[Devel] [PATCH RHEL7 COMMIT] ve/cgroups: Introduce CFTYPE_ONLY_ON_VE_ROOT flag for control files

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-514.6.1.vz7.28.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-514.6.1.vz7.28.2
------>
commit fab84c154ba7d7fe9aaf87685d922b85f57666b2
Author: Andrey Ryabinin <aryabinin at virtuozzo.com>
Date:   Fri Jan 20 16:11:37 2017 +0400

    ve/cgroups: Introduce CFTYPE_ONLY_ON_VE_ROOT flag for control files
    
    This adds CFTYPE_ONLY_ON_VE_ROOT flag for control files. It will
    be used in later patch to create cgroup control file which will
    show up only on ve root cgroups.
    
    https://jira.sw.ru/browse/PSBM-33401
    
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
    Reviewed-by: Cyrill Gorcunov <gorcunov at openvz.org>
---
 include/linux/cgroup.h |  1 +
 kernel/cgroup.c        | 59 +++++++++++++++++++++++++++++++++++++-------------
 2 files changed, 45 insertions(+), 15 deletions(-)

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 7caa14d..816cbac 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -445,6 +445,7 @@ struct cgroup_map_cb {
 #define CFTYPE_NOT_ON_ROOT	(1U << 1)	/* don't create on root cg */
 #define CFTYPE_INSANE		(1U << 2)	/* don't create if sane_behavior */
 #define CFTYPE_VE_WRITABLE	(1U << 15)	/* allow write from CT */
+#define CFTYPE_ONLY_ON_VE_ROOT	(1U << 16)	/* only create on CT's root cg */
 
 #define MAX_CFTYPE_NAME		64
 
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 5ea44e1..9a39c26 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1793,21 +1793,6 @@ static struct file_system_type cgroup_fs_type = {
 
 static struct kobject *cgroup_kobj;
 
-#ifdef CONFIG_VE
-void cgroup_mark_ve_root(struct ve_struct *ve)
-{
-	struct cgroup *cgrp;
-	struct cgroupfs_root *root;
-
-	mutex_lock(&cgroup_mutex);
-	for_each_active_root(root) {
-		cgrp = task_cgroup_from_root(ve->init_task, root);
-		set_bit(CGRP_VE_ROOT, &cgrp->flags);
-	}
-	mutex_unlock(&cgroup_mutex);
-}
-#endif
-
 /**
  * cgroup_path - generate the path of a cgroup
  * @cgrp: the cgroup in question
@@ -2822,6 +2807,9 @@ static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys,
 			continue;
 		if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent)
 			continue;
+		if ((cft->flags & CFTYPE_ONLY_ON_VE_ROOT) &&
+				!test_bit(CGRP_VE_ROOT, &cgrp->flags))
+			continue;
 
 		if (is_add) {
 			err = cgroup_add_file(cgrp, subsys, cft);
@@ -4217,6 +4205,47 @@ static void offline_css(struct cgroup_subsys *ss, struct cgroup *cgrp)
 	cgrp->subsys[ss->subsys_id]->flags &= ~CSS_ONLINE;
 }
 
+#ifdef CONFIG_VE
+static void cgroup_add_ve_root_files(struct cgroup *cgrp,
+				struct cgroup_subsys *subsys,
+				struct cftype cfts[])
+{
+	struct cftype *cft;
+
+	if (!test_bit(CGRP_VE_ROOT, &cgrp->flags))
+		return;
+
+	mutex_lock(&cgrp->dentry->d_inode->i_mutex);
+	for (cft = cfts; cft->name[0] != '\0'; cft++) {
+		int err;
+
+		if (!(cft->flags & CFTYPE_ONLY_ON_VE_ROOT))
+			continue;
+
+		err = cgroup_add_file(cgrp, subsys, cft);
+		if (err)
+			pr_warn("cgroup_add_ve_root_files: failed to add %s, err=%d\n",
+				cft->name, err);
+	}
+	mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
+}
+
+void cgroup_mark_ve_root(struct ve_struct *ve)
+{
+	struct cgroup *cgrp;
+	struct cgroupfs_root *root;
+
+	mutex_lock(&cgroup_mutex);
+	for_each_active_root(root) {
+		cgrp = task_cgroup_from_root(ve->init_task, root);
+		set_bit(CGRP_VE_ROOT, &cgrp->flags);
+		cgroup_add_ve_root_files(cgrp, NULL, files);
+	}
+	mutex_unlock(&cgroup_mutex);
+}
+
+#endif
+
 /*
  * cgroup_create - create a cgroup
  * @parent: cgroup that will be parent of the new cgroup