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1933 lines
50 KiB
1933 lines
50 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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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 <[email protected]> |
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* |
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* Copyright (C) 2008 Fabio Checconi <[email protected]> |
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* Paolo Valente <[email protected]> |
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* |
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* Copyright (C) 2009 Vivek Goyal <[email protected]> |
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* Nauman Rafique <[email protected]> |
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* |
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* For policy-specific per-blkcg data: |
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* Copyright (C) 2015 Paolo Valente <[email protected]> |
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* Arianna Avanzini <[email protected]> |
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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/sched/signal.h> |
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#include <linux/err.h> |
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#include <linux/blkdev.h> |
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#include <linux/backing-dev.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 <linux/ctype.h> |
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#include <linux/blk-cgroup.h> |
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#include <linux/tracehook.h> |
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#include <linux/psi.h> |
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#include "blk.h" |
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#include "blk-ioprio.h" |
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|
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/* |
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* blkcg_pol_mutex protects blkcg_policy[] and policy [de]activation. |
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* blkcg_pol_register_mutex nests outside of it and synchronizes entire |
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* policy [un]register operations including cgroup file additions / |
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* removals. Putting cgroup file registration outside blkcg_pol_mutex |
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* allows grabbing it from cgroup callbacks. |
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*/ |
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static DEFINE_MUTEX(blkcg_pol_register_mutex); |
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static DEFINE_MUTEX(blkcg_pol_mutex); |
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|
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struct blkcg blkcg_root; |
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EXPORT_SYMBOL_GPL(blkcg_root); |
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struct cgroup_subsys_state * const blkcg_root_css = &blkcg_root.css; |
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EXPORT_SYMBOL_GPL(blkcg_root_css); |
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static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS]; |
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|
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static LIST_HEAD(all_blkcgs); /* protected by blkcg_pol_mutex */ |
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bool blkcg_debug_stats = false; |
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static struct workqueue_struct *blkcg_punt_bio_wq; |
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|
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#define BLKG_DESTROY_BATCH_SIZE 64 |
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|
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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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/** |
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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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if (blkg->pd[i]) |
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blkcg_policy[i]->pd_free_fn(blkg->pd[i]); |
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free_percpu(blkg->iostat_cpu); |
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percpu_ref_exit(&blkg->refcnt); |
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kfree(blkg); |
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} |
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static void __blkg_release(struct rcu_head *rcu) |
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{ |
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struct blkcg_gq *blkg = container_of(rcu, struct blkcg_gq, rcu_head); |
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WARN_ON(!bio_list_empty(&blkg->async_bios)); |
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/* release the blkcg and parent blkg refs this blkg has been holding */ |
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css_put(&blkg->blkcg->css); |
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if (blkg->parent) |
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blkg_put(blkg->parent); |
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blkg_free(blkg); |
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} |
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/* |
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* A group is RCU protected, but having an rcu lock does not mean that one |
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* can access all the fields of blkg and assume these are valid. For |
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* example, don't try to follow throtl_data and request queue links. |
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* |
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* Having a reference to blkg under an rcu allows accesses to only values |
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* local to groups like group stats and group rate limits. |
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*/ |
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static void blkg_release(struct percpu_ref *ref) |
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{ |
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struct blkcg_gq *blkg = container_of(ref, struct blkcg_gq, refcnt); |
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call_rcu(&blkg->rcu_head, __blkg_release); |
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} |
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static void blkg_async_bio_workfn(struct work_struct *work) |
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{ |
