882 lines
22 KiB
C
882 lines
22 KiB
C
/*
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* Common Block IO controller cgroup interface
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*
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* Based on ideas and code from CFQ, CFS and BFQ:
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* Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
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*
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* Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
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* Paolo Valente <paolo.valente@unimore.it>
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*
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* Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
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* Nauman Rafique <nauman@google.com>
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*/
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#include <linux/ioprio.h>
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#include <linux/kdev_t.h>
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#include <linux/module.h>
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#include <linux/err.h>
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#include <linux/blkdev.h>
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#include <linux/slab.h>
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#include <linux/genhd.h>
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#include <linux/delay.h>
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#include <linux/atomic.h>
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#include "blk-cgroup.h"
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#include "blk.h"
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#define MAX_KEY_LEN 100
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static DEFINE_MUTEX(blkcg_pol_mutex);
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struct blkcg blkcg_root = { .cfq_weight = 2 * CFQ_WEIGHT_DEFAULT };
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EXPORT_SYMBOL_GPL(blkcg_root);
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static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS];
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struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup)
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{
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return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
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struct blkcg, css);
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}
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EXPORT_SYMBOL_GPL(cgroup_to_blkcg);
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static struct blkcg *task_blkcg(struct task_struct *tsk)
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{
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return container_of(task_subsys_state(tsk, blkio_subsys_id),
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struct blkcg, css);
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}
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struct blkcg *bio_blkcg(struct bio *bio)
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{
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if (bio && bio->bi_css)
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return container_of(bio->bi_css, struct blkcg, css);
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return task_blkcg(current);
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}
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EXPORT_SYMBOL_GPL(bio_blkcg);
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static bool blkcg_policy_enabled(struct request_queue *q,
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const struct blkcg_policy *pol)
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{
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return pol && test_bit(pol->plid, q->blkcg_pols);
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}
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/**
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* blkg_free - free a blkg
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* @blkg: blkg to free
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*
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* Free @blkg which may be partially allocated.
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*/
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static void blkg_free(struct blkcg_gq *blkg)
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{
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int i;
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if (!blkg)
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return;
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for (i = 0; i < BLKCG_MAX_POLS; i++) {
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struct blkcg_policy *pol = blkcg_policy[i];
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struct blkg_policy_data *pd = blkg->pd[i];
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if (!pd)
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continue;
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if (pol && pol->ops.pd_exit_fn)
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pol->ops.pd_exit_fn(blkg);
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kfree(pd);
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}
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kfree(blkg);
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}
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/**
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* blkg_alloc - allocate a blkg
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* @blkcg: block cgroup the new blkg is associated with
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* @q: request_queue the new blkg is associated with
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*
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* Allocate a new blkg assocating @blkcg and @q.
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*/
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static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q)
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{
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struct blkcg_gq *blkg;
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int i;
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/* alloc and init base part */
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blkg = kzalloc_node(sizeof(*blkg), GFP_ATOMIC, q->node);
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if (!blkg)
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return NULL;
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blkg->q = q;
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INIT_LIST_HEAD(&blkg->q_node);
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blkg->blkcg = blkcg;
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blkg->refcnt = 1;
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for (i = 0; i < BLKCG_MAX_POLS; i++) {
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struct blkcg_policy *pol = blkcg_policy[i];
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struct blkg_policy_data *pd;
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if (!blkcg_policy_enabled(q, pol))
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continue;
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/* alloc per-policy data and attach it to blkg */
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pd = kzalloc_node(pol->pd_size, GFP_ATOMIC, q->node);
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if (!pd) {
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blkg_free(blkg);
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return NULL;
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}
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blkg->pd[i] = pd;
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pd->blkg = blkg;
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}
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/* invoke per-policy init */
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for (i = 0; i < BLKCG_MAX_POLS; i++) {
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struct blkcg_policy *pol = blkcg_policy[i];
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if (blkcg_policy_enabled(blkg->q, pol))
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pol->ops.pd_init_fn(blkg);
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}
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return blkg;
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}
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static struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg,
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struct request_queue *q)
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{
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struct blkcg_gq *blkg;
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struct hlist_node *n;
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hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node)
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if (blkg->q == q)
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return blkg;
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return NULL;
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}
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/**
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* blkg_lookup - lookup blkg for the specified blkcg - q pair
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* @blkcg: blkcg of interest
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* @q: request_queue of interest
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*
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* Lookup blkg for the @blkcg - @q pair. This function should be called
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* under RCU read lock and is guaranteed to return %NULL if @q is bypassing
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* - see blk_queue_bypass_start() for details.
