blob: 5bcdfc10c23a6340367c4b9781496a49b5c81efe [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>
Arianna Avanzinie48453c2015-06-05 23:38:42 +020012 *
13 * For policy-specific per-blkcg data:
14 * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
15 * Arianna Avanzini <avanzini.arianna@gmail.com>
Vivek Goyal31e4c282009-12-03 12:59:42 -050016 */
17#include <linux/ioprio.h>
Vivek Goyal22084192009-12-03 12:59:49 -050018#include <linux/kdev_t.h>
Vivek Goyal9d6a9862009-12-04 10:36:41 -050019#include <linux/module.h>
Stephen Rothwellaccee782009-12-07 19:29:39 +110020#include <linux/err.h>
Divyesh Shah91952912010-04-01 15:01:41 -070021#include <linux/blkdev.h>
Tejun Heo52ebea72015-05-22 17:13:37 -040022#include <linux/backing-dev.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090023#include <linux/slab.h>
Gui Jianfeng34d0f172010-04-13 16:05:49 +080024#include <linux/genhd.h>
Tejun Heo72e06c22012-03-05 13:15:00 -080025#include <linux/delay.h>
Tejun Heo9a9e8a22012-03-19 15:10:56 -070026#include <linux/atomic.h>
Tejun Heo36aa9e52015-08-18 14:55:31 -070027#include <linux/ctype.h>
Tejun Heoeea8f412015-05-22 17:13:17 -040028#include <linux/blk-cgroup.h>
Tejun Heo5efd6112012-03-05 13:15:12 -080029#include "blk.h"
Vivek Goyal3e252062009-12-04 10:36:42 -050030
Divyesh Shah84c124d2010-04-09 08:31:19 +020031#define MAX_KEY_LEN 100
32
Tejun Heo838f13b2015-07-09 16:39:47 -040033/*
34 * blkcg_pol_mutex protects blkcg_policy[] and policy [de]activation.
35 * blkcg_pol_register_mutex nests outside of it and synchronizes entire
36 * policy [un]register operations including cgroup file additions /
37 * removals. Putting cgroup file registration outside blkcg_pol_mutex
38 * allows grabbing it from cgroup callbacks.
39 */
40static DEFINE_MUTEX(blkcg_pol_register_mutex);
Tejun Heobc0d6502012-04-13 13:11:26 -070041static DEFINE_MUTEX(blkcg_pol_mutex);
Tejun Heo923adde2012-03-05 13:15:13 -080042
Arianna Avanzinie48453c2015-06-05 23:38:42 +020043struct blkcg blkcg_root;
Tejun Heo3c798392012-04-16 13:57:25 -070044EXPORT_SYMBOL_GPL(blkcg_root);
Vivek Goyal9d6a9862009-12-04 10:36:41 -050045
Tejun Heo496d5e72015-05-22 17:13:21 -040046struct cgroup_subsys_state * const blkcg_root_css = &blkcg_root.css;
47
Tejun Heo3c798392012-04-16 13:57:25 -070048static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS];
Tejun Heo035d10b2012-03-05 13:15:04 -080049
Tejun Heo7876f932015-07-09 16:39:49 -040050static LIST_HEAD(all_blkcgs); /* protected by blkcg_pol_mutex */
51
Tejun Heoa2b16932012-04-13 13:11:33 -070052static bool blkcg_policy_enabled(struct request_queue *q,
Tejun Heo3c798392012-04-16 13:57:25 -070053 const struct blkcg_policy *pol)
Tejun Heoa2b16932012-04-13 13:11:33 -070054{
55 return pol && test_bit(pol->plid, q->blkcg_pols);
56}
57
Tejun Heo03814112012-03-05 13:15:14 -080058/**
59 * blkg_free - free a blkg
60 * @blkg: blkg to free
61 *
62 * Free @blkg which may be partially allocated.
63 */
Tejun Heo3c798392012-04-16 13:57:25 -070064static void blkg_free(struct blkcg_gq *blkg)
Tejun Heo03814112012-03-05 13:15:14 -080065{
Tejun Heoe8989fa2012-03-05 13:15:20 -080066 int i;
Tejun Heo549d3aa2012-03-05 13:15:16 -080067
68 if (!blkg)
69 return;
70
Tejun Heodb613672013-05-14 13:52:31 -070071 for (i = 0; i < BLKCG_MAX_POLS; i++)
Tejun Heo001bea72015-08-18 14:55:11 -070072 if (blkg->pd[i])
73 blkcg_policy[i]->pd_free_fn(blkg->pd[i]);
Tejun Heoe8989fa2012-03-05 13:15:20 -080074
Tejun Heo994b7832015-08-18 14:55:07 -070075 if (blkg->blkcg != &blkcg_root)
76 blk_exit_rl(&blkg->rl);
Tejun Heo77ea7332015-08-18 14:55:24 -070077
78 blkg_rwstat_exit(&blkg->stat_ios);
79 blkg_rwstat_exit(&blkg->stat_bytes);
Tejun Heo549d3aa2012-03-05 13:15:16 -080080 kfree(blkg);
Tejun Heo03814112012-03-05 13:15:14 -080081}
82
83/**
84 * blkg_alloc - allocate a blkg
85 * @blkcg: block cgroup the new blkg is associated with
86 * @q: request_queue the new blkg is associated with
Tejun Heo15974992012-06-04 20:40:52 -070087 * @gfp_mask: allocation mask to use
Tejun Heo03814112012-03-05 13:15:14 -080088 *
Tejun Heoe8989fa2012-03-05 13:15:20 -080089 * Allocate a new blkg assocating @blkcg and @q.
Tejun Heo03814112012-03-05 13:15:14 -080090 */
Tejun Heo15974992012-06-04 20:40:52 -070091static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q,
92 gfp_t gfp_mask)
Tejun Heo03814112012-03-05 13:15:14 -080093{
Tejun Heo3c798392012-04-16 13:57:25 -070094 struct blkcg_gq *blkg;
Tejun Heoe8989fa2012-03-05 13:15:20 -080095 int i;
Tejun Heo03814112012-03-05 13:15:14 -080096
97 /* alloc and init base part */
Tejun Heo15974992012-06-04 20:40:52 -070098 blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node);
Tejun Heo03814112012-03-05 13:15:14 -080099 if (!blkg)
100 return NULL;
101
Tejun Heo77ea7332015-08-18 14:55:24 -0700102 if (blkg_rwstat_init(&blkg->stat_bytes, gfp_mask) ||
103 blkg_rwstat_init(&blkg->stat_ios, gfp_mask))
104 goto err_free;
105
Tejun Heoc875f4d2012-03-05 13:15:22 -0800106 blkg->q = q;
Tejun Heoe8989fa2012-03-05 13:15:20 -0800107 INIT_LIST_HEAD(&blkg->q_node);
Tejun Heo03814112012-03-05 13:15:14 -0800108 blkg->blkcg = blkcg;
Tejun Heoa5049a82014-06-19 17:42:57 -0400109 atomic_set(&blkg->refcnt, 1);
Tejun Heo03814112012-03-05 13:15:14 -0800110
Tejun Heoa0516612012-06-26 15:05:44 -0700111 /* root blkg uses @q->root_rl, init rl only for !root blkgs */
112 if (blkcg != &blkcg_root) {
113 if (blk_init_rl(&blkg->rl, q, gfp_mask))
114 goto err_free;
115 blkg->rl.blkg = blkg;
116 }
117
Tejun Heo8bd435b2012-04-13 13:11:28 -0700118 for (i = 0; i < BLKCG_MAX_POLS; i++) {
Tejun Heo3c798392012-04-16 13:57:25 -0700119 struct blkcg_policy *pol = blkcg_policy[i];
Tejun Heoe8989fa2012-03-05 13:15:20 -0800120 struct blkg_policy_data *pd;
Tejun Heo03814112012-03-05 13:15:14 -0800121
Tejun Heoa2b16932012-04-13 13:11:33 -0700122 if (!blkcg_policy_enabled(q, pol))
Tejun Heoe8989fa2012-03-05 13:15:20 -0800123 continue;
Tejun Heo549d3aa2012-03-05 13:15:16 -0800124
Tejun Heoe8989fa2012-03-05 13:15:20 -0800125 /* alloc per-policy data and attach it to blkg */
Tejun Heo001bea72015-08-18 14:55:11 -0700126 pd = pol->pd_alloc_fn(gfp_mask, q->node);
Tejun Heoa0516612012-06-26 15:05:44 -0700127 if (!pd)
128 goto err_free;
Tejun Heo549d3aa2012-03-05 13:15:16 -0800129
Tejun Heoe8989fa2012-03-05 13:15:20 -0800130 blkg->pd[i] = pd;
131 pd->blkg = blkg;
Tejun Heob276a872013-01-09 08:05:12 -0800132 pd->plid = i;
Tejun Heoe8989fa2012-03-05 13:15:20 -0800133 }
134
Tejun Heo03814112012-03-05 13:15:14 -0800135 return blkg;
Tejun Heoa0516612012-06-26 15:05:44 -0700136
137err_free:
138 blkg_free(blkg);
139 return NULL;
Tejun Heo03814112012-03-05 13:15:14 -0800140}
141
Tejun Heo24f29042015-08-18 14:55:17 -0700142struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg,
143 struct request_queue *q, bool update_hint)
Tejun Heo80fd9972012-04-13 14:50:53 -0700144{
Tejun Heo3c798392012-04-16 13:57:25 -0700145 struct blkcg_gq *blkg;
Tejun Heo80fd9972012-04-13 14:50:53 -0700146
Tejun Heoa6371202012-04-19 16:29:24 -0700147 /*
Tejun Heo86cde6b2013-01-09 08:05:10 -0800148 * Hint didn't match. Look up from the radix tree. Note that the
149 * hint can only be updated under queue_lock as otherwise @blkg
150 * could have already been removed from blkg_tree. The caller is
151 * responsible for grabbing queue_lock if @update_hint.
Tejun Heoa6371202012-04-19 16:29:24 -0700152 */
153 blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id);
Tejun Heo86cde6b2013-01-09 08:05:10 -0800154 if (blkg && blkg->q == q) {
155 if (update_hint) {
156 lockdep_assert_held(q->queue_lock);
157 rcu_assign_pointer(blkcg->blkg_hint, blkg);
158 }
Tejun Heoa6371202012-04-19 16:29:24 -0700159 return blkg;
Tejun Heo86cde6b2013-01-09 08:05:10 -0800160 }
Tejun Heoa6371202012-04-19 16:29:24 -0700161
Tejun Heo80fd9972012-04-13 14:50:53 -0700162 return NULL;
163}
Tejun Heoae118892015-08-18 14:55:20 -0700164EXPORT_SYMBOL_GPL(blkg_lookup_slowpath);
Tejun Heo80fd9972012-04-13 14:50:53 -0700165
Tejun Heo15974992012-06-04 20:40:52 -0700166/*
167 * If @new_blkg is %NULL, this function tries to allocate a new one as
Tejun Heod93a11f2015-08-18 14:55:01 -0700168 * necessary using %GFP_NOWAIT. @new_blkg is always consumed on return.
