blob: e17da947f6bd5d3a988e8acaa7cecf685ae21218 [file] [log] [blame]
Vivek Goyal31e4c282009-12-03 12:59:42 -05001/*
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>
Vivek Goyal22084192009-12-03 12:59:49 -050014#include <linux/kdev_t.h>
Vivek Goyal9d6a9862009-12-04 10:36:41 -050015#include <linux/module.h>
Stephen Rothwellaccee782009-12-07 19:29:39 +110016#include <linux/err.h>
Divyesh Shah91952912010-04-01 15:01:41 -070017#include <linux/blkdev.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090018#include <linux/slab.h>
Gui Jianfeng34d0f172010-04-13 16:05:49 +080019#include <linux/genhd.h>
Tejun Heo72e06c22012-03-05 13:15:00 -080020#include <linux/delay.h>
Tejun Heo9a9e8a22012-03-19 15:10:56 -070021#include <linux/atomic.h>
Tejun Heo72e06c22012-03-05 13:15:00 -080022#include "blk-cgroup.h"
Tejun Heo5efd6112012-03-05 13:15:12 -080023#include "blk.h"
Vivek Goyal3e252062009-12-04 10:36:42 -050024
Divyesh Shah84c124d2010-04-09 08:31:19 +020025#define MAX_KEY_LEN 100
26
Tejun Heobc0d6502012-04-13 13:11:26 -070027static DEFINE_MUTEX(blkcg_pol_mutex);
Tejun Heo923adde2012-03-05 13:15:13 -080028
Tejun Heoe71357e2013-01-09 08:05:10 -080029struct blkcg blkcg_root = { .cfq_weight = 2 * CFQ_WEIGHT_DEFAULT,
30 .cfq_leaf_weight = 2 * CFQ_WEIGHT_DEFAULT, };
Tejun Heo3c798392012-04-16 13:57:25 -070031EXPORT_SYMBOL_GPL(blkcg_root);
Vivek Goyal9d6a9862009-12-04 10:36:41 -050032
Tejun Heo3c798392012-04-16 13:57:25 -070033static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS];
Tejun Heo035d10b2012-03-05 13:15:04 -080034
Tejun Heoa2b16932012-04-13 13:11:33 -070035static bool blkcg_policy_enabled(struct request_queue *q,
Tejun Heo3c798392012-04-16 13:57:25 -070036 const struct blkcg_policy *pol)
Tejun Heoa2b16932012-04-13 13:11:33 -070037{
38 return pol && test_bit(pol->plid, q->blkcg_pols);
39}
40
Tejun Heo03814112012-03-05 13:15:14 -080041/**
42 * blkg_free - free a blkg
43 * @blkg: blkg to free
44 *
45 * Free @blkg which may be partially allocated.
46 */
Tejun Heo3c798392012-04-16 13:57:25 -070047static void blkg_free(struct blkcg_gq *blkg)
Tejun Heo03814112012-03-05 13:15:14 -080048{
Tejun Heoe8989fa2012-03-05 13:15:20 -080049 int i;
Tejun Heo549d3aa2012-03-05 13:15:16 -080050
51 if (!blkg)
52 return;
53
Tejun Heodb613672013-05-14 13:52:31 -070054 for (i = 0; i < BLKCG_MAX_POLS; i++)
55 kfree(blkg->pd[i]);
Tejun Heoe8989fa2012-03-05 13:15:20 -080056
Tejun Heoa0516612012-06-26 15:05:44 -070057 blk_exit_rl(&blkg->rl);
Tejun Heo549d3aa2012-03-05 13:15:16 -080058 kfree(blkg);
Tejun Heo03814112012-03-05 13:15:14 -080059}
60
61/**
62 * blkg_alloc - allocate a blkg
63 * @blkcg: block cgroup the new blkg is associated with
64 * @q: request_queue the new blkg is associated with
Tejun Heo15974992012-06-04 20:40:52 -070065 * @gfp_mask: allocation mask to use
Tejun Heo03814112012-03-05 13:15:14 -080066 *
Tejun Heoe8989fa2012-03-05 13:15:20 -080067 * Allocate a new blkg assocating @blkcg and @q.
Tejun Heo03814112012-03-05 13:15:14 -080068 */
Tejun Heo15974992012-06-04 20:40:52 -070069static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q,
70 gfp_t gfp_mask)
Tejun Heo03814112012-03-05 13:15:14 -080071{
Tejun Heo3c798392012-04-16 13:57:25 -070072 struct blkcg_gq *blkg;
Tejun Heoe8989fa2012-03-05 13:15:20 -080073 int i;
Tejun Heo03814112012-03-05 13:15:14 -080074
75 /* alloc and init base part */
Tejun Heo15974992012-06-04 20:40:52 -070076 blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node);
Tejun Heo03814112012-03-05 13:15:14 -080077 if (!blkg)
78 return NULL;
79
Tejun Heoc875f4d2012-03-05 13:15:22 -080080 blkg->q = q;
Tejun Heoe8989fa2012-03-05 13:15:20 -080081 INIT_LIST_HEAD(&blkg->q_node);
Tejun Heo03814112012-03-05 13:15:14 -080082 blkg->blkcg = blkcg;
Tejun Heoa5049a82014-06-19 17:42:57 -040083 atomic_set(&blkg->refcnt, 1);
Tejun Heo03814112012-03-05 13:15:14 -080084
Tejun Heoa0516612012-06-26 15:05:44 -070085 /* root blkg uses @q->root_rl, init rl only for !root blkgs */
86 if (blkcg != &blkcg_root) {
87 if (blk_init_rl(&blkg->rl, q, gfp_mask))
88 goto err_free;
89 blkg->rl.blkg = blkg;
90 }
91
Tejun Heo8bd435b2012-04-13 13:11:28 -070092 for (i = 0; i < BLKCG_MAX_POLS; i++) {
Tejun Heo3c798392012-04-16 13:57:25 -070093 struct blkcg_policy *pol = blkcg_policy[i];
Tejun Heoe8989fa2012-03-05 13:15:20 -080094 struct blkg_policy_data *pd;
Tejun Heo03814112012-03-05 13:15:14 -080095
Tejun Heoa2b16932012-04-13 13:11:33 -070096 if (!blkcg_policy_enabled(q, pol))
Tejun Heoe8989fa2012-03-05 13:15:20 -080097 continue;
Tejun Heo549d3aa2012-03-05 13:15:16 -080098
Tejun Heoe8989fa2012-03-05 13:15:20 -080099 /* alloc per-policy data and attach it to blkg */
Tejun Heo15974992012-06-04 20:40:52 -0700100 pd = kzalloc_node(pol->pd_size, gfp_mask, q->node);
Tejun Heoa0516612012-06-26 15:05:44 -0700101 if (!pd)
102 goto err_free;
Tejun Heo549d3aa2012-03-05 13:15:16 -0800103
Tejun Heoe8989fa2012-03-05 13:15:20 -0800104 blkg->pd[i] = pd;
105 pd->blkg = blkg;
Tejun Heob276a872013-01-09 08:05:12 -0800106 pd->plid = i;
Tejun Heoe8989fa2012-03-05 13:15:20 -0800107 }
108
Tejun Heo03814112012-03-05 13:15:14 -0800109 return blkg;
Tejun Heoa0516612012-06-26 15:05:44 -0700110
111err_free:
112 blkg_free(blkg);
113 return NULL;
Tejun Heo03814112012-03-05 13:15:14 -0800114}
115
Tejun Heo16b3de62013-01-09 08:05:12 -0800116/**
117 * __blkg_lookup - internal version of blkg_lookup()
118 * @blkcg: blkcg of interest
119 * @q: request_queue of interest
120 * @update_hint: whether to update lookup hint with the result or not
121 *
122 * This is internal version and shouldn't be used by policy
123 * implementations. Looks up blkgs for the @blkcg - @q pair regardless of
124 * @q's bypass state. If @update_hint is %true, the caller should be
125 * holding @q->queue_lock and lookup hint is updated on success.
126 */
Tejun Heodd4a4ff2013-05-14 13:52:30 -0700127struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q,
128 bool update_hint)
Tejun Heo80fd9972012-04-13 14:50:53 -0700129{
Tejun Heo3c798392012-04-16 13:57:25 -0700130 struct blkcg_gq *blkg;
Tejun Heo80fd9972012-04-13 14:50:53 -0700131
Tejun Heoa6371202012-04-19 16:29:24 -0700132 blkg = rcu_dereference(blkcg->blkg_hint);
133 if (blkg && blkg->q == q)
134 return blkg;
135
136 /*
Tejun Heo86cde6b2013-01-09 08:05:10 -0800137 * Hint didn't match. Look up from the radix tree. Note that the
138 * hint can only be updated under queue_lock as otherwise @blkg
139 * could have already been removed from blkg_tree. The caller is
140 * responsible for grabbing queue_lock if @update_hint.