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*/
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struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q)
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{
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WARN_ON_ONCE(!rcu_read_lock_held());
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if (unlikely(blk_queue_bypass(q)))
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return NULL;
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return __blkg_lookup(blkcg, q);
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}
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EXPORT_SYMBOL_GPL(blkg_lookup);
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static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
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struct request_queue *q)
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__releases(q->queue_lock) __acquires(q->queue_lock)
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{
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struct blkcg_gq *blkg;
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WARN_ON_ONCE(!rcu_read_lock_held());
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lockdep_assert_held(q->queue_lock);
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blkg = __blkg_lookup(blkcg, q);
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if (blkg)
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return blkg;
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/* blkg holds a reference to blkcg */
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if (!css_tryget(&blkcg->css))
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return ERR_PTR(-EINVAL);
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/*
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* Allocate and initialize.
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*/
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blkg = blkg_alloc(blkcg, q);
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/* did alloc fail? */
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if (unlikely(!blkg)) {
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blkg = ERR_PTR(-ENOMEM);
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goto out;
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}
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/* insert */
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spin_lock(&blkcg->lock);
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hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
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list_add(&blkg->q_node, &q->blkg_list);
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spin_unlock(&blkcg->lock);
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out:
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return blkg;
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}
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struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
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struct request_queue *q)
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{
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/*
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* This could be the first entry point of blkcg implementation and
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* we shouldn't allow anything to go through for a bypassing queue.
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*/
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if (unlikely(blk_queue_bypass(q)))
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return ERR_PTR(blk_queue_dead(q) ? -EINVAL : -EBUSY);
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return __blkg_lookup_create(blkcg, q);
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}
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EXPORT_SYMBOL_GPL(blkg_lookup_create);
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static void blkg_destroy(struct blkcg_gq *blkg)
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{
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struct request_queue *q = blkg->q;
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struct blkcg *blkcg = blkg->blkcg;
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lockdep_assert_held(q->queue_lock);
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lockdep_assert_held(&blkcg->lock);
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/* Something wrong if we are trying to remove same group twice */
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WARN_ON_ONCE(list_empty(&blkg->q_node));
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WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node));
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list_del_init(&blkg->q_node);
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hlist_del_init_rcu(&blkg->blkcg_node);
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/*
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* Put the reference taken at the time of creation so that when all
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* queues are gone, group can be destroyed.
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*/
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blkg_put(blkg);
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}
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/**
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* blkg_destroy_all - destroy all blkgs associated with a request_queue
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* @q: request_queue of interest
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*
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* Destroy all blkgs associated with @q.
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*/
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static void blkg_destroy_all(struct request_queue *q)
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{
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struct blkcg_gq *blkg, *n;
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lockdep_assert_held(q->queue_lock);
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list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
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struct blkcg *blkcg = blkg->blkcg;
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spin_lock(&blkcg->lock);
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blkg_destroy(blkg);
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spin_unlock(&blkcg->lock);
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}
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}
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static void blkg_rcu_free(struct rcu_head *rcu_head)
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{
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blkg_free(container_of(rcu_head, struct blkcg_gq, rcu_head));
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}
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void __blkg_release(struct blkcg_gq *blkg)
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{
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/* release the extra blkcg reference this blkg has been holding */
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css_put(&blkg->blkcg->css);
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/*
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* A group is freed in rcu manner. But having an rcu lock does not
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* mean that one can access all the fields of blkg and assume these
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* are valid. For example, don't try to follow throtl_data and
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* request queue links.
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*
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* Having a reference to blkg under an rcu allows acess to only
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* values local to groups like group stats and group rate limits
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*/
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call_rcu(&blkg->rcu_head, blkg_rcu_free);
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}
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EXPORT_SYMBOL_GPL(__blkg_release);
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static int blkcg_reset_stats(struct cgroup *cgroup, struct cftype *cftype,
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u64 val)
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{
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struct blkcg *blkcg = cgroup_to_blkcg(cgroup);
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struct blkcg_gq *blkg;
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struct hlist_node *n;
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int i;
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mutex_lock(&blkcg_pol_mutex);
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spin_lock_irq(&blkcg->lock);
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/*
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* Note that stat reset is racy - it doesn't synchronize against
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* stat updates. This is a debug feature which shouldn't exist
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* anyway. If you get hit by a race, retry.