Tejun Heo15974992012-06-04 20:40:52 -0700169 */
Tejun Heo86cde6b2013-01-09 08:05:10 -0800170static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
171 struct request_queue *q,
172 struct blkcg_gq *new_blkg)
Vivek Goyal5624a4e2011-05-19 15:38:28 -0400173{
Tejun Heo3c798392012-04-16 13:57:25 -0700174 struct blkcg_gq *blkg;
Tejun Heoce7acfe2015-05-22 17:13:38 -0400175 struct bdi_writeback_congested *wb_congested;
Tejun Heof427d902013-01-09 08:05:12 -0800176 int i, ret;
Vivek Goyal5624a4e2011-05-19 15:38:28 -0400177
Tejun Heocd1604f2012-03-05 13:15:06 -0800178 WARN_ON_ONCE(!rcu_read_lock_held());
179 lockdep_assert_held(q->queue_lock);
Vivek Goyal31e4c282009-12-03 12:59:42 -0500180
Tejun Heo7ee9c562012-03-05 13:15:11 -0800181 /* blkg holds a reference to blkcg */
Tejun Heoec903c02014-05-13 12:11:01 -0400182 if (!css_tryget_online(&blkcg->css)) {
Tejun Heo20386ce2015-08-18 14:55:28 -0700183 ret = -ENODEV;
Tejun Heo93e6d5d2013-01-09 08:05:10 -0800184 goto err_free_blkg;
Tejun Heo15974992012-06-04 20:40:52 -0700185 }
Tejun Heocd1604f2012-03-05 13:15:06 -0800186
Tejun Heoce7acfe2015-05-22 17:13:38 -0400187 wb_congested = wb_congested_get_create(&q->backing_dev_info,
Tejun Heod93a11f2015-08-18 14:55:01 -0700188 blkcg->css.id, GFP_NOWAIT);
Tejun Heoce7acfe2015-05-22 17:13:38 -0400189 if (!wb_congested) {
190 ret = -ENOMEM;
191 goto err_put_css;
192 }
193
Tejun Heo496fb782012-04-19 16:29:23 -0700194 /* allocate */
Tejun Heo15974992012-06-04 20:40:52 -0700195 if (!new_blkg) {
Tejun Heod93a11f2015-08-18 14:55:01 -0700196 new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT);
Tejun Heo15974992012-06-04 20:40:52 -0700197 if (unlikely(!new_blkg)) {
Tejun Heo93e6d5d2013-01-09 08:05:10 -0800198 ret = -ENOMEM;
Tejun Heoce7acfe2015-05-22 17:13:38 -0400199 goto err_put_congested;
Tejun Heo15974992012-06-04 20:40:52 -0700200 }
201 }
202 blkg = new_blkg;
Tejun Heoce7acfe2015-05-22 17:13:38 -0400203 blkg->wb_congested = wb_congested;
Tejun Heocd1604f2012-03-05 13:15:06 -0800204
Tejun Heodb613672013-05-14 13:52:31 -0700205 /* link parent */
Tejun Heo3c547862013-01-09 08:05:10 -0800206 if (blkcg_parent(blkcg)) {
207 blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false);
208 if (WARN_ON_ONCE(!blkg->parent)) {
Tejun Heo20386ce2015-08-18 14:55:28 -0700209 ret = -ENODEV;
Tejun Heoce7acfe2015-05-22 17:13:38 -0400210 goto err_put_congested;
Tejun Heo3c547862013-01-09 08:05:10 -0800211 }
212 blkg_get(blkg->parent);
213 }
214
Tejun Heodb613672013-05-14 13:52:31 -0700215 /* invoke per-policy init */
216 for (i = 0; i < BLKCG_MAX_POLS; i++) {
217 struct blkcg_policy *pol = blkcg_policy[i];
218
219 if (blkg->pd[i] && pol->pd_init_fn)
Tejun Heoa9520cd2015-08-18 14:55:14 -0700220 pol->pd_init_fn(blkg->pd[i]);
Tejun Heodb613672013-05-14 13:52:31 -0700221 }
222
223 /* insert */
Tejun Heoa6371202012-04-19 16:29:24 -0700224 spin_lock(&blkcg->lock);
225 ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg);
226 if (likely(!ret)) {
227 hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
228 list_add(&blkg->q_node, &q->blkg_list);
Tejun Heof427d902013-01-09 08:05:12 -0800229
230 for (i = 0; i < BLKCG_MAX_POLS; i++) {
231 struct blkcg_policy *pol = blkcg_policy[i];
232
233 if (blkg->pd[i] && pol->pd_online_fn)
Tejun Heoa9520cd2015-08-18 14:55:14 -0700234 pol->pd_online_fn(blkg->pd[i]);
Tejun Heof427d902013-01-09 08:05:12 -0800235 }
Tejun Heoa6371202012-04-19 16:29:24 -0700236 }
Tejun Heof427d902013-01-09 08:05:12 -0800237 blkg->online = true;
Tejun Heoa6371202012-04-19 16:29:24 -0700238 spin_unlock(&blkcg->lock);
239
Tejun Heoec13b1d2015-05-22 17:13:19 -0400240 if (!ret)
Tejun Heoa6371202012-04-19 16:29:24 -0700241 return blkg;
Tejun Heo15974992012-06-04 20:40:52 -0700242
Tejun Heo3c547862013-01-09 08:05:10 -0800243 /* @blkg failed fully initialized, use the usual release path */
244 blkg_put(blkg);
245 return ERR_PTR(ret);
246
Tejun Heoce7acfe2015-05-22 17:13:38 -0400247err_put_congested:
248 wb_congested_put(wb_congested);
Tejun Heo93e6d5d2013-01-09 08:05:10 -0800249err_put_css:
Tejun Heo496fb782012-04-19 16:29:23 -0700250 css_put(&blkcg->css);
Tejun Heo93e6d5d2013-01-09 08:05:10 -0800251err_free_blkg:
Tejun Heo15974992012-06-04 20:40:52 -0700252 blkg_free(new_blkg);
Tejun Heo93e6d5d2013-01-09 08:05:10 -0800253 return ERR_PTR(ret);
Vivek Goyal31e4c282009-12-03 12:59:42 -0500254}
Tejun Heo3c96cb32012-04-13 13:11:34 -0700255
Tejun Heo86cde6b2013-01-09 08:05:10 -0800256/**
257 * blkg_lookup_create - lookup blkg, try to create one if not there
258 * @blkcg: blkcg of interest
259 * @q: request_queue of interest
260 *
261 * Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to
Tejun Heo3c547862013-01-09 08:05:10 -0800262 * create one. blkg creation is performed recursively from blkcg_root such
263 * that all non-root blkg's have access to the parent blkg. This function
264 * should be called under RCU read lock and @q->queue_lock.
Tejun Heo86cde6b2013-01-09 08:05:10 -0800265 *
266 * Returns pointer to the looked up or created blkg on success, ERR_PTR()
267 * value on error. If @q is dead, returns ERR_PTR(-EINVAL). If @q is not
268 * dead and bypassing, returns ERR_PTR(-EBUSY).
269 */
Tejun Heo3c798392012-04-16 13:57:25 -0700270struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
271 struct request_queue *q)
Tejun Heo3c96cb32012-04-13 13:11:34 -0700272{
Tejun Heo86cde6b2013-01-09 08:05:10 -0800273 struct blkcg_gq *blkg;
274
275 WARN_ON_ONCE(!rcu_read_lock_held());
276 lockdep_assert_held(q->queue_lock);
277
Tejun Heo3c96cb32012-04-13 13:11:34 -0700278 /*
279 * This could be the first entry point of blkcg implementation and
280 * we shouldn't allow anything to go through for a bypassing queue.
281 */
282 if (unlikely(blk_queue_bypass(q)))
Tejun Heo20386ce2015-08-18 14:55:28 -0700283 return ERR_PTR(blk_queue_dying(q) ? -ENODEV : -EBUSY);
Tejun Heo86cde6b2013-01-09 08:05:10 -0800284
285 blkg = __blkg_lookup(blkcg, q, true);
286 if (blkg)
287 return blkg;
288
Tejun Heo3c547862013-01-09 08:05:10 -0800289 /*
290 * Create blkgs walking down from blkcg_root to @blkcg, so that all
291 * non-root blkgs have access to their parents.
292 */
293 while (true) {
294 struct blkcg *pos = blkcg;
295 struct blkcg *parent = blkcg_parent(blkcg);
296
297 while (parent && !__blkg_lookup(parent, q, false)) {
298 pos = parent;
299 parent = blkcg_parent(parent);
300 }
301
302 blkg = blkg_create(pos, q, NULL);
303 if (pos == blkcg || IS_ERR(blkg))
304 return blkg;
305 }
Tejun Heo3c96cb32012-04-13 13:11:34 -0700306}
Vivek Goyal31e4c282009-12-03 12:59:42 -0500307
Tejun Heo3c798392012-04-16 13:57:25 -0700308static void blkg_destroy(struct blkcg_gq *blkg)
Tejun Heo72e06c22012-03-05 13:15:00 -0800309{
Tejun Heo3c798392012-04-16 13:57:25 -0700310 struct blkcg *blkcg = blkg->blkcg;
Tejun Heo77ea7332015-08-18 14:55:24 -0700311 struct blkcg_gq *parent = blkg->parent;
Tejun Heof427d902013-01-09 08:05:12 -0800312 int i;
Tejun Heo03aa2642012-03-05 13:15:19 -0800313
Tejun Heo27e1f9d2012-06-05 13:36:44 +0200314 lockdep_assert_held(blkg->q->queue_lock);
Tejun Heo9f13ef62012-03-05 13:15:21 -0800315 lockdep_assert_held(&blkcg->lock);
Tejun Heo03aa2642012-03-05 13:15:19 -0800316
317 /* Something wrong if we are trying to remove same group twice */
Tejun Heoe8989fa2012-03-05 13:15:20 -0800318 WARN_ON_ONCE(list_empty(&blkg->q_node));
Tejun Heo9f13ef62012-03-05 13:15:21 -0800319 WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node));
Tejun Heoa6371202012-04-19 16:29:24 -0700320
Tejun Heof427d902013-01-09 08:05:12 -0800321 for (i = 0; i < BLKCG_MAX_POLS; i++) {
322 struct blkcg_policy *pol = blkcg_policy[i];
323
324 if (blkg->pd[i] && pol->pd_offline_fn)
Tejun Heoa9520cd2015-08-18 14:55:14 -0700325 pol->pd_offline_fn(blkg->pd[i]);
Tejun Heof427d902013-01-09 08:05:12 -0800326 }
Tejun Heo77ea7332015-08-18 14:55:24 -0700327
328 if (parent) {
329 blkg_rwstat_add_aux(&parent->stat_bytes, &blkg->stat_bytes);
330 blkg_rwstat_add_aux(&parent->stat_ios, &blkg->stat_ios);
331 }
332
Tejun Heof427d902013-01-09 08:05:12 -0800333 blkg->online = false;
334
Tejun Heoa6371202012-04-19 16:29:24 -0700335 radix_tree_delete(&blkcg->blkg_tree, blkg->q->id);
Tejun Heoe8989fa2012-03-05 13:15:20 -0800336 list_del_init(&blkg->q_node);
Tejun Heo9f13ef62012-03-05 13:15:21 -0800337 hlist_del_init_rcu(&blkg->blkcg_node);
Tejun Heo03aa2642012-03-05 13:15:19 -0800338
Tejun Heo03aa2642012-03-05 13:15:19 -0800339 /*
Tejun Heoa6371202012-04-19 16:29:24 -0700340 * Both setting lookup hint to and clearing it from @blkg are done
341 * under queue_lock. If it's not pointing to @blkg now, it never
342 * will. Hint assignment itself can race safely.
