diff options
Diffstat (limited to 'block/blk-cgroup.c')
-rw-r--r-- | block/blk-cgroup.c | 277 |
1 files changed, 236 insertions, 41 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index b8858fb0cafa..87ea95d1f533 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -26,11 +26,32 @@ static DEFINE_MUTEX(blkcg_pol_mutex); -struct blkcg blkcg_root = { .cfq_weight = 2 * CFQ_WEIGHT_DEFAULT }; +struct blkcg blkcg_root = { .cfq_weight = 2 * CFQ_WEIGHT_DEFAULT, + .cfq_leaf_weight = 2 * CFQ_WEIGHT_DEFAULT, }; EXPORT_SYMBOL_GPL(blkcg_root); static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS]; +static struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, + struct request_queue *q, bool update_hint); + +/** + * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants + * @d_blkg: loop cursor pointing to the current descendant + * @pos_cgrp: used for iteration + * @p_blkg: target blkg to walk descendants of + * + * Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU + * read locked. If called under either blkcg or queue lock, the iteration + * is guaranteed to include all and only online blkgs. The caller may + * update @pos_cgrp by calling cgroup_rightmost_descendant() to skip + * subtree. + */ +#define blkg_for_each_descendant_pre(d_blkg, pos_cgrp, p_blkg) \ + cgroup_for_each_descendant_pre((pos_cgrp), (p_blkg)->blkcg->css.cgroup) \ + if (((d_blkg) = __blkg_lookup(cgroup_to_blkcg(pos_cgrp), \ + (p_blkg)->q, false))) + static bool blkcg_policy_enabled(struct request_queue *q, const struct blkcg_policy *pol) { @@ -112,9 +133,10 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, blkg->pd[i] = pd; pd->blkg = blkg; + pd->plid = i; /* invoke per-policy init */ - if (blkcg_policy_enabled(blkg->q, pol)) + if (pol->pd_init_fn) pol->pd_init_fn(blkg); } @@ -125,8 +147,19 @@ err_free: return NULL; } +/** + * __blkg_lookup - internal version of blkg_lookup() + * @blkcg: blkcg of interest + * @q: request_queue of interest + * @update_hint: whether to update lookup hint with the result or not + * + * This is internal version and shouldn't be used by policy + * implementations. Looks up blkgs for the @blkcg - @q pair regardless of + * @q's bypass state. If @update_hint is %true, the caller should be + * holding @q->queue_lock and lookup hint is updated on success. + */ static struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, - struct request_queue *q) + struct request_queue *q, bool update_hint) { struct blkcg_gq *blkg; @@ -135,14 +168,19 @@ static struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, return blkg; /* - * Hint didn't match. Look up from the radix tree. Note that we - * may not be holding queue_lock and thus are not sure whether - * @blkg from blkg_tree has already been removed or not, so we - * can't update hint to the lookup result. Leave it to the caller. + * Hint didn't match. Look up from the radix tree. Note that the + * hint can only be updated under queue_lock as otherwise @blkg + * could have already been removed from blkg_tree. The caller is + * responsible for grabbing queue_lock if @update_hint. */ blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id); - if (blkg && blkg->q == q) + if (blkg && blkg->q == q) { + if (update_hint) { + lockdep_assert_held(q->queue_lock); + rcu_assign_pointer(blkcg->blkg_hint, blkg); + } return blkg; + } return NULL; } @@ -162,7 +200,7 @@ struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q) if (unlikely(blk_queue_bypass(q))) return NULL; - return __blkg_lookup(blkcg, q); + return __blkg_lookup(blkcg, q, false); } EXPORT_SYMBOL_GPL(blkg_lookup); @@ -170,75 +208,129 @@ EXPORT_SYMBOL_GPL(blkg_lookup); * If @new_blkg is %NULL, this function tries to allocate a new one as * necessary using %GFP_ATOMIC. @new_blkg is always consumed on return. */ -static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, - struct request_queue *q, - struct blkcg_gq *new_blkg) +static struct blkcg_gq *blkg_create(struct blkcg *blkcg, + struct request_queue *q, + struct blkcg_gq *new_blkg) { struct blkcg_gq *blkg; - int ret; + int i, ret; WARN_ON_ONCE(!rcu_read_lock_held()); lockdep_assert_held(q->queue_lock); - /* lookup and update hint on success, see __blkg_lookup() for details */ - blkg = __blkg_lookup(blkcg, q); - if (blkg) { - rcu_assign_pointer(blkcg->blkg_hint, blkg); - goto out_free; - } - /* blkg holds a reference to blkcg */ if (!css_tryget(&blkcg->css)) { - blkg = ERR_PTR(-EINVAL); - goto out_free; + ret = -EINVAL; + goto err_free_blkg; } /* allocate */ if (!new_blkg) { new_blkg = blkg_alloc(blkcg, q, GFP_ATOMIC); if (unlikely(!new_blkg)) { - blkg = ERR_PTR(-ENOMEM); - goto out_put; + ret = -ENOMEM; + goto err_put_css; } } blkg = new_blkg; - /* insert */ + /* link parent and insert */ + if (blkcg_parent(blkcg)) { + blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false); + if (WARN_ON_ONCE(!blkg->parent)) { + blkg = ERR_PTR(-EINVAL); + goto err_put_css; + } + blkg_get(blkg->parent); + } + spin_lock(&blkcg->lock); ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg); if (likely(!ret)) { hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); list_add(&blkg->q_node, &q->blkg_list); + + for (i = 0; i < BLKCG_MAX_POLS; i++) { + struct blkcg_policy *pol = blkcg_policy[i]; + + if (blkg->pd[i] && pol->pd_online_fn) + pol->pd_online_fn(blkg); + } } + blkg->online = true; spin_unlock(&blkcg->lock); if (!ret) return blkg; - blkg = ERR_PTR(ret); -out_put: + /* @blkg failed fully initialized, use the usual release path */ + blkg_put(blkg); + return ERR_PTR(ret); + +err_put_css: css_put(&blkcg->css); -out_free: +err_free_blkg: blkg_free(new_blkg); - return blkg; + return ERR_PTR(ret); } +/** + * blkg_lookup_create - lookup blkg, try to create one if not there + * @blkcg: blkcg of interest + * @q: request_queue of interest + * + * Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to + * create one. blkg creation is performed recursively from blkcg_root such + * that all non-root blkg's have access to the parent blkg. This function + * should be called under RCU read lock and @q->queue_lock. + * + * Returns pointer to the looked up or created blkg on success, ERR_PTR() + * value on error. If @q is dead, returns ERR_PTR(-EINVAL). If @q is not + * dead and bypassing, returns ERR_PTR(-EBUSY). + */ struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, struct request_queue *q) { + struct blkcg_gq *blkg; + + WARN_ON_ONCE(!rcu_read_lock_held()); + lockdep_assert_held(q->queue_lock); + /* * This could be the first entry point of blkcg implementation and * we shouldn't allow anything to go through for a bypassing queue. */ if (unlikely(blk_queue_bypass(q))) return ERR_PTR(blk_queue_dying(q) ? -EINVAL : -EBUSY); - return __blkg_lookup_create(blkcg, q, NULL); + + blkg = __blkg_lookup(blkcg, q, true); + if (blkg) + return blkg; + + /* + * Create blkgs walking down from blkcg_root to @blkcg, so that all + * non-root blkgs have access to their parents. + */ + while (true) { + struct blkcg *pos = blkcg; + struct blkcg *parent = blkcg_parent(blkcg); + + while (parent && !