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*/
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hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
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for (i = 0; i < BLKCG_MAX_POLS; i++) {
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struct blkcg_policy *pol = blkcg_policy[i];
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if (blkcg_policy_enabled(blkg->q, pol) &&
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pol->ops.pd_reset_stats_fn)
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pol->ops.pd_reset_stats_fn(blkg);
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}
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}
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spin_unlock_irq(&blkcg->lock);
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mutex_unlock(&blkcg_pol_mutex);
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return 0;
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}
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static const char *blkg_dev_name(struct blkcg_gq *blkg)
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{
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/* some drivers (floppy) instantiate a queue w/o disk registered */
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if (blkg->q->backing_dev_info.dev)
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return dev_name(blkg->q->backing_dev_info.dev);
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return NULL;
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}
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/**
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* blkcg_print_blkgs - helper for printing per-blkg data
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* @sf: seq_file to print to
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* @blkcg: blkcg of interest
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* @prfill: fill function to print out a blkg
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* @pol: policy in question
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* @data: data to be passed to @prfill
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* @show_total: to print out sum of prfill return values or not
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*
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* This function invokes @prfill on each blkg of @blkcg if pd for the
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* policy specified by @pol exists. @prfill is invoked with @sf, the
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* policy data and @data. If @show_total is %true, the sum of the return
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* values from @prfill is printed with "Total" label at the end.
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*
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* This is to be used to construct print functions for
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* cftype->read_seq_string method.
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*/
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void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
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u64 (*prfill)(struct seq_file *,
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struct blkg_policy_data *, int),
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const struct blkcg_policy *pol, int data,
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bool show_total)
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{
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struct blkcg_gq *blkg;
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struct hlist_node *n;
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u64 total = 0;
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spin_lock_irq(&blkcg->lock);
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hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node)
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if (blkcg_policy_enabled(blkg->q, pol))
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total += prfill(sf, blkg->pd[pol->plid], data);
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spin_unlock_irq(&blkcg->lock);
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if (show_total)
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seq_printf(sf, "Total %llu\n", (unsigned long long)total);
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}
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EXPORT_SYMBOL_GPL(blkcg_print_blkgs);
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/**
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* __blkg_prfill_u64 - prfill helper for a single u64 value
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* @sf: seq_file to print to
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* @pd: policy private data of interest
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* @v: value to print
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*
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* Print @v to @sf for the device assocaited with @pd.
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*/
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u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v)
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{
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const char *dname = blkg_dev_name(pd->blkg);
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if (!dname)
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return 0;
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seq_printf(sf, "%s %llu\n", dname, (unsigned long long)v);
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return v;
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}
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EXPORT_SYMBOL_GPL(__blkg_prfill_u64);
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/**
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* __blkg_prfill_rwstat - prfill helper for a blkg_rwstat
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* @sf: seq_file to print to
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* @pd: policy private data of interest
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* @rwstat: rwstat to print
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*
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* Print @rwstat to @sf for the device assocaited with @pd.
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*/
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u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
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const struct blkg_rwstat *rwstat)
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{
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static const char *rwstr[] = {
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[BLKG_RWSTAT_READ] = "Read",
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[BLKG_RWSTAT_WRITE] = "Write",
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[BLKG_RWSTAT_SYNC] = "Sync",
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[BLKG_RWSTAT_ASYNC] = "Async",
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};
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const char *dname = blkg_dev_name(pd->blkg);
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u64 v;
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int i;
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if (!dname)
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return 0;
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for (i = 0; i < BLKG_RWSTAT_NR; i++)
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seq_printf(sf, "%s %s %llu\n", dname, rwstr[i],
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(unsigned long long)rwstat->cnt[i]);
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v = rwstat->cnt[BLKG_RWSTAT_READ] + rwstat->cnt[BLKG_RWSTAT_WRITE];
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seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v);
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return v;
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}
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/**
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* blkg_prfill_stat - prfill callback for blkg_stat
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* @sf: seq_file to print to
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* @pd: policy private data of interest
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* @off: offset to the blkg_stat in @pd
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*
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* prfill callback for printing a blkg_stat.