343 */
Paul E. McKenneyec6c6762014-02-17 13:35:57 -0800344 if (rcu_access_pointer(blkcg->blkg_hint) == blkg)
Tejun Heoa6371202012-04-19 16:29:24 -0700345 rcu_assign_pointer(blkcg->blkg_hint, NULL);
346
347 /*
Tejun Heo03aa2642012-03-05 13:15:19 -0800348 * Put the reference taken at the time of creation so that when all
349 * queues are gone, group can be destroyed.
350 */
351 blkg_put(blkg);
352}
353
Tejun Heo9f13ef62012-03-05 13:15:21 -0800354/**
355 * blkg_destroy_all - destroy all blkgs associated with a request_queue
356 * @q: request_queue of interest
Tejun Heo9f13ef62012-03-05 13:15:21 -0800357 *
Tejun Heo3c96cb32012-04-13 13:11:34 -0700358 * Destroy all blkgs associated with @q.
Tejun Heo9f13ef62012-03-05 13:15:21 -0800359 */
Tejun Heo3c96cb32012-04-13 13:11:34 -0700360static void blkg_destroy_all(struct request_queue *q)
Tejun Heo03aa2642012-03-05 13:15:19 -0800361{
Tejun Heo3c798392012-04-16 13:57:25 -0700362 struct blkcg_gq *blkg, *n;
Tejun Heo72e06c22012-03-05 13:15:00 -0800363
Tejun Heo6d18b002012-04-13 13:11:35 -0700364 lockdep_assert_held(q->queue_lock);
Tejun Heo72e06c22012-03-05 13:15:00 -0800365
Tejun Heo9f13ef62012-03-05 13:15:21 -0800366 list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
Tejun Heo3c798392012-04-16 13:57:25 -0700367 struct blkcg *blkcg = blkg->blkcg;
Tejun Heo72e06c22012-03-05 13:15:00 -0800368
Tejun Heo9f13ef62012-03-05 13:15:21 -0800369 spin_lock(&blkcg->lock);
370 blkg_destroy(blkg);
371 spin_unlock(&blkcg->lock);
Tejun Heo72e06c22012-03-05 13:15:00 -0800372 }
Tejun Heo6fe810b2015-09-05 15:47:36 -0400373
374 q->root_blkg = NULL;
375 q->root_rl.blkg = NULL;
Tejun Heo72e06c22012-03-05 13:15:00 -0800376}
377
Tejun Heo2a4fd072013-05-14 13:52:31 -0700378/*
379 * A group is RCU protected, but having an rcu lock does not mean that one
380 * can access all the fields of blkg and assume these are valid. For
381 * example, don't try to follow throtl_data and request queue links.
382 *
383 * Having a reference to blkg under an rcu allows accesses to only values
384 * local to groups like group stats and group rate limits.
385 */
386void __blkg_release_rcu(struct rcu_head *rcu_head)
Tejun Heo1adaf3d2012-03-05 13:15:15 -0800387{
Tejun Heo2a4fd072013-05-14 13:52:31 -0700388 struct blkcg_gq *blkg = container_of(rcu_head, struct blkcg_gq, rcu_head);
Tejun Heodb613672013-05-14 13:52:31 -0700389
Tejun Heo3c547862013-01-09 08:05:10 -0800390 /* release the blkcg and parent blkg refs this blkg has been holding */
Tejun Heo1adaf3d2012-03-05 13:15:15 -0800391 css_put(&blkg->blkcg->css);
Tejun Heoa5049a82014-06-19 17:42:57 -0400392 if (blkg->parent)
Tejun Heo3c547862013-01-09 08:05:10 -0800393 blkg_put(blkg->parent);
Tejun Heo1adaf3d2012-03-05 13:15:15 -0800394
Tejun Heoce7acfe2015-05-22 17:13:38 -0400395 wb_congested_put(blkg->wb_congested);
396
Tejun Heo2a4fd072013-05-14 13:52:31 -0700397 blkg_free(blkg);
Tejun Heo1adaf3d2012-03-05 13:15:15 -0800398}
Tejun Heo2a4fd072013-05-14 13:52:31 -0700399EXPORT_SYMBOL_GPL(__blkg_release_rcu);
Tejun Heo1adaf3d2012-03-05 13:15:15 -0800400
Tejun Heoa0516612012-06-26 15:05:44 -0700401/*
402 * The next function used by blk_queue_for_each_rl(). It's a bit tricky
403 * because the root blkg uses @q->root_rl instead of its own rl.
404 */
405struct request_list *__blk_queue_next_rl(struct request_list *rl,
406 struct request_queue *q)
407{
408 struct list_head *ent;
409 struct blkcg_gq *blkg;
410
411 /*
412 * Determine the current blkg list_head. The first entry is
413 * root_rl which is off @q->blkg_list and mapped to the head.
414 */
415 if (rl == &q->root_rl) {
416 ent = &q->blkg_list;
Jun'ichi Nomura65c77fd2012-10-22 10:15:37 +0900417 /* There are no more block groups, hence no request lists */
418 if (list_empty(ent))
419 return NULL;
Tejun Heoa0516612012-06-26 15:05:44 -0700420 } else {
421 blkg = container_of(rl, struct blkcg_gq, rl);
422 ent = &blkg->q_node;
423 }
424
425 /* walk to the next list_head, skip root blkcg */
426 ent = ent->next;
427 if (ent == &q->root_blkg->q_node)
428 ent = ent->next;
429 if (ent == &q->blkg_list)
430 return NULL;
431
432 blkg = container_of(ent, struct blkcg_gq, q_node);
433 return &blkg->rl;
434}
435
Tejun Heo182446d2013-08-08 20:11:24 -0400436static int blkcg_reset_stats(struct cgroup_subsys_state *css,
437 struct cftype *cftype, u64 val)
Divyesh Shah303a3ac2010-04-01 15:01:24 -0700438{
Tejun Heo182446d2013-08-08 20:11:24 -0400439 struct blkcg *blkcg = css_to_blkcg(css);
Tejun Heo3c798392012-04-16 13:57:25 -0700440 struct blkcg_gq *blkg;
Tejun Heobc0d6502012-04-13 13:11:26 -0700441 int i;
Divyesh Shah303a3ac2010-04-01 15:01:24 -0700442
Tejun Heo838f13b2015-07-09 16:39:47 -0400443 mutex_lock(&blkcg_pol_mutex);
Divyesh Shah303a3ac2010-04-01 15:01:24 -0700444 spin_lock_irq(&blkcg->lock);
Tejun Heo997a0262012-03-08 10:53:58 -0800445
446 /*
447 * Note that stat reset is racy - it doesn't synchronize against
448 * stat updates. This is a debug feature which shouldn't exist
449 * anyway. If you get hit by a race, retry.
450 */
Sasha Levinb67bfe02013-02-27 17:06:00 -0800451 hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
Tejun Heo77ea7332015-08-18 14:55:24 -0700452 blkg_rwstat_reset(&blkg->stat_bytes);
453 blkg_rwstat_reset(&blkg->stat_ios);
454
Tejun Heo8bd435b2012-04-13 13:11:28 -0700455 for (i = 0; i < BLKCG_MAX_POLS; i++) {
Tejun Heo3c798392012-04-16 13:57:25 -0700456 struct blkcg_policy *pol = blkcg_policy[i];
Tejun Heo549d3aa2012-03-05 13:15:16 -0800457
Tejun Heoa9520cd2015-08-18 14:55:14 -0700458 if (blkg->pd[i] && pol->pd_reset_stats_fn)
459 pol->pd_reset_stats_fn(blkg->pd[i]);
Tejun Heobc0d6502012-04-13 13:11:26 -0700460 }
Divyesh Shah303a3ac2010-04-01 15:01:24 -0700461 }
Vivek Goyalf0bdc8c2011-05-19 15:38:30 -0400462
Divyesh Shah303a3ac2010-04-01 15:01:24 -0700463 spin_unlock_irq(&blkcg->lock);
Tejun Heobc0d6502012-04-13 13:11:26 -0700464 mutex_unlock(&blkcg_pol_mutex);
Divyesh Shah303a3ac2010-04-01 15:01:24 -0700465 return 0;
466}
467
Tejun Heodd165eb2015-08-18 14:55:33 -0700468const char *blkg_dev_name(struct blkcg_gq *blkg)
Divyesh Shah303a3ac2010-04-01 15:01:24 -0700469{
Tejun Heod3d32e62012-04-01 14:38:42 -0700470 /* some drivers (floppy) instantiate a queue w/o disk registered */
471 if (blkg->q->backing_dev_info.dev)
472 return dev_name(blkg->q->backing_dev_info.dev);
473 return NULL;
Divyesh Shah303a3ac2010-04-01 15:01:24 -0700474}
Tejun Heodd165eb2015-08-18 14:55:33 -0700475EXPORT_SYMBOL_GPL(blkg_dev_name);
Divyesh Shah303a3ac2010-04-01 15:01:24 -0700476
Tejun Heod3d32e62012-04-01 14:38:42 -0700477/**
478 * blkcg_print_blkgs - helper for printing per-blkg data
479 * @sf: seq_file to print to
480 * @blkcg: blkcg of interest
481 * @prfill: fill function to print out a blkg
482 * @pol: policy in question
483 * @data: data to be passed to @prfill
484 * @show_total: to print out sum of prfill return values or not
485 *
486 * This function invokes @prfill on each blkg of @blkcg if pd for the
487 * policy specified by @pol exists. @prfill is invoked with @sf, the
Tejun Heo810ecfa2013-01-09 08:05:13 -0800488 * policy data and @data and the matching queue lock held. If @show_total
489 * is %true, the sum of the return values from @prfill is printed with
490 * "Total" label at the end.
Tejun Heod3d32e62012-04-01 14:38:42 -0700491 *
492 * This is to be used to construct print functions for
493 * cftype->read_seq_string method.
