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 extern void cfq_unlink_blkio_group(void *, struct blkio_group
*);
18 struct blkio_cgroup blkio_root_cgroup
= { .weight
= 2*BLKIO_WEIGHT_DEFAULT
};
20 struct blkio_cgroup
*cgroup_to_blkio_cgroup(struct cgroup
*cgroup
)
22 return container_of(cgroup_subsys_state(cgroup
, blkio_subsys_id
),
23 struct blkio_cgroup
, css
);
26 void blkiocg_add_blkio_group(struct blkio_cgroup
*blkcg
,
27 struct blkio_group
*blkg
, void *key
)
31 spin_lock_irqsave(&blkcg
->lock
, flags
);
32 rcu_assign_pointer(blkg
->key
, key
);
33 blkg
->blkcg_id
= css_id(&blkcg
->css
);
34 hlist_add_head_rcu(&blkg
->blkcg_node
, &blkcg
->blkg_list
);
35 spin_unlock_irqrestore(&blkcg
->lock
, flags
);
36 #ifdef CONFIG_DEBUG_BLK_CGROUP
37 /* Need to take css reference ? */
38 cgroup_path(blkcg
->css
.cgroup
, blkg
->path
, sizeof(blkg
->path
));
42 static void __blkiocg_del_blkio_group(struct blkio_group
*blkg
)
44 hlist_del_init_rcu(&blkg
->blkcg_node
);
49 * returns 0 if blkio_group was still on cgroup list. Otherwise returns 1
50 * indicating that blk_group was unhashed by the time we got to it.
52 int blkiocg_del_blkio_group(struct blkio_group
*blkg
)
54 struct blkio_cgroup
*blkcg
;
56 struct cgroup_subsys_state
*css
;
60 css
= css_lookup(&blkio_subsys
, blkg
->blkcg_id
);
64 blkcg
= container_of(css
, struct blkio_cgroup
, css
);
65 spin_lock_irqsave(&blkcg
->lock
, flags
);
66 if (!hlist_unhashed(&blkg
->blkcg_node
)) {
67 __blkiocg_del_blkio_group(blkg
);
70 spin_unlock_irqrestore(&blkcg
->lock
, flags
);
76 /* called under rcu_read_lock(). */
77 struct blkio_group
*blkiocg_lookup_group(struct blkio_cgroup
*blkcg
, void *key
)
79 struct blkio_group
*blkg
;
83 hlist_for_each_entry_rcu(blkg
, n
, &blkcg
->blkg_list
, blkcg_node
) {
92 #define SHOW_FUNCTION(__VAR) \
93 static u64 blkiocg_##__VAR##_read(struct cgroup *cgroup, \
94 struct cftype *cftype) \
96 struct blkio_cgroup *blkcg; \
98 blkcg = cgroup_to_blkio_cgroup(cgroup); \
99 return (u64)blkcg->__VAR; \
102 SHOW_FUNCTION(weight
);
106 blkiocg_weight_write(struct cgroup
*cgroup
, struct cftype
*cftype
, u64 val
)
108 struct blkio_cgroup
*blkcg
;
110 if (val
< BLKIO_WEIGHT_MIN
|| val
> BLKIO_WEIGHT_MAX
)
113 blkcg
= cgroup_to_blkio_cgroup(cgroup
);
114 blkcg
->weight
= (unsigned int)val
;
118 struct cftype blkio_files
[] = {
121 .read_u64
= blkiocg_weight_read
,
122 .write_u64
= blkiocg_weight_write
,
126 static int blkiocg_populate(struct cgroup_subsys
*subsys
, struct cgroup
*cgroup
)
128 return cgroup_add_files(cgroup
, subsys
, blkio_files
,
129 ARRAY_SIZE(blkio_files
));
132 static void blkiocg_destroy(struct cgroup_subsys
*subsys
, struct cgroup
*cgroup
)
134 struct blkio_cgroup
*blkcg
= cgroup_to_blkio_cgroup(cgroup
);
136 struct blkio_group
*blkg
;
141 spin_lock_irqsave(&blkcg
->lock
, flags
);
143 if (hlist_empty(&blkcg
->blkg_list
)) {
144 spin_unlock_irqrestore(&blkcg
->lock
, flags
);
148 blkg
= hlist_entry(blkcg
->blkg_list
.first
, struct blkio_group
,
150 key
= rcu_dereference(blkg
->key
);
151 __blkiocg_del_blkio_group(blkg
);
153 spin_unlock_irqrestore(&blkcg
->lock
, flags
);
156 * This blkio_group is being unlinked as associated cgroup is going
157 * away. Let all the IO controlling policies know about this event.
159 * Currently this is static call to one io controlling policy. Once
160 * we have more policies in place, we need some dynamic registration
161 * of callback function.
163 cfq_unlink_blkio_group(key
, blkg
);
166 free_css_id(&blkio_subsys
, &blkcg
->css
);
171 static struct cgroup_subsys_state
*
172 blkiocg_create(struct cgroup_subsys
*subsys
, struct cgroup
*cgroup
)
174 struct blkio_cgroup
*blkcg
, *parent_blkcg
;
176 if (!cgroup
->parent
) {
177 blkcg
= &blkio_root_cgroup
;
181 /* Currently we do not support hierarchy deeper than two level (0,1) */
182 parent_blkcg
= cgroup_to_blkio_cgroup(cgroup
->parent
);
183 if (css_depth(&parent_blkcg
->css
) > 0)
184 return ERR_PTR(-EINVAL
);
186 blkcg
= kzalloc(sizeof(*blkcg
), GFP_KERNEL
);
188 return ERR_PTR(-ENOMEM
);
190 blkcg
->weight
= BLKIO_WEIGHT_DEFAULT
;
192 spin_lock_init(&blkcg
->lock
);
193 INIT_HLIST_HEAD(&blkcg
->blkg_list
);
199 * We cannot support shared io contexts, as we have no mean to support
200 * two tasks with the same ioc in two different groups without major rework
201 * of the main cic data structures. For now we allow a task to change
202 * its cgroup only if it's the only owner of its ioc.
204 static int blkiocg_can_attach(struct cgroup_subsys
*subsys
,
205 struct cgroup
*cgroup
, struct task_struct
*tsk
,
208 struct io_context
*ioc
;
211 /* task_lock() is needed to avoid races with exit_io_context() */
213 ioc
= tsk
->io_context
;
214 if (ioc
&& atomic_read(&ioc
->nr_tasks
) > 1)
221 static void blkiocg_attach(struct cgroup_subsys
*subsys
, struct cgroup
*cgroup
,
222 struct cgroup
*prev
, struct task_struct
*tsk
,
225 struct io_context
*ioc
;
228 ioc
= tsk
->io_context
;
230 ioc
->cgroup_changed
= 1;
234 struct cgroup_subsys blkio_subsys
= {
236 .create
= blkiocg_create
,
237 .can_attach
= blkiocg_can_attach
,
238 .attach
= blkiocg_attach
,
239 .destroy
= blkiocg_destroy
,
240 .populate
= blkiocg_populate
,
241 .subsys_id
= blkio_subsys_id
,