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*/
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u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off)
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{
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return __blkg_prfill_u64(sf, pd, blkg_stat_read((void *)pd + off));
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}
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EXPORT_SYMBOL_GPL(blkg_prfill_stat);
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/**
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* blkg_prfill_rwstat - prfill callback for blkg_rwstat
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* @sf: seq_file to print to
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* @pd: policy private data of interest
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* @off: offset to the blkg_rwstat in @pd
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*
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* prfill callback for printing a blkg_rwstat.
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*/
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u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
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int off)
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{
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struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd + off);
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return __blkg_prfill_rwstat(sf, pd, &rwstat);
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}
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EXPORT_SYMBOL_GPL(blkg_prfill_rwstat);
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/**
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* blkg_conf_prep - parse and prepare for per-blkg config update
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* @blkcg: target block cgroup
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* @pol: target policy
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* @input: input string
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* @ctx: blkg_conf_ctx to be filled
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*
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* Parse per-blkg config update from @input and initialize @ctx with the
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* result. @ctx->blkg points to the blkg to be updated and @ctx->v the new
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* value. This function returns with RCU read lock and queue lock held and
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* must be paired with blkg_conf_finish().
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*/
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int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
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const char *input, struct blkg_conf_ctx *ctx)
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__acquires(rcu) __acquires(disk->queue->queue_lock)
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{
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struct gendisk *disk;
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struct blkcg_gq *blkg;
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unsigned int major, minor;
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unsigned long long v;
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int part, ret;
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if (sscanf(input, "%u:%u %llu", &major, &minor, &v) != 3)
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return -EINVAL;
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disk = get_gendisk(MKDEV(major, minor), &part);
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if (!disk || part)
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return -EINVAL;
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rcu_read_lock();
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spin_lock_irq(disk->queue->queue_lock);
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if (blkcg_policy_enabled(disk->queue, pol))
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blkg = blkg_lookup_create(blkcg, disk->queue);
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else
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blkg = ERR_PTR(-EINVAL);
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if (IS_ERR(blkg)) {
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ret = PTR_ERR(blkg);
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rcu_read_unlock();
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spin_unlock_irq(disk->queue->queue_lock);
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put_disk(disk);
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/*
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* If queue was bypassing, we should retry. Do so after a
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* short msleep(). It isn't strictly necessary but queue
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* can be bypassing for some time and it's always nice to
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* avoid busy looping.
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*/
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if (ret == -EBUSY) {
|
|
msleep(10);
|
|
ret = restart_syscall();
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
ctx->disk = disk;
|
|
ctx->blkg = blkg;
|
|
ctx->v = v;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_conf_prep);
|
|
|
|
/**
|
|
* blkg_conf_finish - finish up per-blkg config update
|
|
* @ctx: blkg_conf_ctx intiailized by blkg_conf_prep()
|
|
*
|
|
* Finish up after per-blkg config update. This function must be paired
|
|
* with blkg_conf_prep().
|
|
*/
|
|
void blkg_conf_finish(struct blkg_conf_ctx *ctx)
|
|
__releases(ctx->disk->queue->queue_lock) __releases(rcu)
|
|
{
|
|
spin_unlock_irq(ctx->disk->queue->queue_lock);
|
|
rcu_read_unlock();
|
|
put_disk(ctx->disk);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_conf_finish);
|
|
|
|
struct cftype blkcg_files[] = {
|
|
{
|
|
.name = "reset_stats",
|
|
.write_u64 = blkcg_reset_stats,
|
|
},
|
|
{ } /* terminate */
|
|
};
|
|
|
|
/**
|
|
* blkcg_pre_destroy - cgroup pre_destroy callback
|
|
* @cgroup: cgroup of interest
|
|
*
|
|
* This function is called when @cgroup is about to go away and responsible
|
|
* for shooting down all blkgs associated with @cgroup. blkgs should be
|
|
* removed while holding both q and blkcg locks. As blkcg lock is nested
|
|
* inside q lock, this function performs reverse double lock dancing.