494 */
Tejun Heo3c798392012-04-16 13:57:25 -0700495void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
Tejun Heof95a04a2012-04-16 13:57:26 -0700496 u64 (*prfill)(struct seq_file *,
497 struct blkg_policy_data *, int),
Tejun Heo3c798392012-04-16 13:57:25 -0700498 const struct blkcg_policy *pol, int data,
Tejun Heoec399342012-04-13 13:11:27 -0700499 bool show_total)
Vivek Goyal5624a4e2011-05-19 15:38:28 -0400500{
Tejun Heo3c798392012-04-16 13:57:25 -0700501 struct blkcg_gq *blkg;
Tejun Heod3d32e62012-04-01 14:38:42 -0700502 u64 total = 0;
503
Tejun Heo810ecfa2013-01-09 08:05:13 -0800504 rcu_read_lock();
Linus Torvaldsee89f812013-02-28 12:52:24 -0800505 hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) {
Tejun Heo810ecfa2013-01-09 08:05:13 -0800506 spin_lock_irq(blkg->q->queue_lock);
Tejun Heoa2b16932012-04-13 13:11:33 -0700507 if (blkcg_policy_enabled(blkg->q, pol))
Tejun Heof95a04a2012-04-16 13:57:26 -0700508 total += prfill(sf, blkg->pd[pol->plid], data);
Tejun Heo810ecfa2013-01-09 08:05:13 -0800509 spin_unlock_irq(blkg->q->queue_lock);
510 }
511 rcu_read_unlock();
Tejun Heod3d32e62012-04-01 14:38:42 -0700512
513 if (show_total)
514 seq_printf(sf, "Total %llu\n", (unsigned long long)total);
515}
Tejun Heo829fdb52012-04-01 14:38:43 -0700516EXPORT_SYMBOL_GPL(blkcg_print_blkgs);
Tejun Heod3d32e62012-04-01 14:38:42 -0700517
518/**
519 * __blkg_prfill_u64 - prfill helper for a single u64 value
520 * @sf: seq_file to print to
Tejun Heof95a04a2012-04-16 13:57:26 -0700521 * @pd: policy private data of interest
Tejun Heod3d32e62012-04-01 14:38:42 -0700522 * @v: value to print
523 *
Tejun Heof95a04a2012-04-16 13:57:26 -0700524 * Print @v to @sf for the device assocaited with @pd.
Tejun Heod3d32e62012-04-01 14:38:42 -0700525 */
Tejun Heof95a04a2012-04-16 13:57:26 -0700526u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v)
Tejun Heod3d32e62012-04-01 14:38:42 -0700527{
Tejun Heof95a04a2012-04-16 13:57:26 -0700528 const char *dname = blkg_dev_name(pd->blkg);
Tejun Heod3d32e62012-04-01 14:38:42 -0700529
530 if (!dname)
531 return 0;
532
533 seq_printf(sf, "%s %llu\n", dname, (unsigned long long)v);
534 return v;
535}
Tejun Heo829fdb52012-04-01 14:38:43 -0700536EXPORT_SYMBOL_GPL(__blkg_prfill_u64);
Tejun Heod3d32e62012-04-01 14:38:42 -0700537
538/**
539 * __blkg_prfill_rwstat - prfill helper for a blkg_rwstat
540 * @sf: seq_file to print to
Tejun Heof95a04a2012-04-16 13:57:26 -0700541 * @pd: policy private data of interest
Tejun Heod3d32e62012-04-01 14:38:42 -0700542 * @rwstat: rwstat to print
543 *
Tejun Heof95a04a2012-04-16 13:57:26 -0700544 * Print @rwstat to @sf for the device assocaited with @pd.
Tejun Heod3d32e62012-04-01 14:38:42 -0700545 */
Tejun Heof95a04a2012-04-16 13:57:26 -0700546u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
Tejun Heo829fdb52012-04-01 14:38:43 -0700547 const struct blkg_rwstat *rwstat)
Tejun Heod3d32e62012-04-01 14:38:42 -0700548{
549 static const char *rwstr[] = {
550 [BLKG_RWSTAT_READ] = "Read",
551 [BLKG_RWSTAT_WRITE] = "Write",
552 [BLKG_RWSTAT_SYNC] = "Sync",
553 [BLKG_RWSTAT_ASYNC] = "Async",
554 };
Tejun Heof95a04a2012-04-16 13:57:26 -0700555 const char *dname = blkg_dev_name(pd->blkg);
Tejun Heod3d32e62012-04-01 14:38:42 -0700556 u64 v;
557 int i;
558
559 if (!dname)
560 return 0;
561
562 for (i = 0; i < BLKG_RWSTAT_NR; i++)
563 seq_printf(sf, "%s %s %llu\n", dname, rwstr[i],
Tejun Heo24bdb8e2015-08-18 14:55:22 -0700564 (unsigned long long)atomic64_read(&rwstat->aux_cnt[i]));
Tejun Heod3d32e62012-04-01 14:38:42 -0700565
Tejun Heo24bdb8e2015-08-18 14:55:22 -0700566 v = atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_READ]) +
567 atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_WRITE]);
Tejun Heod3d32e62012-04-01 14:38:42 -0700568 seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v);
569 return v;
570}
Tejun Heob50da392013-01-09 08:05:12 -0800571EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat);
Tejun Heod3d32e62012-04-01 14:38:42 -0700572
Tejun Heo5bc4afb12012-04-01 14:38:45 -0700573/**
574 * blkg_prfill_stat - prfill callback for blkg_stat
575 * @sf: seq_file to print to
Tejun Heof95a04a2012-04-16 13:57:26 -0700576 * @pd: policy private data of interest
577 * @off: offset to the blkg_stat in @pd
Tejun Heo5bc4afb12012-04-01 14:38:45 -0700578 *
579 * prfill callback for printing a blkg_stat.
580 */
Tejun Heof95a04a2012-04-16 13:57:26 -0700581u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off)
Tejun Heod3d32e62012-04-01 14:38:42 -0700582{
Tejun Heof95a04a2012-04-16 13:57:26 -0700583 return __blkg_prfill_u64(sf, pd, blkg_stat_read((void *)pd + off));
Tejun Heod3d32e62012-04-01 14:38:42 -0700584}
Tejun Heo5bc4afb12012-04-01 14:38:45 -0700585EXPORT_SYMBOL_GPL(blkg_prfill_stat);
Tejun Heod3d32e62012-04-01 14:38:42 -0700586
Tejun Heo5bc4afb12012-04-01 14:38:45 -0700587/**
588 * blkg_prfill_rwstat - prfill callback for blkg_rwstat
589 * @sf: seq_file to print to
Tejun Heof95a04a2012-04-16 13:57:26 -0700590 * @pd: policy private data of interest
591 * @off: offset to the blkg_rwstat in @pd
Tejun Heo5bc4afb12012-04-01 14:38:45 -0700592 *
593 * prfill callback for printing a blkg_rwstat.
594 */
Tejun Heof95a04a2012-04-16 13:57:26 -0700595u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
596 int off)
Tejun Heod3d32e62012-04-01 14:38:42 -0700597{
Tejun Heof95a04a2012-04-16 13:57:26 -0700598 struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd + off);
Tejun Heod3d32e62012-04-01 14:38:42 -0700599
Tejun Heof95a04a2012-04-16 13:57:26 -0700600 return __blkg_prfill_rwstat(sf, pd, &rwstat);
Tejun Heod3d32e62012-04-01 14:38:42 -0700601}
Tejun Heo5bc4afb12012-04-01 14:38:45 -0700602EXPORT_SYMBOL_GPL(blkg_prfill_rwstat);
Tejun Heod3d32e62012-04-01 14:38:42 -0700603
Tejun Heo77ea7332015-08-18 14:55:24 -0700604static u64 blkg_prfill_rwstat_field(struct seq_file *sf,
605 struct blkg_policy_data *pd, int off)
606{
607 struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd->blkg + off);
608
609 return __blkg_prfill_rwstat(sf, pd, &rwstat);
610}
611
612/**
613 * blkg_print_stat_bytes - seq_show callback for blkg->stat_bytes
614 * @sf: seq_file to print to
615 * @v: unused
616 *
617 * To be used as cftype->seq_show to print blkg->stat_bytes.
618 * cftype->private must be set to the blkcg_policy.
619 */
620int blkg_print_stat_bytes(struct seq_file *sf, void *v)
621{
622 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
623 blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private,
624 offsetof(struct blkcg_gq, stat_bytes), true);
625 return 0;
626}
627EXPORT_SYMBOL_GPL(blkg_print_stat_bytes);
628
629/**
630 * blkg_print_stat_bytes - seq_show callback for blkg->stat_ios
631 * @sf: seq_file to print to
632 * @v: unused
633 *
634 * To be used as cftype->seq_show to print blkg->stat_ios. cftype->private
635 * must be set to the blkcg_policy.
636 */
637int blkg_print_stat_ios(struct seq_file *sf, void *v)
638{
639 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
640 blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private,
641 offsetof(struct blkcg_gq, stat_ios), true);
642 return 0;
643}
644EXPORT_SYMBOL_GPL(blkg_print_stat_ios);
645
646static u64 blkg_prfill_rwstat_field_recursive(struct seq_file *sf,
647 struct blkg_policy_data *pd,
648 int off)
649{
650 struct blkg_rwstat rwstat = blkg_rwstat_recursive_sum(pd->blkg,
651 NULL, off);
652 return __blkg_prfill_rwstat(sf, pd, &rwstat);
653}
654
655/**
656 * blkg_print_stat_bytes_recursive - recursive version of blkg_print_stat_bytes
657 * @sf: seq_file to print to
658 * @v: unused
659 */
660int blkg_print_stat_bytes_recursive(struct seq_file *sf, void *v)
661{
662 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
663 blkg_prfill_rwstat_field_recursive,
664 (void *)seq_cft(sf)->private,
665 offsetof(struct blkcg_gq, stat_bytes), true);
666 return 0;
667}
668EXPORT_SYMBOL_GPL(blkg_print_stat_bytes_recursive);
669
670/**
671 * blkg_print_stat_ios_recursive - recursive version of blkg_print_stat_ios
672 * @sf: seq_file to print to
673 * @v: unused
674 */
675int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v)
676{
677 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
678 blkg_prfill_rwstat_field_recursive,
679 (void *)seq_cft(sf)->private,
680 offsetof(struct blkcg_gq, stat_ios), true);
681 return 0;
682}
683EXPORT_SYMBOL_GPL(blkg_print_stat_ios_recursive);
684
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700685/**
Tejun Heo16b3de62013-01-09 08:05:12 -0800686 * blkg_stat_recursive_sum - collect hierarchical blkg_stat
Tejun Heof12c74c2015-08-18 14:55:23 -0700687 * @blkg: blkg of interest
688 * @pol: blkcg_policy which contains the blkg_stat
689 * @off: offset to the blkg_stat in blkg_policy_data or @blkg
Tejun Heo16b3de62013-01-09 08:05:12 -0800690 *
Tejun Heof12c74c2015-08-18 14:55:23 -0700691 * Collect the blkg_stat specified by @blkg, @pol and @off and all its
692 * online descendants and their aux counts. The caller must be holding the
693 * queue lock for online tests.
694 *
695 * If @pol is NULL, blkg_stat is at @off bytes into @blkg; otherwise, it is
696 * at @off bytes into @blkg's blkg_policy_data of the policy.