Tejun Heoa6371202012-04-19 16:29:24 -0700141 */
142 blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id);
Tejun Heo86cde6b2013-01-09 08:05:10 -0800143 if (blkg && blkg->q == q) {
144 if (update_hint) {
145 lockdep_assert_held(q->queue_lock);
146 rcu_assign_pointer(blkcg->blkg_hint, blkg);
147 }
Tejun Heoa6371202012-04-19 16:29:24 -0700148 return blkg;
Tejun Heo86cde6b2013-01-09 08:05:10 -0800149 }
Tejun Heoa6371202012-04-19 16:29:24 -0700150
Tejun Heo80fd9972012-04-13 14:50:53 -0700151 return NULL;
152}
153
154/**
155 * blkg_lookup - lookup blkg for the specified blkcg - q pair
156 * @blkcg: blkcg of interest
157 * @q: request_queue of interest
158 *
159 * Lookup blkg for the @blkcg - @q pair. This function should be called
160 * under RCU read lock and is guaranteed to return %NULL if @q is bypassing
161 * - see blk_queue_bypass_start() for details.
162 */
Tejun Heo3c798392012-04-16 13:57:25 -0700163struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q)
Tejun Heo80fd9972012-04-13 14:50:53 -0700164{
165 WARN_ON_ONCE(!rcu_read_lock_held());
166
167 if (unlikely(blk_queue_bypass(q)))
168 return NULL;
Tejun Heo86cde6b2013-01-09 08:05:10 -0800169 return __blkg_lookup(blkcg, q, false);
Tejun Heo80fd9972012-04-13 14:50:53 -0700170}
171EXPORT_SYMBOL_GPL(blkg_lookup);
172
Tejun Heo15974992012-06-04 20:40:52 -0700173/*
174 * If @new_blkg is %NULL, this function tries to allocate a new one as
175 * necessary using %GFP_ATOMIC. @new_blkg is always consumed on return.
176 */
Tejun Heo86cde6b2013-01-09 08:05:10 -0800177static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
178 struct request_queue *q,
179 struct blkcg_gq *new_blkg)
Vivek Goyal5624a4e2011-05-19 15:38:28 -0400180{
Tejun Heo3c798392012-04-16 13:57:25 -0700181 struct blkcg_gq *blkg;
Tejun Heof427d902013-01-09 08:05:12 -0800182 int i, ret;
Vivek Goyal5624a4e2011-05-19 15:38:28 -0400183
Tejun Heocd1604f2012-03-05 13:15:06 -0800184 WARN_ON_ONCE(!rcu_read_lock_held());
185 lockdep_assert_held(q->queue_lock);
Vivek Goyal31e4c282009-12-03 12:59:42 -0500186
Tejun Heo7ee9c562012-03-05 13:15:11 -0800187 /* blkg holds a reference to blkcg */
Tejun Heoec903c02014-05-13 12:11:01 -0400188 if (!css_tryget_online(&blkcg->css)) {
Tejun Heo93e6d5d2013-01-09 08:05:10 -0800189 ret = -EINVAL;
190 goto err_free_blkg;
Tejun Heo15974992012-06-04 20:40:52 -0700191 }
Tejun Heocd1604f2012-03-05 13:15:06 -0800192
Tejun Heo496fb782012-04-19 16:29:23 -0700193 /* allocate */
Tejun Heo15974992012-06-04 20:40:52 -0700194 if (!new_blkg) {
195 new_blkg = blkg_alloc(blkcg, q, GFP_ATOMIC);
196 if (unlikely(!new_blkg)) {
Tejun Heo93e6d5d2013-01-09 08:05:10 -0800197 ret = -ENOMEM;
198 goto err_put_css;
Tejun Heo15974992012-06-04 20:40:52 -0700199 }
200 }
201 blkg = new_blkg;
Tejun Heocd1604f2012-03-05 13:15:06 -0800202
Tejun Heodb613672013-05-14 13:52:31 -0700203 /* link parent */
Tejun Heo3c547862013-01-09 08:05:10 -0800204 if (blkcg_parent(blkcg)) {
205 blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false);
206 if (WARN_ON_ONCE(!blkg->parent)) {
Tejun Heo2423c9c2013-05-14 13:52:30 -0700207 ret = -EINVAL;
Tejun Heo3c547862013-01-09 08:05:10 -0800208 goto err_put_css;
209 }
210 blkg_get(blkg->parent);
211 }
212
Tejun Heodb613672013-05-14 13:52:31 -0700213 /* invoke per-policy init */
214 for (i = 0; i < BLKCG_MAX_POLS; i++) {
215 struct blkcg_policy *pol = blkcg_policy[i];
216
217 if (blkg->pd[i] && pol->pd_init_fn)
218 pol->pd_init_fn(blkg);
219 }
220
221 /* insert */
Tejun Heoa6371202012-04-19 16:29:24 -0700222 spin_lock(&blkcg->lock);
223 ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg);
224 if (likely(!ret)) {
225 hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
226 list_add(&blkg->q_node, &q->blkg_list);
Tejun Heof427d902013-01-09 08:05:12 -0800227
228 for (i = 0; i < BLKCG_MAX_POLS; i++) {
229 struct blkcg_policy *pol = blkcg_policy[i];
230
231 if (blkg->pd[i] && pol->pd_online_fn)
232 pol->pd_online_fn(blkg);
233 }
Tejun Heoa6371202012-04-19 16:29:24 -0700234 }
Tejun Heof427d902013-01-09 08:05:12 -0800235 blkg->online = true;
Tejun Heoa6371202012-04-19 16:29:24 -0700236 spin_unlock(&blkcg->lock);
237
Tejun Heo577cee12013-08-28 14:26:50 -0400238 if (!ret) {
239 if (blkcg == &blkcg_root) {
240 q->root_blkg = blkg;
241 q->root_rl.blkg = blkg;
242 }
Tejun Heoa6371202012-04-19 16:29:24 -0700243 return blkg;
Tejun Heo577cee12013-08-28 14:26:50 -0400244 }
Tejun Heo15974992012-06-04 20:40:52 -0700245
Tejun Heo3c547862013-01-09 08:05:10 -0800246 /* @blkg failed fully initialized, use the usual release path */
247 blkg_put(blkg);
248 return ERR_PTR(ret);
249
Tejun Heo93e6d5d2013-01-09 08:05:10 -0800250err_put_css:
Tejun Heo496fb782012-04-19 16:29:23 -0700251 css_put(&blkcg->css);
Tejun Heo93e6d5d2013-01-09 08:05:10 -0800252err_free_blkg:
Tejun Heo15974992012-06-04 20:40:52 -0700253 blkg_free(new_blkg);
Tejun Heo93e6d5d2013-01-09 08:05:10 -0800254 return ERR_PTR(ret);
Vivek Goyal31e4c282009-12-03 12:59:42 -0500255}
Tejun Heo3c96cb32012-04-13 13:11:34 -0700256
Tejun Heo86cde6b2013-01-09 08:05:10 -0800257/**
258 * blkg_lookup_create - lookup blkg, try to create one if not there
259 * @blkcg: blkcg of interest
260 * @q: request_queue of interest
261 *
262 * Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to
Tejun Heo3c547862013-01-09 08:05:10 -0800263 * create one. blkg creation is performed recursively from blkcg_root such
264 * that all non-root blkg's have access to the parent blkg. This function
265 * should be called under RCU read lock and @q->queue_lock.
Tejun Heo86cde6b2013-01-09 08:05:10 -0800266 *
267 * Returns pointer to the looked up or created blkg on success, ERR_PTR()
268 * value on error. If @q is dead, returns ERR_PTR(-EINVAL). If @q is not
269 * dead and bypassing, returns ERR_PTR(-EBUSY).
270 */
Tejun Heo3c798392012-04-16 13:57:25 -0700271struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
272 struct request_queue *q)
Tejun Heo3c96cb32012-04-13 13:11:34 -0700273{
Tejun Heo86cde6b2013-01-09 08:05:10 -0800274 struct blkcg_gq *blkg;
275
276 WARN_ON_ONCE(!rcu_read_lock_held());
277 lockdep_assert_held(q->queue_lock);
278
Tejun Heo3c96cb32012-04-13 13:11:34 -0700279 /*
280 * This could be the first entry point of blkcg implementation and
281 * we shouldn't allow anything to go through for a bypassing queue.
282 */
283 if (unlikely(blk_queue_bypass(q)))
Bart Van Assche3f3299d2012-11-28 13:42:38 +0100284 return ERR_PTR(blk_queue_dying(q) ? -EINVAL : -EBUSY);
Tejun Heo86cde6b2013-01-09 08:05:10 -0800285
286 blkg = __blkg_lookup(blkcg, q, true);
287 if (blkg)
288 return blkg;
289
Tejun Heo3c547862013-01-09 08:05:10 -0800290 /*
291 * Create blkgs walking down from blkcg_root to @blkcg, so that all
292 * non-root blkgs have access to their parents.