|
|
*
|
|
* This is the blkcg counterpart of ioc_release_fn().
|
|
*/
|
|
static int blkcg_pre_destroy(struct cgroup *cgroup)
|
|
{
|
|
struct blkcg *blkcg = cgroup_to_blkcg(cgroup);
|
|
|
|
spin_lock_irq(&blkcg->lock);
|
|
|
|
while (!hlist_empty(&blkcg->blkg_list)) {
|
|
struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first,
|
|
struct blkcg_gq, blkcg_node);
|
|
struct request_queue *q = blkg->q;
|
|
|
|
if (spin_trylock(q->queue_lock)) {
|
|
blkg_destroy(blkg);
|
|
spin_unlock(q->queue_lock);
|
|
} else {
|
|
spin_unlock_irq(&blkcg->lock);
|
|
cpu_relax();
|
|
spin_lock_irq(&blkcg->lock);
|
|
}
|
|
}
|
|
|
|
spin_unlock_irq(&blkcg->lock);
|
|
return 0;
|
|
}
|
|
|
|
static void blkcg_destroy(struct cgroup *cgroup)
|
|
{
|
|
struct blkcg *blkcg = cgroup_to_blkcg(cgroup);
|
|
|
|
if (blkcg != &blkcg_root)
|
|
kfree(blkcg);
|
|
}
|
|
|
|
static struct cgroup_subsys_state *blkcg_create(struct cgroup *cgroup)
|
|
{
|
|
static atomic64_t id_seq = ATOMIC64_INIT(0);
|
|
struct blkcg *blkcg;
|
|
struct cgroup *parent = cgroup->parent;
|
|
|
|
if (!parent) {
|
|
blkcg = &blkcg_root;
|
|
goto done;
|
|
}
|
|
|
|
blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
|
|
if (!blkcg)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
blkcg->cfq_weight = CFQ_WEIGHT_DEFAULT;
|
|
blkcg->id = atomic64_inc_return(&id_seq); /* root is 0, start from 1 */
|
|
done:
|
|
spin_lock_init(&blkcg->lock);
|
|
INIT_HLIST_HEAD(&blkcg->blkg_list);
|
|
|
|
return &blkcg->css;
|
|
}
|
|
|
|
/**
|
|
* blkcg_init_queue - initialize blkcg part of request queue
|
|
* @q: request_queue to initialize
|
|
*
|
|
* Called from blk_alloc_queue_node(). Responsible for initializing blkcg
|
|
* part of new request_queue @q.
|
|
*
|
|
* RETURNS:
|
|
* 0 on success, -errno on failure.
|
|
*/
|
|
int blkcg_init_queue(struct request_queue *q)
|
|
{
|
|
might_sleep();
|
|
|
|
return blk_throtl_init(q);
|
|
}
|
|
|
|
/**
|
|
* blkcg_drain_queue - drain blkcg part of request_queue
|
|
* @q: request_queue to drain
|
|
*
|
|
* Called from blk_drain_queue(). Responsible for draining blkcg part.
|
|
*/
|
|
void blkcg_drain_queue(struct request_queue *q)
|
|
{
|
|
lockdep_assert_held(q->queue_lock);
|
|
|
|
blk_throtl_drain(q);
|
|
}
|
|
|
|
/**
|
|
* blkcg_exit_queue - exit and release blkcg part of request_queue
|
|
* @q: request_queue being released
|
|
*
|
|
* Called from blk_release_queue(). Responsible for exiting blkcg part.
|
|
*/
|
|
void blkcg_exit_queue(struct request_queue *q)
|
|
{
|
|
spin_lock_irq(q->queue_lock);
|
|
blkg_destroy_all(q);
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
blk_throtl_exit(q);
|
|
}
|
|
|
|
/*
|
|
* We cannot support shared io contexts, as we have no mean to support
|
|
* two tasks with the same ioc in two different groups without major rework
|
|
* of the main cic data structures. For now we allow a task to change
|
|
* its cgroup only if it's the only owner of its ioc.
