2 * Common Block IO controller cgroup interface
4 * Based on ideas and code from CFQ, CFS and BFQ:
5 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
7 * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
8 * Paolo Valente <paolo.valente@unimore.it>
10 * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
11 * Nauman Rafique <nauman@google.com>
13 #include <linux/ioprio.h>
14 #include "blk-cgroup.h"
16 struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
18 struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
20 return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
21 struct blkio_cgroup, css);
24 void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
25 struct blkio_group *blkg, void *key)
29 spin_lock_irqsave(&blkcg->lock, flags);
30 rcu_assign_pointer(blkg->key, key);
31 hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
32 spin_unlock_irqrestore(&blkcg->lock, flags);
35 int blkiocg_del_blkio_group(struct blkio_group *blkg)
37 /* Implemented later */
41 /* called under rcu_read_lock(). */
42 struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key)
44 struct blkio_group *blkg;
48 hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
57 #define SHOW_FUNCTION(__VAR) \
58 static u64 blkiocg_##__VAR##_read(struct cgroup *cgroup, \
59 struct cftype *cftype) \
61 struct blkio_cgroup *blkcg; \
63 blkcg = cgroup_to_blkio_cgroup(cgroup); \
64 return (u64)blkcg->__VAR; \
67 SHOW_FUNCTION(weight);
71 blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val)
73 struct blkio_cgroup *blkcg;
75 if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
78 blkcg = cgroup_to_blkio_cgroup(cgroup);
79 blkcg->weight = (unsigned int)val;
83 struct cftype blkio_files[] = {
86 .read_u64 = blkiocg_weight_read,
87 .write_u64 = blkiocg_weight_write,
91 static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
93 return cgroup_add_files(cgroup, subsys, blkio_files,
94 ARRAY_SIZE(blkio_files));
97 static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
99 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
101 free_css_id(&blkio_subsys, &blkcg->css);
105 static struct cgroup_subsys_state *
106 blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
108 struct blkio_cgroup *blkcg, *parent_blkcg;
110 if (!cgroup->parent) {
111 blkcg = &blkio_root_cgroup;
115 /* Currently we do not support hierarchy deeper than two level (0,1) */
116 parent_blkcg = cgroup_to_blkio_cgroup(cgroup->parent);
117 if (css_depth(&parent_blkcg->css) > 0)
118 return ERR_PTR(-EINVAL);
120 blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
122 return ERR_PTR(-ENOMEM);
124 blkcg->weight = BLKIO_WEIGHT_DEFAULT;
126 spin_lock_init(&blkcg->lock);
127 INIT_HLIST_HEAD(&blkcg->blkg_list);
133 * We cannot support shared io contexts, as we have no mean to support
134 * two tasks with the same ioc in two different groups without major rework
135 * of the main cic data structures. For now we allow a task to change
136 * its cgroup only if it's the only owner of its ioc.
138 static int blkiocg_can_attach(struct cgroup_subsys *subsys,
139 struct cgroup *cgroup, struct task_struct *tsk,
142 struct io_context *ioc;
145 /* task_lock() is needed to avoid races with exit_io_context() */
147 ioc = tsk->io_context;
148 if (ioc && atomic_read(&ioc->nr_tasks) > 1)
155 static void blkiocg_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup,
156 struct cgroup *prev, struct task_struct *tsk,
159 struct io_context *ioc;
162 ioc = tsk->io_context;
164 ioc->cgroup_changed = 1;
168 struct cgroup_subsys blkio_subsys = {
170 .create = blkiocg_create,
171 .can_attach = blkiocg_can_attach,
172 .attach = blkiocg_attach,
173 .destroy = blkiocg_destroy,
174 .populate = blkiocg_populate,
175 .subsys_id = blkio_subsys_id,