Tejun Heo16b3de62013-01-09 08:05:12 -0800697 */
Tejun Heof12c74c2015-08-18 14:55:23 -0700698u64 blkg_stat_recursive_sum(struct blkcg_gq *blkg,
699 struct blkcg_policy *pol, int off)
Tejun Heo16b3de62013-01-09 08:05:12 -0800700{
Tejun Heo16b3de62013-01-09 08:05:12 -0800701 struct blkcg_gq *pos_blkg;
Tejun Heo492eb212013-08-08 20:11:25 -0400702 struct cgroup_subsys_state *pos_css;
Tejun Heobd8815a2013-08-08 20:11:27 -0400703 u64 sum = 0;
Tejun Heo16b3de62013-01-09 08:05:12 -0800704
Tejun Heof12c74c2015-08-18 14:55:23 -0700705 lockdep_assert_held(blkg->q->queue_lock);
Tejun Heo16b3de62013-01-09 08:05:12 -0800706
Tejun Heo16b3de62013-01-09 08:05:12 -0800707 rcu_read_lock();
Tejun Heof12c74c2015-08-18 14:55:23 -0700708 blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
709 struct blkg_stat *stat;
Tejun Heo16b3de62013-01-09 08:05:12 -0800710
Tejun Heof12c74c2015-08-18 14:55:23 -0700711 if (!pos_blkg->online)
712 continue;
713
714 if (pol)
715 stat = (void *)blkg_to_pd(pos_blkg, pol) + off;
716 else
717 stat = (void *)blkg + off;
718
719 sum += blkg_stat_read(stat) + atomic64_read(&stat->aux_cnt);
Tejun Heo16b3de62013-01-09 08:05:12 -0800720 }
721 rcu_read_unlock();
722
723 return sum;
724}
725EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum);
726
727/**
728 * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat
Tejun Heof12c74c2015-08-18 14:55:23 -0700729 * @blkg: blkg of interest
730 * @pol: blkcg_policy which contains the blkg_rwstat
731 * @off: offset to the blkg_rwstat in blkg_policy_data or @blkg
Tejun Heo16b3de62013-01-09 08:05:12 -0800732 *
Tejun Heof12c74c2015-08-18 14:55:23 -0700733 * Collect the blkg_rwstat specified by @blkg, @pol and @off and all its
734 * online descendants and their aux counts. The caller must be holding the
735 * queue lock for online tests.
736 *
737 * If @pol is NULL, blkg_rwstat is at @off bytes into @blkg; otherwise, it
738 * is at @off bytes into @blkg's blkg_policy_data of the policy.
Tejun Heo16b3de62013-01-09 08:05:12 -0800739 */
Tejun Heof12c74c2015-08-18 14:55:23 -0700740struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg,
741 struct blkcg_policy *pol, int off)
Tejun Heo16b3de62013-01-09 08:05:12 -0800742{
Tejun Heo16b3de62013-01-09 08:05:12 -0800743 struct blkcg_gq *pos_blkg;
Tejun Heo492eb212013-08-08 20:11:25 -0400744 struct cgroup_subsys_state *pos_css;
Tejun Heobd8815a2013-08-08 20:11:27 -0400745 struct blkg_rwstat sum = { };
Tejun Heo16b3de62013-01-09 08:05:12 -0800746 int i;
747
Tejun Heof12c74c2015-08-18 14:55:23 -0700748 lockdep_assert_held(blkg->q->queue_lock);
Tejun Heo16b3de62013-01-09 08:05:12 -0800749
Tejun Heo16b3de62013-01-09 08:05:12 -0800750 rcu_read_lock();
Tejun Heof12c74c2015-08-18 14:55:23 -0700751 blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
Tejun Heo3a7faea2015-08-18 14:55:26 -0700752 struct blkg_rwstat *rwstat;
Tejun Heo16b3de62013-01-09 08:05:12 -0800753
754 if (!pos_blkg->online)
755 continue;
756
Tejun Heof12c74c2015-08-18 14:55:23 -0700757 if (pol)
758 rwstat = (void *)blkg_to_pd(pos_blkg, pol) + off;
759 else
760 rwstat = (void *)pos_blkg + off;
761
Tejun Heo16b3de62013-01-09 08:05:12 -0800762 for (i = 0; i < BLKG_RWSTAT_NR; i++)
Tejun Heo3a7faea2015-08-18 14:55:26 -0700763 atomic64_add(atomic64_read(&rwstat->aux_cnt[i]) +
764 percpu_counter_sum_positive(&rwstat->cpu_cnt[i]),
765 &sum.aux_cnt[i]);
Tejun Heo16b3de62013-01-09 08:05:12 -0800766 }
767 rcu_read_unlock();
768
769 return sum;
770}
771EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum);
772
773/**
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700774 * blkg_conf_prep - parse and prepare for per-blkg config update
775 * @blkcg: target block cgroup
Tejun Heoda8b0662012-04-13 13:11:29 -0700776 * @pol: target policy
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700777 * @input: input string
778 * @ctx: blkg_conf_ctx to be filled
779 *
780 * Parse per-blkg config update from @input and initialize @ctx with the
Tejun Heo36aa9e52015-08-18 14:55:31 -0700781 * result. @ctx->blkg points to the blkg to be updated and @ctx->body the
782 * part of @input following MAJ:MIN. This function returns with RCU read
783 * lock and queue lock held and must be paired with blkg_conf_finish().
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700784 */
Tejun Heo3c798392012-04-16 13:57:25 -0700785int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
Tejun Heo36aa9e52015-08-18 14:55:31 -0700786 char *input, struct blkg_conf_ctx *ctx)
Tejun Heoda8b0662012-04-13 13:11:29 -0700787 __acquires(rcu) __acquires(disk->queue->queue_lock)
Gui Jianfeng34d0f172010-04-13 16:05:49 +0800788{
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700789 struct gendisk *disk;
Tejun Heo3c798392012-04-16 13:57:25 -0700790 struct blkcg_gq *blkg;
Tejun Heo726fa692012-04-01 14:38:43 -0700791 unsigned int major, minor;
Tejun Heo36aa9e52015-08-18 14:55:31 -0700792 int key_len, part, ret;
793 char *body;
Gui Jianfeng34d0f172010-04-13 16:05:49 +0800794
Tejun Heo36aa9e52015-08-18 14:55:31 -0700795 if (sscanf(input, "%u:%u%n", &major, &minor, &key_len) != 2)
Tejun Heo726fa692012-04-01 14:38:43 -0700796 return -EINVAL;
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700797
Tejun Heo36aa9e52015-08-18 14:55:31 -0700798 body = input + key_len;
799 if (!isspace(*body))
800 return -EINVAL;
801 body = skip_spaces(body);
802
Tejun Heo726fa692012-04-01 14:38:43 -0700803 disk = get_gendisk(MKDEV(major, minor), &part);
Tejun Heo5f6c2d22015-07-22 18:05:53 -0400804 if (!disk)
Tejun Heo20386ce2015-08-18 14:55:28 -0700805 return -ENODEV;
Tejun Heo5f6c2d22015-07-22 18:05:53 -0400806 if (part) {
807 put_disk(disk);
Tejun Heo20386ce2015-08-18 14:55:28 -0700808 return -ENODEV;
Tejun Heo5f6c2d22015-07-22 18:05:53 -0400809 }
Tejun Heoe56da7e2012-03-05 13:15:07 -0800810
811 rcu_read_lock();
Tejun Heo4bfd4822012-03-05 13:15:08 -0800812 spin_lock_irq(disk->queue->queue_lock);
Tejun Heoda8b0662012-04-13 13:11:29 -0700813
Tejun Heoa2b16932012-04-13 13:11:33 -0700814 if (blkcg_policy_enabled(disk->queue, pol))
Tejun Heo3c96cb32012-04-13 13:11:34 -0700815 blkg = blkg_lookup_create(blkcg, disk->queue);
Tejun Heoa2b16932012-04-13 13:11:33 -0700816 else
Tejun Heo20386ce2015-08-18 14:55:28 -0700817 blkg = ERR_PTR(-EOPNOTSUPP);
Tejun Heoe56da7e2012-03-05 13:15:07 -0800818
Tejun Heo4bfd4822012-03-05 13:15:08 -0800819 if (IS_ERR(blkg)) {
820 ret = PTR_ERR(blkg);
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700821 rcu_read_unlock();
Tejun Heoda8b0662012-04-13 13:11:29 -0700822 spin_unlock_irq(disk->queue->queue_lock);
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700823 put_disk(disk);
824 /*
825 * If queue was bypassing, we should retry. Do so after a
826 * short msleep(). It isn't strictly necessary but queue
827 * can be bypassing for some time and it's always nice to
828 * avoid busy looping.
829 */
830 if (ret == -EBUSY) {
831 msleep(10);
832 ret = restart_syscall();
Vivek Goyal7702e8f2010-09-15 17:06:36 -0400833 }
Tejun Heo726fa692012-04-01 14:38:43 -0700834 return ret;
Vivek Goyal062a6442010-09-15 17:06:33 -0400835 }
Tejun Heoe56da7e2012-03-05 13:15:07 -0800836
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700837 ctx->disk = disk;
838 ctx->blkg = blkg;
Tejun Heo36aa9e52015-08-18 14:55:31 -0700839 ctx->body = body;
Tejun Heo726fa692012-04-01 14:38:43 -0700840 return 0;
Gui Jianfeng34d0f172010-04-13 16:05:49 +0800841}
Tejun Heo829fdb52012-04-01 14:38:43 -0700842EXPORT_SYMBOL_GPL(blkg_conf_prep);
Gui Jianfeng34d0f172010-04-13 16:05:49 +0800843
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700844/**
845 * blkg_conf_finish - finish up per-blkg config update
846 * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep()
847 *
848 * Finish up after per-blkg config update. This function must be paired
849 * with blkg_conf_prep().