|
|
*/
|
|
static int blkcg_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
|
|
{
|
|
struct task_struct *task;
|
|
struct io_context *ioc;
|
|
int ret = 0;
|
|
|
|
/* task_lock() is needed to avoid races with exit_io_context() */
|
|
cgroup_taskset_for_each(task, cgrp, tset) {
|
|
task_lock(task);
|
|
ioc = task->io_context;
|
|
if (ioc && atomic_read(&ioc->nr_tasks) > 1)
|
|
ret = -EINVAL;
|
|
task_unlock(task);
|
|
if (ret)
|
|
break;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
struct cgroup_subsys blkio_subsys = {
|
|
.name = "blkio",
|
|
.create = blkcg_create,
|
|
.can_attach = blkcg_can_attach,
|
|
.pre_destroy = blkcg_pre_destroy,
|
|
.destroy = blkcg_destroy,
|
|
.subsys_id = blkio_subsys_id,
|
|
.base_cftypes = blkcg_files,
|
|
.module = THIS_MODULE,
|
|
};
|
|
EXPORT_SYMBOL_GPL(blkio_subsys);
|
|
|
|
/**
|
|
* blkcg_activate_policy - activate a blkcg policy on a request_queue
|
|
* @q: request_queue of interest
|
|
* @pol: blkcg policy to activate
|
|
*
|
|
* Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through
|
|
* bypass mode to populate its blkgs with policy_data for @pol.
|
|
*
|
|
* Activation happens with @q bypassed, so nobody would be accessing blkgs
|
|
* from IO path. Update of each blkg is protected by both queue and blkcg
|
|
* locks so that holding either lock and testing blkcg_policy_enabled() is
|
|
* always enough for dereferencing policy data.
|
|
*
|
|
* The caller is responsible for synchronizing [de]activations and policy
|
|
* [un]registerations. Returns 0 on success, -errno on failure.
|
|
*/
|
|
int blkcg_activate_policy(struct request_queue *q,
|
|
const struct blkcg_policy *pol)
|
|
{
|
|
LIST_HEAD(pds);
|
|
struct blkcg_gq *blkg;
|
|
struct blkg_policy_data *pd, *n;
|
|
int cnt = 0, ret;
|
|
|
|
if (blkcg_policy_enabled(q, pol))
|
|
return 0;
|
|
|
|
blk_queue_bypass_start(q);
|
|
|
|
/* make sure the root blkg exists and count the existing blkgs */
|
|
spin_lock_irq(q->queue_lock);
|
|
|
|
rcu_read_lock();
|
|
blkg = __blkg_lookup_create(&blkcg_root, q);
|
|
rcu_read_unlock();
|
|
|
|
if (IS_ERR(blkg)) {
|
|
ret = PTR_ERR(blkg);
|
|
goto out_unlock;
|
|
}
|
|
q->root_blkg = blkg;
|
|
|
|
list_for_each_entry(blkg, &q->blkg_list, q_node)
|
|
cnt++;
|
|
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
/* allocate policy_data for all existing blkgs */
|
|
while (cnt--) {
|
|
pd = kzalloc_node(pol->pd_size, GFP_KERNEL, q->node);
|
|
if (!pd) {
|
|
ret = -ENOMEM;
|
|
goto out_free;
|
|
}
|
|
list_add_tail(&pd->alloc_node, &pds);
|
|
}
|
|
|
|
/*
|
|
* Install the allocated pds. With @q bypassing, no new blkg
|
|
* should have been created while the queue lock was dropped.
|
|
*/
|
|
spin_lock_irq(q->queue_lock);
|
|
|
|
list_for_each_entry(blkg, &q->blkg_list, q_node) {
|
|
if (WARN_ON(list_empty(&pds))) {
|
|
/* umm... this shouldn't happen, just abort */
|
|
ret = -ENOMEM;
|
|
goto out_unlock;
|
|
}
|
|
pd = list_first_entry(&pds, struct blkg_policy_data, alloc_node);
|
|
list_del_init(&pd->alloc_node);
|
|
|
|
/* grab blkcg lock too while installing @pd on @blkg */
|
|
spin_lock(&blkg->blkcg->lock);
|
|
|
|
blkg->pd[pol->plid] = pd;
|
|
pd->blkg = blkg;
|
|
pol->ops.pd_init_fn(blkg);
|
|
|
|
spin_unlock(&blkg->blkcg->lock);
|
|
}
|
|
|
|
__set_bit(pol->plid, q->blkcg_pols);
|
|
ret = 0;
|
|
out_unlock:
|
|
spin_unlock_irq(q->queue_lock);
|
|
out_free:
|
|
blk_queue_bypass_end(q);
|
|
list_for_each_entry_safe(pd, n, &pds, alloc_node)
|
|
kfree(pd);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_activate_policy);
|
|
|
|
/**
|
|
* blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue
|
|
* @q: request_queue of interest
|
|
* @pol: blkcg policy to deactivate
|
|
*
|
|
* Deactivate @pol on @q. Follows the same synchronization rules as
|
|
* blkcg_activate_policy().
