1 files changed, 132 insertions, 143 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 9450f025fe0c..c2515851c1aa 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -14,18 +14,17 @@
 #include <linux/rcupdate.h>
 #include <linux/rculist.h>
 #include <linux/cgroupstats.h>
-#include <linux/prio_heap.h>
 #include <linux/rwsem.h>
 #include <linux/idr.h>
 #include <linux/workqueue.h>
-#include <linux/xattr.h>
 #include <linux/fs.h>
 #include <linux/percpu-refcount.h>
 #include <linux/seq_file.h>
+#include <linux/kernfs.h>
 
 #ifdef CONFIG_CGROUPS
 
-struct cgroupfs_root;
+struct cgroup_root;
 struct cgroup_subsys;
 struct inode;
 struct cgroup;
@@ -34,31 +33,16 @@ extern int cgroup_init_early(void);
 extern int cgroup_init(void);
 extern void cgroup_fork(struct task_struct *p);
 extern void cgroup_post_fork(struct task_struct *p);
-extern void cgroup_exit(struct task_struct *p, int run_callbacks);
+extern void cgroup_exit(struct task_struct *p);
 extern int cgroupstats_build(struct cgroupstats *stats,
 				struct dentry *dentry);
-extern int cgroup_load_subsys(struct cgroup_subsys *ss);
-extern void cgroup_unload_subsys(struct cgroup_subsys *ss);
 
 extern int proc_cgroup_show(struct seq_file *, void *);
 
-/*
- * Define the enumeration of all cgroup subsystems.
- *
- * We define ids for builtin subsystems and then modular ones.
- */
-#define SUBSYS(_x) _x ## _subsys_id,
+/* define the enumeration of all cgroup subsystems */
+#define SUBSYS(_x) _x ## _cgrp_id,
 enum cgroup_subsys_id {
-#define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option)
-#include <linux/cgroup_subsys.h>
-#undef IS_SUBSYS_ENABLED
-	CGROUP_BUILTIN_SUBSYS_COUNT,
-
-	__CGROUP_SUBSYS_TEMP_PLACEHOLDER = CGROUP_BUILTIN_SUBSYS_COUNT - 1,
-
-#define IS_SUBSYS_ENABLED(option) IS_MODULE(option)
 #include <linux/cgroup_subsys.h>
-#undef IS_SUBSYS_ENABLED
 	CGROUP_SUBSYS_COUNT,
 };
 #undef SUBSYS
@@ -153,11 +137,6 @@ enum {
 	CGRP_SANE_BEHAVIOR,
 };
 
-struct cgroup_name {
-	struct rcu_head rcu_head;
-	char name[];
-};
-
 struct cgroup {
 	unsigned long flags;		/* "unsigned long" so bitops work */
 
@@ -174,16 +153,17 @@ struct cgroup {
 	/* the number of attached css's */
 	int nr_css;
 
+	atomic_t refcnt;
+
 	/*
 	 * We link our 'sibling' struct into our parent's 'children'.
 	 * Our children link their 'sibling' into our 'children'.
 	 */
 	struct list_head sibling;	/* my parent's children */
 	struct list_head children;	/* my children */
-	struct list_head files;		/* my files */
 
 	struct cgroup *parent;		/* my parent */
-	struct dentry *dentry;		/* cgroup fs entry, RCU protected */
+	struct kernfs_node *kn;		/* cgroup kernfs entry */
 
 	/*
 	 * Monotonically increasing unique serial number which defines a
@@ -193,23 +173,13 @@ struct cgroup {
 	 */
 	u64 serial_nr;
 
-	/*
-	 * This is a copy of dentry->d_name, and it's needed because
-	 * we can't use dentry->d_name in cgroup_path().
-	 *
-	 * You must acquire rcu_read_lock() to access cgrp->name, and
-	 * the only place that can change it is rename(), which is
-	 * protected by parent dir's i_mutex.
-	 *
-	 * Normally you should use cgroup_name() wrapper rather than
-	 * access it directly.
-	 */
-	struct cgroup_name __rcu *name;
+	/* The bitmask of subsystems attached to this cgroup */
+	unsigned long subsys_mask;
 
