1 files changed, 1051 insertions, 0 deletions

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
new file mode 100644
index 00000000..5d2dcbad
--- /dev/null
+++ b/block/blk-cgroup.c
@@ -0,0 +1,1051 @@
+/*
+ * Common Block IO controller cgroup interface
+ *
+ * Based on ideas and code from CFQ, CFS and BFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ *		      Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
+ * 	              Nauman Rafique <nauman@google.com>
+ */
+#include <linux/ioprio.h>
+#include <linux/seq_file.h>
+#include <linux/kdev_t.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/blkdev.h>
+#include <linux/slab.h>
+#include "blk-cgroup.h"
+#include <linux/genhd.h>
+
+#define MAX_KEY_LEN 100
+
+static DEFINE_SPINLOCK(blkio_list_lock);
+static LIST_HEAD(blkio_list);
+
+struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
+EXPORT_SYMBOL_GPL(blkio_root_cgroup);
+
+static struct cgroup_subsys_state *blkiocg_create(struct cgroup_subsys *,
+						  struct cgroup *);
+static int blkiocg_can_attach(struct cgroup_subsys *, struct cgroup *,
+			      struct task_struct *, bool);
+static void blkiocg_attach(struct cgroup_subsys *, struct cgroup *,
+			   struct cgroup *, struct task_struct *, bool);
+static void blkiocg_destroy(struct cgroup_subsys *, struct cgroup *);
+static int blkiocg_populate(struct cgroup_subsys *, struct cgroup *);
+
+struct cgroup_subsys blkio_subsys = {
+	.name = "blkio",
+	.create = blkiocg_create,
+	.can_attach = blkiocg_can_attach,
+	.attach = blkiocg_attach,
+	.destroy = blkiocg_destroy,
+	.populate = blkiocg_populate,
+#ifdef CONFIG_BLK_CGROUP
+	/* note: blkio_subsys_id is otherwise defined in blk-cgroup.h */
+	.subsys_id = blkio_subsys_id,
+#endif
+	.use_id = 1,
+	.module = THIS_MODULE,
+};
+EXPORT_SYMBOL_GPL(blkio_subsys);
+
+static inline void blkio_policy_insert_node(struct blkio_cgroup *blkcg,
+					    struct blkio_policy_node *pn)
+{
+	list_add(&pn->node, &blkcg->policy_list);
+}
+
+/* Must be called with blkcg->lock held */
+static inline void blkio_policy_delete_node(struct blkio_policy_node *pn)
+{
+	list_del(&pn->node);
+}
+
+/* Must be called with blkcg->lock held */
+static struct blkio_policy_node *
+blkio_policy_search_node(const struct blkio_cgroup *blkcg, dev_t dev)
+{
+	struct blkio_policy_node *pn;
+
+	list_for_each_entry(pn, &blkcg->policy_list, node) {
+		if (pn->dev == dev)
+			return pn;
+	}
+
+	return NULL;
+}
+
+struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
+{
+	return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
+			    struct blkio_cgroup, css);
+}
+EXPORT_SYMBOL_GPL(cgroup_to_blkio_cgroup);
+
+/*
+ * Add to the appropriate stat variable depending on the request type.
+ * This should be called with the blkg->stats_lock held.
+ */
+static void blkio_add_stat(uint64_t *stat, uint64_t add, bool direction,
+				bool sync)
+{
+	if (direction)
+		stat[BLKIO_STAT_WRITE] += add;
+	else
+		stat[BLKIO_STAT_READ] += add;
+	if (sync)
+		stat[BLKIO_STAT_SYNC] += add;
+	else
+		stat[BLKIO_STAT_ASYNC] += add;
+}
+
+/*
+ * Decrements the appropriate stat variable if non-zero depending on the
+ * request type. Panics on value being zero.
+ * This should be called with the blkg->stats_lock held.
