cgroup: pass around cgroup_subsys_state instead of cgroup in file methods

cgroup is currently in the process of transitioning to using struct
cgroup_subsys_state * as the primary handle instead of struct cgroup.
Please see the previous commit which converts the subsystem methods
for rationale.

This patch converts all cftype file operations to take @css instead of
@cgroup.  cftypes for the cgroup core files don't have their subsytem
pointer set.  These will automatically use the dummy_css added by the
previous patch and can be converted the same way.

Most subsystem conversions are straight forwards but there are some
interesting ones.

* freezer: update_if_frozen() is also converted to take @css instead
  of @cgroup for consistency.  This will make the code look simpler
  too once iterators are converted to use css.

* memory/vmpressure: mem_cgroup_from_css() needs to be exported to
  vmpressure while mem_cgroup_from_cont() can be made static.
  Updated accordingly.

* cpu: cgroup_tg() doesn't have any user left.  Removed.

* cpuacct: cgroup_ca() doesn't have any user left.  Removed.

* hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left.
  Removed.

* net_cls: cgrp_cls_state() doesn't have any user left.  Removed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Steven Rostedt <rostedt@goodmis.org>

3 files changed, 58 insertions, 60 deletions

diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
index e2132435060..bda8e44f6fd 100644
--- a/mm/hugetlb_cgroup.c
+++ b/mm/hugetlb_cgroup.c
@@ -40,12 +40,6 @@ struct hugetlb_cgroup *hugetlb_cgroup_from_css(struct cgroup_subsys_state *s)
 }
 
 static inline
-struct hugetlb_cgroup *hugetlb_cgroup_from_cgroup(struct cgroup *cgroup)
-{
-	return hugetlb_cgroup_from_css(cgroup_css(cgroup, hugetlb_subsys_id));
-}
-
-static inline
 struct hugetlb_cgroup *hugetlb_cgroup_from_task(struct task_struct *task)
 {
 	return hugetlb_cgroup_from_css(task_css(task, hugetlb_subsys_id));
@@ -248,14 +242,15 @@ void hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages,
 	return;
 }
 
-static ssize_t hugetlb_cgroup_read(struct cgroup *cgroup, struct cftype *cft,
-				   struct file *file, char __user *buf,
-				   size_t nbytes, loff_t *ppos)
+static ssize_t hugetlb_cgroup_read(struct cgroup_subsys_state *css,
+				   struct cftype *cft, struct file *file,
+				   char __user *buf, size_t nbytes,
+				   loff_t *ppos)
 {
 	u64 val;
 	char str[64];
 	int idx, name, len;
-	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_cgroup(cgroup);
+	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
 
 	idx = MEMFILE_IDX(cft->private);
 	name = MEMFILE_ATTR(cft->private);
@@ -265,12 +260,12 @@ static ssize_t hugetlb_cgroup_read(struct cgroup *cgroup, struct cftype *cft,
 	return simple_read_from_buffer(buf, nbytes, ppos, str, len);
 }
 
-static int hugetlb_cgroup_write(struct cgroup *cgroup, struct cftype *cft,
-				const char *buffer)
+static int hugetlb_cgroup_write(struct cgroup_subsys_state *css,
+				struct cftype *cft, const char *buffer)
 {
 	int idx, name, ret;
 	unsigned long long val;
-	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_cgroup(cgroup);
+	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
 
 	idx = MEMFILE_IDX(cft->private);
 	name = MEMFILE_ATTR(cft->private);
@@ -295,10 +290,11 @@ static int hugetlb_cgroup_write(struct cgroup *cgroup, struct cftype *cft,
 	return ret;
 }
 
-static int hugetlb_cgroup_reset(struct cgroup *cgroup, unsigned int event)
+static int hugetlb_cgroup_reset(struct cgroup_subsys_state *css,
+				unsigned int event)
 {
 	int idx, name, ret = 0;
-	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_cgroup(cgroup);
+	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
 
 	idx = MEMFILE_IDX(event);
 	name = MEMFILE_ATTR(event);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 32cca0f0af0..ab64dfc84f8 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -483,7 +483,6 @@ enum res_type {
  */
 static DEFINE_MUTEX(memcg_create_mutex);
 
-static inline
 struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *s)
 {
 	return s ? container_of(s, struct mem_cgroup, css) : NULL;
@@ -1035,7 +1034,7 @@ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
 		preempt_enable();
 }
 
-struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
+static inline struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
 {
 	return mem_cgroup_from_css(cgroup_css(cont, mem_cgroup_subsys_id));
 }
@@ -2951,10 +2950,10 @@ static struct kmem_cache *memcg_params_to_cache(struct memcg_cache_params *p)
 }
 
 #ifdef CONFIG_SLABINFO
-static int mem_cgroup_slabinfo_read(struct cgroup *cont, struct cftype *cft,
-					struct seq_file *m)
+static int mem_cgroup_slabinfo_read(struct cgroup_subsys_state *css,
+				    struct cftype *cft, struct seq_file *m)
 {
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 	struct memcg_cache_params *params;
 
 	if (!memcg_can_account_kmem(memcg))
@@ -4999,9 +4998,10 @@ static int mem_cgroup_force_empty(struct mem_cgroup *memcg)
 	return 0;
 }
 
-static int mem_cgroup_force_empty_write(struct cgroup *cont, unsigned int event)
+static int mem_cgroup_force_empty_write(struct cgroup_subsys_state *css,
+					unsigned int event)
 {
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 	int ret;
 
 	if (mem_cgroup_is_root(memcg))
@@ -5014,16 +5014,17 @@ static int mem_cgroup_force_empty_write(struct cgroup *cont, unsigned int event)
 }
 
 
-static u64 mem_cgroup_hierarchy_read(struct cgroup *cont, struct cftype *cft)
+static u64 mem_cgroup_hierarchy_read(struct cgroup_subsys_state *css,
+				     struct cftype *cft)
 {
-	return mem_cgroup_from_cont(cont)->use_hierarchy;
+	return mem_cgroup_from_css(css)->use_hierarchy;
 }
 
-static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft,
-					u64 val)
+static int mem_cgroup_hierarchy_write(struct cgroup_subsys_state *css,
+				      struct cftype *cft, u64 val)
 {
 	int retval = 0;
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 	struct mem_cgroup *parent_memcg = mem_cgroup_from_css(css_parent(&memcg->css));
 
 	mutex_lock(&memcg_create_mutex);
@@ -5094,11 +5095,11 @@ static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
 	return val << PAGE_SHIFT;
 }
 
-static ssize_t mem_cgroup_read(struct cgroup *cont, struct cftype *cft,
-			       struct file *file, char __user *buf,
-			       size_t nbytes, loff_t *ppos)
+static ssize_t mem_cgroup_read(struct cgroup_subsys_state *css,
+			       struct cftype *cft, struct file *file,
+			       char __user *buf, size_t nbytes, loff_t *ppos)
 {
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 	char str[64];
 	u64 val;
 	int name, len;
@@ -5131,11 +5132,11 @@ static ssize_t mem_cgroup_read(struct cgroup *cont, struct cftype *cft,
 	return simple_read_from_buffer(buf, nbytes, ppos, str, len);
 }
 
-static int memcg_update_kmem_limit(struct cgroup *cont, u64 val)
+static int memcg_update_kmem_limit(struct cgroup_subsys_state *css, u64 val)
 {
 	int ret = -EINVAL;
 #ifdef CONFIG_MEMCG_KMEM
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 	/*
 	 * For simplicity, we won't allow this to be disabled.  It also can't
 	 * be changed if the cgroup has children already, or if tasks had
@@ -5151,7 +5152,7 @@ static int memcg_update_kmem_limit(struct cgroup *cont, u64 val)
 	mutex_lock(&memcg_create_mutex);
 	mutex_lock(&set_limit_mutex);
 	if (!memcg->kmem_account_flags && val != RESOURCE_MAX) {
-		if (cgroup_task_count(cont) || memcg_has_children(memcg)) {
+		if (cgroup_task_count(css->cgroup) || memcg_has_children(memcg)) {
 			ret = -EBUSY;
 			goto out;
 		}
@@ -5221,10 +5222,10 @@ out:
  * The user of this function is...
  * RES_LIMIT.
  */
-static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
+static int mem_cgroup_write(struct cgroup_subsys_state *css, struct cftype *cft,
 			    const char *buffer)
 {
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 	enum res_type type;
 	int name;
 	unsigned long long val;
@@ -5248,7 +5249,7 @@ static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
 		else if (type == _MEMSWAP)
 			ret = mem_cgroup_resize_memsw_limit(memcg, val);
 		else if (type == _KMEM)
-			ret = memcg_update_kmem_limit(cont, val);
+			ret = memcg_update_kmem_limit(css, val);
 		else
 			return -EINVAL;
 		break;
@@ -5297,9 +5298,9 @@ out:
 	*memsw_limit = min_memsw_limit;
 }
 
