Commit | Line | Data |
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31e4c28d VG |
1 | /* |
2 | * Common Block IO controller cgroup interface | |
3 | * | |
4 | * Based on ideas and code from CFQ, CFS and BFQ: | |
5 | * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> | |
6 | * | |
7 | * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it> | |
8 | * Paolo Valente <paolo.valente@unimore.it> | |
9 | * | |
10 | * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com> | |
11 | * Nauman Rafique <nauman@google.com> | |
12 | */ | |
13 | #include <linux/ioprio.h> | |
14 | #include "blk-cgroup.h" | |
15 | ||
b1c35769 VG |
16 | extern void cfq_unlink_blkio_group(void *, struct blkio_group *); |
17 | ||
31e4c28d VG |
18 | struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT }; |
19 | ||
20 | struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup) | |
21 | { | |
22 | return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id), | |
23 | struct blkio_cgroup, css); | |
24 | } | |
25 | ||
26 | void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg, | |
27 | struct blkio_group *blkg, void *key) | |
28 | { | |
29 | unsigned long flags; | |
30 | ||
31 | spin_lock_irqsave(&blkcg->lock, flags); | |
32 | rcu_assign_pointer(blkg->key, key); | |
b1c35769 | 33 | blkg->blkcg_id = css_id(&blkcg->css); |
31e4c28d VG |
34 | hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); |
35 | spin_unlock_irqrestore(&blkcg->lock, flags); | |
36 | } | |
37 | ||
b1c35769 VG |
38 | static void __blkiocg_del_blkio_group(struct blkio_group *blkg) |
39 | { | |
40 | hlist_del_init_rcu(&blkg->blkcg_node); | |
41 | blkg->blkcg_id = 0; | |
42 | } | |
43 | ||
44 | /* | |
45 | * returns 0 if blkio_group was still on cgroup list. Otherwise returns 1 | |
46 | * indicating that blk_group was unhashed by the time we got to it. | |
47 | */ | |
31e4c28d VG |
48 | int blkiocg_del_blkio_group(struct blkio_group *blkg) |
49 | { | |
b1c35769 VG |
50 | struct blkio_cgroup *blkcg; |
51 | unsigned long flags; | |
52 | struct cgroup_subsys_state *css; | |
53 | int ret = 1; | |
54 | ||
55 | rcu_read_lock(); | |
56 | css = css_lookup(&blkio_subsys, blkg->blkcg_id); | |
57 | if (!css) | |
58 | goto out; | |
59 | ||
60 | blkcg = container_of(css, struct blkio_cgroup, css); | |
61 | spin_lock_irqsave(&blkcg->lock, flags); | |
62 | if (!hlist_unhashed(&blkg->blkcg_node)) { | |
63 | __blkiocg_del_blkio_group(blkg); | |
64 | ret = 0; | |
65 | } | |
66 | spin_unlock_irqrestore(&blkcg->lock, flags); | |
67 | out: | |
68 | rcu_read_unlock(); | |
69 | return ret; | |
31e4c28d VG |
70 | } |
71 | ||
72 | /* called under rcu_read_lock(). */ | |
73 | struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) | |
74 | { | |
75 | struct blkio_group *blkg; | |
76 | struct hlist_node *n; | |
77 | void *__key; | |
78 | ||
79 | hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) { | |
80 | __key = blkg->key; | |
81 | if (__key == key) | |
82 | return blkg; | |
83 | } | |
84 | ||
85 | return NULL; | |
86 | } | |
87 | ||
88 | #define SHOW_FUNCTION(__VAR) \ | |
89 | static u64 blkiocg_##__VAR##_read(struct cgroup *cgroup, \ | |
90 | struct cftype *cftype) \ | |
91 | { \ | |
92 | struct blkio_cgroup *blkcg; \ | |
93 | \ | |
94 | blkcg = cgroup_to_blkio_cgroup(cgroup); \ | |
95 | return (u64)blkcg->__VAR; \ | |
96 | } | |
97 | ||
98 | SHOW_FUNCTION(weight); | |
99 | #undef SHOW_FUNCTION | |
100 | ||
101 | static int | |
102 | blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val) | |
103 | { | |
104 | struct blkio_cgroup *blkcg; | |
105 | ||
106 | if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX) | |
107 | return -EINVAL; | |
108 | ||
109 | blkcg = cgroup_to_blkio_cgroup(cgroup); | |
110 | blkcg->weight = (unsigned int)val; | |
111 | return 0; | |
112 | } | |
113 | ||
114 | struct cftype blkio_files[] = { | |
115 | { | |
116 | .name = "weight", | |
117 | .read_u64 = blkiocg_weight_read, | |
118 | .write_u64 = blkiocg_weight_write, | |
119 | }, | |
120 | }; | |
121 | ||
122 | static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup) | |