293 */
294 while (true) {
295 struct blkcg *pos = blkcg;
296 struct blkcg *parent = blkcg_parent(blkcg);
297
298 while (parent && !__blkg_lookup(parent, q, false)) {
299 pos = parent;
300 parent = blkcg_parent(parent);
301 }
302
303 blkg = blkg_create(pos, q, NULL);
304 if (pos == blkcg || IS_ERR(blkg))
305 return blkg;
306 }
Tejun Heo3c96cb32012-04-13 13:11:34 -0700307}
Tejun Heocd1604f2012-03-05 13:15:06 -0800308EXPORT_SYMBOL_GPL(blkg_lookup_create);
Vivek Goyal31e4c282009-12-03 12:59:42 -0500309
Tejun Heo3c798392012-04-16 13:57:25 -0700310static void blkg_destroy(struct blkcg_gq *blkg)
Tejun Heo72e06c22012-03-05 13:15:00 -0800311{
Tejun Heo3c798392012-04-16 13:57:25 -0700312 struct blkcg *blkcg = blkg->blkcg;
Tejun Heof427d902013-01-09 08:05:12 -0800313 int i;
Tejun Heo03aa2642012-03-05 13:15:19 -0800314
Tejun Heo27e1f9d2012-06-05 13:36:44 +0200315 lockdep_assert_held(blkg->q->queue_lock);
Tejun Heo9f13ef62012-03-05 13:15:21 -0800316 lockdep_assert_held(&blkcg->lock);
Tejun Heo03aa2642012-03-05 13:15:19 -0800317
318 /* Something wrong if we are trying to remove same group twice */
Tejun Heoe8989fa2012-03-05 13:15:20 -0800319 WARN_ON_ONCE(list_empty(&blkg->q_node));
Tejun Heo9f13ef62012-03-05 13:15:21 -0800320 WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node));
Tejun Heoa6371202012-04-19 16:29:24 -0700321
Tejun Heof427d902013-01-09 08:05:12 -0800322 for (i = 0; i < BLKCG_MAX_POLS; i++) {
323 struct blkcg_policy *pol = blkcg_policy[i];
324
325 if (blkg->pd[i] && pol->pd_offline_fn)
326 pol->pd_offline_fn(blkg);
327 }
328 blkg->online = false;
329
Tejun Heoa6371202012-04-19 16:29:24 -0700330 radix_tree_delete(&blkcg->blkg_tree, blkg->q->id);
Tejun Heoe8989fa2012-03-05 13:15:20 -0800331 list_del_init(&blkg->q_node);
Tejun Heo9f13ef62012-03-05 13:15:21 -0800332 hlist_del_init_rcu(&blkg->blkcg_node);
Tejun Heo03aa2642012-03-05 13:15:19 -0800333
Tejun Heo03aa2642012-03-05 13:15:19 -0800334 /*
Tejun Heoa6371202012-04-19 16:29:24 -0700335 * Both setting lookup hint to and clearing it from @blkg are done
336 * under queue_lock. If it's not pointing to @blkg now, it never
337 * will. Hint assignment itself can race safely.
338 */
Paul E. McKenneyec6c6762014-02-17 13:35:57 -0800339 if (rcu_access_pointer(blkcg->blkg_hint) == blkg)
Tejun Heoa6371202012-04-19 16:29:24 -0700340 rcu_assign_pointer(blkcg->blkg_hint, NULL);
341
342 /*
Tejun Heo577cee12013-08-28 14:26:50 -0400343 * If root blkg is destroyed. Just clear the pointer since root_rl
344 * does not take reference on root blkg.
345 */
346 if (blkcg == &blkcg_root) {
347 blkg->q->root_blkg = NULL;
348 blkg->q->root_rl.blkg = NULL;
349 }
350
351 /*
Tejun Heo03aa2642012-03-05 13:15:19 -0800352 * Put the reference taken at the time of creation so that when all
353 * queues are gone, group can be destroyed.
354 */
355 blkg_put(blkg);
356}
357
Tejun Heo9f13ef62012-03-05 13:15:21 -0800358/**
359 * blkg_destroy_all - destroy all blkgs associated with a request_queue
360 * @q: request_queue of interest
Tejun Heo9f13ef62012-03-05 13:15:21 -0800361 *
Tejun Heo3c96cb32012-04-13 13:11:34 -0700362 * Destroy all blkgs associated with @q.
Tejun Heo9f13ef62012-03-05 13:15:21 -0800363 */
Tejun Heo3c96cb32012-04-13 13:11:34 -0700364static void blkg_destroy_all(struct request_queue *q)
Tejun Heo03aa2642012-03-05 13:15:19 -0800365{
Tejun Heo3c798392012-04-16 13:57:25 -0700366 struct blkcg_gq *blkg, *n;
Tejun Heo72e06c22012-03-05 13:15:00 -0800367
Tejun Heo6d18b002012-04-13 13:11:35 -0700368 lockdep_assert_held(q->queue_lock);
Tejun Heo72e06c22012-03-05 13:15:00 -0800369
Tejun Heo9f13ef62012-03-05 13:15:21 -0800370 list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
Tejun Heo3c798392012-04-16 13:57:25 -0700371 struct blkcg *blkcg = blkg->blkcg;
Tejun Heo72e06c22012-03-05 13:15:00 -0800372
Tejun Heo9f13ef62012-03-05 13:15:21 -0800373 spin_lock(&blkcg->lock);
374 blkg_destroy(blkg);
375 spin_unlock(&blkcg->lock);
Tejun Heo72e06c22012-03-05 13:15:00 -0800376 }
377}
378
Tejun Heo2a4fd072013-05-14 13:52:31 -0700379/*
380 * A group is RCU protected, but having an rcu lock does not mean that one
381 * can access all the fields of blkg and assume these are valid. For
382 * example, don't try to follow throtl_data and request queue links.
383 *
384 * Having a reference to blkg under an rcu allows accesses to only values
385 * local to groups like group stats and group rate limits.
386 */
387void __blkg_release_rcu(struct rcu_head *rcu_head)
Tejun Heo1adaf3d2012-03-05 13:15:15 -0800388{
Tejun Heo2a4fd072013-05-14 13:52:31 -0700389 struct blkcg_gq *blkg = container_of(rcu_head, struct blkcg_gq, rcu_head);
Tejun Heodb613672013-05-14 13:52:31 -0700390 int i;
391
392 /* tell policies that this one is being freed */
393 for (i = 0; i < BLKCG_MAX_POLS; i++) {
394 struct blkcg_policy *pol = blkcg_policy[i];
395
396 if (blkg->pd[i] && pol->pd_exit_fn)
397 pol->pd_exit_fn(blkg);
398 }
399
Tejun Heo3c547862013-01-09 08:05:10 -0800400 /* release the blkcg and parent blkg refs this blkg has been holding */
Tejun Heo1adaf3d2012-03-05 13:15:15 -0800401 css_put(&blkg->blkcg->css);
Tejun Heoa5049a82014-06-19 17:42:57 -0400402 if (blkg->parent)
Tejun Heo3c547862013-01-09 08:05:10 -0800403 blkg_put(blkg->parent);
Tejun Heo1adaf3d2012-03-05 13:15:15 -0800404
Tejun Heo2a4fd072013-05-14 13:52:31 -0700405 blkg_free(blkg);
Tejun Heo1adaf3d2012-03-05 13:15:15 -0800406}
Tejun Heo2a4fd072013-05-14 13:52:31 -0700407EXPORT_SYMBOL_GPL(__blkg_release_rcu);
Tejun Heo1adaf3d2012-03-05 13:15:15 -0800408
Tejun Heoa0516612012-06-26 15:05:44 -0700409/*
410 * The next function used by blk_queue_for_each_rl(). It's a bit tricky
411 * because the root blkg uses @q->root_rl instead of its own rl.
412 */
413struct request_list *__blk_queue_next_rl(struct request_list *rl,
414 struct request_queue *q)
415{
416 struct list_head *ent;
417 struct blkcg_gq *blkg;
418
419 /*
420 * Determine the current blkg list_head. The first entry is
421 * root_rl which is off @q->blkg_list and mapped to the head.
