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"
18 extern void cfq_unlink_blkio_group(void *, struct blkio_group
*);
20 struct blkio_cgroup blkio_root_cgroup
= { .weight
= 2*BLKIO_WEIGHT_DEFAULT
};
22 struct blkio_cgroup
*cgroup_to_blkio_cgroup(struct cgroup
*cgroup
)
24 return container_of(cgroup_subsys_state(cgroup
, blkio_subsys_id
),
25 struct blkio_cgroup
, css
);
28 void blkiocg_update_blkio_group_stats(struct blkio_group
*blkg
,
29 unsigned long time
, unsigned long sectors
)
32 blkg
->sectors
+= sectors
;
35 void blkiocg_add_blkio_group(struct blkio_cgroup
*blkcg
,
36 struct blkio_group
*blkg
, void *key
, dev_t dev
)
40 spin_lock_irqsave(&blkcg
->lock
, flags
);
41 rcu_assign_pointer(blkg
->key
, key
);
42 blkg
->blkcg_id
= css_id(&blkcg
->css
);
43 hlist_add_head_rcu(&blkg
->blkcg_node
, &blkcg
->blkg_list
);
44 spin_unlock_irqrestore(&blkcg
->lock
, flags
);
45 #ifdef CONFIG_DEBUG_BLK_CGROUP
46 /* Need to take css reference ? */
47 cgroup_path(blkcg
->css
.cgroup
, blkg
->path
, sizeof(blkg
->path
));
52 static void __blkiocg_del_blkio_group(struct blkio_group
*blkg
)
54 hlist_del_init_rcu(&blkg
->blkcg_node
);
59 * returns 0 if blkio_group was still on cgroup list. Otherwise returns 1
60 * indicating that blk_group was unhashed by the time we got to it.
62 int blkiocg_del_blkio_group(struct blkio_group
*blkg
)
64 struct blkio_cgroup
*blkcg
;
66 struct cgroup_subsys_state
*css
;
70 css
= css_lookup(&blkio_subsys
, blkg
->blkcg_id
);
74 blkcg
= container_of(css
, struct blkio_cgroup
, css
);
75 spin_lock_irqsave(&blkcg
->lock
, flags
);
76 if (!hlist_unhashed(&blkg
->blkcg_node
)) {
77 __blkiocg_del_blkio_group(blkg
);
80 spin_unlock_irqrestore(&blkcg
->lock
, flags
);
86 /* called under rcu_read_lock(). */
87 struct blkio_group
*blkiocg_lookup_group(struct blkio_cgroup
*blkcg
, void *key
)
89 struct blkio_group
*blkg
;
93 hlist_for_each_entry_rcu(blkg
, n
, &blkcg
->blkg_list
, blkcg_node
) {
102 #define SHOW_FUNCTION(__VAR) \
103 static u64 blkiocg_##__VAR##_read(struct cgroup *cgroup, \
104 struct cftype *cftype) \
106 struct blkio_cgroup *blkcg; \
108 blkcg = cgroup_to_blkio_cgroup(cgroup); \
109 return (u64)blkcg->__VAR; \
112 SHOW_FUNCTION(weight
);
116 blkiocg_weight_write(struct cgroup
*cgroup
, struct cftype
*cftype
, u64 val
)
118 struct blkio_cgroup
*blkcg
;
120 if (val
< BLKIO_WEIGHT_MIN
|| val
> BLKIO_WEIGHT_MAX
)
123 blkcg
= cgroup_to_blkio_cgroup(cgroup
);
124 blkcg
->weight
= (unsigned int)val
;
128 #define SHOW_FUNCTION_PER_GROUP(__VAR) \
129 static int blkiocg_##__VAR##_read(struct cgroup *cgroup, \
130 struct cftype *cftype, struct seq_file *m) \
132 struct blkio_cgroup *blkcg; \
133 struct blkio_group *blkg; \
134 struct hlist_node *n; \
136 if (!cgroup_lock_live_group(cgroup)) \
139 blkcg = cgroup_to_blkio_cgroup(cgroup); \
141 hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {\
143 seq_printf(m, "%u:%u %lu\n", MAJOR(blkg->dev), \
144 MINOR(blkg->dev), blkg->__VAR); \
151 SHOW_FUNCTION_PER_GROUP(time
);
152 SHOW_FUNCTION_PER_GROUP(sectors
);
153 #ifdef CONFIG_DEBUG_BLK_CGROUP
154 SHOW_FUNCTION_PER_GROUP(dequeue
);
156 #undef SHOW_FUNCTION_PER_GROUP
158 #ifdef CONFIG_DEBUG_BLK_CGROUP