 	/* Private pointers for each registered subsystem */
 	struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
 
-	struct cgroupfs_root *root;
+	struct cgroup_root *root;
 
 	/*
 	 * List of cgrp_cset_links pointing at css_sets with tasks in this
@@ -237,14 +207,11 @@ struct cgroup {
 	/* For css percpu_ref killing and RCU-protected deletion */
 	struct rcu_head rcu_head;
 	struct work_struct destroy_work;
-
-	/* directory xattrs */
-	struct simple_xattrs xattrs;
 };
 
 #define MAX_CGROUP_ROOT_NAMELEN 64
 
-/* cgroupfs_root->flags */
+/* cgroup_root->flags */
 enum {
 	/*
 	 * Unfortunately, cgroup core and various controllers are riddled
@@ -262,8 +229,8 @@ enum {
 	 *
 	 * The followings are the behaviors currently affected this flag.
 	 *
-	 * - Mount options "noprefix" and "clone_children" are disallowed.
-	 *   Also, cgroupfs file cgroup.clone_children is not created.
+	 * - Mount options "noprefix", "xattr", "clone_children",
+	 *   "release_agent" and "name" are disallowed.
 	 *
 	 * - When mounting an existing superblock, mount options should
 	 *   match.
@@ -281,6 +248,11 @@ enum {
 	 * - "release_agent" and "notify_on_release" are removed.
 	 *   Replacement notification mechanism will be implemented.
 	 *
+	 * - "cgroup.clone_children" is removed.
+	 *
+	 * - If mount is requested with sane_behavior but without any
+	 *   subsystem, the default unified hierarchy is mounted.
+	 *
 	 * - cpuset: tasks will be kept in empty cpusets when hotplug happens
 	 *   and take masks of ancestors with non-empty cpus/mems, instead of
 	 *   being moved to an ancestor.
@@ -300,29 +272,24 @@ enum {
 
 	/* mount options live below bit 16 */
 	CGRP_ROOT_OPTION_MASK	= (1 << 16) - 1,
-
-	CGRP_ROOT_SUBSYS_BOUND	= (1 << 16), /* subsystems finished binding */
 };
 
 /*
- * A cgroupfs_root represents the root of a cgroup hierarchy, and may be
- * associated with a superblock to form an active hierarchy.  This is
+ * A cgroup_root represents the root of a cgroup hierarchy, and may be
+ * associated with a kernfs_root to form an active hierarchy.  This is
  * internal to cgroup core.  Don't access directly from controllers.
  */
-struct cgroupfs_root {
-	struct super_block *sb;
-
-	/* The bitmask of subsystems attached to this hierarchy */
-	unsigned long subsys_mask;
+struct cgroup_root {
+	struct kernfs_root *kf_root;
 
 	/* Unique id for this hierarchy. */
 	int hierarchy_id;
 
-	/* The root cgroup for this hierarchy */
-	struct cgroup top_cgroup;
+	/* The root cgroup.  Root is destroyed on its release. */
+	struct cgroup cgrp;
 
-	/* Tracks how many cgroups are currently defined in hierarchy.*/
-	int number_of_cgroups;
+	/* Number of cgroups in the hierarchy, used only for /proc/cgroups */
+	atomic_t nr_cgrps;
 
 	/* A list running through the active hierarchies */
 	struct list_head root_list;
@@ -360,10 +327,14 @@ struct css_set {
 	struct hlist_node hlist;
 
 	/*
-	 * List running through all tasks using this cgroup
-	 * group. Protected by css_set_lock
+	 * Lists running through all tasks using this cgroup group.
+	 * mg_tasks lists tasks which belong to this cset but are in the
+	 * process of being migrated out or in.  Protected by
+	 * css_set_rwsem, but, during migration, once tasks are moved to
+	 * mg_tasks, it can be read safely while holding cgroup_mutex.
 	 */
 	struct list_head tasks;
+	struct list_head mg_tasks;
 