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struct blkcg_gq *blkg = container_of(work, struct blkcg_gq, |
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async_bio_work); |
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struct bio_list bios = BIO_EMPTY_LIST; |
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struct bio *bio; |
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struct blk_plug plug; |
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bool need_plug = false; |
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/* as long as there are pending bios, @blkg can't go away */ |
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spin_lock_bh(&blkg->async_bio_lock); |
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bio_list_merge(&bios, &blkg->async_bios); |
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bio_list_init(&blkg->async_bios); |
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spin_unlock_bh(&blkg->async_bio_lock); |
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/* start plug only when bio_list contains at least 2 bios */ |
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if (bios.head && bios.head->bi_next) { |
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need_plug = true; |
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blk_start_plug(&plug); |
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} |
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while ((bio = bio_list_pop(&bios))) |
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submit_bio(bio); |
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if (need_plug) |
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blk_finish_plug(&plug); |
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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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* @gfp_mask: allocation mask to use |
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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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gfp_t gfp_mask) |
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{ |
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struct blkcg_gq *blkg; |
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int i, cpu; |
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/* alloc and init base part */ |
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blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node); |
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if (!blkg) |
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return NULL; |
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if (percpu_ref_init(&blkg->refcnt, blkg_release, 0, gfp_mask)) |
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goto err_free; |
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blkg->iostat_cpu = alloc_percpu_gfp(struct blkg_iostat_set, gfp_mask); |
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if (!blkg->iostat_cpu) |
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goto err_free; |
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blkg->q = q; |
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INIT_LIST_HEAD(&blkg->q_node); |
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spin_lock_init(&blkg->async_bio_lock); |
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bio_list_init(&blkg->async_bios); |
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INIT_WORK(&blkg->async_bio_work, blkg_async_bio_workfn); |
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blkg->blkcg = blkcg; |
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u64_stats_init(&blkg->iostat.sync); |
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for_each_possible_cpu(cpu) |
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u64_stats_init(&per_cpu_ptr(blkg->iostat_cpu, cpu)->sync); |
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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 = pol->pd_alloc_fn(gfp_mask, q, blkcg); |
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if (!pd) |
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goto err_free; |
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blkg->pd[i] = pd; |
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pd->blkg = blkg; |
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pd->plid = i; |
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} |
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return blkg; |
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err_free: |
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blkg_free(blkg); |
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return NULL; |
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} |
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struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg, |
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struct request_queue *q, bool update_hint) |
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{ |
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struct blkcg_gq *blkg; |
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/* |
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* Hint didn't match. Look up from the radix tree. Note that the |
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* hint can only be updated under queue_lock as otherwise @blkg |
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* could have already been removed from blkg_tree. The caller is |
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* responsible for grabbing queue_lock if @update_hint. |
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*/ |
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blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id); |
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if (blkg && blkg->q == q) { |
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if (update_hint) { |
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lockdep_assert_held(&q->queue_lock); |
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rcu_assign_pointer(blkcg->blkg_hint, blkg); |
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} |
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return blkg; |
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} |
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return NULL; |
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} |
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EXPORT_SYMBOL_GPL(blkg_lookup_slowpath); |
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/* |
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* If @new_blkg is %NULL, this function tries to allocate a new one as |
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* necessary using %GFP_NOWAIT. @new_blkg is always consumed on return. |
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*/ |
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static struct blkcg_gq *blkg_create(struct blkcg *blkcg, |
