are bind-mounted from node
+ * so they are like '/' from inside, thus we have
+ * to mangle cgroup path output.
+ */
+ if (!ve_is_super(get_exec_env())) {
+ if (cgrp->parent && !cgrp->parent->parent) {
+ if (strlcpy(buf, "/", buflen) >= buflen)
+ return -ENAMETOOLONG;
+ return 0;
+ }
+ }
+#endif
+
start = buf + buflen - 1;
*start = '\0';
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