 	/*
 	 * List of cgrp_cset_links pointing at cgroups referenced from this
@@ -372,13 +343,29 @@ struct css_set {
 	struct list_head cgrp_links;
 
 	/*
-	 * Set of subsystem states, one for each subsystem. This array
-	 * is immutable after creation apart from the init_css_set
-	 * during subsystem registration (at boot time) and modular subsystem
-	 * loading/unloading.
+	 * Set of subsystem states, one for each subsystem. This array is
+	 * immutable after creation apart from the init_css_set during
+	 * subsystem registration (at boot time).
 	 */
 	struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
 
+	/*
+	 * List of csets participating in the on-going migration either as
+	 * source or destination.  Protected by cgroup_mutex.
+	 */
+	struct list_head mg_preload_node;
+	struct list_head mg_node;
+
+	/*
+	 * If this cset is acting as the source of migration the following
+	 * two fields are set.  mg_src_cgrp is the source cgroup of the
+	 * on-going migration and mg_dst_cset is the destination cset the
+	 * target tasks on this cset should be migrated to.  Protected by
+	 * cgroup_mutex.
+	 */
+	struct cgroup *mg_src_cgrp;
+	struct css_set *mg_dst_cset;
+
 	/* For RCU-protected deletion */
 	struct rcu_head rcu_head;
 };
@@ -397,6 +384,7 @@ enum {
 	CFTYPE_NOT_ON_ROOT	= (1 << 1),	/* don't create on root cgrp */
 	CFTYPE_INSANE		= (1 << 2),	/* don't create if sane_behavior */
 	CFTYPE_NO_PREFIX	= (1 << 3),	/* (DON'T USE FOR NEW FILES) no subsys prefix */
+	CFTYPE_ONLY_ON_DFL	= (1 << 4),	/* only on default hierarchy */
 };
 
 #define MAX_CFTYPE_NAME		64
@@ -416,8 +404,9 @@ struct cftype {
 	umode_t mode;
 
 	/*
-	 * If non-zero, defines the maximum length of string that can
-	 * be passed to write_string; defaults to 64
+	 * The maximum length of string, excluding trailing nul, that can
+	 * be passed to write_string.  If < PAGE_SIZE-1, PAGE_SIZE-1 is
+	 * assumed.
 	 */
 	size_t max_write_len;
 
@@ -425,10 +414,12 @@ struct cftype {
 	unsigned int flags;
 
 	/*
-	 * The subsys this file belongs to.  Initialized automatically
-	 * during registration.  NULL for cgroup core files.
+	 * Fields used for internal bookkeeping.  Initialized automatically
+	 * during registration.
 	 */
-	struct cgroup_subsys *ss;
+	struct cgroup_subsys *ss;	/* NULL for cgroup core files */
+	struct list_head node;		/* anchored at ss->cfts */
+	struct kernfs_ops *kf_ops;
 
 	/*
 	 * read_u64() is a shortcut for the common case of returning a
@@ -467,7 +458,7 @@ struct cftype {
 	 * Returns 0 or -ve error code.
 	 */
 	int (*write_string)(struct cgroup_subsys_state *css, struct cftype *cft,
-			    const char *buffer);
+			    char *buffer);
 	/*
 	 * trigger() callback can be used to get some kick from the
 	 * userspace, when the actual string written is not important
@@ -475,37 +466,18 @@ struct cftype {
 	 * kick type for multiplexing.
 	 */
 	int (*trigger)(struct cgroup_subsys_state *css, unsigned int event);
-};
 
-/*
- * cftype_sets describe cftypes belonging to a subsystem and are chained at
- * cgroup_subsys->cftsets.  Each cftset points to an array of cftypes
- * terminated by zero length name.
- */
-struct cftype_set {
-	struct list_head		node;	/* chained at subsys->cftsets */
-	struct cftype			*cfts;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lock_class_key	lockdep_key;
+#endif
 };
 