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struct request_queue *q, |
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struct blkcg_gq *new_blkg) |
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{ |
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struct blkcg_gq *blkg; |
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int i, ret; |
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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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/* request_queue is dying, do not create/recreate a blkg */ |
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if (blk_queue_dying(q)) { |
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ret = -ENODEV; |
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goto err_free_blkg; |
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} |
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/* blkg holds a reference to blkcg */ |
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if (!css_tryget_online(&blkcg->css)) { |
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ret = -ENODEV; |
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goto err_free_blkg; |
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} |
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/* allocate */ |
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if (!new_blkg) { |
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new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT | __GFP_NOWARN); |
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if (unlikely(!new_blkg)) { |
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ret = -ENOMEM; |
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goto err_put_css; |
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} |
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} |
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blkg = new_blkg; |
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/* link parent */ |
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if (blkcg_parent(blkcg)) { |
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blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false); |
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if (WARN_ON_ONCE(!blkg->parent)) { |
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ret = -ENODEV; |
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goto err_put_css; |
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} |
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blkg_get(blkg->parent); |
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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 (blkg->pd[i] && pol->pd_init_fn) |
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pol->pd_init_fn(blkg->pd[i]); |
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} |
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/* insert */ |
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spin_lock(&blkcg->lock); |
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ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg); |
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if (likely(!ret)) { |
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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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for (i = 0; i < BLKCG_MAX_POLS; i++) { |
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struct blkcg_policy *pol = blkcg_policy[i]; |
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if (blkg->pd[i] && pol->pd_online_fn) |
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pol->pd_online_fn(blkg->pd[i]); |
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} |
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} |
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blkg->online = true; |
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spin_unlock(&blkcg->lock); |
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if (!ret) |
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return blkg; |
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/* @blkg failed fully initialized, use the usual release path */ |
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blkg_put(blkg); |
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return ERR_PTR(ret); |
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err_put_css: |
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css_put(&blkcg->css); |
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err_free_blkg: |
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blkg_free(new_blkg); |
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return ERR_PTR(ret); |
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} |
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/** |
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* blkg_lookup_create - lookup blkg, try to create one if not there |
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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. If it doesn't exist, try to |
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* create one. blkg creation is performed recursively from blkcg_root such |
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* that all non-root blkg's have access to the parent blkg. This function |
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* should be called under RCU read lock and takes @q->queue_lock. |
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* |
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* Returns the blkg or the closest blkg if blkg_create() fails as it walks |
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* down from root. |
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*/ |
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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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{ |
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struct blkcg_gq *blkg; |
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unsigned long flags; |
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WARN_ON_ONCE(!rcu_read_lock_held()); |
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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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spin_lock_irqsave(&q->queue_lock, flags); |
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blkg = __blkg_lookup(blkcg, q, true); |
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if (blkg) |
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goto found; |
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/* |
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* Create blkgs walking down from blkcg_root to @blkcg, so that all |
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* non-root blkgs have access to their parents. Returns the closest |
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* blkg to the intended blkg should blkg_create() fail. |
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*/ |