422 */
423 if (rl == &q->root_rl) {
424 ent = &q->blkg_list;
Jun'ichi Nomura65c77fd2012-10-22 10:15:37 +0900425 /* There are no more block groups, hence no request lists */
426 if (list_empty(ent))
427 return NULL;
Tejun Heoa0516612012-06-26 15:05:44 -0700428 } else {
429 blkg = container_of(rl, struct blkcg_gq, rl);
430 ent = &blkg->q_node;
431 }
432
433 /* walk to the next list_head, skip root blkcg */
434 ent = ent->next;
435 if (ent == &q->root_blkg->q_node)
436 ent = ent->next;
437 if (ent == &q->blkg_list)
438 return NULL;
439
440 blkg = container_of(ent, struct blkcg_gq, q_node);
441 return &blkg->rl;
442}
443
Tejun Heo182446d2013-08-08 20:11:24 -0400444static int blkcg_reset_stats(struct cgroup_subsys_state *css,
445 struct cftype *cftype, u64 val)
Divyesh Shah303a3ac2010-04-01 15:01:24 -0700446{
Tejun Heo182446d2013-08-08 20:11:24 -0400447 struct blkcg *blkcg = css_to_blkcg(css);
Tejun Heo3c798392012-04-16 13:57:25 -0700448 struct blkcg_gq *blkg;
Tejun Heobc0d6502012-04-13 13:11:26 -0700449 int i;
Divyesh Shah303a3ac2010-04-01 15:01:24 -0700450
Tejun Heo36c38fb2014-05-05 12:37:30 -0400451 /*
452 * XXX: We invoke cgroup_add/rm_cftypes() under blkcg_pol_mutex
453 * which ends up putting cgroup's internal cgroup_tree_mutex under
454 * it; however, cgroup_tree_mutex is nested above cgroup file
455 * active protection and grabbing blkcg_pol_mutex from a cgroup
456 * file operation creates a possible circular dependency. cgroup
457 * internal locking is planned to go through further simplification
458 * and this issue should go away soon. For now, let's trylock
459 * blkcg_pol_mutex and restart the write on failure.
460 *
461 * http://lkml.kernel.org/g/5363C04B.4010400@oracle.com
462 */
463 if (!mutex_trylock(&blkcg_pol_mutex))
464 return restart_syscall();
Divyesh Shah303a3ac2010-04-01 15:01:24 -0700465 spin_lock_irq(&blkcg->lock);
Tejun Heo997a0262012-03-08 10:53:58 -0800466
467 /*
468 * Note that stat reset is racy - it doesn't synchronize against
469 * stat updates. This is a debug feature which shouldn't exist
470 * anyway. If you get hit by a race, retry.
471 */
Sasha Levinb67bfe02013-02-27 17:06:00 -0800472 hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
Tejun Heo8bd435b2012-04-13 13:11:28 -0700473 for (i = 0; i < BLKCG_MAX_POLS; i++) {
Tejun Heo3c798392012-04-16 13:57:25 -0700474 struct blkcg_policy *pol = blkcg_policy[i];
Tejun Heo549d3aa2012-03-05 13:15:16 -0800475
Tejun Heoa2b16932012-04-13 13:11:33 -0700476 if (blkcg_policy_enabled(blkg->q, pol) &&
Tejun Heof9fcc2d2012-04-16 13:57:27 -0700477 pol->pd_reset_stats_fn)
478 pol->pd_reset_stats_fn(blkg);
Tejun Heobc0d6502012-04-13 13:11:26 -0700479 }
Divyesh Shah303a3ac2010-04-01 15:01:24 -0700480 }
Vivek Goyalf0bdc8c2011-05-19 15:38:30 -0400481
Divyesh Shah303a3ac2010-04-01 15:01:24 -0700482 spin_unlock_irq(&blkcg->lock);
Tejun Heobc0d6502012-04-13 13:11:26 -0700483 mutex_unlock(&blkcg_pol_mutex);
Divyesh Shah303a3ac2010-04-01 15:01:24 -0700484 return 0;
485}
486
Tejun Heo3c798392012-04-16 13:57:25 -0700487static const char *blkg_dev_name(struct blkcg_gq *blkg)
Divyesh Shah303a3ac2010-04-01 15:01:24 -0700488{
Tejun Heod3d32e62012-04-01 14:38:42 -0700489 /* some drivers (floppy) instantiate a queue w/o disk registered */
490 if (blkg->q->backing_dev_info.dev)
491 return dev_name(blkg->q->backing_dev_info.dev);
492 return NULL;
Divyesh Shah303a3ac2010-04-01 15:01:24 -0700493}
494
Tejun Heod3d32e62012-04-01 14:38:42 -0700495/**
496 * blkcg_print_blkgs - helper for printing per-blkg data
497 * @sf: seq_file to print to
498 * @blkcg: blkcg of interest
499 * @prfill: fill function to print out a blkg
500 * @pol: policy in question
501 * @data: data to be passed to @prfill
502 * @show_total: to print out sum of prfill return values or not
503 *
504 * This function invokes @prfill on each blkg of @blkcg if pd for the
505 * policy specified by @pol exists. @prfill is invoked with @sf, the
Tejun Heo810ecfa2013-01-09 08:05:13 -0800506 * policy data and @data and the matching queue lock held. If @show_total
507 * is %true, the sum of the return values from @prfill is printed with
508 * "Total" label at the end.
Tejun Heod3d32e62012-04-01 14:38:42 -0700509 *
510 * This is to be used to construct print functions for
511 * cftype->read_seq_string method.
512 */
Tejun Heo3c798392012-04-16 13:57:25 -0700513void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
Tejun Heof95a04a2012-04-16 13:57:26 -0700514 u64 (*prfill)(struct seq_file *,
515 struct blkg_policy_data *, int),
Tejun Heo3c798392012-04-16 13:57:25 -0700516 const struct blkcg_policy *pol, int data,
Tejun Heoec399342012-04-13 13:11:27 -0700517 bool show_total)
Vivek Goyal5624a4e2011-05-19 15:38:28 -0400518{
Tejun Heo3c798392012-04-16 13:57:25 -0700519 struct blkcg_gq *blkg;
Tejun Heod3d32e62012-04-01 14:38:42 -0700520 u64 total = 0;
521
Tejun Heo810ecfa2013-01-09 08:05:13 -0800522 rcu_read_lock();
Linus Torvaldsee89f812013-02-28 12:52:24 -0800523 hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) {
Tejun Heo810ecfa2013-01-09 08:05:13 -0800524 spin_lock_irq(blkg->q->queue_lock);
Tejun Heoa2b16932012-04-13 13:11:33 -0700525 if (blkcg_policy_enabled(blkg->q, pol))
Tejun Heof95a04a2012-04-16 13:57:26 -0700526 total += prfill(sf, blkg->pd[pol->plid], data);
Tejun Heo810ecfa2013-01-09 08:05:13 -0800527 spin_unlock_irq(blkg->q->queue_lock);
528 }
529 rcu_read_unlock();
Tejun Heod3d32e62012-04-01 14:38:42 -0700530
531 if (show_total)
532 seq_printf(sf, "Total %llu\n", (unsigned long long)total);
533}
Tejun Heo829fdb52012-04-01 14:38:43 -0700534EXPORT_SYMBOL_GPL(blkcg_print_blkgs);
Tejun Heod3d32e62012-04-01 14:38:42 -0700535
536/**
537 * __blkg_prfill_u64 - prfill helper for a single u64 value
538 * @sf: seq_file to print to
Tejun Heof95a04a2012-04-16 13:57:26 -0700539 * @pd: policy private data of interest
Tejun Heod3d32e62012-04-01 14:38:42 -0700540 * @v: value to print
541 *
Tejun Heof95a04a2012-04-16 13:57:26 -0700542 * Print @v to @sf for the device assocaited with @pd.
Tejun Heod3d32e62012-04-01 14:38:42 -0700543 */
Tejun Heof95a04a2012-04-16 13:57:26 -0700544u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v)
Tejun Heod3d32e62012-04-01 14:38:42 -0700545{
Tejun Heof95a04a2012-04-16 13:57:26 -0700546 const char *dname = blkg_dev_name(pd->blkg);
Tejun Heod3d32e62012-04-01 14:38:42 -0700547
548 if (!dname)
549 return 0;
550
551 seq_printf(sf, "%s %llu\n", dname, (unsigned long long)v);
552 return v;
553}
Tejun Heo829fdb52012-04-01 14:38:43 -0700554EXPORT_SYMBOL_GPL(__blkg_prfill_u64);
Tejun Heod3d32e62012-04-01 14:38:42 -0700555
556/**
557 * __blkg_prfill_rwstat - prfill helper for a blkg_rwstat
558 * @sf: seq_file to print to
Tejun Heof95a04a2012-04-16 13:57:26 -0700559 * @pd: policy private data of interest
Tejun Heod3d32e62012-04-01 14:38:42 -0700560 * @rwstat: rwstat to print
561 *
Tejun Heof95a04a2012-04-16 13:57:26 -0700562 * Print @rwstat to @sf for the device assocaited with @pd.