-/*
- * cgroupfs file entry, pointed to from leaf dentry->d_fsdata.  Don't
- * access directly.
- */
-struct cfent {
-	struct list_head		node;
-	struct dentry			*dentry;
-	struct cftype			*type;
-	struct cgroup_subsys_state	*css;
-
-	/* file xattrs */
-	struct simple_xattrs		xattrs;
-};
+extern struct cgroup_root cgrp_dfl_root;
 
-/* seq_file->private points to the following, only ->priv is public */
-struct cgroup_open_file {
-	struct cfent			*cfe;
-	void				*priv;
-};
+static inline bool cgroup_on_dfl(const struct cgroup *cgrp)
+{
+	return cgrp->root == &cgrp_dfl_root;
+}
 
 /*
  * See the comment above CGRP_ROOT_SANE_BEHAVIOR for details.  This
@@ -516,34 +488,63 @@ static inline bool cgroup_sane_behavior(const struct cgroup *cgrp)
 	return cgrp->root->flags & CGRP_ROOT_SANE_BEHAVIOR;
 }
 
-/* Caller should hold rcu_read_lock() */
-static inline const char *cgroup_name(const struct cgroup *cgrp)
+/* no synchronization, the result can only be used as a hint */
+static inline bool cgroup_has_tasks(struct cgroup *cgrp)
 {
-	return rcu_dereference(cgrp->name)->name;
+	return !list_empty(&cgrp->cset_links);
 }
 
-static inline struct cgroup_subsys_state *seq_css(struct seq_file *seq)
+/* returns ino associated with a cgroup, 0 indicates unmounted root */
+static inline ino_t cgroup_ino(struct cgroup *cgrp)
 {
-	struct cgroup_open_file *of = seq->private;
-	return of->cfe->css;
+	if (cgrp->kn)
+		return cgrp->kn->ino;
+	else
+		return 0;
 }
 
 static inline struct cftype *seq_cft(struct seq_file *seq)
 {
-	struct cgroup_open_file *of = seq->private;
-	return of->cfe->type;
+	struct kernfs_open_file *of = seq->private;
+
+	return of->kn->priv;
+}
+
+struct cgroup_subsys_state *seq_css(struct seq_file *seq);
+
+/*
+ * Name / path handling functions.  All are thin wrappers around the kernfs
+ * counterparts and can be called under any context.
+ */
+
+static inline int cgroup_name(struct cgroup *cgrp, char *buf, size_t buflen)
+{
+	return kernfs_name(cgrp->kn, buf, buflen);
 }
 
+static inline char * __must_check cgroup_path(struct cgroup *cgrp, char *buf,
+					      size_t buflen)
+{
+	return kernfs_path(cgrp->kn, buf, buflen);
+}
+
+static inline void pr_cont_cgroup_name(struct cgroup *cgrp)
+{
+	pr_cont_kernfs_name(cgrp->kn);
+}
+
+static inline void pr_cont_cgroup_path(struct cgroup *cgrp)
+{
+	pr_cont_kernfs_path(cgrp->kn);
+}
+
+char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen);
+
 int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
 int cgroup_rm_cftypes(struct cftype *cfts);
 
 bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor);
 
-int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen);
-int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen);
-
-int cgroup_task_count(const struct cgroup *cgrp);
-
 /*
  * Control Group taskset, used to pass around set of tasks to cgroup_subsys
  * methods.
@@ -551,22 +552,15 @@ int cgroup_task_count(const struct cgroup *cgrp);
 struct cgroup_taskset;
 struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset);
 struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset);
-struct cgroup_subsys_state *cgroup_taskset_cur_css(struct cgroup_taskset *tset,
-						   int subsys_id);
-int cgroup_taskset_size(struct cgroup_taskset *tset);
 