+ */
+static void blkio_check_and_dec_stat(uint64_t *stat, bool direction, bool sync)
+{
+	if (direction) {
+		BUG_ON(stat[BLKIO_STAT_WRITE] == 0);
+		stat[BLKIO_STAT_WRITE]--;
+	} else {
+		BUG_ON(stat[BLKIO_STAT_READ] == 0);
+		stat[BLKIO_STAT_READ]--;
+	}
+	if (sync) {
+		BUG_ON(stat[BLKIO_STAT_SYNC] == 0);
+		stat[BLKIO_STAT_SYNC]--;
+	} else {
+		BUG_ON(stat[BLKIO_STAT_ASYNC] == 0);
+		stat[BLKIO_STAT_ASYNC]--;
+	}
+}
+
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+/* This should be called with the blkg->stats_lock held. */
+static void blkio_set_start_group_wait_time(struct blkio_group *blkg,
+						struct blkio_group *curr_blkg)
+{
+	if (blkio_blkg_waiting(&blkg->stats))
+		return;
+	if (blkg == curr_blkg)
+		return;
+	blkg->stats.start_group_wait_time = sched_clock();
+	blkio_mark_blkg_waiting(&blkg->stats);
+}
+
+/* This should be called with the blkg->stats_lock held. */
+static void blkio_update_group_wait_time(struct blkio_group_stats *stats)
+{
+	unsigned long long now;
+
+	if (!blkio_blkg_waiting(stats))
+		return;
+
+	now = sched_clock();
+	if (time_after64(now, stats->start_group_wait_time))
+		stats->group_wait_time += now - stats->start_group_wait_time;
+	blkio_clear_blkg_waiting(stats);
+}
+
+/* This should be called with the blkg->stats_lock held. */
+static void blkio_end_empty_time(struct blkio_group_stats *stats)
+{
+	unsigned long long now;
+
+	if (!blkio_blkg_empty(stats))
+		return;
+
+	now = sched_clock();
+	if (time_after64(now, stats->start_empty_time))
+		stats->empty_time += now - stats->start_empty_time;
+	blkio_clear_blkg_empty(stats);
+}
+
+void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&blkg->stats_lock, flags);
+	BUG_ON(blkio_blkg_idling(&blkg->stats));
+	blkg->stats.start_idle_time = sched_clock();
+	blkio_mark_blkg_idling(&blkg->stats);
+	spin_unlock_irqrestore(&blkg->stats_lock, flags);
+}
+EXPORT_SYMBOL_GPL(blkiocg_update_set_idle_time_stats);
+
+void blkiocg_update_idle_time_stats(struct blkio_group *blkg)
+{
+	unsigned long flags;
+	unsigned long long now;
+	struct blkio_group_stats *stats;
+
+	spin_lock_irqsave(&blkg->stats_lock, flags);
+	stats = &blkg->stats;
+	if (blkio_blkg_idling(stats)) {
+		now = sched_clock();
+		if (time_after64(now, stats->start_idle_time))
+			stats->idle_time += now - stats->start_idle_time;
+		blkio_clear_blkg_idling(stats);
+	}
+	spin_unlock_irqrestore(&blkg->stats_lock, flags);
+}
+EXPORT_SYMBOL_GPL(blkiocg_update_idle_time_stats);
+
+void blkiocg_update_avg_queue_size_stats(struct blkio_group *blkg)
+{
+	unsigned long flags;
+	struct blkio_group_stats *stats;
+
+	spin_lock_irqsave(&blkg->stats_lock, flags);
+	stats = &blkg->stats;
+	stats->avg_queue_size_sum +=
+			stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] +
+			stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE];
+	stats->avg_queue_size_samples++;
+	blkio_update_group_wait_time(stats);
+	spin_unlock_irqrestore(&blkg->stats_lock, flags);
+}
+EXPORT_SYMBOL_GPL(blkiocg_update_avg_queue_size_stats);
+
+void blkiocg_set_start_empty_time(struct blkio_group *blkg)
+{
+	unsigned long flags;
+	struct blkio_group_stats *stats;
+
+	spin_lock_irqsave(&blkg->stats_lock, flags);
+	stats = &blkg->stats;
+
+	if (stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] ||
+			stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE]) {
+		spin_unlock_irqrestore(&blkg->stats_lock, flags);
+		return;
+	}
+
+	/*
+	 * group is already marked empty. This can happen if cfqq got new
+	 * request in parent group and moved to this group while being added
+	 * to service tree. Just ignore the event and move on.