850 */
Tejun Heo829fdb52012-04-01 14:38:43 -0700851void blkg_conf_finish(struct blkg_conf_ctx *ctx)
Tejun Heoda8b0662012-04-13 13:11:29 -0700852 __releases(ctx->disk->queue->queue_lock) __releases(rcu)
Gui Jianfeng34d0f172010-04-13 16:05:49 +0800853{
Tejun Heoda8b0662012-04-13 13:11:29 -0700854 spin_unlock_irq(ctx->disk->queue->queue_lock);
Tejun Heo3a8b31d2012-04-01 14:38:43 -0700855 rcu_read_unlock();
856 put_disk(ctx->disk);
Gui Jianfeng34d0f172010-04-13 16:05:49 +0800857}
Tejun Heo829fdb52012-04-01 14:38:43 -0700858EXPORT_SYMBOL_GPL(blkg_conf_finish);
Gui Jianfeng34d0f172010-04-13 16:05:49 +0800859
Tejun Heo2ee867dc2015-08-18 14:55:34 -0700860static int blkcg_print_stat(struct seq_file *sf, void *v)
861{
862 struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
863 struct blkcg_gq *blkg;
864
865 rcu_read_lock();
866
867 hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) {
868 const char *dname;
869 struct blkg_rwstat rwstat;
870 u64 rbytes, wbytes, rios, wios;
871
872 dname = blkg_dev_name(blkg);
873 if (!dname)
874 continue;
875
876 spin_lock_irq(blkg->q->queue_lock);
877
878 rwstat = blkg_rwstat_recursive_sum(blkg, NULL,
879 offsetof(struct blkcg_gq, stat_bytes));
880 rbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_READ]);
881 wbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_WRITE]);
882
883 rwstat = blkg_rwstat_recursive_sum(blkg, NULL,
884 offsetof(struct blkcg_gq, stat_ios));
885 rios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_READ]);
886 wios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_WRITE]);
887
888 spin_unlock_irq(blkg->q->queue_lock);
889
890 if (rbytes || wbytes || rios || wios)
891 seq_printf(sf, "%s rbytes=%llu wbytes=%llu rios=%llu wios=%llu\n",
892 dname, rbytes, wbytes, rios, wios);
893 }
894
895 rcu_read_unlock();
896 return 0;
897}
898
899struct cftype blkcg_files[] = {
900 {
901 .name = "stat",
Tejun Heoca0752c2015-10-22 09:48:37 +0900902 .flags = CFTYPE_NOT_ON_ROOT,
Tejun Heo2ee867dc2015-08-18 14:55:34 -0700903 .seq_show = blkcg_print_stat,
904 },
905 { } /* terminate */
906};
907
Tejun Heo880f50e2015-08-18 14:55:30 -0700908struct cftype blkcg_legacy_files[] = {
Vivek Goyal31e4c282009-12-03 12:59:42 -0500909 {
Divyesh Shah84c124d2010-04-09 08:31:19 +0200910 .name = "reset_stats",
Tejun Heo3c798392012-04-16 13:57:25 -0700911 .write_u64 = blkcg_reset_stats,
Vivek Goyal22084192009-12-03 12:59:49 -0500912 },
Tejun Heo4baf6e32012-04-01 12:09:55 -0700913 { } /* terminate */
Vivek Goyal31e4c282009-12-03 12:59:42 -0500914};
915
Tejun Heo9f13ef62012-03-05 13:15:21 -0800916/**
Tejun Heo92fb9742012-11-19 08:13:38 -0800917 * blkcg_css_offline - cgroup css_offline callback
Tejun Heoeb954192013-08-08 20:11:23 -0400918 * @css: css of interest
Tejun Heo9f13ef62012-03-05 13:15:21 -0800919 *
Tejun Heoeb954192013-08-08 20:11:23 -0400920 * This function is called when @css is about to go away and responsible
921 * for shooting down all blkgs associated with @css. blkgs should be
Tejun Heo9f13ef62012-03-05 13:15:21 -0800922 * removed while holding both q and blkcg locks. As blkcg lock is nested
923 * inside q lock, this function performs reverse double lock dancing.
924 *
925 * This is the blkcg counterpart of ioc_release_fn().
926 */
Tejun Heoeb954192013-08-08 20:11:23 -0400927static void blkcg_css_offline(struct cgroup_subsys_state *css)
Vivek Goyal31e4c282009-12-03 12:59:42 -0500928{
Tejun Heoeb954192013-08-08 20:11:23 -0400929 struct blkcg *blkcg = css_to_blkcg(css);
Vivek Goyal31e4c282009-12-03 12:59:42 -0500930
Tejun Heo9f13ef62012-03-05 13:15:21 -0800931 spin_lock_irq(&blkcg->lock);
Tejun Heo7ee9c562012-03-05 13:15:11 -0800932
Tejun Heo9f13ef62012-03-05 13:15:21 -0800933 while (!hlist_empty(&blkcg->blkg_list)) {
Tejun Heo3c798392012-04-16 13:57:25 -0700934 struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first,
935 struct blkcg_gq, blkcg_node);
Tejun Heoc875f4d2012-03-05 13:15:22 -0800936 struct request_queue *q = blkg->q;
Vivek Goyalb1c35762009-12-03 12:59:47 -0500937
Tejun Heo9f13ef62012-03-05 13:15:21 -0800938 if (spin_trylock(q->queue_lock)) {
939 blkg_destroy(blkg);
940 spin_unlock(q->queue_lock);
941 } else {
942 spin_unlock_irq(&blkcg->lock);
Tejun Heo9f13ef62012-03-05 13:15:21 -0800943 cpu_relax();
Dan Carpentera5567932012-03-29 20:57:08 +0200944 spin_lock_irq(&blkcg->lock);
Jens Axboe0f3942a2010-05-03 14:28:55 +0200945 }
Tejun Heo9f13ef62012-03-05 13:15:21 -0800946 }
Jens Axboe0f3942a2010-05-03 14:28:55 +0200947
Tejun Heo9f13ef62012-03-05 13:15:21 -0800948 spin_unlock_irq(&blkcg->lock);
Tejun Heo52ebea72015-05-22 17:13:37 -0400949
950 wb_blkcg_offline(blkcg);
Tejun Heo7ee9c562012-03-05 13:15:11 -0800951}
952
Tejun Heoeb954192013-08-08 20:11:23 -0400953static void blkcg_css_free(struct cgroup_subsys_state *css)
Tejun Heo7ee9c562012-03-05 13:15:11 -0800954{
Tejun Heoeb954192013-08-08 20:11:23 -0400955 struct blkcg *blkcg = css_to_blkcg(css);
Tejun Heobc915e62015-08-18 14:55:08 -0700956 int i;
Tejun Heo7ee9c562012-03-05 13:15:11 -0800957
Tejun Heo7876f932015-07-09 16:39:49 -0400958 mutex_lock(&blkcg_pol_mutex);
Tejun Heoe4a9bde2015-08-18 14:55:16 -0700959
Tejun Heo7876f932015-07-09 16:39:49 -0400960 list_del(&blkcg->all_blkcgs_node);
Tejun Heo7876f932015-07-09 16:39:49 -0400961
Tejun Heobc915e62015-08-18 14:55:08 -0700962 for (i = 0; i < BLKCG_MAX_POLS; i++)
Tejun Heoe4a9bde2015-08-18 14:55:16 -0700963 if (blkcg->cpd[i])
964 blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]);
965
966 mutex_unlock(&blkcg_pol_mutex);
967
Tejun Heobc915e62015-08-18 14:55:08 -0700968 kfree(blkcg);
Vivek Goyal31e4c282009-12-03 12:59:42 -0500969}
970
Tejun Heoeb954192013-08-08 20:11:23 -0400971static struct cgroup_subsys_state *
972blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
Vivek Goyal31e4c282009-12-03 12:59:42 -0500973{
Tejun Heo3c798392012-04-16 13:57:25 -0700974 struct blkcg *blkcg;
Arianna Avanzinie48453c2015-06-05 23:38:42 +0200975 struct cgroup_subsys_state *ret;
976 int i;
Vivek Goyal31e4c282009-12-03 12:59:42 -0500977
Tejun Heo7876f932015-07-09 16:39:49 -0400978 mutex_lock(&blkcg_pol_mutex);
979
Tejun Heoeb954192013-08-08 20:11:23 -0400980 if (!parent_css) {
Tejun Heo3c798392012-04-16 13:57:25 -0700981 blkcg = &blkcg_root;
Tejun Heobc915e62015-08-18 14:55:08 -0700982 } else {
983 blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
984 if (!blkcg) {
985 ret = ERR_PTR(-ENOMEM);
986 goto free_blkcg;
987 }
Arianna Avanzinie48453c2015-06-05 23:38:42 +0200988 }
Vivek Goyal31e4c282009-12-03 12:59:42 -0500989
Arianna Avanzinie48453c2015-06-05 23:38:42 +0200990 for (i = 0; i < BLKCG_MAX_POLS ; i++) {
991 struct blkcg_policy *pol = blkcg_policy[i];
992 struct blkcg_policy_data *cpd;
993
994 /*
995 * If the policy hasn't been attached yet, wait for it
996 * to be attached before doing anything else. Otherwise,
997 * check if the policy requires any specific per-cgroup
998 * data: if it does, allocate and initialize it.
999 */
Tejun Heoe4a9bde2015-08-18 14:55:16 -07001000 if (!pol || !pol->cpd_alloc_fn)
Arianna Avanzinie48453c2015-06-05 23:38:42 +02001001 continue;
1002
Tejun Heoe4a9bde2015-08-18 14:55:16 -07001003 cpd = pol->cpd_alloc_fn(GFP_KERNEL);
Arianna Avanzinie48453c2015-06-05 23:38:42 +02001004 if (!cpd) {
1005 ret = ERR_PTR(-ENOMEM);
1006 goto free_pd_blkcg;
1007 }
Tejun Heo81437642015-08-18 14:55:15 -07001008 blkcg->cpd[i] = cpd;
1009 cpd->blkcg = blkcg;
Arianna Avanzinie48453c2015-06-05 23:38:42 +02001010 cpd->plid = i;
Tejun Heoe4a9bde2015-08-18 14:55:16 -07001011 if (pol->cpd_init_fn)
1012 pol->cpd_init_fn(cpd);
Arianna Avanzinie48453c2015-06-05 23:38:42 +02001013 }
1014
Vivek Goyal31e4c282009-12-03 12:59:42 -05001015 spin_lock_init(&blkcg->lock);
Tejun Heod93a11f2015-08-18 14:55:01 -07001016 INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT);
Vivek Goyal31e4c282009-12-03 12:59:42 -05001017 INIT_HLIST_HEAD(&blkcg->blkg_list);
Tejun Heo52ebea72015-05-22 17:13:37 -04001018#ifdef CONFIG_CGROUP_WRITEBACK
1019 INIT_LIST_HEAD(&blkcg->cgwb_list);
1020#endif
Tejun Heo7876f932015-07-09 16:39:49 -04001021 list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs);
1022
1023 mutex_unlock(&blkcg_pol_mutex);
Vivek Goyal31e4c282009-12-03 12:59:42 -05001024 return &blkcg->css;
Arianna Avanzinie48453c2015-06-05 23:38:42 +02001025
1026free_pd_blkcg:
1027 for (i--; i >= 0; i--)
Tejun Heoe4a9bde2015-08-18 14:55:16 -07001028 if (blkcg->cpd[i])
1029 blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]);
Arianna Avanzinie48453c2015-06-05 23:38:42 +02001030free_blkcg:
1031 kfree(blkcg);
Tejun Heo7876f932015-07-09 16:39:49 -04001032 mutex_unlock(&blkcg_pol_mutex);
Arianna Avanzinie48453c2015-06-05 23:38:42 +02001033 return ret;
Vivek Goyal31e4c282009-12-03 12:59:42 -05001034}
1035
Tejun Heo5efd6112012-03-05 13:15:12 -08001036/**
1037 * blkcg_init_queue - initialize blkcg part of request queue
1038 * @q: request_queue to initialize
1039 *
1040 * Called from blk_alloc_queue_node(). Responsible for initializing blkcg
1041 * part of new request_queue @q.
1042 *
1043 * RETURNS:
1044 * 0 on success, -errno on failure.
1045 */
1046int blkcg_init_queue(struct request_queue *q)
1047{
Tejun Heoec13b1d2015-05-22 17:13:19 -04001048 struct blkcg_gq *new_blkg, *blkg;
1049 bool preloaded;
1050 int ret;
Tejun Heo5efd6112012-03-05 13:15:12 -08001051
Tejun Heoec13b1d2015-05-22 17:13:19 -04001052 new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL);
1053 if (!new_blkg)
1054 return -ENOMEM;
1055
1056 preloaded = !radix_tree_preload(GFP_KERNEL);
1057
1058 /*
1059 * Make sure the root blkg exists and count the existing blkgs. As
1060 * @q is bypassing at this point, blkg_lookup_create() can't be
1061 * used. Open code insertion.