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while (true) { |
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struct blkcg *pos = blkcg; |
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struct blkcg *parent = blkcg_parent(blkcg); |
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struct blkcg_gq *ret_blkg = q->root_blkg; |
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while (parent) { |
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blkg = __blkg_lookup(parent, q, false); |
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if (blkg) { |
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/* remember closest blkg */ |
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ret_blkg = blkg; |
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break; |
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} |
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pos = parent; |
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parent = blkcg_parent(parent); |
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} |
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blkg = blkg_create(pos, q, NULL); |
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if (IS_ERR(blkg)) { |
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blkg = ret_blkg; |
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break; |
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} |
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if (pos == blkcg) |
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break; |
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} |
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found: |
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spin_unlock_irqrestore(&q->queue_lock, flags); |
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return blkg; |
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} |
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static void blkg_destroy(struct blkcg_gq *blkg) |
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{ |
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struct blkcg *blkcg = blkg->blkcg; |
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int i; |
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lockdep_assert_held(&blkg->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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for (i = 0; i < BLKCG_MAX_POLS; i++) { |
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struct blkcg_policy *pol = blkcg_policy[i]; |
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if (blkg->pd[i] && pol->pd_offline_fn) |
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pol->pd_offline_fn(blkg->pd[i]); |
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} |
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blkg->online = false; |
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radix_tree_delete(&blkcg->blkg_tree, blkg->q->id); |
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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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* Both setting lookup hint to and clearing it from @blkg are done |
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* under queue_lock. If it's not pointing to @blkg now, it never |
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* will. Hint assignment itself can race safely. |
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*/ |
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if (rcu_access_pointer(blkcg->blkg_hint) == blkg) |
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rcu_assign_pointer(blkcg->blkg_hint, NULL); |
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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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percpu_ref_kill(&blkg->refcnt); |
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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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int count = BLKG_DESTROY_BATCH_SIZE; |
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restart: |
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spin_lock_irq(&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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* in order to avoid holding the spin lock for too long, release |
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* it when a batch of blkgs are destroyed. |
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*/ |
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if (!(--count)) { |
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count = BLKG_DESTROY_BATCH_SIZE; |
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spin_unlock_irq(&q->queue_lock); |
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cond_resched(); |
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goto restart; |
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} |
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} |
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q->root_blkg = NULL; |
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spin_unlock_irq(&q->queue_lock); |
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} |
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static int blkcg_reset_stats(struct cgroup_subsys_state *css, |
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struct cftype *cftype, u64 val) |
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{ |
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struct blkcg *blkcg = css_to_blkcg(css); |
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struct blkcg_gq *blkg; |
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int i, cpu; |
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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, &blkcg->blkg_list, blkcg_node) { |
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for_each_possible_cpu(cpu) { |
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struct blkg_iostat_set *bis = |
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per_cpu_ptr(blkg->iostat_cpu, cpu); |
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memset(bis, 0, sizeof(*bis)); |
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} |
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memset(&blkg->iostat, 0, sizeof(blkg->iostat)); |
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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 (blkg->pd[i] && pol->pd_reset_stats_fn) |
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pol->pd_reset_stats_fn(blkg->pd[i]); |
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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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const char *blkg_dev_name(struct blkcg_gq *blkg) |
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{ |
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if (!blkg->q->disk || !blkg->q->disk->bdi->dev) |
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return NULL; |