-static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
+static int mem_cgroup_reset(struct cgroup_subsys_state *css, unsigned int event)
 {
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 	int name;
 	enum res_type type;
 
@@ -5332,17 +5333,17 @@ static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
 	return 0;
 }
 
-static u64 mem_cgroup_move_charge_read(struct cgroup *cgrp,
+static u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css,
 					struct cftype *cft)
 {
-	return mem_cgroup_from_cont(cgrp)->move_charge_at_immigrate;
+	return mem_cgroup_from_css(css)->move_charge_at_immigrate;
 }
 
 #ifdef CONFIG_MMU
-static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
+static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
 					struct cftype *cft, u64 val)
 {
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 
 	if (val >= (1 << NR_MOVE_TYPE))
 		return -EINVAL;
@@ -5357,7 +5358,7 @@ static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
 	return 0;
 }
 #else
-static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
+static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
 					struct cftype *cft, u64 val)
 {
 	return -ENOSYS;
@@ -5365,13 +5366,13 @@ static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
 #endif
 
 #ifdef CONFIG_NUMA
-static int memcg_numa_stat_show(struct cgroup *cont, struct cftype *cft,
-				      struct seq_file *m)
+static int memcg_numa_stat_show(struct cgroup_subsys_state *css,
+				struct cftype *cft, struct seq_file *m)
 {
 	int nid;
 	unsigned long total_nr, file_nr, anon_nr, unevictable_nr;
 	unsigned long node_nr;
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 
 	total_nr = mem_cgroup_nr_lru_pages(memcg, LRU_ALL);
 	seq_printf(m, "total=%lu", total_nr);
@@ -5416,10 +5417,10 @@ static inline void mem_cgroup_lru_names_not_uptodate(void)
 	BUILD_BUG_ON(ARRAY_SIZE(mem_cgroup_lru_names) != NR_LRU_LISTS);
 }
 
-static int memcg_stat_show(struct cgroup *cont, struct cftype *cft,
+static int memcg_stat_show(struct cgroup_subsys_state *css, struct cftype *cft,
 				 struct seq_file *m)
 {
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 	struct mem_cgroup *mi;
 	unsigned int i;
 
@@ -5503,17 +5504,18 @@ static int memcg_stat_show(struct cgroup *cont, struct cftype *cft,
 	return 0;
 }
 
-static u64 mem_cgroup_swappiness_read(struct cgroup *cgrp, struct cftype *cft)
+static u64 mem_cgroup_swappiness_read(struct cgroup_subsys_state *css,
+				      struct cftype *cft)
 {
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 
 	return mem_cgroup_swappiness(memcg);
 }
 
-static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft,
-				       u64 val)
+static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
+				       struct cftype *cft, u64 val)
 {
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 	struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(&memcg->css));
 
 	if (val > 100 || !parent)
@@ -5829,10 +5831,10 @@ static void mem_cgroup_oom_unregister_event(struct cgroup *cgrp,
 	spin_unlock(&memcg_oom_lock);
 }
 
-static int mem_cgroup_oom_control_read(struct cgroup *cgrp,
+static int mem_cgroup_oom_control_read(struct cgroup_subsys_state *css,
 	struct cftype *cft,  struct cgroup_map_cb *cb)
 {
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 
 	cb->fill(cb, "oom_kill_disable", memcg->oom_kill_disable);
 
@@ -5843,10 +5845,10 @@ static int mem_cgroup_oom_control_read(struct cgroup *cgrp,
 	return 0;
 }
 
-static int mem_cgroup_oom_control_write(struct cgroup *cgrp,
+static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css,
 	struct cftype *cft, u64 val)
 {
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 	struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(&memcg->css));
 
 	/* cannot set to root cgroup and only 0 and 1 are allowed */
diff --git a/mm/vmpressure.c b/mm/vmpressure.c
index 7f1654d3cec..2a8a736e95c 100644
--- a/mm/vmpressure.c
+++ b/mm/vmpressure.c
@@ -81,8 +81,8 @@ static struct vmpressure *cg_to_vmpressure(struct cgroup *cg)
 
 static struct vmpressure *vmpressure_parent(struct vmpressure *vmpr)
 {
-	struct cgroup *cg = vmpressure_to_css(vmpr)->cgroup;
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cg);
+	struct cgroup_subsys_state *css = vmpressure_to_css(vmpr);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 
 	memcg = parent_mem_cgroup(memcg);
 	if (!memcg)