+	 */
+	if(blkio_blkg_empty(stats)) {
+		spin_unlock_irqrestore(&blkg->stats_lock, flags);
+		return;
+	}
+
+	stats->start_empty_time = sched_clock();
+	blkio_mark_blkg_empty(stats);
+	spin_unlock_irqrestore(&blkg->stats_lock, flags);
+}
+EXPORT_SYMBOL_GPL(blkiocg_set_start_empty_time);
+
+void blkiocg_update_dequeue_stats(struct blkio_group *blkg,
+			unsigned long dequeue)
+{
+	blkg->stats.dequeue += dequeue;
+}
+EXPORT_SYMBOL_GPL(blkiocg_update_dequeue_stats);
+#else
+static inline void blkio_set_start_group_wait_time(struct blkio_group *blkg,
+					struct blkio_group *curr_blkg) {}
+static inline void blkio_end_empty_time(struct blkio_group_stats *stats) {}
+#endif
+
+void blkiocg_update_io_add_stats(struct blkio_group *blkg,
+			struct blkio_group *curr_blkg, bool direction,
+			bool sync)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&blkg->stats_lock, flags);
+	blkio_add_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED], 1, direction,
+			sync);
+	blkio_end_empty_time(&blkg->stats);
+	blkio_set_start_group_wait_time(blkg, curr_blkg);
+	spin_unlock_irqrestore(&blkg->stats_lock, flags);
+}
+EXPORT_SYMBOL_GPL(blkiocg_update_io_add_stats);
+
+void blkiocg_update_io_remove_stats(struct blkio_group *blkg,
+						bool direction, bool sync)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&blkg->stats_lock, flags);
+	blkio_check_and_dec_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED],
+					direction, sync);
+	spin_unlock_irqrestore(&blkg->stats_lock, flags);
+}
+EXPORT_SYMBOL_GPL(blkiocg_update_io_remove_stats);
+
+void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&blkg->stats_lock, flags);
+	blkg->stats.time += time;
+	spin_unlock_irqrestore(&blkg->stats_lock, flags);
+}
+EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used);
+
+void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
+				uint64_t bytes, bool direction, bool sync)
+{
+	struct blkio_group_stats *stats;
+	unsigned long flags;
+
+	spin_lock_irqsave(&blkg->stats_lock, flags);
+	stats = &blkg->stats;
+	stats->sectors += bytes >> 9;
+	blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICED], 1, direction,
+			sync);
+	blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_BYTES], bytes,
+			direction, sync);
+	spin_unlock_irqrestore(&blkg->stats_lock, flags);
+}
+EXPORT_SYMBOL_GPL(blkiocg_update_dispatch_stats);
+
+void blkiocg_update_completion_stats(struct blkio_group *blkg,
+	uint64_t start_time, uint64_t io_start_time, bool direction, bool sync)
+{
+	struct blkio_group_stats *stats;
+	unsigned long flags;
+	unsigned long long now = sched_clock();
+
+	spin_lock_irqsave(&blkg->stats_lock, flags);
+	stats = &blkg->stats;
+	if (time_after64(now, io_start_time))
+		blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_TIME],
+				now - io_start_time, direction, sync);
+	if (time_after64(io_start_time, start_time))
+		blkio_add_stat(stats->stat_arr[BLKIO_STAT_WAIT_TIME],
+				io_start_time - start_time, direction, sync);
+	spin_unlock_irqrestore(&blkg->stats_lock, flags);
+}
+EXPORT_SYMBOL_GPL(blkiocg_update_completion_stats);
+
+void blkiocg_update_io_merged_stats(struct blkio_group *blkg, bool direction,
+					bool sync)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&blkg->stats_lock, flags);
+	blkio_add_stat(blkg->stats.stat_arr[BLKIO_STAT_MERGED], 1, direction,
+			sync);
+	spin_unlock_irqrestore(&blkg->stats_lock, flags);
+}
+EXPORT_SYMBOL_GPL(blkiocg_update_io_merged_stats);
+
+void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
+			struct blkio_group *blkg, void *key, dev_t dev)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&blkcg->lock, flags);
+	spin_lock_init(&blkg->stats_lock);
+	rcu_assign_pointer(blkg->key, key);
+	blkg->blkcg_id = css_id(&blkcg->css);
+	hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
+	spin_unlock_irqrestore(&blkcg->lock, flags);
+	/* Need to take css reference ? */
+	cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
+	blkg->dev = dev;
+}
+EXPORT_SYMBOL_GPL(blkiocg_add_blkio_group);
+
+static void __blkiocg_del_blkio_group(struct blkio_group *blkg)
+{
+	hlist_del_init_rcu(&blkg->blkcg_node);
+	blkg->blkcg_id = 0;
+}
+
+/*
+ * returns 0 if blkio_group was still on cgroup list. Otherwise returns 1
+ * indicating that blk_group was unhashed by the time we got to it.
