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 <linux/seq_file.h>
15 #include <linux/kdev_t.h>
16 #include "blk-cgroup.h"
17 #include "cfq-iosched.h"
19 struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
21 struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
23 return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
24 struct blkio_cgroup, css);
27 void blkiocg_update_blkio_group_stats(struct blkio_group *blkg,
28 unsigned long time, unsigned long sectors)
31 blkg->sectors += sectors;
34 void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
35 struct blkio_group *blkg, void *key, dev_t dev)
39 spin_lock_irqsave(&blkcg->lock, flags);
40 rcu_assign_pointer(blkg->key, key);
41 blkg->blkcg_id = css_id(&blkcg->css);
42 hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
43 spin_unlock_irqrestore(&blkcg->lock, flags);
44 #ifdef CONFIG_DEBUG_BLK_CGROUP
45 /* Need to take css reference ? */
46 cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
51 static void __blkiocg_del_blkio_group(struct blkio_group *blkg)
53 hlist_del_init_rcu(&blkg->blkcg_node);
58 * returns 0 if blkio_group was still on cgroup list. Otherwise returns 1
59 * indicating that blk_group was unhashed by the time we got to it.
61 int blkiocg_del_blkio_group(struct blkio_group *blkg)
63 struct blkio_cgroup *blkcg;
65 struct cgroup_subsys_state *css;
69 css = css_lookup(&blkio_subsys, blkg->blkcg_id);
73 blkcg = container_of(css, struct blkio_cgroup, css);
74 spin_lock_irqsave(&blkcg->lock, flags);
75 if (!hlist_unhashed(&blkg->blkcg_node)) {
76 __blkiocg_del_blkio_group(blkg);
79 spin_unlock_irqrestore(&blkcg->lock, flags);
85 /* called under rcu_read_lock(). */
86 struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key)
88 struct blkio_group *blkg;
92 hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
101 #define SHOW_FUNCTION(__VAR) \
102 static u64 blkiocg_##__VAR##_read(struct cgroup *cgroup, \
103 struct cftype *cftype) \
105 struct blkio_cgroup *blkcg; \
107 blkcg = cgroup_to_blkio_cgroup(cgroup); \
108 return (u64)blkcg->__VAR; \
111 SHOW_FUNCTION(weight);
115 blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val)
117 struct blkio_cgroup *blkcg;
118 struct blkio_group *blkg;
119 struct hlist_node *n;
121 if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
124 blkcg = cgroup_to_blkio_cgroup(cgroup);
125 spin_lock_irq(&blkcg->lock);
126 blkcg->weight = (unsigned int)val;
127 hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node)
128 cfq_update_blkio_group_weight(blkg, blkcg->weight);
129 spin_unlock_irq(&blkcg->lock);
133 #define SHOW_FUNCTION_PER_GROUP(__VAR) \
134 static int blkiocg_##__VAR##_read(struct cgroup *cgroup, \
135 struct cftype *cftype, struct seq_file *m) \
137 struct blkio_cgroup *blkcg; \
138 struct blkio_group *blkg; \
139 struct hlist_node *n; \
141 if (!cgroup_lock_live_group(cgroup)) \
144 blkcg = cgroup_to_blkio_cgroup(cgroup); \
146 hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {\
148 seq_printf(m, "%u:%u %lu\n", MAJOR(blkg->dev), \
149 MINOR(blkg->dev), blkg->__VAR); \
156 SHOW_FUNCTION_PER_GROUP(time);
157 SHOW_FUNCTION_PER_GROUP(sectors);
158 #ifdef CONFIG_DEBUG_BLK_CGROUP
159 SHOW_FUNCTION_PER_GROUP(dequeue);
161 #undef SHOW_FUNCTION_PER_GROUP
163 #ifdef CONFIG_DEBUG_BLK_CGROUP
164 void blkiocg_update_blkio_group_dequeue_stats(struct blkio_group *blkg,
165 unsigned long dequeue)
167 blkg->dequeue += dequeue;
171 struct cftype blkio_files[] = {
174 .read_u64 = blkiocg_weight_read,
175 .write_u64 = blkiocg_weight_write,
179 .read_seq_string = blkiocg_time_read,
183 .read_seq_string = blkiocg_sectors_read,
185 #ifdef CONFIG_DEBUG_BLK_CGROUP
188 .read_seq_string = blkiocg_dequeue_read,
193 static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
195 return cgroup_add_files(cgroup, subsys, blkio_files,
196 ARRAY_SIZE(blkio_files));
199 static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
201 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
203 struct blkio_group *blkg;
208 spin_lock_irqsave(&blkcg->lock, flags);
210 if (hlist_empty(&blkcg->blkg_list)) {
211 spin_unlock_irqrestore(&blkcg->lock, flags);
215 blkg = hlist_entry(blkcg->blkg_list.first, struct blkio_group,
217 key = rcu_dereference(blkg->key);
218 __blkiocg_del_blkio_group(blkg);
220 spin_unlock_irqrestore(&blkcg->lock, flags);
223 * This blkio_group is being unlinked as associated cgroup is going
224 * away. Let all the IO controlling policies know about this event.
226 * Currently this is static call to one io controlling policy. Once
227 * we have more policies in place, we need some dynamic registration
228 * of callback function.
230 cfq_unlink_blkio_group(key, blkg);
233 free_css_id(&blkio_subsys, &blkcg->css);
238 static struct cgroup_subsys_state *
239 blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
241 struct blkio_cgroup *blkcg, *parent_blkcg;
243 if (!cgroup->parent) {
244 blkcg = &blkio_root_cgroup;
248 /* Currently we do not support hierarchy deeper than two level (0,1) */
249 parent_blkcg = cgroup_to_blkio_cgroup(cgroup->parent);
250 if (css_depth(&parent_blkcg->css) > 0)
251 return ERR_PTR(-EINVAL);
253 blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
255 return ERR_PTR(-ENOMEM);
257 blkcg->weight = BLKIO_WEIGHT_DEFAULT;
259 spin_lock_init(&blkcg->lock);
260 INIT_HLIST_HEAD(&blkcg->blkg_list);
266 * We cannot support shared io contexts, as we have no mean to support
267 * two tasks with the same ioc in two different groups without major rework
268 * of the main cic data structures. For now we allow a task to change
269 * its cgroup only if it's the only owner of its ioc.
271 static int blkiocg_can_attach(struct cgroup_subsys *subsys,
272 struct cgroup *cgroup, struct task_struct *tsk,
275 struct io_context *ioc;
278 /* task_lock() is needed to avoid races with exit_io_context() */
280 ioc = tsk->io_context;
281 if (ioc && atomic_read(&ioc->nr_tasks) > 1)
288 static void blkiocg_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup,
289 struct cgroup *prev, struct task_struct *tsk,
292 struct io_context *ioc;
295 ioc = tsk->io_context;
297 ioc->cgroup_changed = 1;
301 struct cgroup_subsys blkio_subsys = {
303 .create = blkiocg_create,
304 .can_attach = blkiocg_can_attach,
305 .attach = blkiocg_attach,
306 .destroy = blkiocg_destroy,
307 .populate = blkiocg_populate,
308 .subsys_id = blkio_subsys_id,