blkio: Introduce blkio controller cgroup interface

o This is basic implementation of blkio controller cgroup interface. This is
  the common interface visible to user space and should be used by different
  IO control policies as we implement those.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 58 insertions, 0 deletions

diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
new file mode 100644
index 000000000000..ba5703f69b42
--- /dev/null
+++ b/block/blk-cgroup.h
@@ -0,0 +1,58 @@
+#ifndef _BLK_CGROUP_H
+#define _BLK_CGROUP_H
+/*
+ * 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/cgroup.h>
+
+struct blkio_cgroup {
+        struct cgroup_subsys_state css;
+        unsigned int weight;
+        spinlock_t lock;
+        struct hlist_head blkg_list;
+};
+
+struct blkio_group {
+        /* An rcu protected unique identifier for the group */
+        void *key;
+        struct hlist_node blkcg_node;
+};
+
+#define BLKIO_WEIGHT_MIN        100
+#define BLKIO_WEIGHT_MAX        1000
+#define BLKIO_WEIGHT_DEFAULT    500
+
+#ifdef CONFIG_BLK_CGROUP
+extern struct blkio_cgroup blkio_root_cgroup;
+extern struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup);
+extern void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
+                                struct blkio_group *blkg, void *key);
+extern int blkiocg_del_blkio_group(struct blkio_group *blkg);
+extern struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg,
+                                                void *key);
+#else
+static inline struct blkio_cgroup *
+cgroup_to_blkio_cgroup(struct cgroup *cgroup) { return NULL; }
+
+static inline void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
+                        struct blkio_group *blkg, void *key)
+{
+}
+
+static inline int
+blkiocg_del_blkio_group(struct blkio_group *blkg) { return 0; }
+
+static inline struct blkio_group *
+blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) { return NULL; }
+#endif
+#endif /* _BLK_CGROUP_H */