+ */
+int blkiocg_del_blkio_group(struct blkio_group *blkg)
+{
+	struct blkio_cgroup *blkcg;
+	unsigned long flags;
+	struct cgroup_subsys_state *css;
+	int ret = 1;
+
+	rcu_read_lock();
+	css = css_lookup(&blkio_subsys, blkg->blkcg_id);
+	if (css) {
+		blkcg = container_of(css, struct blkio_cgroup, css);
+		spin_lock_irqsave(&blkcg->lock, flags);
+		if (!hlist_unhashed(&blkg->blkcg_node)) {
+			__blkiocg_del_blkio_group(blkg);
+			ret = 0;
+		}
+		spin_unlock_irqrestore(&blkcg->lock, flags);
+	}
+
+	rcu_read_unlock();
+	return ret;
+}
+EXPORT_SYMBOL_GPL(blkiocg_del_blkio_group);
+
+/* called under rcu_read_lock(). */
+struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key)
+{
+	struct blkio_group *blkg;
+	struct hlist_node *n;
+	void *__key;
+
+	hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
+		__key = blkg->key;
+		if (__key == key)
+			return blkg;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(blkiocg_lookup_group);
+
+#define SHOW_FUNCTION(__VAR)						\
+static u64 blkiocg_##__VAR##_read(struct cgroup *cgroup,		\
+				       struct cftype *cftype)		\
+{									\
+	struct blkio_cgroup *blkcg;					\
+									\
+	blkcg = cgroup_to_blkio_cgroup(cgroup);				\
+	return (u64)blkcg->__VAR;					\
+}
+
+SHOW_FUNCTION(weight);
+#undef SHOW_FUNCTION
+
+static int
+blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val)
+{
+	struct blkio_cgroup *blkcg;
+	struct blkio_group *blkg;
+	struct hlist_node *n;
+	struct blkio_policy_type *blkiop;
+	struct blkio_policy_node *pn;
+
+	if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
+		return -EINVAL;
+
+	blkcg = cgroup_to_blkio_cgroup(cgroup);
+	spin_lock(&blkio_list_lock);
+	spin_lock_irq(&blkcg->lock);
+	blkcg->weight = (unsigned int)val;
+
+	hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
+		pn = blkio_policy_search_node(blkcg, blkg->dev);
+
+		if (pn)
+			continue;
+
+		list_for_each_entry(blkiop, &blkio_list, list)
+			blkiop->ops.blkio_update_group_weight_fn(blkg,
+					blkcg->weight);
+	}
+	spin_unlock_irq(&blkcg->lock);
+	spin_unlock(&blkio_list_lock);
+	return 0;
+}
+
+static int
+blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
+{
+	struct blkio_cgroup *blkcg;
+	struct blkio_group *blkg;
+	struct blkio_group_stats *stats;
+	struct hlist_node *n;
+	uint64_t queued[BLKIO_STAT_TOTAL];
+	int i;
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+	bool idling, waiting, empty;
+	unsigned long long now = sched_clock();
+#endif
+
+	blkcg = cgroup_to_blkio_cgroup(cgroup);
+	spin_lock_irq(&blkcg->lock);
+	hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
+		spin_lock(&blkg->stats_lock);
+		stats = &blkg->stats;
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+		idling = blkio_blkg_idling(stats);
+		waiting = blkio_blkg_waiting(stats);
+		empty = blkio_blkg_empty(stats);
+#endif
+		for (i = 0; i < BLKIO_STAT_TOTAL; i++)
+			queued[i] = stats->stat_arr[BLKIO_STAT_QUEUED][i];
+		memset(stats, 0, sizeof(struct blkio_group_stats));
+		for (i = 0; i < BLKIO_STAT_TOTAL; i++)
+			stats->stat_arr[BLKIO_STAT_QUEUED][i] = queued[i];
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+		if (idling) {
+			blkio_mark_blkg_idling(stats);
+			stats->start_idle_time = now;
+		}
+		if (waiting) {
+			blkio_mark_blkg_waiting(stats);
+			stats->start_group_wait_time = now;
+		}
+		if (empty) {
+			blkio_mark_blkg_empty(stats);
+			stats->start_empty_time = now;
+		}
+#endif
+		spin_unlock(&blkg->stats_lock);
+	}
+	spin_unlock_irq(&blkcg->lock);
+	return 0;
+}
+
+static void blkio_get_key_name(enum stat_sub_type type, dev_t dev, char *str,
+				int chars_left, bool diskname_only)
+{
+	snprintf(str, chars_left, "%d:%d", MAJOR(dev), MINOR(dev));
+	chars_left -= strlen(str);
+	if (chars_left <= 0) {
+		printk(KERN_WARNING