123 | { | |
124 | return cgroup_add_files(cgroup, subsys, blkio_files, | |
125 | ARRAY_SIZE(blkio_files)); | |
126 | } | |
127 | ||
128 | static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup) | |
129 | { | |
130 | struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup); | |
b1c35769 VG |
131 | unsigned long flags; |
132 | struct blkio_group *blkg; | |
133 | void *key; | |
134 | ||
135 | rcu_read_lock(); | |
136 | remove_entry: | |
137 | spin_lock_irqsave(&blkcg->lock, flags); | |
138 | ||
139 | if (hlist_empty(&blkcg->blkg_list)) { | |
140 | spin_unlock_irqrestore(&blkcg->lock, flags); | |
141 | goto done; | |
142 | } | |
143 | ||
144 | blkg = hlist_entry(blkcg->blkg_list.first, struct blkio_group, | |
145 | blkcg_node); | |
146 | key = rcu_dereference(blkg->key); | |
147 | __blkiocg_del_blkio_group(blkg); | |
31e4c28d | 148 | |
b1c35769 VG |
149 | spin_unlock_irqrestore(&blkcg->lock, flags); |
150 | ||
151 | /* | |
152 | * This blkio_group is being unlinked as associated cgroup is going | |
153 | * away. Let all the IO controlling policies know about this event. | |
154 | * | |
155 | * Currently this is static call to one io controlling policy. Once | |
156 | * we have more policies in place, we need some dynamic registration | |
157 | * of callback function. | |
158 | */ | |
159 | cfq_unlink_blkio_group(key, blkg); | |
160 | goto remove_entry; | |
161 | done: | |
31e4c28d | 162 | free_css_id(&blkio_subsys, &blkcg->css); |
b1c35769 | 163 | rcu_read_unlock(); |
31e4c28d VG |
164 | kfree(blkcg); |
165 | } | |
166 | ||
167 | static struct cgroup_subsys_state * | |
168 | blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup) | |
169 | { | |
170 | struct blkio_cgroup *blkcg, *parent_blkcg; | |
171 | ||
172 | if (!cgroup->parent) { | |
173 | blkcg = &blkio_root_cgroup; | |
174 | goto done; | |
175 | } | |
176 | ||
177 | /* Currently we do not support hierarchy deeper than two level (0,1) */ | |
178 | parent_blkcg = cgroup_to_blkio_cgroup(cgroup->parent); | |
179 | if (css_depth(&parent_blkcg->css) > 0) | |
180 | return ERR_PTR(-EINVAL); | |
181 | ||
182 | blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); | |
183 | if (!blkcg) | |
184 | return ERR_PTR(-ENOMEM); | |
185 | ||
186 | blkcg->weight = BLKIO_WEIGHT_DEFAULT; | |
187 | done: | |
188 | spin_lock_init(&blkcg->lock); | |
189 | INIT_HLIST_HEAD(&blkcg->blkg_list); | |
190 | ||
191 | return &blkcg->css; | |
192 | } | |
193 | ||
194 | /* | |
195 | * We cannot support shared io contexts, as we have no mean to support | |
196 | * two tasks with the same ioc in two different groups without major rework | |
197 | * of the main cic data structures. For now we allow a task to change | |
198 | * its cgroup only if it's the only owner of its ioc. | |
199 | */ | |
200 | static int blkiocg_can_attach(struct cgroup_subsys *subsys, | |
201 | struct cgroup *cgroup, struct task_struct *tsk, | |
202 | bool threadgroup) | |
203 | { | |
204 | struct io_context *ioc; | |
205 | int ret = 0; | |
206 | ||
207 | /* task_lock() is needed to avoid races with exit_io_context() */ | |
208 | task_lock(tsk); | |
209 | ioc = tsk->io_context; | |
210 | if (ioc && atomic_read(&ioc->nr_tasks) > 1) | |
211 | ret = -EINVAL; | |
212 | task_unlock(tsk); | |
213 | ||
214 | return ret; | |
215 | } | |
216 | ||
217 | static void blkiocg_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup, | |
218 | struct cgroup *prev, struct task_struct *tsk, | |
219 | bool threadgroup) | |
220 | { | |
221 | struct io_context *ioc; | |
222 | ||
223 | task_lock(tsk); | |
224 | ioc = tsk->io_context; | |
225 | if (ioc) | |
226 | ioc->cgroup_changed = 1; | |
227 | task_unlock(tsk); | |
228 | } | |
229 | ||
230 | struct cgroup_subsys blkio_subsys = { | |
231 | .name = "blkio", | |
232 | .create = blkiocg_create, | |
233 | .can_attach = blkiocg_can_attach, | |
234 | .attach = blkiocg_attach, | |
235 | .destroy = blkiocg_destroy, | |
236 | .populate = blkiocg_populate, | |
237 | .subsys_id = blkio_subsys_id, | |
238 | .use_id = 1, | |
239 | }; |