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 <linux/seq_file.h> 15 #include <linux/kdev_t.h> 16 #include <linux/module.h> 17 #include <linux/err.h> 18 #include "blk-cgroup.h" 19 20 static DEFINE_SPINLOCK(blkio_list_lock); 21 static LIST_HEAD(blkio_list); 22 23 struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT }; 24 EXPORT_SYMBOL_GPL(blkio_root_cgroup); 25 26 bool blkiocg_css_tryget(struct blkio_cgroup *blkcg) 27 { 28 if (!css_tryget(&blkcg->css)) 29 return false; 30 return true; 31 } 32 EXPORT_SYMBOL_GPL(blkiocg_css_tryget); 33 34 void blkiocg_css_put(struct blkio_cgroup *blkcg) 35 { 36 css_put(&blkcg->css); 37 } 38 EXPORT_SYMBOL_GPL(blkiocg_css_put); 39 40 struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup) 41 { 42 return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id), 43 struct blkio_cgroup, css); 44 } 45 EXPORT_SYMBOL_GPL(cgroup_to_blkio_cgroup); 46 47 void blkiocg_update_blkio_group_stats(struct blkio_group *blkg, 48 unsigned long time, unsigned long sectors) 49 { 50 blkg->time += time; 51 blkg->sectors += sectors; 52 } 53 EXPORT_SYMBOL_GPL(blkiocg_update_blkio_group_stats); 54 55 void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg, 56 struct blkio_group *blkg, void *key, dev_t dev) 57 { 58 unsigned long flags; 59 60 spin_lock_irqsave(&blkcg->lock, flags); 61 rcu_assign_pointer(blkg->key, key); 62 blkg->blkcg_id = css_id(&blkcg->css); 63 hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); 64 spin_unlock_irqrestore(&blkcg->lock, flags); 65 #ifdef CONFIG_DEBUG_BLK_CGROUP 66 /* Need to take css reference ? */ 67 cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path)); 68 #endif 69 blkg->dev = dev; 70 } 71 EXPORT_SYMBOL_GPL(blkiocg_add_blkio_group); 72 73 static void __blkiocg_del_blkio_group(struct blkio_group *blkg) 74 { 75 hlist_del_init_rcu(&blkg->blkcg_node); 76 blkg->blkcg_id = 0; 77 } 78 79 /* 80 * returns 0 if blkio_group was still on cgroup list. Otherwise returns 1 81 * indicating that blk_group was unhashed by the time we got to it. 82 */ 83 int blkiocg_del_blkio_group(struct blkio_group *blkg) 84 { 85 struct blkio_cgroup *blkcg; 86 unsigned long flags; 87 struct cgroup_subsys_state *css; 88 int ret = 1; 89 90 rcu_read_lock(); 91 css = css_lookup(&blkio_subsys, blkg->blkcg_id); 92 if (!css) 93 goto out; 94 95 blkcg = container_of(css, struct blkio_cgroup, css); 96 spin_lock_irqsave(&blkcg->lock, flags); 97 if (!hlist_unhashed(&blkg->blkcg_node)) { 98 __blkiocg_del_blkio_group(blkg); 99 ret = 0; 100 } 101 spin_unlock_irqrestore(&blkcg->lock, flags); 102 out: 103 rcu_read_unlock(); 104 return ret; 105 } 106 EXPORT_SYMBOL_GPL(blkiocg_del_blkio_group); 107 108 /* called under rcu_read_lock(). */ 109 struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) 110 { 111 struct blkio_group *blkg; 112 struct hlist_node *n; 113 void *__key; 114 115 hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) { 116 __key = blkg->key; 117 if (__key == key) 118 return blkg; 119 } 120 121 return NULL; 122 } 123 EXPORT_SYMBOL_GPL(blkiocg_lookup_group); 124 125 #define SHOW_FUNCTION(__VAR) \ 126 static u64 blkiocg_##__VAR##_read(struct cgroup *cgroup, \ 127 struct cftype *cftype) \ 128 { \ 129 struct blkio_cgroup *blkcg; \ 