__blkg_lookup(parent, q, false)) { + pos = parent; + parent = blkcg_parent(parent); + } + + blkg = blkg_create(pos, q, NULL); + if (pos == blkcg || IS_ERR(blkg)) + return blkg; + } } EXPORT_SYMBOL_GPL(blkg_lookup_create); static void blkg_destroy(struct blkcg_gq *blkg) { struct blkcg *blkcg = blkg->blkcg; + int i; lockdep_assert_held(blkg->q->queue_lock); lockdep_assert_held(&blkcg->lock); @@ -247,6 +339,14 @@ static void blkg_destroy(struct blkcg_gq *blkg) WARN_ON_ONCE(list_empty(&blkg->q_node)); WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node)); + for (i = 0; i < BLKCG_MAX_POLS; i++) { + struct blkcg_policy *pol = blkcg_policy[i]; + + if (blkg->pd[i] && pol->pd_offline_fn) + pol->pd_offline_fn(blkg); + } + blkg->online = false; + radix_tree_delete(&blkcg->blkg_tree, blkg->q->id); list_del_init(&blkg->q_node); hlist_del_init_rcu(&blkg->blkcg_node); @@ -301,8 +401,10 @@ static void blkg_rcu_free(struct rcu_head *rcu_head) void __blkg_release(struct blkcg_gq *blkg) { - /* release the extra blkcg reference this blkg has been holding */ + /* release the blkcg and parent blkg refs this blkg has been holding */ css_put(&blkg->blkcg->css); + if (blkg->parent) + blkg_put(blkg->parent); /* * A group is freed in rcu manner. But having an rcu lock does not @@ -402,8 +504,9 @@ static const char *blkg_dev_name(struct blkcg_gq *blkg) * * This function invokes @prfill on each blkg of @blkcg if pd for the * policy specified by @pol exists. @prfill is invoked with @sf, the - * policy data and @data. If @show_total is %true, the sum of the return - * values from @prfill is printed with "Total" label at the end. + * policy data and @data and the matching queue lock held. If @show_total + * is %true, the sum of the return values from @prfill is printed with + * "Total" label at the end. * * This is to be used to construct print functions for * cftype->read_seq_string method. @@ -418,11 +521,14 @@ void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg, struct hlist_node *n; u64 total = 0; - spin_lock_irq(&blkcg->lock); - hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) + rcu_read_lock(); + hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) { + spin_lock_irq(blkg->q->queue_lock); if (blkcg_policy_enabled(blkg->q, pol)) total += prfill(sf, blkg->pd[pol->plid], data); - spin_unlock_irq(&blkcg->lock); + spin_unlock_irq(blkg->q->queue_lock); + } + rcu_read_unlock(); if (show_total) seq_printf(sf, "Total %llu\n", (unsigned long long)total); @@ -481,6 +587,7 @@ u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v); return v; } +EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat); /** * blkg_prfill_stat - prfill callback for blkg_stat @@ -514,6 +621,82 @@ u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, EXPORT_SYMBOL_GPL(blkg_prfill_rwstat); /** + * blkg_stat_recursive_sum - collect hierarchical blkg_stat + * @pd: policy private data of interest + * @off: offset to the blkg_stat in @pd + * + * Collect the blkg_stat specified by @off from @pd and all its online + * descendants and return the sum. The caller must be holding the queue + * lock for online tests. + */ +u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off) +{ + struct blkcg_policy *pol = blkcg_policy[pd->plid]; + struct blkcg_gq *pos_blkg; + struct cgroup *pos_cgrp; + u64 sum; + + lockdep_assert_held(pd->blkg->q->queue_lock); + + sum = blkg_stat_read((void *)pd + off); + + rcu_read_lock(); + blkg_for_each_descendant_pre(pos_blkg, pos_cgrp, pd_to_blkg(pd)) { + struct blkg_policy_data *pos_pd = blkg_to_pd(pos_blkg, pol); + struct blkg_stat *stat = (void *)pos_pd + off; + + if (pos_blkg->online) + sum += blkg_stat_read(stat); + } + rcu_read_unlock(); + + return sum; +} +EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum); + +/** + * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat + * @pd: policy private data of interest + * @off: offset to the blkg_stat in @pd + * + * Collect the blkg_rwstat specified by @off from @pd and all its online + * descendants and return the sum. The caller must be holding the queue + * lock for online tests. + */ +struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd, + int off) +{ + struct blkcg_policy *pol = blkcg_policy[pd->plid]; + struct blkcg_gq *pos_blkg; + struct cgroup *pos_cgrp; + struct blkg_rwstat sum; + int i; + + lockdep_assert_held(pd->blkg->q->queue_lock); + + sum = blkg_rwstat_read((void *)pd + off); + + rcu_read_lock(); + blkg_for_each_descendant_pre(pos_blkg, pos_cgrp, pd_to_blkg(pd)) { + struct blkg_policy_data *pos_pd = blkg_to_pd(pos_blkg, pol); + struct blkg_rwstat *rwstat = (void *)pos_pd + off; + struct blkg_rwstat tmp; + + if (!pos_blkg->online) + continue; + + tmp = blkg_rwstat_read(rwstat); + + for (i = 0; i < BLKG_RWSTAT_NR; i++) + sum.cnt[i] += tmp.cnt[i]; + } + rcu_read_unlock(); + + return sum; +} +EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum); + +/** * blkg_conf_prep - parse and prepare for per-blkg config update * @blkcg: target block cgroup * @pol: target policy @@ -658,6 +841,7 @@ static struct cgroup_subsys_state *blkcg_css_alloc(struct cgroup *cgroup) return ERR_PTR(-ENOMEM); blkcg->cfq_weight = CFQ_WEIGHT_DEFAULT; + blkcg->cfq_leaf_weight = CFQ_WEIGHT_DEFAULT; blkcg->id = atomic64_inc_return(&id_seq); /* root is 0, start from 1 */ done: spin_lock_init(&blkcg->lock); @@ -777,7 +961,7 @@ int blkcg_activate_policy(struct request_queue *q, const struct blkcg_policy *pol) { LIST_HEAD(pds); - struct blkcg_gq *blkg; + struct blkcg_gq *blkg, *new_blkg; struct blkg_policy_data *pd, *n; int cnt = 0, ret; bool preloaded; @@ -786,19 +970,27 @@ int blkcg_activate_policy(struct request_queue *q, return 0; /* preallocations for root blkg */ - blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL); - if (!blkg) + new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL); + if (!new_blkg) return -ENOMEM; preloaded = !radix_tree_preload(GFP_KERNEL); blk_queue_bypass_start(q); - /* make sure the root blkg exists and count the existing blkgs */ + /* + * Make sure the root blkg exists and count the existing blkgs. As + * @q is bypassing at this point, blkg_lookup_create() can't be + * used. Open code it. + */ spin_lock_irq(q->queue_lock); rcu_read_lock(); - blkg = __blkg_lookup_create(&blkcg_root, q, blkg); + blkg = __blkg_lookup(&blkcg_root, q, false); + if (blkg) + blkg_free(new_blkg); + else + blkg = blkg_create(&blkcg_root, q, new_blkg); rcu_read_unlock(); if (preloaded) @@ -846,6 +1038,7 @@ int blkcg_activate_policy(struct request_queue *q, blkg->pd[pol->plid] = pd; pd->blkg = blkg; + pd->plid = pol->plid; pol->pd_init_fn(blkg); spin_unlock(&blkg->blkcg->lock); @@ -892,6 +1085,8 @@ void blkcg_deactivate_policy(struct request_queue *q, /* grab blkcg lock too while removing @pd from @blkg */ spin_lock(&blkg->blkcg->lock); + if (pol->pd_offline_fn) + pol->pd_offline_fn(blkg); if (pol->pd_exit_fn) pol->pd_exit_fn(blkg); |