Tejun Heod3d32e62012-04-01 14:38:42 -0700563 */
Tejun Heof95a04a2012-04-16 13:57:26 -0700564u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
Tejun Heo829fdb52012-04-01 14:38:43 -0700565 const struct blkg_rwstat *rwstat)
Tejun Heod3d32e62012-04-01 14:38:42 -0700566{
567 static const char *rwstr[] = {
568 [BLKG_RWSTAT_READ] = "Read",
569 [BLKG_RWSTAT_WRITE] = "Write",
570 [BLKG_RWSTAT_SYNC] = "Sync",
571 [BLKG_RWSTAT_ASYNC] = "Async",
572 };
Tejun Heof95a04a2012-04-16 13:57:26 -0700573 const char *dname = blkg_dev_name(pd->blkg);
Tejun Heod3d32e62012-04-01 14:38:42 -0700574 u64 v;
575 int i;
576
577 if (!dname)
578 return 0;
579
580 for (i = 0; i < BLKG_RWSTAT_NR; i++)
581 seq_printf(sf, "%s %s %llu\n", dname, rwstr[i],
582 (unsigned long long)rwstat->cnt[i]);
583
584 v = rwstat->cnt[BLKG_RWSTAT_READ] + rwstat->cnt[BLKG_RWSTAT_WRITE];
585 seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v);
586 return v;
587}
Tejun Heob50da392013-01-09 08:05:12 -0800588EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat);
Tejun Heod3d32e62012-04-01 14:38:42 -0700589
Tejun Heo5bc4afb12012-04-01 14:38:45 -0700590/**
591 * blkg_prfill_stat - prfill callback for blkg_stat
592 * @sf: seq_file to print to
Tejun Heof95a04a2012-04-16 13:57:26 -0700593 * @pd: policy private data of interest
594 * @off: offset to the blkg_stat in @pd
Tejun Heo5bc4afb12012-04-01 14:38:45 -0700595 *
596 * prfill callback for printing a blkg_stat.
597 */
Tejun Heof95a04a2012-04-16 13:57:26 -0700598u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off)
Tejun Heod3d32e62012-04-01 14:38:42 -0700599{
Tejun Heof95a04a2012-04-16 13:57:26 -0700600 return __blkg_prfill_u64(sf, pd, blkg_stat_read((void *)pd + off));
Tejun Heod3d32e62012-04-01 14:38:42 -0700601}
Tejun Heo5bc4afb12012-04-01 14:38:45 -0700602EXPORT_SYMBOL_GPL(blkg_prfill_stat);
Tejun Heod3d32e62012-04-01 14:38:42 -0700603
Tejun Heo5bc4afb12012-04-01 14:38:45 -0700604/**
605 * blkg_prfill_rwstat - prfill callback for blkg_rwstat
606 * @sf: seq_file to print to
Tejun Heof95a04a2012-04-16 13:57:26 -0700607 * @pd: policy private data of interest
608 * @off: offset to the blkg_rwstat in @pd
Tejun Heo5bc4afb12012-04-01 14:38:45 -0700609 *
610 * prfill callback for printing a blkg_rwstat.
611 */
Tejun Heof95a04a2012-04-16 13:57:26 -0700612u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
613 int off)
Tejun Heod3d32e62012-04-01 14:38:42 -0700614{
Tejun Heof95a04a2012-04-16 13:57:26 -0700615 struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd + off);
Tejun Heod3d32e62012-04-01 14:38:42 -0700616
Tejun Heof95a04a2012-04-16 13:57:26 -0700617 return __blkg_prfill_rwstat(sf, pd, &rwstat);
Tejun Heod3d32e62012-04-01 14:38:42 -0700618}
Tejun Heo5bc4afb12012-04-01 14:38:45 -0700619EXPORT_SYMBOL_GPL(blkg_prfill_rwstat);
Tejun Heod3d32e62012-04-01 14:38:42 -0700620
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700621/**
Tejun Heo16b3de62013-01-09 08:05:12 -0800622 * blkg_stat_recursive_sum - collect hierarchical blkg_stat
623 * @pd: policy private data of interest
624 * @off: offset to the blkg_stat in @pd
625 *
626 * Collect the blkg_stat specified by @off from @pd and all its online
627 * descendants and return the sum. The caller must be holding the queue
628 * lock for online tests.
629 */
630u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off)
631{
632 struct blkcg_policy *pol = blkcg_policy[pd->plid];
633 struct blkcg_gq *pos_blkg;
Tejun Heo492eb212013-08-08 20:11:25 -0400634 struct cgroup_subsys_state *pos_css;
Tejun Heobd8815a2013-08-08 20:11:27 -0400635 u64 sum = 0;
Tejun Heo16b3de62013-01-09 08:05:12 -0800636
637 lockdep_assert_held(pd->blkg->q->queue_lock);
638
Tejun Heo16b3de62013-01-09 08:05:12 -0800639 rcu_read_lock();
Tejun Heo492eb212013-08-08 20:11:25 -0400640 blkg_for_each_descendant_pre(pos_blkg, pos_css, pd_to_blkg(pd)) {
Tejun Heo16b3de62013-01-09 08:05:12 -0800641 struct blkg_policy_data *pos_pd = blkg_to_pd(pos_blkg, pol);
642 struct blkg_stat *stat = (void *)pos_pd + off;
643
644 if (pos_blkg->online)
645 sum += blkg_stat_read(stat);
646 }
647 rcu_read_unlock();
648
649 return sum;
650}
651EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum);
652
653/**
654 * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat
655 * @pd: policy private data of interest
656 * @off: offset to the blkg_stat in @pd
657 *
658 * Collect the blkg_rwstat specified by @off from @pd and all its online
659 * descendants and return the sum. The caller must be holding the queue
660 * lock for online tests.
661 */
662struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd,
663 int off)
664{
665 struct blkcg_policy *pol = blkcg_policy[pd->plid];
666 struct blkcg_gq *pos_blkg;
Tejun Heo492eb212013-08-08 20:11:25 -0400667 struct cgroup_subsys_state *pos_css;
Tejun Heobd8815a2013-08-08 20:11:27 -0400668 struct blkg_rwstat sum = { };
Tejun Heo16b3de62013-01-09 08:05:12 -0800669 int i;
670
671 lockdep_assert_held(pd->blkg->q->queue_lock);
672
Tejun Heo16b3de62013-01-09 08:05:12 -0800673 rcu_read_lock();
Tejun Heo492eb212013-08-08 20:11:25 -0400674 blkg_for_each_descendant_pre(pos_blkg, pos_css, pd_to_blkg(pd)) {
Tejun Heo16b3de62013-01-09 08:05:12 -0800675 struct blkg_policy_data *pos_pd = blkg_to_pd(pos_blkg, pol);
676 struct blkg_rwstat *rwstat = (void *)pos_pd + off;
677 struct blkg_rwstat tmp;
678
679 if (!pos_blkg->online)
680 continue;
681
682 tmp = blkg_rwstat_read(rwstat);
683
684 for (i = 0; i < BLKG_RWSTAT_NR; i++)
685 sum.cnt[i] += tmp.cnt[i];
686 }
687 rcu_read_unlock();
688
689 return sum;
690}
691EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum);
692
693/**
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700694 * blkg_conf_prep - parse and prepare for per-blkg config update
695 * @blkcg: target block cgroup
Tejun Heoda8b0662012-04-13 13:11:29 -0700696 * @pol: target policy
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700697 * @input: input string
698 * @ctx: blkg_conf_ctx to be filled
699 *
700 * Parse per-blkg config update from @input and initialize @ctx with the
701 * result. @ctx->blkg points to the blkg to be updated and @ctx->v the new
Tejun Heoda8b0662012-04-13 13:11:29 -0700702 * value. This function returns with RCU read lock and queue lock held and
703 * must be paired with blkg_conf_finish().
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700704 */
Tejun Heo3c798392012-04-16 13:57:25 -0700705int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
706 const char *input, struct blkg_conf_ctx *ctx)
Tejun Heoda8b0662012-04-13 13:11:29 -0700707 __acquires(rcu) __acquires(disk->queue->queue_lock)
Gui Jianfeng34d0f172010-04-13 16:05:49 +0800708{
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700709 struct gendisk *disk;
Tejun Heo3c798392012-04-16 13:57:25 -0700710 struct blkcg_gq *blkg;
Tejun Heo726fa692012-04-01 14:38:43 -0700711 unsigned int major, minor;
712 unsigned long long v;
713 int part, ret;
Gui Jianfeng34d0f172010-04-13 16:05:49 +0800714
Tejun Heo726fa692012-04-01 14:38:43 -0700715 if (sscanf(input, "%u:%u %llu", &major, &minor, &v) != 3)
716 return -EINVAL;
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700717
Tejun Heo726fa692012-04-01 14:38:43 -0700718 disk = get_gendisk(MKDEV(major, minor), &part);
Tejun Heo4bfd4822012-03-05 13:15:08 -0800719 if (!disk || part)
Tejun Heo726fa692012-04-01 14:38:43 -0700720 return -EINVAL;
Tejun Heoe56da7e2012-03-05 13:15:07 -0800721
722 rcu_read_lock();
Tejun Heo4bfd4822012-03-05 13:15:08 -0800723 spin_lock_irq(disk->queue->queue_lock);
Tejun Heoda8b0662012-04-13 13:11:29 -0700724
Tejun Heoa2b16932012-04-13 13:11:33 -0700725 if (blkcg_policy_enabled(disk->queue, pol))
Tejun Heo3c96cb32012-04-13 13:11:34 -0700726 blkg = blkg_lookup_create(blkcg, disk->queue);
Tejun Heoa2b16932012-04-13 13:11:33 -0700727 else
728 blkg = ERR_PTR(-EINVAL);
Tejun Heoe56da7e2012-03-05 13:15:07 -0800729
Tejun Heo4bfd4822012-03-05 13:15:08 -0800730 if (IS_ERR(blkg)) {
731 ret = PTR_ERR(blkg);
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700732 rcu_read_unlock();
Tejun Heoda8b0662012-04-13 13:11:29 -0700733 spin_unlock_irq(disk->queue->queue_lock);
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700734 put_disk(disk);
735 /*
736 * If queue was bypassing, we should retry. Do so after a
737 * short msleep(). It isn't strictly necessary but queue
738 * can be bypassing for some time and it's always nice to
739 * avoid busy looping.
