1 files changed, 361 insertions, 0 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
new file mode 100644
index 00000000000..1fa2654db0a
--- /dev/null
+++ b/block/blk-cgroup.c
@@ -0,0 +1,361 @@
+/*
+ * 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 "blk-cgroup.h"
+
+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);
+
+bool blkiocg_css_tryget(struct blkio_cgroup *blkcg)
+{
+	if (!css_tryget(&blkcg->css))
+		return false;
+	return true;
+}
+EXPORT_SYMBOL_GPL(blkiocg_css_tryget);
+
+void blkiocg_css_put(struct blkio_cgroup *blkcg)
+{
+	css_put(&blkcg->css);
+}
+EXPORT_SYMBOL_GPL(blkiocg_css_put);
+
+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);
+
+void blkiocg_update_blkio_group_stats(struct blkio_group *blkg,
+			unsigned long time, unsigned long sectors)
+{
+	blkg->time += time;
+	blkg->sectors += sectors;
+}
+EXPORT_SYMBOL_GPL(blkiocg_update_blkio_group_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);
+	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);
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+	/* Need to take css reference ? */
+	cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
+#endif
+	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)
+		goto out;
+
+	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);
+out:
+	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;
+
+	if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
+		return -EINVAL;
+
+	blkcg = cgroup_to_blkio_cgroup(cgroup);
+	spin_lock_irq(&blkcg->lock);
+	blkcg->weight = (unsigned int)val;
+	hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
+		spin_lock(&blkio_list_lock);
+		list_for_each_entry(blkiop, &blkio_list, list)
+			blkiop->ops.blkio_update_group_weight_fn(blkg,
+					blkcg->weight);
+		spin_unlock(&blkio_list_lock);
+	}
+	spin_unlock_irq(&blkcg->lock);
+	return 0;
+}
+
+#define SHOW_FUNCTION_PER_GROUP(__VAR)					\
+static int blkiocg_##__VAR##_read(struct cgroup *cgroup,		\
+			struct cftype *cftype, struct seq_file *m)	\
+{									\
+	struct blkio_cgroup *blkcg;					\
+	struct blkio_group *blkg;					\
+	struct hlist_node *n;						\
+									\
+	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)						\
+			seq_printf(m, "%u:%u %lu\n", MAJOR(blkg->dev),	\
+				 MINOR(blkg->dev), blkg->__VAR);	\
+	}								\
+	rcu_read_unlock();						\
+	cgroup_unlock();						\
+	return 0;							\
+}
+
+SHOW_FUNCTION_PER_GROUP(time);
+SHOW_FUNCTION_PER_GROUP(sectors);
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+SHOW_FUNCTION_PER_GROUP(dequeue);
+#endif
+#undef SHOW_FUNCTION_PER_GROUP
+
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+void blkiocg_update_blkio_group_dequeue_stats(struct blkio_group *blkg,
+			unsigned long dequeue)
+{
+	blkg->dequeue += dequeue;
+}
+EXPORT_SYMBOL_GPL(blkiocg_update_blkio_group_dequeue_stats);
+#endif
+
+struct cftype blkio_files[] = {
+	{
+		.name = "weight",
+		.read_u64 = blkiocg_weight_read,
+		.write_u64 = blkiocg_weight_write,
+	},
+	{
+		.name = "time",
+		.read_seq_string = blkiocg_time_read,
+	},
+	{
+		.name = "sectors",
+		.read_seq_string = blkiocg_sectors_read,
+	},
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+       {
+		.name = "dequeue",
+		.read_seq_string = 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;
+
+	rcu_read_lock();
+remove_entry:
+	spin_lock_irqsave(&blkcg->lock, flags);
+
+	if (hlist_empty(&blkcg->blkg_list)) {
+		spin_unlock_irqrestore(&blkcg->lock, flags);
+		goto done;
+	}
+
+	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);
+	goto remove_entry;
+done:
+	free_css_id(&blkio_subsys, &blkcg->css);
+	rcu_read_unlock();
+	kfree(blkcg);
+}
+
+static struct cgroup_subsys_state *
+blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
+{
+	struct blkio_cgroup *blkcg, *parent_blkcg;
+
+	if (!cgroup->parent) {
+		blkcg = &blkio_root_cgroup;
+		goto done;
+	}
+
+	/* Currently we do not support hierarchy deeper than two level (0,1) */
+	parent_blkcg = cgroup_to_blkio_cgroup(cgroup->parent);
+	if (css_depth(&parent_blkcg->css) > 0)
+		return ERR_PTR(-EINVAL);
+
+	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);
+
+	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);
+}
+
+struct cgroup_subsys blkio_subsys = {
+	.name = "blkio",
+	.create = blkiocg_create,
+	.can_attach = blkiocg_can_attach,
+	.attach = blkiocg_attach,
+	.destroy = blkiocg_destroy,
+	.populate = blkiocg_populate,
+	.subsys_id = blkio_subsys_id,
+	.use_id = 1,
+};
+
+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);