+			"Possibly incorrect cgroup stat display format");
+		return;
+	}
+	if (diskname_only)
+		return;
+	switch (type) {
+	case BLKIO_STAT_READ:
+		strlcat(str, " Read", chars_left);
+		break;
+	case BLKIO_STAT_WRITE:
+		strlcat(str, " Write", chars_left);
+		break;
+	case BLKIO_STAT_SYNC:
+		strlcat(str, " Sync", chars_left);
+		break;
+	case BLKIO_STAT_ASYNC:
+		strlcat(str, " Async", chars_left);
+		break;
+	case BLKIO_STAT_TOTAL:
+		strlcat(str, " Total", chars_left);
+		break;
+	default:
+		strlcat(str, " Invalid", chars_left);
+	}
+}
+
+static uint64_t blkio_fill_stat(char *str, int chars_left, uint64_t val,
+				struct cgroup_map_cb *cb, dev_t dev)
+{
+	blkio_get_key_name(0, dev, str, chars_left, true);
+	cb->fill(cb, str, val);
+	return val;
+}
+
+/* This should be called with blkg->stats_lock held */
+static uint64_t blkio_get_stat(struct blkio_group *blkg,
+		struct cgroup_map_cb *cb, dev_t dev, enum stat_type type)
+{
+	uint64_t disk_total;
+	char key_str[MAX_KEY_LEN];
+	enum stat_sub_type sub_type;
+
+	if (type == BLKIO_STAT_TIME)
+		return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
+					blkg->stats.time, cb, dev);
+	if (type == BLKIO_STAT_SECTORS)
+		return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
+					blkg->stats.sectors, cb, dev);
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+	if (type == BLKIO_STAT_AVG_QUEUE_SIZE) {
+		uint64_t sum = blkg->stats.avg_queue_size_sum;
+		uint64_t samples = blkg->stats.avg_queue_size_samples;
+		if (samples)
+			do_div(sum, samples);
+		else
+			sum = 0;
+		return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, sum, cb, dev);
+	}
+	if (type == BLKIO_STAT_GROUP_WAIT_TIME)
+		return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
+					blkg->stats.group_wait_time, cb, dev);
+	if (type == BLKIO_STAT_IDLE_TIME)
+		return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
+					blkg->stats.idle_time, cb, dev);
+	if (type == BLKIO_STAT_EMPTY_TIME)
+		return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
+					blkg->stats.empty_time, cb, dev);
+	if (type == BLKIO_STAT_DEQUEUE)
+		return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
+					blkg->stats.dequeue, cb, dev);
+#endif
+
+	for (sub_type = BLKIO_STAT_READ; sub_type < BLKIO_STAT_TOTAL;
+			sub_type++) {
+		blkio_get_key_name(sub_type, dev, key_str, MAX_KEY_LEN, false);
+		cb->fill(cb, key_str, blkg->stats.stat_arr[type][sub_type]);
+	}
+	disk_total = blkg->stats.stat_arr[type][BLKIO_STAT_READ] +
+			blkg->stats.stat_arr[type][BLKIO_STAT_WRITE];
+	blkio_get_key_name(BLKIO_STAT_TOTAL, dev, key_str, MAX_KEY_LEN, false);
+	cb->fill(cb, key_str, disk_total);
+	return disk_total;
+}
+
+#define SHOW_FUNCTION_PER_GROUP(__VAR, type, show_total)		\
+static int blkiocg_##__VAR##_read(struct cgroup *cgroup,		\
+		struct cftype *cftype, struct cgroup_map_cb *cb)	\
+{									\
+	struct blkio_cgroup *blkcg;					\
+	struct blkio_group *blkg;					\
+	struct hlist_node *n;						\
+	uint64_t cgroup_total = 0;					\
+									\
+	if (!cgroup_lock_live_group(cgroup))				\
+		return -ENODEV;						\
+									\
+	blkcg = cgroup_to_blkio_cgroup(cgroup);				\
+	rcu_read_lock();						\
+	hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {\
+		if (blkg->dev) {					\
+			spin_lock_irq(&blkg->stats_lock);		\
+			cgroup_total += blkio_get_stat(blkg, cb,	\
+						blkg->dev, type);	\
+			spin_unlock_irq(&blkg->stats_lock);		\
+		}							\
+	}								\
+	if (show_total)							\
+		cb->fill(cb, "Total", cgroup_total);			\
+	rcu_read_unlock();						\
+	cgroup_unlock();						\
+	return 0;							\
+}
+
+SHOW_FUNCTION_PER_GROUP(time, BLKIO_STAT_TIME, 0);
+SHOW_FUNCTION_PER_GROUP(sectors, BLKIO_STAT_SECTORS, 0);
+SHOW_FUNCTION_PER_GROUP(io_service_bytes, BLKIO_STAT_SERVICE_BYTES, 1);