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return bdi_dev_name(blkg->q->disk->bdi); |
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} |
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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 and the matching queue lock held. If @show_total |
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* is %true, the sum of the return values from @prfill is printed with |
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* "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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u64 total = 0; |
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|
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rcu_read_lock(); |
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hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { |
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spin_lock_irq(&blkg->q->queue_lock); |
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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(&blkg->q->queue_lock); |
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} |
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rcu_read_unlock(); |
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|
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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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/** |
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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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|
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if (!dname) |
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return 0; |
|
|
|
seq_printf(sf, "%s %llu\n", dname, (unsigned long long)v); |
|
return v; |
|
} |
|
EXPORT_SYMBOL_GPL(__blkg_prfill_u64); |
|
|
|
/* Performs queue bypass and policy enabled checks then looks up blkg. */ |
|
static struct blkcg_gq *blkg_lookup_check(struct blkcg *blkcg, |
|
const struct blkcg_policy *pol, |
|
struct request_queue *q) |
|
{ |
|
WARN_ON_ONCE(!rcu_read_lock_held()); |
|
lockdep_assert_held(&q->queue_lock); |
|
|
|
if (!blkcg_policy_enabled(q, pol)) |
|
return ERR_PTR(-EOPNOTSUPP); |
|
return __blkg_lookup(blkcg, q, true /* update_hint */); |
|
} |
|
|
|
/** |
|
* blkcg_conf_open_bdev - parse and open bdev for per-blkg config update |
|
* @inputp: input string pointer |
|
* |
|
* Parse the device node prefix part, MAJ:MIN, of per-blkg config update |
|
* from @input and get and return the matching bdev. *@inputp is |
|
* updated to point past the device node prefix. Returns an ERR_PTR() |
|
* value on error. |
|
* |
|
* Use this function iff blkg_conf_prep() can't be used for some reason. |
|
*/ |
|
struct block_device *blkcg_conf_open_bdev(char **inputp) |
|
{ |
|
char *input = *inputp; |
|
unsigned int major, minor; |
|
struct block_device *bdev; |
|
int key_len; |
|
|
|
if (sscanf(input, "%u:%u%n", &major, &minor, &key_len) != 2) |
|
return ERR_PTR(-EINVAL); |
|
|
|
input += key_len; |
|
if (!isspace(*input)) |
|
return ERR_PTR(-EINVAL); |
|
input = skip_spaces(input); |
|
|
|
bdev = blkdev_get_no_open(MKDEV(major, minor)); |
|
if (!bdev) |
|
return ERR_PTR(-ENODEV); |
|
if (bdev_is_partition(bdev)) { |
|
blkdev_put_no_open(bdev); |
|
return ERR_PTR(-ENODEV); |
|
} |
|
|
|
*inputp = input; |
|
return bdev; |
|
} |
|
|
|
/** |
|
* blkg_conf_prep - parse and prepare for per-blkg config update |
|
* @blkcg: target block cgroup |
|
* @pol: target policy |
|
* @input: input string |
|
* @ctx: blkg_conf_ctx to be filled |
|
* |
|
* Parse per-blkg config update from @input and initialize @ctx with the |
|
* result. @ctx->blkg points to the blkg to be updated and @ctx->body the |
|
* part of @input following MAJ:MIN. This function returns with RCU read |
|
* lock and queue lock held and must be paired with blkg_conf_finish(). |
|
*/ |
|
int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, |
|
char *input, struct blkg_conf_ctx *ctx) |
|
__acquires(rcu) __acquires(&bdev->bd_disk->queue->queue_lock) |
|
{ |
|
struct block_device *bdev; |
|
struct request_queue *q; |
|
struct blkcg_gq *blkg; |
|
int ret; |
|
|
|
bdev = blkcg_conf_open_bdev(&input); |
|
if (IS_ERR(bdev)) |
|
return PTR_ERR(bdev); |
|
|
|
q = bdev->bd_disk->queue; |
|
|
|
rcu_read_lock(); |
|
spin_lock_irq(&q->queue_lock); |
|
|
|
blkg = blkg_lookup_check(blkcg, pol, q); |
|
if (IS_ERR(blkg)) { |
|
ret = PTR_ERR(blkg); |
|
goto fail_unlock; |
|
} |
|
|
|
if (blkg) |
|
goto success; |
|
|
|
/* |
|
* 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; |
|
struct blkcg_gq *new_blkg; |
|
|
|
parent = blkcg_parent(blkcg); |
|
while (parent && !__blkg_lookup(parent, q, false)) { |
|
pos = parent; |
|
parent = blkcg_parent(parent); |
|
} |
|
|
|
/* Drop locks to do new blkg allocation with GFP_KERNEL. */ |
|
spin_unlock_irq(&q->queue_lock); |
|
rcu_read_unlock(); |
|
|
|
new_blkg = blkg_alloc(pos, q, GFP_KERNEL); |
|
if (unlikely(!new_blkg)) { |
|
ret = -ENOMEM; |
|
goto fail; |
|
} |
|
|
|
if (radix_tree_preload(GFP_KERNEL)) { |
|
blkg_free(new_blkg); |
|
ret = -ENOMEM; |
|
goto fail; |
|
} |
|
|
|
rcu_read_lock(); |
|
spin_lock_irq(&q->queue_lock); |
|
|
|
blkg = blkg_lookup_check(pos, pol, q); |
|
if (IS_ERR(blkg)) { |
|
ret = PTR_ERR(blkg); |
|
blkg_free(new_blkg); |
|
goto fail_preloaded; |
|
} |
|
|
|
if (blkg) { |
|
blkg_free(new_blkg); |
|
} else { |
|
blkg = blkg_create(pos, q, new_blkg); |
|
if (IS_ERR(blkg)) { |
|
ret = PTR_ERR(blkg); |
|
goto fail_preloaded; |
|
} |
|
} |
|
|
|
radix_tree_preload_end(); |
|
|
|
if (pos == blkcg) |
|
goto success; |
|
} |
|
success: |
|
ctx->bdev = bdev; |
|
ctx->blkg = blkg; |
|
ctx->body = input; |
|
return 0; |
|
|
|
fail_preloaded: |
|
radix_tree_preload_end(); |
|
fail_unlock: |
|
spin_unlock_irq(&q->queue_lock); |
|
rcu_read_unlock(); |
|
fail: |
|
blkdev_put_no_open(bdev); |
|
/* |
|
* If queue was bypassing, we should retry. Do so after a |
|
* short msleep(). It isn't strictly necessary but queue |
|
* can be bypassing for some time and it's always nice to |
|
* avoid busy looping. |
|
*/ |
|
if (ret == -EBUSY) { |
|
msleep(10); |
|
ret = restart_syscall(); |
|
} |
|
return ret; |
|
} |
|
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->bdev->bd_disk->queue->queue_lock) __releases(rcu) |
|
{ |
|
spin_unlock_irq(&ctx->bdev->bd_disk->queue->queue_lock); |
|
rcu_read_unlock(); |
|
blkdev_put_no_open(ctx->bdev); |
|
} |
|
EXPORT_SYMBOL_GPL(blkg_conf_finish); |
|
|
|
static void blkg_iostat_set(struct blkg_iostat *dst, struct blkg_iostat *src) |
|
{ |
|
int i; |
|
|
|
for (i = 0; i < BLKG_IOSTAT_NR; i++) { |
|
dst->bytes[i] = src->bytes[i]; |
|
dst->ios[i] = src->ios[i]; |
|
} |
|
} |
|
|
|
static void blkg_iostat_add(struct blkg_iostat *dst, struct blkg_iostat *src) |
|
{ |
|
int i; |
|
|
|
for (i = 0; i < BLKG_IOSTAT_NR; i++) { |
|
dst->bytes[i] += src->bytes[i]; |
|
dst->ios[i] += src->ios[i]; |
|
} |
|
} |
|
|
|
static void blkg_iostat_sub(struct blkg_iostat *dst, struct blkg_iostat *src) |
|
{ |
|
int i; |
|
|
|
