1 files changed, 177 insertions, 0 deletions

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
new file mode 100644
index 000000000000..4f6afd76ec59
--- /dev/null
+++ b/block/blk-cgroup.c
@@ -0,0 +1,177 @@
+/*
+ * 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 "blk-cgroup.h"
+
+struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
+
+struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
+{
+        return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
+                            struct blkio_cgroup, css);
+}
+
+void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
+                                struct blkio_group *blkg, void *key)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&blkcg->lock, flags);
+        rcu_assign_pointer(blkg->key, key);
+        hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
+        spin_unlock_irqrestore(&blkcg->lock, flags);
+}
+
+int blkiocg_del_blkio_group(struct blkio_group *blkg)
+{
+        /* Implemented later */
+        return 0;
+}
+
+/* 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;
+}
+
+#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;
+
+        if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
+                return -EINVAL;
+
+        blkcg = cgroup_to_blkio_cgroup(cgroup);
+        blkcg->weight = (unsigned int)val;
+        return 0;
+}
+
+struct cftype blkio_files[] = {
+        {
+                .name = "weight",
+                .read_u64 = blkiocg_weight_read,
+                .write_u64 = blkiocg_weight_write,
+        },
+};
+
+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);
+
+        free_css_id(&blkio_subsys, &blkcg->css);
+        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,
+};