+SHOW_FUNCTION_PER_GROUP(io_serviced, BLKIO_STAT_SERVICED, 1);
+SHOW_FUNCTION_PER_GROUP(io_service_time, BLKIO_STAT_SERVICE_TIME, 1);
+SHOW_FUNCTION_PER_GROUP(io_wait_time, BLKIO_STAT_WAIT_TIME, 1);
+SHOW_FUNCTION_PER_GROUP(io_merged, BLKIO_STAT_MERGED, 1);
+SHOW_FUNCTION_PER_GROUP(io_queued, BLKIO_STAT_QUEUED, 1);
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+SHOW_FUNCTION_PER_GROUP(dequeue, BLKIO_STAT_DEQUEUE, 0);
+SHOW_FUNCTION_PER_GROUP(avg_queue_size, BLKIO_STAT_AVG_QUEUE_SIZE, 0);
+SHOW_FUNCTION_PER_GROUP(group_wait_time, BLKIO_STAT_GROUP_WAIT_TIME, 0);
+SHOW_FUNCTION_PER_GROUP(idle_time, BLKIO_STAT_IDLE_TIME, 0);
+SHOW_FUNCTION_PER_GROUP(empty_time, BLKIO_STAT_EMPTY_TIME, 0);
+#endif
+#undef SHOW_FUNCTION_PER_GROUP
+
+static int blkio_check_dev_num(dev_t dev)
+{
+	int part = 0;
+	struct gendisk *disk;
+
+	disk = get_gendisk(dev, &part);
+	if (!disk || part)
+		return -ENODEV;
+
+	return 0;
+}
+
+static int blkio_policy_parse_and_set(char *buf,
+				      struct blkio_policy_node *newpn)
+{
+	char *s[4], *p, *major_s = NULL, *minor_s = NULL;
+	int ret;
+	unsigned long major, minor, temp;
+	int i = 0;
+	dev_t dev;
+
+	memset(s, 0, sizeof(s));
+
+	while ((p = strsep(&buf, " ")) != NULL) {
+		if (!*p)
+			continue;
+
+		s[i++] = p;
+
+		/* Prevent from inputing too many things */
+		if (i == 3)
+			break;
+	}
+
+	if (i != 2)
+		return -EINVAL;
+
+	p = strsep(&s[0], ":");
+	if (p != NULL)
+		major_s = p;
+	else
+		return -EINVAL;
+
+	minor_s = s[0];
+	if (!minor_s)
+		return -EINVAL;
+
+	ret = strict_strtoul(major_s, 10, &major);
+	if (ret)
+		return -EINVAL;
+
+	ret = strict_strtoul(minor_s, 10, &minor);
+	if (ret)
+		return -EINVAL;
+
+	dev = MKDEV(major, minor);
+
+	ret = blkio_check_dev_num(dev);
+	if (ret)
+		return ret;
+
+	newpn->dev = dev;
+
+	if (s[1] == NULL)
+		return -EINVAL;
+
+	ret = strict_strtoul(s[1], 10, &temp);
+	if (ret || (temp < BLKIO_WEIGHT_MIN && temp > 0) ||
+	    temp > BLKIO_WEIGHT_MAX)
+		return -EINVAL;
+
+	newpn->weight =  temp;
+
+	return 0;
+}
+
+unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
+			      dev_t dev)
+{
+	struct blkio_policy_node *pn;
+
+	pn = blkio_policy_search_node(blkcg, dev);
+	if (pn)
+		return pn->weight;
+	else
+		return blkcg->weight;
+}
+EXPORT_SYMBOL_GPL(blkcg_get_weight);
+
+
+static int blkiocg_weight_device_write(struct cgroup *cgrp, struct cftype *cft,
+				       const char *buffer)
+{
+	int ret = 0;
+	char *buf;
+	struct blkio_policy_node *newpn, *pn;
+	struct blkio_cgroup *blkcg;
+	struct blkio_group *blkg;
+	int keep_newpn = 0;
+	struct hlist_node *n;
+	struct blkio_policy_type *blkiop;
+
+	buf = kstrdup(buffer, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	newpn = kzalloc(sizeof(*newpn), GFP_KERNEL);
+	if (!newpn) {
+		ret = -ENOMEM;
+		goto free_buf;
+	}
+
+	ret = blkio_policy_parse_and_set(buf, newpn);
+	if (ret)
+		goto free_newpn;
+
+	blkcg = cgroup_to_blkio_cgroup(cgrp);
+
+	spin_lock_irq(&blkcg->lock);
+
+	pn = blkio_policy_search_node(blkcg, newpn->dev);
+	if (!pn) {
+		if (newpn->weight != 0) {
+			blkio_policy_insert_node(blkcg, newpn);
+			keep_newpn = 1;
+		}
+		spin_unlock_irq(&blkcg->lock);
+		goto update_io_group;
+	}
+
+	if (newpn->weight == 0) {
+		/* weight == 0 means deleteing a specific weight */
+		blkio_policy_delete_node(pn);
+		spin_unlock_irq(&blkcg->lock);
+		goto update_io_group;
+	}
+	spin_unlock_irq(&blkcg->lock);
+
+	pn->weight = newpn->weight;
+
+update_io_group:
+	/* update weight for each cfqg */
+	spin_lock(&blkio_list_lock);
+	spin_lock_irq(&blkcg->lock);
+
+	hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
+		if (newpn->dev == blkg->dev) {
+			list_for_each_entry(blkiop, &blkio_list, list)
+				blkiop->ops.blkio_update_group_weight_fn(blkg,
+							 newpn->weight ?