130 \ 131 blkcg = cgroup_to_blkio_cgroup(cgroup); \ 132 return (u64)blkcg->__VAR; \ 133 } 134 135 SHOW_FUNCTION(weight); 136 #undef SHOW_FUNCTION 137 138 static int 139 blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val) 140 { 141 struct blkio_cgroup *blkcg; 142 struct blkio_group *blkg; 143 struct hlist_node *n; 144 struct blkio_policy_type *blkiop; 145 146 if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX) 147 return -EINVAL; 148 149 blkcg = cgroup_to_blkio_cgroup(cgroup); 150 spin_lock(&blkio_list_lock); 151 spin_lock_irq(&blkcg->lock); 152 blkcg->weight = (unsigned int)val; 153 hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) { 154 list_for_each_entry(blkiop, &blkio_list, list) 155 blkiop->ops.blkio_update_group_weight_fn(blkg, 156 blkcg->weight); 157 } 158 spin_unlock_irq(&blkcg->lock); 159 spin_unlock(&blkio_list_lock); 160 return 0; 161 } 162 163 #define SHOW_FUNCTION_PER_GROUP(__VAR) \ 164 static int blkiocg_##__VAR##_read(struct cgroup *cgroup, \ 165 struct cftype *cftype, struct seq_file *m) \ 166 { \ 167 struct blkio_cgroup *blkcg; \ 168 struct blkio_group *blkg; \ 169 struct hlist_node *n; \ 170 \ 171 if (!cgroup_lock_live_group(cgroup)) \ 172 return -ENODEV; \ 173 \ 174 blkcg = cgroup_to_blkio_cgroup(cgroup); \ 175 rcu_read_lock(); \ 176 hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {\ 177 if (blkg->dev) \ 178 seq_printf(m, "%u:%u %lu\n", MAJOR(blkg->dev), \ 179 MINOR(blkg->dev), blkg->__VAR); \ 180 } \ 181 rcu_read_unlock(); \ 182 cgroup_unlock(); \ 183 return 0; \ 184 } 185 186 SHOW_FUNCTION_PER_GROUP(time); 187 SHOW_FUNCTION_PER_GROUP(sectors); 188 #ifdef CONFIG_DEBUG_BLK_CGROUP 189 SHOW_FUNCTION_PER_GROUP(dequeue); 190 #endif 191 #undef SHOW_FUNCTION_PER_GROUP 192 193 #ifdef CONFIG_DEBUG_BLK_CGROUP 194 void blkiocg_update_blkio_group_dequeue_stats(struct blkio_group *blkg, 195 unsigned long dequeue) 196 { 197 blkg->dequeue += dequeue; 198 } 199 EXPORT_SYMBOL_GPL(blkiocg_update_blkio_group_dequeue_stats); 200 #endif 201 202 struct cftype blkio_files[] = { 203 { 204 .name = "weight", 205 .read_u64 = blkiocg_weight_read, 206 .write_u64 = blkiocg_weight_write, 207 }, 208 { 209 .name = "time", 210 .read_seq_string = blkiocg_time_read, 211 }, 212 { 213 .name = "sectors", 214 .read_seq_string = blkiocg_sectors_read, 215 }, 216 #ifdef CONFIG_DEBUG_BLK_CGROUP 217 { 218 .name = "dequeue", 219 .read_seq_string = blkiocg_dequeue_read, 220 }, 221 #endif 222 }; 223 224 static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup) 225 { 226 return cgroup_add_files(cgroup, subsys, blkio_files, 227 ARRAY_SIZE(blkio_files)); 228 } 229 230 static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup) 231 { 232 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup); 233 unsigned long flags; 234 struct blkio_group *blkg; 235 void *key; 236 struct blkio_policy_type *blkiop; 237 238 rcu_read_lock(); 239 remove_entry: 240 spin_lock_irqsave(&blkcg->lock, flags); 241 242 if (hlist_empty(&blkcg->blkg_list)) { 243 spin_unlock_irqrestore(&blkcg->lock, flags); 244 goto done; 245 } 246 247 blkg = hlist_entry(blkcg->blkg_list.first, struct blkio_group, 248 blkcg_node); 249 key = rcu_dereference(blkg->key); 250 __blkiocg_del_blkio_group(blkg); 251 252 spin_unlock_irqrestore(&blkcg->lock, flags); 253 254 /* 255 * This blkio_group is being unlinked as associated cgroup is going 256 * away. Let all the IO controlling policies know about this event. 