for (i = 0; i < BLKG_IOSTAT_NR; i++) { |
|
dst->bytes[i] -= src->bytes[i]; |
|
dst->ios[i] -= src->ios[i]; |
|
} |
|
} |
|
|
|
static void blkcg_rstat_flush(struct cgroup_subsys_state *css, int cpu) |
|
{ |
|
struct blkcg *blkcg = css_to_blkcg(css); |
|
struct blkcg_gq *blkg; |
|
|
|
/* Root-level stats are sourced from system-wide IO stats */ |
|
if (!cgroup_parent(css->cgroup)) |
|
return; |
|
|
|
rcu_read_lock(); |
|
|
|
hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { |
|
struct blkcg_gq *parent = blkg->parent; |
|
struct blkg_iostat_set *bisc = per_cpu_ptr(blkg->iostat_cpu, cpu); |
|
struct blkg_iostat cur, delta; |
|
unsigned long flags; |
|
unsigned int seq; |
|
|
|
/* fetch the current per-cpu values */ |
|
do { |
|
seq = u64_stats_fetch_begin(&bisc->sync); |
|
blkg_iostat_set(&cur, &bisc->cur); |
|
} while (u64_stats_fetch_retry(&bisc->sync, seq)); |
|
|
|
/* propagate percpu delta to global */ |
|
flags = u64_stats_update_begin_irqsave(&blkg->iostat.sync); |
|
blkg_iostat_set(&delta, &cur); |
|
blkg_iostat_sub(&delta, &bisc->last); |
|
blkg_iostat_add(&blkg->iostat.cur, &delta); |
|
blkg_iostat_add(&bisc->last, &delta); |
|
u64_stats_update_end_irqrestore(&blkg->iostat.sync, flags); |
|
|
|
/* propagate global delta to parent (unless that's root) */ |
|
if (parent && parent->parent) { |
|
flags = u64_stats_update_begin_irqsave(&parent->iostat.sync); |
|
blkg_iostat_set(&delta, &blkg->iostat.cur); |
|
blkg_iostat_sub(&delta, &blkg->iostat.last); |
|
blkg_iostat_add(&parent->iostat.cur, &delta); |
|
blkg_iostat_add(&blkg->iostat.last, &delta); |
|
u64_stats_update_end_irqrestore(&parent->iostat.sync, flags); |
|
} |
|
} |
|
|
|
rcu_read_unlock(); |
|
} |
|
|
|
/* |
|
* We source root cgroup stats from the system-wide stats to avoid |
|
* tracking the same information twice and incurring overhead when no |
|
* cgroups are defined. For that reason, cgroup_rstat_flush in |
|
* blkcg_print_stat does not actually fill out the iostat in the root |
|
* cgroup's blkcg_gq. |
|
* |
|
* However, we would like to re-use the printing code between the root and |
|
* non-root cgroups to the extent possible. For that reason, we simulate |
|
* flushing the root cgroup's stats by explicitly filling in the iostat |
|
* with disk level statistics. |
|
*/ |
|
static void blkcg_fill_root_iostats(void) |
|
{ |
|
struct class_dev_iter iter; |
|
struct device *dev; |
|
|
|
class_dev_iter_init(&iter, &block_class, NULL, &disk_type); |
|
while ((dev = class_dev_iter_next(&iter))) { |
|
struct block_device *bdev = dev_to_bdev(dev); |
|
struct blkcg_gq *blkg = |
|
blk_queue_root_blkg(bdev->bd_disk->queue); |
|
struct blkg_iostat tmp; |
|
int cpu; |
|
|
|
memset(&tmp, 0, sizeof(tmp)); |
|
for_each_possible_cpu(cpu) { |
|
struct disk_stats *cpu_dkstats; |
|
unsigned long flags; |
|
|
|
cpu_dkstats = per_cpu_ptr(bdev->bd_stats, cpu); |
|
tmp.ios[BLKG_IOSTAT_READ] += |
|
cpu_dkstats->ios[STAT_READ]; |
|
tmp.ios[BLKG_IOSTAT_WRITE] += |
|
cpu_dkstats->ios[STAT_WRITE]; |
|
tmp.ios[BLKG_IOSTAT_DISCARD] += |
|
cpu_dkstats->ios[STAT_DISCARD]; |
|
// convert sectors to bytes |
|
tmp.bytes[BLKG_IOSTAT_READ] += |
|
cpu_dkstats->sectors[STAT_READ] << 9; |
|
tmp.bytes[BLKG_IOSTAT_WRITE] += |
|
cpu_dkstats->sectors[STAT_WRITE] << 9; |
|
tmp.bytes[BLKG_IOSTAT_DISCARD] += |
|
cpu_dkstats->sectors[STAT_DISCARD] << 9; |
|
|
|
flags = u64_stats_update_begin_irqsave(&blkg->iostat.sync); |
|
blkg_iostat_set(&blkg->iostat.cur, &tmp); |
|
u64_stats_update_end_irqrestore(&blkg->iostat.sync, flags); |
|
} |
|
} |
|
} |
|
|
|
static void blkcg_print_one_stat(struct blkcg_gq *blkg, struct seq_file *s) |
|
{ |
|
struct blkg_iostat_set *bis = &blkg->iostat; |
|
u64 rbytes, wbytes, rios, wios, dbytes, dios; |
|
bool has_stats = false; |
|
const char *dname; |
|
unsigned seq; |
|
int i; |
|
|
|
if (!blkg->online) |
|
return; |
|
|
|
dname = blkg_dev_name(blkg); |
|
if (!dname) |
|
return; |
|
|
|
seq_printf(s, "%s ", dname); |
|
|
|
do { |
|
seq = u64_stats_fetch_begin(&bis->sync); |
|
|
|
rbytes = bis->cur.bytes[BLKG_IOSTAT_READ]; |
|
wbytes = bis->cur.bytes[BLKG_IOSTAT_WRITE]; |
|
dbytes = bis->cur.bytes[BLKG_IOSTAT_DISCARD]; |
|
rios = bis->cur.ios[BLKG_IOSTAT_READ]; |
|
wios = bis->cur.ios[BLKG_IOSTAT_WRITE]; |
|
dios = bis->cur.ios[BLKG_IOSTAT_DISCARD]; |
|
} while (u64_stats_fetch_retry(&bis->sync, seq)); |
|
|
|
if (rbytes || wbytes || rios || wios) { |
|
has_stats = true; |
|
seq_printf(s, "rbytes=%llu wbytes=%llu rios=%llu wios=%llu dbytes=%llu dios=%llu", |
|
rbytes, wbytes, rios, wios, |
|
dbytes, dios); |
|
} |
|
|
|
if (blkcg_debug_stats && atomic_read(&blkg->use_delay)) { |
|
has_stats = true; |
|
seq_printf(s, " use_delay=%d delay_nsec=%llu", |
|
atomic_read(&blkg->use_delay), |
|
atomic64_read(&blkg->delay_nsec)); |
|
} |
|
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++) { |
|
struct blkcg_policy *pol = blkcg_policy[i]; |
|
|
|
if (!blkg->pd[i] || !pol->pd_stat_fn) |
|
continue; |
|
|
|
if (pol->pd_stat_fn(blkg->pd[i], s)) |
|
has_stats = true; |
|
} |
|
|
|
if (has_stats) |
|
seq_printf(s, "\n"); |
|
} |
|
|
|
static int blkcg_print_stat(struct seq_file *sf, void *v) |
|
{ |
|
struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); |
|
struct blkcg_gq *blkg; |
|
|
|
if (!seq_css(sf)->parent) |
|
blkcg_fill_root_iostats(); |
|
else |
|
cgroup_rstat_flush(blkcg->css.cgroup); |
|
|
|
rcu_read_lock(); |
|
hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { |
|
spin_lock_irq(&blkg->q->queue_lock); |
|
blkcg_print_one_stat(blkg, sf); |
|
spin_unlock_irq(&blkg->q->queue_lock); |
|
} |
|
rcu_read_unlock(); |
|
return 0; |
|
} |
|
|
|
static struct cftype blkcg_files[] = { |
|
{ |
|
.name = "stat", |
|
.seq_show = blkcg_print_stat, |
|
}, |
|
{ } /* terminate */ |
|
}; |
|
|
|
static struct cftype blkcg_legacy_files[] = { |
|
{ |
|
.name = "reset_stats", |
|
.write_u64 = blkcg_reset_stats, |
|
}, |
|
{ } /* terminate */ |
|
}; |
|
|
|
/* |
|
* blkcg destruction is a three-stage process. |
|
* |
|
* 1. Destruction starts. The blkcg_css_offline() callback is invoked |
|
* which offlines writeback. Here we tie the next stage of blkg destruction |
|
* to the completion of writeback associated with the blkcg. This lets us |
|
* avoid punting potentially large amounts of outstanding writeback to root |
|
* while maintaining any ongoing policies. The next stage is triggered when |
|
* the nr_cgwbs count goes to zero. |
|
* |
|
* 2. When the nr_cgwbs count goes to zero, blkcg_destroy_blkgs() is called |
|
* and handles the destruction of blkgs. Here the css reference held by |
|
* the blkg is put back eventually allowing blkcg_css_free() to be called. |
|
* This work may occur in cgwb_release_workfn() on the cgwb_release |
|
* workqueue. Any submitted ios that fail to get the blkg ref will be |
|
* punted to the root_blkg. |
|
* |
|
* 3. Once the blkcg ref count goes to zero, blkcg_css_free() is called. |
|
* This finally frees the blkcg. |
|
*/ |
|
|
|
/** |
|
* blkcg_css_offline - cgroup css_offline callback |
|
* @css: css of interest |
|
* |
|
* This function is called when @css is about to go away. Here the cgwbs are |