740 */
741 if (ret == -EBUSY) {
742 msleep(10);
743 ret = restart_syscall();
Vivek Goyal7702e8f2010-09-15 17:06:36 -0400744 }
Tejun Heo726fa692012-04-01 14:38:43 -0700745 return ret;
Vivek Goyal062a6442010-09-15 17:06:33 -0400746 }
Tejun Heoe56da7e2012-03-05 13:15:07 -0800747
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700748 ctx->disk = disk;
749 ctx->blkg = blkg;
Tejun Heo726fa692012-04-01 14:38:43 -0700750 ctx->v = v;
751 return 0;
Gui Jianfeng34d0f172010-04-13 16:05:49 +0800752}
Tejun Heo829fdb52012-04-01 14:38:43 -0700753EXPORT_SYMBOL_GPL(blkg_conf_prep);
Gui Jianfeng34d0f172010-04-13 16:05:49 +0800754
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700755/**
756 * blkg_conf_finish - finish up per-blkg config update
757 * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep()
758 *
759 * Finish up after per-blkg config update. This function must be paired
760 * with blkg_conf_prep().
761 */
Tejun Heo829fdb52012-04-01 14:38:43 -0700762void blkg_conf_finish(struct blkg_conf_ctx *ctx)
Tejun Heoda8b0662012-04-13 13:11:29 -0700763 __releases(ctx->disk->queue->queue_lock) __releases(rcu)
Gui Jianfeng34d0f172010-04-13 16:05:49 +0800764{
Tejun Heoda8b0662012-04-13 13:11:29 -0700765 spin_unlock_irq(ctx->disk->queue->queue_lock);
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700766 rcu_read_unlock();
767 put_disk(ctx->disk);
Gui Jianfeng34d0f172010-04-13 16:05:49 +0800768}
Tejun Heo829fdb52012-04-01 14:38:43 -0700769EXPORT_SYMBOL_GPL(blkg_conf_finish);
Gui Jianfeng34d0f172010-04-13 16:05:49 +0800770
Tejun Heo3c798392012-04-16 13:57:25 -0700771struct cftype blkcg_files[] = {
Vivek Goyal31e4c282009-12-03 12:59:42 -0500772 {
Divyesh Shah84c124d2010-04-09 08:31:19 +0200773 .name = "reset_stats",
Tejun Heo3c798392012-04-16 13:57:25 -0700774 .write_u64 = blkcg_reset_stats,
Vivek Goyal22084192009-12-03 12:59:49 -0500775 },
Tejun Heo4baf6e32012-04-01 12:09:55 -0700776 { } /* terminate */
Vivek Goyal31e4c282009-12-03 12:59:42 -0500777};
778
Tejun Heo9f13ef62012-03-05 13:15:21 -0800779/**
Tejun Heo92fb9742012-11-19 08:13:38 -0800780 * blkcg_css_offline - cgroup css_offline callback
Tejun Heoeb954192013-08-08 20:11:23 -0400781 * @css: css of interest
Tejun Heo9f13ef62012-03-05 13:15:21 -0800782 *
Tejun Heoeb954192013-08-08 20:11:23 -0400783 * This function is called when @css is about to go away and responsible
784 * for shooting down all blkgs associated with @css. blkgs should be
Tejun Heo9f13ef62012-03-05 13:15:21 -0800785 * removed while holding both q and blkcg locks. As blkcg lock is nested
786 * inside q lock, this function performs reverse double lock dancing.
787 *
788 * This is the blkcg counterpart of ioc_release_fn().
789 */
Tejun Heoeb954192013-08-08 20:11:23 -0400790static void blkcg_css_offline(struct cgroup_subsys_state *css)
Vivek Goyal31e4c282009-12-03 12:59:42 -0500791{
Tejun Heoeb954192013-08-08 20:11:23 -0400792 struct blkcg *blkcg = css_to_blkcg(css);
Vivek Goyal31e4c282009-12-03 12:59:42 -0500793
Tejun Heo9f13ef62012-03-05 13:15:21 -0800794 spin_lock_irq(&blkcg->lock);
Tejun Heo7ee9c562012-03-05 13:15:11 -0800795
Tejun Heo9f13ef62012-03-05 13:15:21 -0800796 while (!hlist_empty(&blkcg->blkg_list)) {
Tejun Heo3c798392012-04-16 13:57:25 -0700797 struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first,
798 struct blkcg_gq, blkcg_node);
Tejun Heoc875f4d2012-03-05 13:15:22 -0800799 struct request_queue *q = blkg->q;
Vivek Goyalb1c35762009-12-03 12:59:47 -0500800
Tejun Heo9f13ef62012-03-05 13:15:21 -0800801 if (spin_trylock(q->queue_lock)) {
802 blkg_destroy(blkg);
803 spin_unlock(q->queue_lock);
804 } else {
805 spin_unlock_irq(&blkcg->lock);
Tejun Heo9f13ef62012-03-05 13:15:21 -0800806 cpu_relax();
Dan Carpentera5567932012-03-29 20:57:08 +0200807 spin_lock_irq(&blkcg->lock);
Jens Axboe0f3942a2010-05-03 14:28:55 +0200808 }
Tejun Heo9f13ef62012-03-05 13:15:21 -0800809 }
Jens Axboe0f3942a2010-05-03 14:28:55 +0200810
Tejun Heo9f13ef62012-03-05 13:15:21 -0800811 spin_unlock_irq(&blkcg->lock);
Tejun Heo7ee9c562012-03-05 13:15:11 -0800812}
813
Tejun Heoeb954192013-08-08 20:11:23 -0400814static void blkcg_css_free(struct cgroup_subsys_state *css)
Tejun Heo7ee9c562012-03-05 13:15:11 -0800815{
Tejun Heoeb954192013-08-08 20:11:23 -0400816 struct blkcg *blkcg = css_to_blkcg(css);
Tejun Heo7ee9c562012-03-05 13:15:11 -0800817
Tejun Heo3c798392012-04-16 13:57:25 -0700818 if (blkcg != &blkcg_root)
Ben Blum67523c42010-03-10 15:22:11 -0800819 kfree(blkcg);
Vivek Goyal31e4c282009-12-03 12:59:42 -0500820}
821
Tejun Heoeb954192013-08-08 20:11:23 -0400822static struct cgroup_subsys_state *
823blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
Vivek Goyal31e4c282009-12-03 12:59:42 -0500824{
Tejun Heo9a9e8a22012-03-19 15:10:56 -0700825 static atomic64_t id_seq = ATOMIC64_INIT(0);
Tejun Heo3c798392012-04-16 13:57:25 -0700826 struct blkcg *blkcg;
Vivek Goyal31e4c282009-12-03 12:59:42 -0500827
Tejun Heoeb954192013-08-08 20:11:23 -0400828 if (!parent_css) {
Tejun Heo3c798392012-04-16 13:57:25 -0700829 blkcg = &blkcg_root;
Vivek Goyal31e4c282009-12-03 12:59:42 -0500830 goto done;
831 }
832
Vivek Goyal31e4c282009-12-03 12:59:42 -0500833 blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
834 if (!blkcg)
835 return ERR_PTR(-ENOMEM);
836
Tejun Heo3381cb82012-04-01 14:38:44 -0700837 blkcg->cfq_weight = CFQ_WEIGHT_DEFAULT;
Tejun Heoe71357e2013-01-09 08:05:10 -0800838 blkcg->cfq_leaf_weight = CFQ_WEIGHT_DEFAULT;
Tejun Heo9a9e8a22012-03-19 15:10:56 -0700839 blkcg->id = atomic64_inc_return(&id_seq); /* root is 0, start from 1 */
Vivek Goyal31e4c282009-12-03 12:59:42 -0500840done:
841 spin_lock_init(&blkcg->lock);
Tejun Heoa6371202012-04-19 16:29:24 -0700842 INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_ATOMIC);
Vivek Goyal31e4c282009-12-03 12:59:42 -0500843 INIT_HLIST_HEAD(&blkcg->blkg_list);
844
845 return &blkcg->css;
846}
847
Tejun Heo5efd6112012-03-05 13:15:12 -0800848/**
849 * blkcg_init_queue - initialize blkcg part of request queue
850 * @q: request_queue to initialize
851 *
852 * Called from blk_alloc_queue_node(). Responsible for initializing blkcg
853 * part of new request_queue @q.
