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
,