|
* offlined first and only once writeback associated with the blkcg has |
|
* finished do we start step 2 (see above). |
|
*/ |
|
static void blkcg_css_offline(struct cgroup_subsys_state *css) |
|
{ |
|
struct blkcg *blkcg = css_to_blkcg(css); |
|
|
|
/* this prevents anyone from attaching or migrating to this blkcg */ |
|
wb_blkcg_offline(blkcg); |
|
|
|
/* put the base online pin allowing step 2 to be triggered */ |
|
blkcg_unpin_online(blkcg); |
|
} |
|
|
|
/** |
|
* blkcg_destroy_blkgs - responsible for shooting down blkgs |
|
* @blkcg: blkcg of interest |
|
* |
|
* 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. |
|
* Destroying the blkgs releases the reference held on the blkcg's css allowing |
|
* blkcg_css_free to eventually be called. |
|
* |
|
* This is the blkcg counterpart of ioc_release_fn(). |
|
*/ |
|
void blkcg_destroy_blkgs(struct blkcg *blkcg) |
|
{ |
|
might_sleep(); |
|
|
|
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 (need_resched() || !spin_trylock(&q->queue_lock)) { |
|
/* |
|
* Given that the system can accumulate a huge number |
|
* of blkgs in pathological cases, check to see if we |
|
* need to rescheduling to avoid softlockup. |
|
*/ |
|
spin_unlock_irq(&blkcg->lock); |
|
cond_resched(); |
|
spin_lock_irq(&blkcg->lock); |
|
continue; |
|
} |
|
|
|
blkg_destroy(blkg); |
|
spin_unlock(&q->queue_lock); |
|
} |
|
|
|
spin_unlock_irq(&blkcg->lock); |
|
} |
|
|
|
static void blkcg_css_free(struct cgroup_subsys_state *css) |
|
{ |
|
struct blkcg *blkcg = css_to_blkcg(css); |
|
int i; |
|
|
|
mutex_lock(&blkcg_pol_mutex); |
|
|
|
list_del(&blkcg->all_blkcgs_node); |
|
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++) |
|
if (blkcg->cpd[i]) |
|
blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]); |
|
|
|
mutex_unlock(&blkcg_pol_mutex); |
|
|
|
kfree(blkcg); |
|
} |
|
|
|
static struct cgroup_subsys_state * |
|
blkcg_css_alloc(struct cgroup_subsys_state *parent_css) |
|
{ |
|
struct blkcg *blkcg; |
|
struct cgroup_subsys_state *ret; |
|
int i; |
|
|
|
mutex_lock(&blkcg_pol_mutex); |
|
|
|
if (!parent_css) { |
|
blkcg = &blkcg_root; |
|
} else { |
|
blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); |
|
if (!blkcg) { |
|
ret = ERR_PTR(-ENOMEM); |
|
goto unlock; |
|
} |
|
} |
|
|
|
for (i = 0; i < BLKCG_MAX_POLS ; i++) { |
|
struct blkcg_policy *pol = blkcg_policy[i]; |
|
struct blkcg_policy_data *cpd; |
|
|
|
/* |
|
* If the policy hasn't been attached yet, wait for it |
|
* to be attached before doing anything else. Otherwise, |
|
* check if the policy requires any specific per-cgroup |
|
* data: if it does, allocate and initialize it. |
|
*/ |
|
if (!pol || !pol->cpd_alloc_fn) |
|
continue; |
|
|
|
cpd = pol->cpd_alloc_fn(GFP_KERNEL); |
|
if (!cpd) { |
|
ret = ERR_PTR(-ENOMEM); |
|
goto free_pd_blkcg; |
|
} |
|
blkcg->cpd[i] = cpd; |
|
cpd->blkcg = blkcg; |
|
cpd->plid = i; |
|
if (pol->cpd_init_fn) |
|
pol->cpd_init_fn(cpd); |
|
} |
|
|
|
spin_lock_init(&blkcg->lock); |
|
refcount_set(&blkcg->online_pin, 1); |
|
INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT | __GFP_NOWARN); |
|
INIT_HLIST_HEAD(&blkcg->blkg_list); |
|
#ifdef CONFIG_CGROUP_WRITEBACK |
|
INIT_LIST_HEAD(&blkcg->cgwb_list); |
|
#endif |
|
list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs); |
|
|
|
mutex_unlock(&blkcg_pol_mutex); |
|
return &blkcg->css; |
|
|
|
free_pd_blkcg: |
|
for (i--; i >= 0; i--) |
|
if (blkcg->cpd[i]) |
|
blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]); |
|
|
|
if (blkcg != &blkcg_root) |
|
kfree(blkcg); |
|
unlock: |
|
mutex_unlock(&blkcg_pol_mutex); |
|
return ret; |
|
} |
|
|
|
static int blkcg_css_online(struct cgroup_subsys_state *css) |
|
{ |
|
struct blkcg *blkcg = css_to_blkcg(css); |
|
struct blkcg *parent = blkcg_parent(blkcg); |
|
|
|
/* |
|
* blkcg_pin_online() is used to delay blkcg offline so that blkgs |
|
* don't go offline while cgwbs are still active on them. Pin the |
|
* parent so that offline always happens towards the root. |
|
*/ |
|
if (parent) |
|
blkcg_pin_online(parent); |
|
return 0; |
|
} |
|
|
|
/** |
|
* blkcg_init_queue - initialize blkcg part of request queue |
|
* @q: request_queue to initialize |
|
* |
|
* Called from blk_alloc_queue(). 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) |
|
{ |
|
struct blkcg_gq *new_blkg, *blkg; |
|
bool preloaded; |
|
int ret; |
|
|
|
new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL); |
|
if (!new_blkg) |
|
return -ENOMEM; |
|
|
|
preloaded = !radix_tree_preload(GFP_KERNEL); |
|
|
|
/* Make sure the root blkg exists. */ |
|
rcu_read_lock(); |
|
spin_lock_irq(&q->queue_lock); |
|
blkg = blkg_create(&blkcg_root, q, new_blkg); |
|
if (IS_ERR(blkg)) |
|
goto err_unlock; |
|
q->root_blkg = blkg; |
|
spin_unlock_irq(&q->queue_lock); |
|
rcu_read_unlock(); |
|
|
|
if (preloaded) |
|
radix_tree_preload_end(); |
|
|
|
ret = blk_ioprio_init(q); |
|
if (ret) |
|
goto err_destroy_all; |
|
|
|
ret = blk_throtl_init(q); |
|
if (ret) |
|
goto err_destroy_all; |
|
|
|
ret = blk_iolatency_init(q); |
|
if (ret) { |
|
blk_throtl_exit(q); |
|
goto err_destroy_all; |
|
} |
|
|
|
return 0; |
|
|
|
err_destroy_all: |
|
blkg_destroy_all(q); |
|
return ret; |
|
err_unlock: |
|
spin_unlock_irq(&q->queue_lock); |
|
rcu_read_unlock(); |
|
if (preloaded) |
|
radix_tree_preload_end(); |
|
return PTR_ERR(blkg); |
|
} |
|
|
|
/** |
|
* blkcg_exit_queue - exit and release blkcg part of request_queue |
|
* @q: request_queue being released |
|
* |
|
* Called from blk_exit_queue(). Responsible for exiting blkcg part. |
|
*/ |
|
void blkcg_exit_queue(struct request_queue *q) |
|
{ |
|
blkg_destroy_all(q); |
|
blk_throtl_exit(q); |
|
} |
|
|
|
static void blkcg_bind(struct cgroup_subsys_state *root_css) |
|
{ |
|
int i; |
|
|
|
mutex_lock(&blkcg_pol_mutex); |
|
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++) { |
|
struct blkcg_policy *pol = blkcg_policy[i]; |
|
struct blkcg *blkcg; |
|
|
|
if (!pol || !pol->cpd_bind_fn) |
|
continue; |
|
|
|
list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) |
|
if (blkcg->cpd[pol->plid]) |
|
pol->cpd_bind_fn(blkcg->cpd[pol->plid]); |
|
} |
|
mutex_unlock(&blkcg_pol_mutex); |
|
} |
|
|
|
static void blkcg_exit(struct task_struct *tsk) |
|
{ |
|
if (tsk->throttle_queue) |
|
blk_put_queue(tsk->throttle_queue); |
|
tsk->throttle_queue = NULL; |
|
} |
|
|
|
struct cgroup_subsys io_cgrp_subsys = { |
|
.css_alloc = blkcg_css_alloc, |
|
.css_online = blkcg_css_online, |
|
.css_offline = blkcg_css_offline, |
|
.css_free = blkcg_css_free, |
|
.css_rstat_flush = blkcg_rstat_flush, |
|
.bind = blkcg_bind, |
|
.dfl_cftypes = blkcg_files, |
|
.legacy_cftypes = blkcg_legacy_files, |
|
.legacy_name = "blkio", |
|
.exit = blkcg_exit, |
|
#ifdef CONFIG_MEMCG |
|
/* |
|
* This ensures that, if available, memcg is automatically enabled |
|
* together on the default hierarchy so that the owner cgroup can |
|
* be retrieved from writeback pages. |
|
*/ |
|
.depends_on = 1 << memory_cgrp_id, |
|
#endif |
|
}; |
|
EXPORT_SYMBOL_GPL(io_cgrp_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) |