854 *
855 * RETURNS:
856 * 0 on success, -errno on failure.
857 */
858int blkcg_init_queue(struct request_queue *q)
859{
860 might_sleep();
861
Tejun Heo3c96cb32012-04-13 13:11:34 -0700862 return blk_throtl_init(q);
Tejun Heo5efd6112012-03-05 13:15:12 -0800863}
864
865/**
866 * blkcg_drain_queue - drain blkcg part of request_queue
867 * @q: request_queue to drain
868 *
869 * Called from blk_drain_queue(). Responsible for draining blkcg part.
870 */
871void blkcg_drain_queue(struct request_queue *q)
872{
873 lockdep_assert_held(q->queue_lock);
874
Tejun Heo0b462c82014-07-05 18:43:21 -0400875 /*
876 * @q could be exiting and already have destroyed all blkgs as
877 * indicated by NULL root_blkg. If so, don't confuse policies.
878 */
879 if (!q->root_blkg)
880 return;
881
Tejun Heo5efd6112012-03-05 13:15:12 -0800882 blk_throtl_drain(q);
883}
884
885/**
886 * blkcg_exit_queue - exit and release blkcg part of request_queue
887 * @q: request_queue being released
888 *
889 * Called from blk_release_queue(). Responsible for exiting blkcg part.
890 */
891void blkcg_exit_queue(struct request_queue *q)
892{
Tejun Heo6d18b002012-04-13 13:11:35 -0700893 spin_lock_irq(q->queue_lock);
Tejun Heo3c96cb32012-04-13 13:11:34 -0700894 blkg_destroy_all(q);
Tejun Heo6d18b002012-04-13 13:11:35 -0700895 spin_unlock_irq(q->queue_lock);
896
Tejun Heo5efd6112012-03-05 13:15:12 -0800897 blk_throtl_exit(q);
898}
899
Vivek Goyal31e4c282009-12-03 12:59:42 -0500900/*
901 * We cannot support shared io contexts, as we have no mean to support
902 * two tasks with the same ioc in two different groups without major rework
903 * of the main cic data structures. For now we allow a task to change
904 * its cgroup only if it's the only owner of its ioc.
905 */
Tejun Heoeb954192013-08-08 20:11:23 -0400906static int blkcg_can_attach(struct cgroup_subsys_state *css,
907 struct cgroup_taskset *tset)
Vivek Goyal31e4c282009-12-03 12:59:42 -0500908{
Tejun Heobb9d97b2011-12-12 18:12:21 -0800909 struct task_struct *task;
Vivek Goyal31e4c282009-12-03 12:59:42 -0500910 struct io_context *ioc;
911 int ret = 0;
912
913 /* task_lock() is needed to avoid races with exit_io_context() */
Tejun Heo924f0d92014-02-13 06:58:41 -0500914 cgroup_taskset_for_each(task, tset) {
Tejun Heobb9d97b2011-12-12 18:12:21 -0800915 task_lock(task);
916 ioc = task->io_context;
917 if (ioc && atomic_read(&ioc->nr_tasks) > 1)
918 ret = -EINVAL;
919 task_unlock(task);
920 if (ret)
921 break;
922 }
Vivek Goyal31e4c282009-12-03 12:59:42 -0500923 return ret;
924}
925
Tejun Heo073219e2014-02-08 10:36:58 -0500926struct cgroup_subsys blkio_cgrp_subsys = {
Tejun Heo92fb9742012-11-19 08:13:38 -0800927 .css_alloc = blkcg_css_alloc,
928 .css_offline = blkcg_css_offline,
929 .css_free = blkcg_css_free,
Tejun Heo3c798392012-04-16 13:57:25 -0700930 .can_attach = blkcg_can_attach,
Tejun Heo55779642014-07-15 11:05:09 -0400931 .legacy_cftypes = blkcg_files,
Tejun Heo1ced9532014-07-08 18:02:57 -0400932#ifdef CONFIG_MEMCG
933 /*
934 * This ensures that, if available, memcg is automatically enabled
935 * together on the default hierarchy so that the owner cgroup can
936 * be retrieved from writeback pages.
937 */
938 .depends_on = 1 << memory_cgrp_id,
939#endif
Tejun Heo676f7c82012-04-01 12:09:55 -0700940};
Tejun Heo073219e2014-02-08 10:36:58 -0500941EXPORT_SYMBOL_GPL(blkio_cgrp_subsys);
Tejun Heo676f7c82012-04-01 12:09:55 -0700942
Tejun Heo8bd435b2012-04-13 13:11:28 -0700943/**
Tejun Heoa2b16932012-04-13 13:11:33 -0700944 * blkcg_activate_policy - activate a blkcg policy on a request_queue
945 * @q: request_queue of interest
946 * @pol: blkcg policy to activate
947 *
948 * Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through
949 * bypass mode to populate its blkgs with policy_data for @pol.
950 *
951 * Activation happens with @q bypassed, so nobody would be accessing blkgs
952 * from IO path. Update of each blkg is protected by both queue and blkcg
953 * locks so that holding either lock and testing blkcg_policy_enabled() is
954 * always enough for dereferencing policy data.
955 *
956 * The caller is responsible for synchronizing [de]activations and policy
957 * [un]registerations. Returns 0 on success, -errno on failure.
958 */
959int blkcg_activate_policy(struct request_queue *q,
Tejun Heo3c798392012-04-16 13:57:25 -0700960 const struct blkcg_policy *pol)
Tejun Heoa2b16932012-04-13 13:11:33 -0700961{
962 LIST_HEAD(pds);
Tejun Heo86cde6b2013-01-09 08:05:10 -0800963 struct blkcg_gq *blkg, *new_blkg;
Tejun Heoa2b16932012-04-13 13:11:33 -0700964 struct blkg_policy_data *pd, *n;
965 int cnt = 0, ret;
Tejun Heo15974992012-06-04 20:40:52 -0700966 bool preloaded;
Tejun Heoa2b16932012-04-13 13:11:33 -0700967
968 if (blkcg_policy_enabled(q, pol))
969 return 0;
970
Tejun Heo15974992012-06-04 20:40:52 -0700971 /* preallocations for root blkg */
Tejun Heo86cde6b2013-01-09 08:05:10 -0800972 new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL);
973 if (!new_blkg)
Tejun Heo15974992012-06-04 20:40:52 -0700974 return -ENOMEM;
975
Tejun Heoa2b16932012-04-13 13:11:33 -0700976 blk_queue_bypass_start(q);
977
Jun'ichi Nomurae5072662013-04-09 15:01:21 +0200978 preloaded = !radix_tree_preload(GFP_KERNEL);
979
Tejun Heo86cde6b2013-01-09 08:05:10 -0800980 /*
981 * Make sure the root blkg exists and count the existing blkgs. As
982 * @q is bypassing at this point, blkg_lookup_create() can't be
983 * used. Open code it.
984 */
Tejun Heoa2b16932012-04-13 13:11:33 -0700985 spin_lock_irq(q->queue_lock);
986
987 rcu_read_lock();
Tejun Heo86cde6b2013-01-09 08:05:10 -0800988 blkg = __blkg_lookup(&blkcg_root, q, false);
989 if (blkg)
990 blkg_free(new_blkg);
991 else
992 blkg = blkg_create(&blkcg_root, q, new_blkg);
Tejun Heoa2b16932012-04-13 13:11:33 -0700993 rcu_read_unlock();
994
Tejun Heo15974992012-06-04 20:40:52 -0700995 if (preloaded)
996 radix_tree_preload_end();
997
Tejun Heoa2b16932012-04-13 13:11:33 -0700998 if (IS_ERR(blkg)) {
999 ret = PTR_ERR(blkg);
1000 goto out_unlock;
1001 }
Tejun Heoa2b16932012-04-13 13:11:33 -07001002
1003 list_for_each_entry(blkg, &q->blkg_list, q_node)
1004 cnt++;
1005
1006 spin_unlock_irq(q->queue_lock);
1007
1008 /* allocate policy_data for all existing blkgs */
1009 while (cnt--) {
Tejun Heof95a04a2012-04-16 13:57:26 -07001010 pd = kzalloc_node(pol->pd_size, GFP_KERNEL, q->node);
Tejun Heoa2b16932012-04-13 13:11:33 -07001011 if (!pd) {
1012 ret = -ENOMEM;
1013 goto out_free;
1014 }
1015 list_add_tail(&pd->alloc_node, &pds);
1016 }
1017
1018 /*
1019 * Install the allocated pds. With @q bypassing, no new blkg
1020 * should have been created while the queue lock was dropped.