1062 */
1063 rcu_read_lock();
1064 spin_lock_irq(q->queue_lock);
1065 blkg = blkg_create(&blkcg_root, q, new_blkg);
1066 spin_unlock_irq(q->queue_lock);
1067 rcu_read_unlock();
1068
1069 if (preloaded)
1070 radix_tree_preload_end();
1071
1072 if (IS_ERR(blkg)) {
Tejun Heo994b7832015-08-18 14:55:07 -07001073 blkg_free(new_blkg);
Tejun Heoec13b1d2015-05-22 17:13:19 -04001074 return PTR_ERR(blkg);
1075 }
1076
1077 q->root_blkg = blkg;
1078 q->root_rl.blkg = blkg;
1079
1080 ret = blk_throtl_init(q);
1081 if (ret) {
1082 spin_lock_irq(q->queue_lock);
1083 blkg_destroy_all(q);
1084 spin_unlock_irq(q->queue_lock);
1085 }
1086 return ret;
Tejun Heo5efd6112012-03-05 13:15:12 -08001087}
1088
1089/**
1090 * blkcg_drain_queue - drain blkcg part of request_queue
1091 * @q: request_queue to drain
1092 *
1093 * Called from blk_drain_queue(). Responsible for draining blkcg part.
1094 */
1095void blkcg_drain_queue(struct request_queue *q)
1096{
1097 lockdep_assert_held(q->queue_lock);
1098
Tejun Heo0b462c82014-07-05 18:43:21 -04001099 /*
1100 * @q could be exiting and already have destroyed all blkgs as
1101 * indicated by NULL root_blkg. If so, don't confuse policies.
1102 */
1103 if (!q->root_blkg)
1104 return;
1105
Tejun Heo5efd6112012-03-05 13:15:12 -08001106 blk_throtl_drain(q);
1107}
1108
1109/**
1110 * blkcg_exit_queue - exit and release blkcg part of request_queue
1111 * @q: request_queue being released
1112 *
1113 * Called from blk_release_queue(). Responsible for exiting blkcg part.
1114 */
1115void blkcg_exit_queue(struct request_queue *q)
1116{
Tejun Heo6d18b002012-04-13 13:11:35 -07001117 spin_lock_irq(q->queue_lock);
Tejun Heo3c96cb32012-04-13 13:11:34 -07001118 blkg_destroy_all(q);
Tejun Heo6d18b002012-04-13 13:11:35 -07001119 spin_unlock_irq(q->queue_lock);
1120
Tejun Heo5efd6112012-03-05 13:15:12 -08001121 blk_throtl_exit(q);
1122}
1123
Vivek Goyal31e4c282009-12-03 12:59:42 -05001124/*
1125 * We cannot support shared io contexts, as we have no mean to support
1126 * two tasks with the same ioc in two different groups without major rework
1127 * of the main cic data structures. For now we allow a task to change
1128 * its cgroup only if it's the only owner of its ioc.
1129 */
Tejun Heoeb954192013-08-08 20:11:23 -04001130static int blkcg_can_attach(struct cgroup_subsys_state *css,
1131 struct cgroup_taskset *tset)
Vivek Goyal31e4c282009-12-03 12:59:42 -05001132{
Tejun Heobb9d97b2011-12-12 18:12:21 -08001133 struct task_struct *task;
Vivek Goyal31e4c282009-12-03 12:59:42 -05001134 struct io_context *ioc;
1135 int ret = 0;
1136
1137 /* task_lock() is needed to avoid races with exit_io_context() */
Tejun Heo924f0d92014-02-13 06:58:41 -05001138 cgroup_taskset_for_each(task, tset) {
Tejun Heobb9d97b2011-12-12 18:12:21 -08001139 task_lock(task);
1140 ioc = task->io_context;
1141 if (ioc && atomic_read(&ioc->nr_tasks) > 1)
1142 ret = -EINVAL;
1143 task_unlock(task);
1144 if (ret)
1145 break;
1146 }
Vivek Goyal31e4c282009-12-03 12:59:42 -05001147 return ret;
1148}
1149
Tejun Heo69d7fde2015-08-18 14:55:36 -07001150static void blkcg_bind(struct cgroup_subsys_state *root_css)
1151{
1152 int i;
1153
1154 mutex_lock(&blkcg_pol_mutex);
1155
1156 for (i = 0; i < BLKCG_MAX_POLS; i++) {
1157 struct blkcg_policy *pol = blkcg_policy[i];
1158 struct blkcg *blkcg;
1159
1160 if (!pol || !pol->cpd_bind_fn)
1161 continue;
1162
1163 list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node)
1164 if (blkcg->cpd[pol->plid])
1165 pol->cpd_bind_fn(blkcg->cpd[pol->plid]);
1166 }
1167 mutex_unlock(&blkcg_pol_mutex);
1168}
1169
Tejun Heoc165b3e2015-08-18 14:55:29 -07001170struct cgroup_subsys io_cgrp_subsys = {
Tejun Heo92fb9742012-11-19 08:13:38 -08001171 .css_alloc = blkcg_css_alloc,
1172 .css_offline = blkcg_css_offline,
1173 .css_free = blkcg_css_free,
Tejun Heo3c798392012-04-16 13:57:25 -07001174 .can_attach = blkcg_can_attach,
Tejun Heo69d7fde2015-08-18 14:55:36 -07001175 .bind = blkcg_bind,
Tejun Heo2ee867dc2015-08-18 14:55:34 -07001176 .dfl_cftypes = blkcg_files,
Tejun Heo880f50e2015-08-18 14:55:30 -07001177 .legacy_cftypes = blkcg_legacy_files,
Tejun Heoc165b3e2015-08-18 14:55:29 -07001178 .legacy_name = "blkio",
Tejun Heo1ced9532014-07-08 18:02:57 -04001179#ifdef CONFIG_MEMCG
1180 /*
1181 * This ensures that, if available, memcg is automatically enabled
1182 * together on the default hierarchy so that the owner cgroup can
1183 * be retrieved from writeback pages.
1184 */
1185 .depends_on = 1 << memory_cgrp_id,
1186#endif
Tejun Heo676f7c82012-04-01 12:09:55 -07001187};
Tejun Heoc165b3e2015-08-18 14:55:29 -07001188EXPORT_SYMBOL_GPL(io_cgrp_subsys);
Tejun Heo676f7c82012-04-01 12:09:55 -07001189
Tejun Heo8bd435b2012-04-13 13:11:28 -07001190/**
Tejun Heoa2b16932012-04-13 13:11:33 -07001191 * blkcg_activate_policy - activate a blkcg policy on a request_queue
1192 * @q: request_queue of interest
1193 * @pol: blkcg policy to activate
1194 *
1195 * Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through
1196 * bypass mode to populate its blkgs with policy_data for @pol.
1197 *
1198 * Activation happens with @q bypassed, so nobody would be accessing blkgs
1199 * from IO path. Update of each blkg is protected by both queue and blkcg
1200 * locks so that holding either lock and testing blkcg_policy_enabled() is
1201 * always enough for dereferencing policy data.
1202 *
1203 * The caller is responsible for synchronizing [de]activations and policy
1204 * [un]registerations. Returns 0 on success, -errno on failure.
1205 */
1206int blkcg_activate_policy(struct request_queue *q,
Tejun Heo3c798392012-04-16 13:57:25 -07001207 const struct blkcg_policy *pol)
Tejun Heoa2b16932012-04-13 13:11:33 -07001208{
Tejun Heo4c55f4f2015-08-18 14:55:09 -07001209 struct blkg_policy_data *pd_prealloc = NULL;
Tejun Heoec13b1d2015-05-22 17:13:19 -04001210 struct blkcg_gq *blkg;
Tejun Heo4c55f4f2015-08-18 14:55:09 -07001211 int ret;
Tejun Heoa2b16932012-04-13 13:11:33 -07001212
1213 if (blkcg_policy_enabled(q, pol))
1214 return 0;
1215
1216 blk_queue_bypass_start(q);
Tejun Heo4c55f4f2015-08-18 14:55:09 -07001217pd_prealloc:
1218 if (!pd_prealloc) {
Tejun Heo001bea72015-08-18 14:55:11 -07001219 pd_prealloc = pol->pd_alloc_fn(GFP_KERNEL, q->node);
Tejun Heo4c55f4f2015-08-18 14:55:09 -07001220 if (!pd_prealloc) {
Tejun Heoa2b16932012-04-13 13:11:33 -07001221 ret = -ENOMEM;
Tejun Heo4c55f4f2015-08-18 14:55:09 -07001222 goto out_bypass_end;
Tejun Heoa2b16932012-04-13 13:11:33 -07001223 }
Tejun Heoa2b16932012-04-13 13:11:33 -07001224 }
1225
Tejun Heoa2b16932012-04-13 13:11:33 -07001226 spin_lock_irq(q->queue_lock);
1227
1228 list_for_each_entry(blkg, &q->blkg_list, q_node) {
Tejun Heo4c55f4f2015-08-18 14:55:09 -07001229 struct blkg_policy_data *pd;
Tejun Heoa2b16932012-04-13 13:11:33 -07001230
Tejun Heo4c55f4f2015-08-18 14:55:09 -07001231 if (blkg->pd[pol->plid])
1232 continue;
1233
Tejun Heo001bea72015-08-18 14:55:11 -07001234 pd = pol->pd_alloc_fn(GFP_NOWAIT, q->node);
Tejun Heo4c55f4f2015-08-18 14:55:09 -07001235 if (!pd)
1236 swap(pd, pd_prealloc);
1237 if (!pd) {
1238 spin_unlock_irq(q->queue_lock);
1239 goto pd_prealloc;
1240 }
Tejun Heoa2b16932012-04-13 13:11:33 -07001241
1242 blkg->pd[pol->plid] = pd;
1243 pd->blkg = blkg;
Tejun Heob276a872013-01-09 08:05:12 -08001244 pd->plid = pol->plid;
Tejun Heo3e418712015-08-18 14:55:10 -07001245 if (pol->pd_init_fn)
Tejun Heoa9520cd2015-08-18 14:55:14 -07001246 pol->pd_init_fn(pd);
Tejun Heoa2b16932012-04-13 13:11:33 -07001247 }
1248
1249 __set_bit(pol->plid, q->blkcg_pols);
1250 ret = 0;
Tejun Heo4c55f4f2015-08-18 14:55:09 -07001251
Tejun Heoa2b16932012-04-13 13:11:33 -07001252 spin_unlock_irq(q->queue_lock);
Tejun Heo4c55f4f2015-08-18 14:55:09 -07001253out_bypass_end:
Tejun Heoa2b16932012-04-13 13:11:33 -07001254 blk_queue_bypass_end(q);
Tejun Heo001bea72015-08-18 14:55:11 -07001255 if (pd_prealloc)
1256 pol->pd_free_fn(pd_prealloc);
Tejun Heoa2b16932012-04-13 13:11:33 -07001257 return ret;
1258}
1259EXPORT_SYMBOL_GPL(blkcg_activate_policy);
1260
1261/**
1262 * blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue
1263 * @q: request_queue of interest
1264 * @pol: blkcg policy to deactivate
1265 *
1266 * Deactivate @pol on @q. Follows the same synchronization rules as
1267 * blkcg_activate_policy().
