1 files changed, 48 insertions, 2 deletions

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 300b0c416341..753afbca549f 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -2201,8 +2201,7 @@ static int cgroup_init_fs_context(struct fs_context *fc)
                 fc->ops = &cgroup_fs_context_ops;
         else
                 fc->ops = &cgroup1_fs_context_ops;
-        if (fc->user_ns)
-                put_user_ns(fc->user_ns);
+        put_user_ns(fc->user_ns);
         fc->user_ns = get_user_ns(ctx->ns->user_ns);
         fc->global = true;
         return 0;
@@ -2243,6 +2242,50 @@ static struct file_system_type cgroup2_fs_type = {
         .fs_flags               = FS_USERNS_MOUNT,
 };
 
+#ifdef CONFIG_CPUSETS
+static const struct fs_context_operations cpuset_fs_context_ops = {
+        .get_tree       = cgroup1_get_tree,
+        .free           = cgroup_fs_context_free,
+};
+
+/*
+ * This is ugly, but preserves the userspace API for existing cpuset
+ * users. If someone tries to mount the "cpuset" filesystem, we
+ * silently switch it to mount "cgroup" instead
+ */
+static int cpuset_init_fs_context(struct fs_context *fc)
+{
+        char *agent = kstrdup("/sbin/cpuset_release_agent", GFP_USER);
+        struct cgroup_fs_context *ctx;
+        int err;
+
+        err = cgroup_init_fs_context(fc);
+        if (err) {
+                kfree(agent);
+                return err;
+        }
+
+        fc->ops = &cpuset_fs_context_ops;
+
+        ctx = cgroup_fc2context(fc);
+        ctx->subsys_mask = 1 << cpuset_cgrp_id;
+        ctx->flags |= CGRP_ROOT_NOPREFIX;
+        ctx->release_agent = agent;
+
+        get_filesystem(&cgroup_fs_type);
+        put_filesystem(fc->fs_type);
+        fc->fs_type = &cgroup_fs_type;
+
+        return 0;
+}
+
+static struct file_system_type cpuset_fs_type = {
+        .name                   = "cpuset",
+        .init_fs_context        = cpuset_init_fs_context,
+        .fs_flags               = FS_USERNS_MOUNT,
+};
+#endif
+
 int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
                           struct cgroup_namespace *ns)
 {
@@ -5761,6 +5804,9 @@ int __init cgroup_init(void)
         WARN_ON(register_filesystem(&cgroup_fs_type));
         WARN_ON(register_filesystem(&cgroup2_fs_type));
         WARN_ON(!proc_create_single("cgroups", 0, NULL, proc_cgroupstats_show));
+#ifdef CONFIG_CPUSETS
+        WARN_ON(register_filesystem(&cpuset_fs_type));
+#endif
 
         return 0;
 }