159 void blkiocg_update_blkio_group_dequeue_stats(struct blkio_group
*blkg
,
160 unsigned long dequeue
)
162 blkg
->dequeue
+= dequeue
;
166 struct cftype blkio_files
[] = {
169 .read_u64
= blkiocg_weight_read
,
170 .write_u64
= blkiocg_weight_write
,
174 .read_seq_string
= blkiocg_time_read
,
178 .read_seq_string
= blkiocg_sectors_read
,
180 #ifdef CONFIG_DEBUG_BLK_CGROUP
183 .read_seq_string
= blkiocg_dequeue_read
,
188 static int blkiocg_populate(struct cgroup_subsys
*subsys
, struct cgroup
*cgroup
)
190 return cgroup_add_files(cgroup
, subsys
, blkio_files
,
191 ARRAY_SIZE(blkio_files
));
194 static void blkiocg_destroy(struct cgroup_subsys
*subsys
, struct cgroup
*cgroup
)
196 struct blkio_cgroup
*blkcg
= cgroup_to_blkio_cgroup(cgroup
);
198 struct blkio_group
*blkg
;
203 spin_lock_irqsave(&blkcg
->lock
, flags
);
205 if (hlist_empty(&blkcg
->blkg_list
)) {
206 spin_unlock_irqrestore(&blkcg
->lock
, flags
);
210 blkg
= hlist_entry(blkcg
->blkg_list
.first
, struct blkio_group
,
212 key
= rcu_dereference(blkg
->key
);
213 __blkiocg_del_blkio_group(blkg
);
215 spin_unlock_irqrestore(&blkcg
->lock
, flags
);
218 * This blkio_group is being unlinked as associated cgroup is going
219 * away. Let all the IO controlling policies know about this event.
221 * Currently this is static call to one io controlling policy. Once
222 * we have more policies in place, we need some dynamic registration
223 * of callback function.
225 cfq_unlink_blkio_group(key
, blkg
);
228 free_css_id(&blkio_subsys
, &blkcg
->css
);
233 static struct cgroup_subsys_state
*
234 blkiocg_create(struct cgroup_subsys
*subsys
, struct cgroup
*cgroup
)
236 struct blkio_cgroup
*blkcg
, *parent_blkcg
;
238 if (!cgroup
->parent
) {
239 blkcg
= &blkio_root_cgroup
;
243 /* Currently we do not support hierarchy deeper than two level (0,1) */
244 parent_blkcg
= cgroup_to_blkio_cgroup(cgroup
->parent
);
245 if (css_depth(&parent_blkcg
->css
) > 0)
246 return ERR_PTR(-EINVAL
);
248 blkcg
= kzalloc(sizeof(*blkcg
), GFP_KERNEL
);
250 return ERR_PTR(-ENOMEM
);
252 blkcg
->weight
= BLKIO_WEIGHT_DEFAULT
;
254 spin_lock_init(&blkcg
->lock
);
255 INIT_HLIST_HEAD(&blkcg
->blkg_list
);
261 * We cannot support shared io contexts, as we have no mean to support
262 * two tasks with the same ioc in two different groups without major rework
263 * of the main cic data structures. For now we allow a task to change
264 * its cgroup only if it's the only owner of its ioc.
266 static int blkiocg_can_attach(struct cgroup_subsys
*subsys
,
267 struct cgroup
*cgroup
, struct task_struct
*tsk
,
270 struct io_context
*ioc
;
273 /* task_lock() is needed to avoid races with exit_io_context() */
275 ioc
= tsk
->io_context
;
276 if (ioc
&& atomic_read(&ioc
->nr_tasks
) > 1)
283 static void blkiocg_attach(struct cgroup_subsys
*subsys
, struct cgroup
*cgroup
,
284 struct cgroup
*prev
, struct task_struct
*tsk
,
287 struct io_context
*ioc
;
290 ioc
= tsk
->io_context
;
292 ioc
->cgroup_changed
= 1;
296 struct cgroup_subsys blkio_subsys
= {
298 .create
= blkiocg_create
,
299 .can_attach
= blkiocg_can_attach
,
300 .attach
= blkiocg_attach
,
301 .destroy
= blkiocg_destroy
,
302 .populate
= blkiocg_populate
,
303 .subsys_id
= blkio_subsys_id
,