+							 newpn->weight :
+							 blkcg->weight);
+		}
+	}
+
+	spin_unlock_irq(&blkcg->lock);
+	spin_unlock(&blkio_list_lock);
+
+free_newpn:
+	if (!keep_newpn)
+		kfree(newpn);
+free_buf:
+	kfree(buf);
+	return ret;
+}
+
+static int blkiocg_weight_device_read(struct cgroup *cgrp, struct cftype *cft,
+				      struct seq_file *m)
+{
+	struct blkio_cgroup *blkcg;
+	struct blkio_policy_node *pn;
+
+	seq_printf(m, "dev\tweight\n");
+
+	blkcg = cgroup_to_blkio_cgroup(cgrp);
+	if (!list_empty(&blkcg->policy_list)) {
+		spin_lock_irq(&blkcg->lock);
+		list_for_each_entry(pn, &blkcg->policy_list, node) {
+			seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
+				   MINOR(pn->dev), pn->weight);
+		}
+		spin_unlock_irq(&blkcg->lock);
+	}
+
+	return 0;
+}
+
+struct cftype blkio_files[] = {
+	{
+		.name = "weight_device",
+		.read_seq_string = blkiocg_weight_device_read,
+		.write_string = blkiocg_weight_device_write,
+		.max_write_len = 256,
+	},
+	{
+		.name = "weight",
+		.read_u64 = blkiocg_weight_read,
+		.write_u64 = blkiocg_weight_write,
+	},
+	{
+		.name = "time",
+		.read_map = blkiocg_time_read,
+	},
+	{
+		.name = "sectors",
+		.read_map = blkiocg_sectors_read,
+	},
+	{
+		.name = "io_service_bytes",
+		.read_map = blkiocg_io_service_bytes_read,
+	},
+	{
+		.name = "io_serviced",
+		.read_map = blkiocg_io_serviced_read,
+	},
+	{
+		.name = "io_service_time",
+		.read_map = blkiocg_io_service_time_read,
+	},
+	{
+		.name = "io_wait_time",
+		.read_map = blkiocg_io_wait_time_read,
+	},
+	{
+		.name = "io_merged",
+		.read_map = blkiocg_io_merged_read,
+	},
+	{
+		.name = "io_queued",
+		.read_map = blkiocg_io_queued_read,
+	},
+	{
+		.name = "reset_stats",
+		.write_u64 = blkiocg_reset_stats,
+	},
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+	{
+		.name = "avg_queue_size",
+		.read_map = blkiocg_avg_queue_size_read,
+	},
+	{
+		.name = "group_wait_time",
+		.read_map = blkiocg_group_wait_time_read,
+	},
+	{
+		.name = "idle_time",
+		.read_map = blkiocg_idle_time_read,
+	},
+	{
+		.name = "empty_time",
+		.read_map = blkiocg_empty_time_read,
+	},
+	{
+		.name = "dequeue",
+		.read_map = blkiocg_dequeue_read,
+	},
+#endif
+};
+
+static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
+{
+	return cgroup_add_files(cgroup, subsys, blkio_files,
+				ARRAY_SIZE(blkio_files));
+}
+
+static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
+{
+	struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
+	unsigned long flags;
+	struct blkio_group *blkg;
+	void *key;
+	struct blkio_policy_type *blkiop;
+	struct blkio_policy_node *pn, *pntmp;
+
+	rcu_read_lock();
+	do {
+		spin_lock_irqsave(&blkcg->lock, flags);
+
+		if (hlist_empty(&blkcg->blkg_list)) {
+			spin_unlock_irqrestore(&blkcg->lock, flags);
+			break;
+		}
+
+		blkg = hlist_entry(blkcg->blkg_list.first, struct blkio_group,
+					blkcg_node);
+		key = rcu_dereference(blkg->key);
+		__blkiocg_del_blkio_group(blkg);
+
+		spin_unlock_irqrestore(&blkcg->lock, flags);
+
+		/*
+		 * This blkio_group is being unlinked as associated cgroup is
+		 * going away. Let all the IO controlling policies know about
+		 * this event. Currently this is static call to one io
+		 * controlling policy. Once we have more policies in place, we
+		 * need some dynamic registration of callback function.