|
|
*/
|
|
void blkcg_deactivate_policy(struct request_queue *q,
|
|
const struct blkcg_policy *pol)
|
|
{
|
|
struct blkcg_gq *blkg;
|
|
|
|
if (!blkcg_policy_enabled(q, pol))
|
|
return;
|
|
|
|
blk_queue_bypass_start(q);
|
|
spin_lock_irq(q->queue_lock);
|
|
|
|
__clear_bit(pol->plid, q->blkcg_pols);
|
|
|
|
/* if no policy is left, no need for blkgs - shoot them down */
|
|
if (bitmap_empty(q->blkcg_pols, BLKCG_MAX_POLS))
|
|
blkg_destroy_all(q);
|
|
|
|
list_for_each_entry(blkg, &q->blkg_list, q_node) {
|
|
/* grab blkcg lock too while removing @pd from @blkg */
|
|
spin_lock(&blkg->blkcg->lock);
|
|
|
|
if (pol->ops.pd_exit_fn)
|
|
pol->ops.pd_exit_fn(blkg);
|
|
|
|
kfree(blkg->pd[pol->plid]);
|
|
blkg->pd[pol->plid] = NULL;
|
|
|
|
spin_unlock(&blkg->blkcg->lock);
|
|
}
|
|
|
|
spin_unlock_irq(q->queue_lock);
|
|
blk_queue_bypass_end(q);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_deactivate_policy);
|
|
|
|
/**
|
|
* blkcg_policy_register - register a blkcg policy
|
|
* @pol: blkcg policy to register
|
|
*
|
|
* Register @pol with blkcg core. Might sleep and @pol may be modified on
|
|
* successful registration. Returns 0 on success and -errno on failure.
|
|
*/
|
|
int blkcg_policy_register(struct blkcg_policy *pol)
|
|
{
|
|
int i, ret;
|
|
|
|
if (WARN_ON(pol->pd_size < sizeof(struct blkg_policy_data)))
|
|
return -EINVAL;
|
|
|
|
mutex_lock(&blkcg_pol_mutex);
|
|
|
|
/* find an empty slot */
|
|
ret = -ENOSPC;
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++)
|
|
if (!blkcg_policy[i])
|
|
break;
|
|
if (i >= BLKCG_MAX_POLS)
|
|
goto out_unlock;
|
|
|
|
/* register and update blkgs */
|
|
pol->plid = i;
|
|
blkcg_policy[i] = pol;
|
|
|
|
/* everything is in place, add intf files for the new policy */
|
|
if (pol->cftypes)
|
|
WARN_ON(cgroup_add_cftypes(&blkio_subsys, pol->cftypes));
|
|
ret = 0;
|
|
out_unlock:
|
|
mutex_unlock(&blkcg_pol_mutex);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_policy_register);
|
|
|
|
/**
|
|
* blkcg_policy_unregister - unregister a blkcg policy
|
|
* @pol: blkcg policy to unregister
|
|
*
|
|
* Undo blkcg_policy_register(@pol). Might sleep.
|
|
*/
|
|
void blkcg_policy_unregister(struct blkcg_policy *pol)
|
|
{
|
|
mutex_lock(&blkcg_pol_mutex);
|
|
|
|
if (WARN_ON(blkcg_policy[pol->plid] != pol))
|
|
goto out_unlock;
|
|
|
|
/* kill the intf files first */
|
|
if (pol->cftypes)
|
|
cgroup_rm_cftypes(&blkio_subsys, pol->cftypes);
|
|
|
|
/* unregister and update blkgs */
|
|
blkcg_policy[pol->plid] = NULL;
|
|
out_unlock:
|
|
mutex_unlock(&blkcg_pol_mutex);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_policy_unregister);
|