 /**
  * cgroup_taskset_for_each - iterate cgroup_taskset
  * @task: the loop cursor
- * @skip_css: skip if task's css matches this, %NULL to iterate through all
  * @tset: taskset to iterate
  */
-#define cgroup_taskset_for_each(task, skip_css, tset)			\
+#define cgroup_taskset_for_each(task, tset)				\
 	for ((task) = cgroup_taskset_first((tset)); (task);		\
-	     (task) = cgroup_taskset_next((tset)))			\
-		if (!(skip_css) ||					\
-		    cgroup_taskset_cur_css((tset),			\
-			(skip_css)->ss->subsys_id) != (skip_css))
+	     (task) = cgroup_taskset_next((tset)))
 
 /*
  * Control Group subsystem type.
@@ -591,7 +585,6 @@ struct cgroup_subsys {
 		     struct task_struct *task);
 	void (*bind)(struct cgroup_subsys_state *root_css);
 
-	int subsys_id;
 	int disabled;
 	int early_init;
 
@@ -610,27 +603,26 @@ struct cgroup_subsys {
 	bool broken_hierarchy;
 	bool warned_broken_hierarchy;
 
+	/* the following two fields are initialized automtically during boot */
+	int id;
 #define MAX_CGROUP_TYPE_NAMELEN 32
 	const char *name;
 
 	/* link to parent, protected by cgroup_lock() */
-	struct cgroupfs_root *root;
+	struct cgroup_root *root;
 
-	/* list of cftype_sets */
-	struct list_head cftsets;
+	/*
+	 * List of cftypes.  Each entry is the first entry of an array
+	 * terminated by zero length name.
+	 */
+	struct list_head cfts;
 
-	/* base cftypes, automatically [de]registered with subsys itself */
+	/* base cftypes, automatically registered with subsys itself */
 	struct cftype *base_cftypes;
-	struct cftype_set base_cftset;
-
-	/* should be defined only by modular subsystems */
-	struct module *module;
 };
 
-#define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys;
-#define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option)
+#define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys;
 #include <linux/cgroup_subsys.h>
-#undef IS_SUBSYS_ENABLED
 #undef SUBSYS
 
 /**
@@ -661,10 +653,12 @@ struct cgroup_subsys_state *css_parent(struct cgroup_subsys_state *css)
  */
 #ifdef CONFIG_PROVE_RCU
 extern struct mutex cgroup_mutex;
+extern struct rw_semaphore css_set_rwsem;
 #define task_css_set_check(task, __c)					\
 	rcu_dereference_check((task)->cgroups,				\
-		lockdep_is_held(&(task)->alloc_lock) ||			\
-		lockdep_is_held(&cgroup_mutex) || (__c))
+		lockdep_is_held(&cgroup_mutex) ||			\
+		lockdep_is_held(&css_set_rwsem) ||			\
+		((task)->flags & PF_EXITING) || (__c))
 #else
 #define task_css_set_check(task, __c)					\
 	rcu_dereference((task)->cgroups)
@@ -837,16 +831,11 @@ void css_task_iter_start(struct cgroup_subsys_state *css,
 struct task_struct *css_task_iter_next(struct css_task_iter *it);
 void css_task_iter_end(struct css_task_iter *it);
 
-int css_scan_tasks(struct cgroup_subsys_state *css,
-		   bool (*test)(struct task_struct *, void *),
-		   void (*process)(struct task_struct *, void *),
-		   void *data, struct ptr_heap *heap);
-
 int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
 int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);
 
-struct cgroup_subsys_state *css_from_dir(struct dentry *dentry,
-					 struct cgroup_subsys *ss);
+struct cgroup_subsys_state *css_tryget_from_dir(struct dentry *dentry,
+						struct cgroup_subsys *ss);
 
 #else /* !CONFIG_CGROUPS */
 
@@ -854,7 +843,7 @@ static inline int cgroup_init_early(void) { return 0; }
 static inline int cgroup_init(void) { return 0; }
 static inline void cgroup_fork(struct task_struct *p) {}
 static inline void cgroup_post_fork(struct task_struct *p) {}
-static inline void cgroup_exit(struct task_struct *p, int callbacks) {}
+static inline void cgroup_exit(struct task_struct *p) {}
 
 static inline int cgroupstats_build(struct cgroupstats *stats,
 					struct dentry *dentry)