+		 */
+		spin_lock(&blkio_list_lock);
+		list_for_each_entry(blkiop, &blkio_list, list)
+			blkiop->ops.blkio_unlink_group_fn(key, blkg);
+		spin_unlock(&blkio_list_lock);
+	} while (1);
+
+	list_for_each_entry_safe(pn, pntmp, &blkcg->policy_list, node) {
+		blkio_policy_delete_node(pn);
+		kfree(pn);
+	}
+
+	free_css_id(&blkio_subsys, &blkcg->css);
+	rcu_read_unlock();
+	if (blkcg != &blkio_root_cgroup)
+		kfree(blkcg);
+}
+
+static struct cgroup_subsys_state *
+blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
+{
+	struct blkio_cgroup *blkcg;
+	struct cgroup *parent = cgroup->parent;
+
+	if (!parent) {
+		blkcg = &blkio_root_cgroup;
+		goto done;
+	}
+
+	/* Currently we do not support hierarchy deeper than two level (0,1) */
+	if (parent != cgroup->top_cgroup)
+		return ERR_PTR(-EPERM);
+
+	blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
+	if (!blkcg)
+		return ERR_PTR(-ENOMEM);
+
+	blkcg->weight = BLKIO_WEIGHT_DEFAULT;
+done:
+	spin_lock_init(&blkcg->lock);
+	INIT_HLIST_HEAD(&blkcg->blkg_list);
+
+	INIT_LIST_HEAD(&blkcg->policy_list);
+	return &blkcg->css;
+}
+
+/*
+ * We cannot support shared io contexts, as we have no mean to support
+ * two tasks with the same ioc in two different groups without major rework
+ * of the main cic data structures.  For now we allow a task to change
+ * its cgroup only if it's the only owner of its ioc.
+ */
+static int blkiocg_can_attach(struct cgroup_subsys *subsys,
+				struct cgroup *cgroup, struct task_struct *tsk,
+				bool threadgroup)
+{
+	struct io_context *ioc;
+	int ret = 0;
+
+	/* task_lock() is needed to avoid races with exit_io_context() */
+	task_lock(tsk);
+	ioc = tsk->io_context;
+	if (ioc && atomic_read(&ioc->nr_tasks) > 1)
+		ret = -EINVAL;
+	task_unlock(tsk);
+
+	return ret;
+}
+
+static void blkiocg_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup,
+				struct cgroup *prev, struct task_struct *tsk,
+				bool threadgroup)
+{
+	struct io_context *ioc;
+
+	task_lock(tsk);
+	ioc = tsk->io_context;
+	if (ioc)
+		ioc->cgroup_changed = 1;
+	task_unlock(tsk);
+}
+
+void blkio_policy_register(struct blkio_policy_type *blkiop)
+{
+	spin_lock(&blkio_list_lock);
+	list_add_tail(&blkiop->list, &blkio_list);
+	spin_unlock(&blkio_list_lock);
+}
+EXPORT_SYMBOL_GPL(blkio_policy_register);
+
+void blkio_policy_unregister(struct blkio_policy_type *blkiop)
+{
+	spin_lock(&blkio_list_lock);
+	list_del_init(&blkiop->list);
+	spin_unlock(&blkio_list_lock);
+}
+EXPORT_SYMBOL_GPL(blkio_policy_unregister);
+
+static int __init init_cgroup_blkio(void)
+{
+	return cgroup_load_subsys(&blkio_subsys);
+}
+
+static void __exit exit_cgroup_blkio(void)
+{
+	cgroup_unload_subsys(&blkio_subsys);
+}
+#ifdef CONFIG_FAST_RESUME
+beforeresume_initcall(init_cgroup_blkio);
+#else
+module_init(init_cgroup_blkio);
+#endif
+module_exit(exit_cgroup_blkio);
+MODULE_LICENSE("GPL");