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 | ||
16 | struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT }; | |
17 | ||
18 | struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup) | |
19 | { | |
20 | return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id), | |
21 | struct blkio_cgroup, css); | |
22 | } | |
23 | ||
24 | void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg, | |
25 | struct blkio_group *blkg, void *key) | |
26 | { | |
27 | unsigned long flags; | |
28 | ||
29 | spin_lock_irqsave(&blkcg->lock, flags); | |
30 | rcu_assign_pointer(blkg->key, key); | |
31 | hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); | |
32 | spin_unlock_irqrestore(&blkcg->lock, flags); | |
33 | } | |
34 | ||
35 | int blkiocg_del_blkio_group(struct blkio_group *blkg) | |
36 | { | |
37 | /* Implemented later */ | |
38 | return 0; | |
39 | } | |
40 | ||
41 | /* called under rcu_read_lock(). */ | |
42 | struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) | |
43 | { | |
44 | struct blkio_group *blkg; | |
45 | struct hlist_node *n; | |
46 | void *__key; | |
47 | ||
48 | hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) { | |
49 | __key = blkg->key; | |
50 | if (__key == key) | |
51 | return blkg; | |
52 | } | |
53 | ||
54 | return NULL; | |
55 | } | |
56 | ||
57 | #define SHOW_FUNCTION(__VAR) \ | |
58 | static u64 blkiocg_##__VAR##_read(struct cgroup *cgroup, \ | |
59 | struct cftype *cftype) \ | |
60 | { \ | |
61 | struct blkio_cgroup *blkcg; \ | |
62 | \ | |
63 | blkcg = cgroup_to_blkio_cgroup(cgroup); \ | |
64 | return (u64)blkcg->__VAR; \ | |
65 | } | |
66 | ||
67 | SHOW_FUNCTION(weight); | |
68 | #undef SHOW_FUNCTION | |
69 | ||
70 | static int | |
71 | blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val) | |
72 | { | |
73 | struct blkio_cgroup *blkcg; | |
74 | ||
75 | if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX) | |
76 | return -EINVAL; | |
77 | ||
78 | blkcg = cgroup_to_blkio_cgroup(cgroup); | |
79 | blkcg->weight = (unsigned int)val; | |
80 | return 0; | |
81 | } | |
82 | ||
83 | struct cftype blkio_files[] = { | |
84 | { | |
85 | .name = "weight", | |
86 | .read_u64 = blkiocg_weight_read, | |
87 | .write_u64 = blkiocg_weight_write, | |
88 | }, | |
89 | }; | |
90 | ||
91 | static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup) | |
92 | { | |
93 | return cgroup_add_files(cgroup, subsys, blkio_files, | |
94 | ARRAY_SIZE(blkio_files)); | |
95 | } | |
96 | ||
97 | static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup) | |
98 | { | |
99 | struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup); | |
100 | ||
101 | free_css_id(&blkio_subsys, &blkcg->css); | |
102 | kfree(blkcg); | |
103 | } | |
104 | ||
105 | static struct cgroup_subsys_state * | |
106 | blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup) | |
107 | { | |
108 | struct blkio_cgroup *blkcg, *parent_blkcg; | |
109 | ||
110 | if (!cgroup->parent) { | |
111 | blkcg = &blkio_root_cgroup; | |
112 | goto done; | |
113 | } | |
114 | ||
115 | /* Currently we do not support hierarchy deeper than two level (0,1) */ | |
116 | parent_blkcg = cgroup_to_blkio_cgroup(cgroup->parent); | |
117 | if (css_depth(&parent_blkcg->css) > 0) | |
118 | return ERR_PTR(-EINVAL); | |
119 | ||
120 | blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); | |
121 | if (!blkcg) | |
122 | return ERR_PTR(-ENOMEM); | |
123 | ||
124 | blkcg->weight = BLKIO_WEIGHT_DEFAULT; | |
125 | done: | |
126 | spin_lock_init(&blkcg->lock); | |
127 | INIT_HLIST_HEAD(&blkcg->blkg_list); | |
128 | ||
129 | return &blkcg->css; | |
130 | } | |
131 | ||
132 | /* | |
133 | * We cannot support shared io contexts, as we have no mean to support | |
134 | * two tasks with the same ioc in two different groups without major rework | |
135 | * of the main cic data structures. For now we allow a task to change | |
136 | * its cgroup only if it's the only owner of its ioc. | |
137 | */ | |
138 | static int blkiocg_can_attach(struct cgroup_subsys *subsys, | |
139 | struct cgroup *cgroup, struct task_struct *tsk, | |
140 | bool threadgroup) | |
141 | { | |
142 | struct io_context *ioc; | |
143 | int ret = 0; | |
144 | ||
145 | /* task_lock() is needed to avoid races with exit_io_context() */ | |
146 | task_lock(tsk); | |
147 | ioc = tsk->io_context; | |
148 | if (ioc && atomic_read(&ioc->nr_tasks) > 1) | |
149 | ret = -EINVAL; | |
150 | task_unlock(tsk); | |
151 | ||
152 | return ret; | |
153 | } | |
154 | ||
155 | static void blkiocg_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup, | |
156 | struct cgroup *prev, struct task_struct *tsk, | |
157 | bool threadgroup) | |
158 | { | |
159 | struct io_context *ioc; | |
160 | ||
161 | task_lock(tsk); | |
162 | ioc = tsk->io_context; | |
163 | if (ioc) | |
164 | ioc->cgroup_changed = 1; | |
165 | task_unlock(tsk); | |
166 | } | |
167 | ||
168 | struct cgroup_subsys blkio_subsys = { | |
169 | .name = "blkio", | |
170 | .create = blkiocg_create, | |
171 | .can_attach = blkiocg_can_attach, | |
172 | .attach = blkiocg_attach, | |
173 | .destroy = blkiocg_destroy, | |
174 | .populate = blkiocg_populate, | |
175 | .subsys_id = blkio_subsys_id, | |
176 | .use_id = 1, | |
177 | }; |