1268 */
1269void blkcg_deactivate_policy(struct request_queue *q,
Tejun Heo3c798392012-04-16 13:57:25 -07001270 const struct blkcg_policy *pol)
Tejun Heoa2b16932012-04-13 13:11:33 -07001271{
Tejun Heo3c798392012-04-16 13:57:25 -07001272 struct blkcg_gq *blkg;
Tejun Heoa2b16932012-04-13 13:11:33 -07001273
1274 if (!blkcg_policy_enabled(q, pol))
1275 return;
1276
1277 blk_queue_bypass_start(q);
1278 spin_lock_irq(q->queue_lock);
1279
1280 __clear_bit(pol->plid, q->blkcg_pols);
1281
1282 list_for_each_entry(blkg, &q->blkg_list, q_node) {
1283 /* grab blkcg lock too while removing @pd from @blkg */
1284 spin_lock(&blkg->blkcg->lock);
1285
Tejun Heo001bea72015-08-18 14:55:11 -07001286 if (blkg->pd[pol->plid]) {
Tejun Heoa9520cd2015-08-18 14:55:14 -07001287 if (pol->pd_offline_fn)
1288 pol->pd_offline_fn(blkg->pd[pol->plid]);
Tejun Heo001bea72015-08-18 14:55:11 -07001289 pol->pd_free_fn(blkg->pd[pol->plid]);
1290 blkg->pd[pol->plid] = NULL;
1291 }
Tejun Heoa2b16932012-04-13 13:11:33 -07001292
1293 spin_unlock(&blkg->blkcg->lock);
1294 }
1295
1296 spin_unlock_irq(q->queue_lock);
1297 blk_queue_bypass_end(q);
1298}
1299EXPORT_SYMBOL_GPL(blkcg_deactivate_policy);
1300
1301/**
Tejun Heo3c798392012-04-16 13:57:25 -07001302 * blkcg_policy_register - register a blkcg policy
1303 * @pol: blkcg policy to register
Tejun Heo8bd435b2012-04-13 13:11:28 -07001304 *
Tejun Heo3c798392012-04-16 13:57:25 -07001305 * Register @pol with blkcg core. Might sleep and @pol may be modified on
1306 * successful registration. Returns 0 on success and -errno on failure.
Tejun Heo8bd435b2012-04-13 13:11:28 -07001307 */
Jens Axboed5bf0292014-06-22 16:31:56 -06001308int blkcg_policy_register(struct blkcg_policy *pol)
Vivek Goyal3e252062009-12-04 10:36:42 -05001309{
Tejun Heo06b285b2015-07-09 16:39:50 -04001310 struct blkcg *blkcg;
Tejun Heo8bd435b2012-04-13 13:11:28 -07001311 int i, ret;
Tejun Heoe8989fa2012-03-05 13:15:20 -08001312
Tejun Heo838f13b2015-07-09 16:39:47 -04001313 mutex_lock(&blkcg_pol_register_mutex);
Tejun Heobc0d6502012-04-13 13:11:26 -07001314 mutex_lock(&blkcg_pol_mutex);
1315
Tejun Heo8bd435b2012-04-13 13:11:28 -07001316 /* find an empty slot */
1317 ret = -ENOSPC;
1318 for (i = 0; i < BLKCG_MAX_POLS; i++)
Tejun Heo3c798392012-04-16 13:57:25 -07001319 if (!blkcg_policy[i])
Tejun Heo8bd435b2012-04-13 13:11:28 -07001320 break;
1321 if (i >= BLKCG_MAX_POLS)
Tejun Heo838f13b2015-07-09 16:39:47 -04001322 goto err_unlock;
Tejun Heo035d10b2012-03-05 13:15:04 -08001323
Tejun Heo06b285b2015-07-09 16:39:50 -04001324 /* register @pol */
Tejun Heo3c798392012-04-16 13:57:25 -07001325 pol->plid = i;
Tejun Heo06b285b2015-07-09 16:39:50 -04001326 blkcg_policy[pol->plid] = pol;
1327
1328 /* allocate and install cpd's */
Tejun Heoe4a9bde2015-08-18 14:55:16 -07001329 if (pol->cpd_alloc_fn) {
Tejun Heo06b285b2015-07-09 16:39:50 -04001330 list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
1331 struct blkcg_policy_data *cpd;
1332
Tejun Heoe4a9bde2015-08-18 14:55:16 -07001333 cpd = pol->cpd_alloc_fn(GFP_KERNEL);
Tejun Heo06b285b2015-07-09 16:39:50 -04001334 if (!cpd) {
1335 mutex_unlock(&blkcg_pol_mutex);
1336 goto err_free_cpds;
1337 }
1338
Tejun Heo81437642015-08-18 14:55:15 -07001339 blkcg->cpd[pol->plid] = cpd;
1340 cpd->blkcg = blkcg;
Tejun Heo06b285b2015-07-09 16:39:50 -04001341 cpd->plid = pol->plid;
Tejun Heo81437642015-08-18 14:55:15 -07001342 pol->cpd_init_fn(cpd);
Tejun Heo06b285b2015-07-09 16:39:50 -04001343 }
1344 }
1345
Tejun Heo838f13b2015-07-09 16:39:47 -04001346 mutex_unlock(&blkcg_pol_mutex);
Tejun Heo8bd435b2012-04-13 13:11:28 -07001347
Tejun Heo8bd435b2012-04-13 13:11:28 -07001348 /* everything is in place, add intf files for the new policy */
Tejun Heo2ee867dc2015-08-18 14:55:34 -07001349 if (pol->dfl_cftypes)
1350 WARN_ON(cgroup_add_dfl_cftypes(&io_cgrp_subsys,
1351 pol->dfl_cftypes));
Tejun Heo880f50e2015-08-18 14:55:30 -07001352 if (pol->legacy_cftypes)
Tejun Heoc165b3e2015-08-18 14:55:29 -07001353 WARN_ON(cgroup_add_legacy_cftypes(&io_cgrp_subsys,
Tejun Heo880f50e2015-08-18 14:55:30 -07001354 pol->legacy_cftypes));
Tejun Heo838f13b2015-07-09 16:39:47 -04001355 mutex_unlock(&blkcg_pol_register_mutex);
1356 return 0;
1357
Tejun Heo06b285b2015-07-09 16:39:50 -04001358err_free_cpds:
Tejun Heoe4a9bde2015-08-18 14:55:16 -07001359 if (pol->cpd_alloc_fn) {
Tejun Heo06b285b2015-07-09 16:39:50 -04001360 list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
Tejun Heoe4a9bde2015-08-18 14:55:16 -07001361 if (blkcg->cpd[pol->plid]) {
1362 pol->cpd_free_fn(blkcg->cpd[pol->plid]);
1363 blkcg->cpd[pol->plid] = NULL;
1364 }
Tejun Heo06b285b2015-07-09 16:39:50 -04001365 }
1366 }
1367 blkcg_policy[pol->plid] = NULL;
Tejun Heo838f13b2015-07-09 16:39:47 -04001368err_unlock:
Tejun Heobc0d6502012-04-13 13:11:26 -07001369 mutex_unlock(&blkcg_pol_mutex);
Tejun Heo838f13b2015-07-09 16:39:47 -04001370 mutex_unlock(&blkcg_pol_register_mutex);
Tejun Heo8bd435b2012-04-13 13:11:28 -07001371 return ret;
Vivek Goyal3e252062009-12-04 10:36:42 -05001372}
Tejun Heo3c798392012-04-16 13:57:25 -07001373EXPORT_SYMBOL_GPL(blkcg_policy_register);
Vivek Goyal3e252062009-12-04 10:36:42 -05001374
Tejun Heo8bd435b2012-04-13 13:11:28 -07001375/**
Tejun Heo3c798392012-04-16 13:57:25 -07001376 * blkcg_policy_unregister - unregister a blkcg policy
1377 * @pol: blkcg policy to unregister
Tejun Heo8bd435b2012-04-13 13:11:28 -07001378 *
Tejun Heo3c798392012-04-16 13:57:25 -07001379 * Undo blkcg_policy_register(@pol). Might sleep.
Tejun Heo8bd435b2012-04-13 13:11:28 -07001380 */
Tejun Heo3c798392012-04-16 13:57:25 -07001381void blkcg_policy_unregister(struct blkcg_policy *pol)
Vivek Goyal3e252062009-12-04 10:36:42 -05001382{
Tejun Heo06b285b2015-07-09 16:39:50 -04001383 struct blkcg *blkcg;
1384
Tejun Heo838f13b2015-07-09 16:39:47 -04001385 mutex_lock(&blkcg_pol_register_mutex);
Tejun Heobc0d6502012-04-13 13:11:26 -07001386
Tejun Heo3c798392012-04-16 13:57:25 -07001387 if (WARN_ON(blkcg_policy[pol->plid] != pol))
Tejun Heo8bd435b2012-04-13 13:11:28 -07001388 goto out_unlock;
1389
1390 /* kill the intf files first */
Tejun Heo2ee867dc2015-08-18 14:55:34 -07001391 if (pol->dfl_cftypes)
1392 cgroup_rm_cftypes(pol->dfl_cftypes);
Tejun Heo880f50e2015-08-18 14:55:30 -07001393 if (pol->legacy_cftypes)
1394 cgroup_rm_cftypes(pol->legacy_cftypes);
Tejun Heo44ea53d2012-04-01 14:38:43 -07001395
Tejun Heo06b285b2015-07-09 16:39:50 -04001396 /* remove cpds and unregister */
Tejun Heo838f13b2015-07-09 16:39:47 -04001397 mutex_lock(&blkcg_pol_mutex);
Tejun Heo06b285b2015-07-09 16:39:50 -04001398
Tejun Heoe4a9bde2015-08-18 14:55:16 -07001399 if (pol->cpd_alloc_fn) {
Tejun Heo06b285b2015-07-09 16:39:50 -04001400 list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
Tejun Heoe4a9bde2015-08-18 14:55:16 -07001401 if (blkcg->cpd[pol->plid]) {
1402 pol->cpd_free_fn(blkcg->cpd[pol->plid]);
1403 blkcg->cpd[pol->plid] = NULL;
1404 }
Tejun Heo06b285b2015-07-09 16:39:50 -04001405 }
1406 }
Tejun Heo3c798392012-04-16 13:57:25 -07001407 blkcg_policy[pol->plid] = NULL;
Tejun Heo06b285b2015-07-09 16:39:50 -04001408
Tejun Heobc0d6502012-04-13 13:11:26 -07001409 mutex_unlock(&blkcg_pol_mutex);
Tejun Heo838f13b2015-07-09 16:39:47 -04001410out_unlock:
1411 mutex_unlock(&blkcg_pol_register_mutex);
Vivek Goyal3e252062009-12-04 10:36:42 -05001412}
Tejun Heo3c798392012-04-16 13:57:25 -07001413EXPORT_SYMBOL_GPL(blkcg_policy_unregister);