257 * 258 * Currently this is static call to one io controlling policy. Once 259 * we have more policies in place, we need some dynamic registration 260 * of callback function. 261 */ 262 spin_lock(&blkio_list_lock); 263 list_for_each_entry(blkiop, &blkio_list, list) 264 blkiop->ops.blkio_unlink_group_fn(key, blkg); 265 spin_unlock(&blkio_list_lock); 266 goto remove_entry; 267 done: 268 free_css_id(&blkio_subsys, &blkcg->css); 269 rcu_read_unlock(); 270 kfree(blkcg); 271 } 272 273 static struct cgroup_subsys_state * 274 blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup) 275 { 276 struct blkio_cgroup *blkcg, *parent_blkcg; 277 278 if (!cgroup->parent) { 279 blkcg = &blkio_root_cgroup; 280 goto done; 281 } 282 283 /* Currently we do not support hierarchy deeper than two level (0,1) */ 284 parent_blkcg = cgroup_to_blkio_cgroup(cgroup->parent); 285 if (css_depth(&parent_blkcg->css) > 0) 286 return ERR_PTR(-EINVAL); 287 288 blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); 289 if (!blkcg) 290 return ERR_PTR(-ENOMEM); 291 292 blkcg->weight = BLKIO_WEIGHT_DEFAULT; 293 done: 294 spin_lock_init(&blkcg->lock); 295 INIT_HLIST_HEAD(&blkcg->blkg_list); 296 297 return &blkcg->css; 298 } 299 300 /* 301 * We cannot support shared io contexts, as we have no mean to support 302 * two tasks with the same ioc in two different groups without major rework 303 * of the main cic data structures. For now we allow a task to change 304 * its cgroup only if it's the only owner of its ioc. 305 */ 306 static int blkiocg_can_attach(struct cgroup_subsys *subsys, 307 struct cgroup *cgroup, struct task_struct *tsk, 308 bool threadgroup) 309 { 310 struct io_context *ioc; 311 int ret = 0; 312 313 /* task_lock() is needed to avoid races with exit_io_context() */ 314 task_lock(tsk); 315 ioc = tsk->io_context; 316 if (ioc && atomic_read(&ioc->nr_tasks) > 1) 317 ret = -EINVAL; 318 task_unlock(tsk); 319 320 return ret; 321 } 322 323 static void blkiocg_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup, 324 struct cgroup *prev, struct task_struct *tsk, 325 bool threadgroup) 326 { 327 struct io_context *ioc; 328 329 task_lock(tsk); 330 ioc = tsk->io_context; 331 if (ioc) 332 ioc->cgroup_changed = 1; 333 task_unlock(tsk); 334 } 335 336 struct cgroup_subsys blkio_subsys = { 337 .name = "blkio", 338 .create = blkiocg_create, 339 .can_attach = blkiocg_can_attach, 340 .attach = blkiocg_attach, 341 .destroy = blkiocg_destroy, 342 .populate = blkiocg_populate, 343 .subsys_id = blkio_subsys_id, 344 .use_id = 1, 345 }; 346 347 void blkio_policy_register(struct blkio_policy_type *blkiop) 348 { 349 spin_lock(&blkio_list_lock); 350 list_add_tail(&blkiop->list, &blkio_list); 351 spin_unlock(&blkio_list_lock); 352 } 353 EXPORT_SYMBOL_GPL(blkio_policy_register); 354 355 void blkio_policy_unregister(struct blkio_policy_type *blkiop) 356 { 357 spin_lock(&blkio_list_lock); 358 list_del_init(&blkiop->list); 359 spin_unlock(&blkio_list_lock); 360 } 361 EXPORT_SYMBOL_GPL(blkio_policy_unregister); 362