1021 */
1022 spin_lock_irq(q->queue_lock);
1023
1024 list_for_each_entry(blkg, &q->blkg_list, q_node) {
1025 if (WARN_ON(list_empty(&pds))) {
1026 /* umm... this shouldn't happen, just abort */
1027 ret = -ENOMEM;
1028 goto out_unlock;
1029 }
1030 pd = list_first_entry(&pds, struct blkg_policy_data, alloc_node);
1031 list_del_init(&pd->alloc_node);
1032
1033 /* grab blkcg lock too while installing @pd on @blkg */
1034 spin_lock(&blkg->blkcg->lock);
1035
1036 blkg->pd[pol->plid] = pd;
1037 pd->blkg = blkg;
Tejun Heob276a872013-01-09 08:05:12 -08001038 pd->plid = pol->plid;
Tejun Heof9fcc2d2012-04-16 13:57:27 -07001039 pol->pd_init_fn(blkg);
Tejun Heoa2b16932012-04-13 13:11:33 -07001040
1041 spin_unlock(&blkg->blkcg->lock);
1042 }
1043
1044 __set_bit(pol->plid, q->blkcg_pols);
1045 ret = 0;
1046out_unlock:
1047 spin_unlock_irq(q->queue_lock);
1048out_free:
1049 blk_queue_bypass_end(q);
1050 list_for_each_entry_safe(pd, n, &pds, alloc_node)
1051 kfree(pd);
1052 return ret;
1053}
1054EXPORT_SYMBOL_GPL(blkcg_activate_policy);
1055
1056/**
1057 * blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue
1058 * @q: request_queue of interest
1059 * @pol: blkcg policy to deactivate
1060 *
1061 * Deactivate @pol on @q. Follows the same synchronization rules as
1062 * blkcg_activate_policy().
1063 */
1064void blkcg_deactivate_policy(struct request_queue *q,
Tejun Heo3c798392012-04-16 13:57:25 -07001065 const struct blkcg_policy *pol)
Tejun Heoa2b16932012-04-13 13:11:33 -07001066{
Tejun Heo3c798392012-04-16 13:57:25 -07001067 struct blkcg_gq *blkg;
Tejun Heoa2b16932012-04-13 13:11:33 -07001068
1069 if (!blkcg_policy_enabled(q, pol))
1070 return;
1071
1072 blk_queue_bypass_start(q);
1073 spin_lock_irq(q->queue_lock);
1074
1075 __clear_bit(pol->plid, q->blkcg_pols);
1076
Tejun Heo6d18b002012-04-13 13:11:35 -07001077 /* if no policy is left, no need for blkgs - shoot them down */
1078 if (bitmap_empty(q->blkcg_pols, BLKCG_MAX_POLS))
1079 blkg_destroy_all(q);
1080
Tejun Heoa2b16932012-04-13 13:11:33 -07001081 list_for_each_entry(blkg, &q->blkg_list, q_node) {
1082 /* grab blkcg lock too while removing @pd from @blkg */
1083 spin_lock(&blkg->blkcg->lock);
1084
Tejun Heof427d902013-01-09 08:05:12 -08001085 if (pol->pd_offline_fn)
1086 pol->pd_offline_fn(blkg);
Tejun Heof9fcc2d2012-04-16 13:57:27 -07001087 if (pol->pd_exit_fn)
1088 pol->pd_exit_fn(blkg);
Tejun Heoa2b16932012-04-13 13:11:33 -07001089
1090 kfree(blkg->pd[pol->plid]);
1091 blkg->pd[pol->plid] = NULL;
1092
1093 spin_unlock(&blkg->blkcg->lock);
1094 }
1095
1096 spin_unlock_irq(q->queue_lock);
1097 blk_queue_bypass_end(q);
1098}
1099EXPORT_SYMBOL_GPL(blkcg_deactivate_policy);
1100
1101/**
Tejun Heo3c798392012-04-16 13:57:25 -07001102 * blkcg_policy_register - register a blkcg policy
1103 * @pol: blkcg policy to register
Tejun Heo8bd435b2012-04-13 13:11:28 -07001104 *
Tejun Heo3c798392012-04-16 13:57:25 -07001105 * Register @pol with blkcg core. Might sleep and @pol may be modified on
1106 * successful registration. Returns 0 on success and -errno on failure.
Tejun Heo8bd435b2012-04-13 13:11:28 -07001107 */
Jens Axboed5bf0292014-06-22 16:31:56 -06001108int blkcg_policy_register(struct blkcg_policy *pol)
Vivek Goyal3e252062009-12-04 10:36:42 -05001109{
Tejun Heo8bd435b2012-04-13 13:11:28 -07001110 int i, ret;
Tejun Heoe8989fa2012-03-05 13:15:20 -08001111
Tejun Heof95a04a2012-04-16 13:57:26 -07001112 if (WARN_ON(pol->pd_size < sizeof(struct blkg_policy_data)))
1113 return -EINVAL;
1114
Tejun Heobc0d6502012-04-13 13:11:26 -07001115 mutex_lock(&blkcg_pol_mutex);
1116
Tejun Heo8bd435b2012-04-13 13:11:28 -07001117 /* find an empty slot */
1118 ret = -ENOSPC;
1119 for (i = 0; i < BLKCG_MAX_POLS; i++)
Tejun Heo3c798392012-04-16 13:57:25 -07001120 if (!blkcg_policy[i])
Tejun Heo8bd435b2012-04-13 13:11:28 -07001121 break;
1122 if (i >= BLKCG_MAX_POLS)
1123 goto out_unlock;
Tejun Heo035d10b2012-03-05 13:15:04 -08001124
Tejun Heo8bd435b2012-04-13 13:11:28 -07001125 /* register and update blkgs */
Tejun Heo3c798392012-04-16 13:57:25 -07001126 pol->plid = i;
1127 blkcg_policy[i] = pol;
Tejun Heo8bd435b2012-04-13 13:11:28 -07001128
Tejun Heo8bd435b2012-04-13 13:11:28 -07001129 /* everything is in place, add intf files for the new policy */
Tejun Heo3c798392012-04-16 13:57:25 -07001130 if (pol->cftypes)
Tejun Heo2cf669a2014-07-15 11:05:09 -04001131 WARN_ON(cgroup_add_legacy_cftypes(&blkio_cgrp_subsys,
1132 pol->cftypes));
Tejun Heo8bd435b2012-04-13 13:11:28 -07001133 ret = 0;
1134out_unlock:
Tejun Heobc0d6502012-04-13 13:11:26 -07001135 mutex_unlock(&blkcg_pol_mutex);
Tejun Heo8bd435b2012-04-13 13:11:28 -07001136 return ret;
Vivek Goyal3e252062009-12-04 10:36:42 -05001137}
Tejun Heo3c798392012-04-16 13:57:25 -07001138EXPORT_SYMBOL_GPL(blkcg_policy_register);
Vivek Goyal3e252062009-12-04 10:36:42 -05001139
Tejun Heo8bd435b2012-04-13 13:11:28 -07001140/**
Tejun Heo3c798392012-04-16 13:57:25 -07001141 * blkcg_policy_unregister - unregister a blkcg policy
1142 * @pol: blkcg policy to unregister
Tejun Heo8bd435b2012-04-13 13:11:28 -07001143 *
Tejun Heo3c798392012-04-16 13:57:25 -07001144 * Undo blkcg_policy_register(@pol). Might sleep.
Tejun Heo8bd435b2012-04-13 13:11:28 -07001145 */
Tejun Heo3c798392012-04-16 13:57:25 -07001146void blkcg_policy_unregister(struct blkcg_policy *pol)
Vivek Goyal3e252062009-12-04 10:36:42 -05001147{
Tejun Heobc0d6502012-04-13 13:11:26 -07001148 mutex_lock(&blkcg_pol_mutex);
1149
Tejun Heo3c798392012-04-16 13:57:25 -07001150 if (WARN_ON(blkcg_policy[pol->plid] != pol))
Tejun Heo8bd435b2012-04-13 13:11:28 -07001151 goto out_unlock;
1152
1153 /* kill the intf files first */
Tejun Heo3c798392012-04-16 13:57:25 -07001154 if (pol->cftypes)
Tejun Heo2bb566c2013-08-08 20:11:23 -04001155 cgroup_rm_cftypes(pol->cftypes);
Tejun Heo44ea53d2012-04-01 14:38:43 -07001156
Tejun Heo8bd435b2012-04-13 13:11:28 -07001157 /* unregister and update blkgs */
Tejun Heo3c798392012-04-16 13:57:25 -07001158 blkcg_policy[pol->plid] = NULL;
Tejun Heo8bd435b2012-04-13 13:11:28 -07001159out_unlock:
Tejun Heobc0d6502012-04-13 13:11:26 -07001160 mutex_unlock(&blkcg_pol_mutex);
Vivek Goyal3e252062009-12-04 10:36:42 -05001161}
Tejun Heo3c798392012-04-16 13:57:25 -07001162EXPORT_SYMBOL_GPL(blkcg_policy_unregister);