|
{ |
|
struct blkg_policy_data *pd_prealloc = NULL; |
|
struct blkcg_gq *blkg, *pinned_blkg = NULL; |
|
int ret; |
|
|
|
if (blkcg_policy_enabled(q, pol)) |
|
return 0; |
|
|
|
if (queue_is_mq(q)) |
|
blk_mq_freeze_queue(q); |
|
retry: |
|
spin_lock_irq(&q->queue_lock); |
|
|
|
/* blkg_list is pushed at the head, reverse walk to allocate parents first */ |
|
list_for_each_entry_reverse(blkg, &q->blkg_list, q_node) { |
|
struct blkg_policy_data *pd; |
|
|
|
if (blkg->pd[pol->plid]) |
|
continue; |
|
|
|
/* If prealloc matches, use it; otherwise try GFP_NOWAIT */ |
|
if (blkg == pinned_blkg) { |
|
pd = pd_prealloc; |
|
pd_prealloc = NULL; |
|
} else { |
|
pd = pol->pd_alloc_fn(GFP_NOWAIT | __GFP_NOWARN, q, |
|
blkg->blkcg); |
|
} |
|
|
|
if (!pd) { |
|
/* |
|
* GFP_NOWAIT failed. Free the existing one and |
|
* prealloc for @blkg w/ GFP_KERNEL. |
|
*/ |
|
if (pinned_blkg) |
|
blkg_put(pinned_blkg); |
|
blkg_get(blkg); |
|
pinned_blkg = blkg; |
|
|
|
spin_unlock_irq(&q->queue_lock); |
|
|
|
if (pd_prealloc) |
|
pol->pd_free_fn(pd_prealloc); |
|
pd_prealloc = pol->pd_alloc_fn(GFP_KERNEL, q, |
|
blkg->blkcg); |
|
if (pd_prealloc) |
|
goto retry; |
|
else |
|
goto enomem; |
|
} |
|
|
|
blkg->pd[pol->plid] = pd; |
|
pd->blkg = blkg; |
|
pd->plid = pol->plid; |
|
} |
|
|
|
/* all allocated, init in the same order */ |
|
if (pol->pd_init_fn) |
|
list_for_each_entry_reverse(blkg, &q->blkg_list, q_node) |
|
pol->pd_init_fn(blkg->pd[pol->plid]); |
|
|
|
__set_bit(pol->plid, q->blkcg_pols); |
|
ret = 0; |
|
|
|
spin_unlock_irq(&q->queue_lock); |
|
out: |
|
if (queue_is_mq(q)) |
|
blk_mq_unfreeze_queue(q); |
|
if (pinned_blkg) |
|
blkg_put(pinned_blkg); |
|
if (pd_prealloc) |
|
pol->pd_free_fn(pd_prealloc); |
|
return ret; |
|
|
|
enomem: |
|
/* alloc failed, nothing's initialized yet, free everything */ |
|
spin_lock_irq(&q->queue_lock); |
|
list_for_each_entry(blkg, &q->blkg_list, q_node) { |
|
struct blkcg *blkcg = blkg->blkcg; |
|
|
|
spin_lock(&blkcg->lock); |
|
if (blkg->pd[pol->plid]) { |
|
pol->pd_free_fn(blkg->pd[pol->plid]); |
|
blkg->pd[pol->plid] = NULL; |
|
} |
|
spin_unlock(&blkcg->lock); |
|
} |
|
spin_unlock_irq(&q->queue_lock); |
|
ret = -ENOMEM; |
|
goto out; |
|
} |
|
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; |
|
|
|
if (queue_is_mq(q)) |
|
blk_mq_freeze_queue(q); |
|
|
|
spin_lock_irq(&q->queue_lock); |
|
|
|
__clear_bit(pol->plid, q->blkcg_pols); |
|
|
|
list_for_each_entry(blkg, &q->blkg_list, q_node) { |
|
struct blkcg *blkcg = blkg->blkcg; |
|
|
|
spin_lock(&blkcg->lock); |
|
if (blkg->pd[pol->plid]) { |
|
if (pol->pd_offline_fn) |
|
pol->pd_offline_fn(blkg->pd[pol->plid]); |
|
pol->pd_free_fn(blkg->pd[pol->plid]); |
|
blkg->pd[pol->plid] = NULL; |
|
} |
|
spin_unlock(&blkcg->lock); |
|
} |
|
|
|
spin_unlock_irq(&q->queue_lock); |
|
|
|
if (queue_is_mq(q)) |
|
blk_mq_unfreeze_queue(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) |
|
{ |
|
struct blkcg *blkcg; |
|
int i, ret; |
|
|
|
mutex_lock(&blkcg_pol_register_mutex); |
|
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) { |
|
pr_warn("blkcg_policy_register: BLKCG_MAX_POLS too small\n"); |
|
goto err_unlock; |
|
} |
|
|
|
/* Make sure cpd/pd_alloc_fn and cpd/pd_free_fn in pairs */ |
|
if ((!pol->cpd_alloc_fn ^ !pol->cpd_free_fn) || |
|
(!pol->pd_alloc_fn ^ !pol->pd_free_fn)) |
|
goto err_unlock; |
|
|
|
/* register @pol */ |
|
pol->plid = i; |
|
blkcg_policy[pol->plid] = pol; |
|
|
|
/* allocate and install cpd's */ |
|
if (pol->cpd_alloc_fn) { |
|
list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
|
struct blkcg_policy_data *cpd; |
|
|
|
cpd = pol->cpd_alloc_fn(GFP_KERNEL); |
|
if (!cpd) |
|
goto err_free_cpds; |
|
|
|
blkcg->cpd[pol->plid] = cpd; |
|
cpd->blkcg = blkcg; |
|
cpd->plid = pol->plid; |
|
if (pol->cpd_init_fn) |
|
pol->cpd_init_fn(cpd); |
|
} |
|
} |
|
|
|
mutex_unlock(&blkcg_pol_mutex); |
|
|
|
/* everything is in place, add intf files for the new policy */ |
|
if (pol->dfl_cftypes) |
|
WARN_ON(cgroup_add_dfl_cftypes(&io_cgrp_subsys, |
|
pol->dfl_cftypes)); |
|
if (pol->legacy_cftypes) |
|
WARN_ON(cgroup_add_legacy_cftypes(&io_cgrp_subsys, |
|
pol->legacy_cftypes)); |
|
mutex_unlock(&blkcg_pol_register_mutex); |
|
return 0; |
|
|
|
err_free_cpds: |
|
if (pol->cpd_free_fn) { |
|
list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
|
if (blkcg->cpd[pol->plid]) { |
|
pol->cpd_free_fn(blkcg->cpd[pol->plid]); |
|
blkcg->cpd[pol->plid] = NULL; |
|
} |
|
} |
|
} |
|
blkcg_policy[pol->plid] = NULL; |
|
err_unlock: |
|
mutex_unlock(&blkcg_pol_mutex); |
|
mutex_unlock(&blkcg_pol_register_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) |
|
{ |
|
struct blkcg *blkcg; |
|
|
|
mutex_lock(&blkcg_pol_register_mutex); |
|
|
|
if (WARN_ON(blkcg_policy[pol->plid] != pol)) |
|
goto out_unlock; |
|
|
|
/* kill the intf files first */ |
|
if (pol->dfl_cftypes) |
|
cgroup_rm_cftypes(pol->dfl_cftypes); |
|
if (pol->legacy_cftypes) |
|
cgroup_rm_cftypes(pol->legacy_cftypes); |
|
|
|
/* remove cpds and unregister */ |
|
mutex_lock(&blkcg_pol_mutex); |
|
|
|
if (pol->cpd_free_fn) { |
|
list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
|
if (blkcg->cpd[pol->plid]) { |
|
pol->cpd_free_fn(blkcg->cpd[pol->plid]); |
|
blkcg->cpd[pol->plid] = NULL; |
|
} |
|
} |
|
} |
|
blkcg_policy[pol->plid] = NULL; |
|
|
|
mutex_unlock(&blkcg_pol_mutex); |
|
out_unlock: |
|
mutex_unlock(&blkcg_pol_register_mutex); |
|
} |
|
EXPORT_SYMBOL_GPL(blkcg_policy_unregister); |
|
|
|
bool __blkcg_punt_bio_submit(struct bio *bio) |
|
{ |
|
struct blkcg_gq *blkg = bio->bi_blkg; |
|
|
|
/* consume the flag first */ |
|
bio->bi_opf &= ~REQ_CGROUP_PUNT; |
|
|
|
/* never bounce for the root cgroup */ |
|
if (!blkg->parent) |
|
return false; |
|
|
|
spin_lock_bh(&blkg->async_bio_lock); |
|
bio_list_add(&blkg->async_bios, bio); |
|
spin_unlock_bh(&blkg->async_bio_lock); |
|
|
|
queue_work(blkcg_punt_bio_wq, &blkg->async_bio_work); |
|
return true; |
|
} |
|
|
|
/* |
|
* Scale the accumulated delay based on how long it has been since we updated |
|
* the delay. We only call this when we are adding delay, in case it's been a |
|
* while since we added delay, and when we are checking to see if we need to |
|
* delay a task, to account for any delays that may have occurred. |
|
*/ |
|
static void blkcg_scale_delay(struct blkcg_gq *blkg, u64 now) |
|
{ |
|
u64 old = atomic64_read(&blkg->delay_start); |
|
|
|
/* negative use_delay means no scaling, see blkcg_set_delay() */ |
|
if (atomic_read(&blkg->use_delay) < 0) |
|
return; |
|
|
|
/* |
|
* We only want to scale down every second. The idea here is that we |
|
* want to delay people for min(delay_nsec, NSEC_PER_SEC) in a certain |
|
* time window. We only want to throttle tasks for recent delay that |
|
* has occurred, in 1 second time windows since that's the maximum |
|
* things can be throttled. We save the current delay window in |
|
* blkg->last_delay so we know what amount is still left to be charged |
|
* to the blkg from this point onward. blkg->last_use keeps track of |
|
* the use_delay counter. The idea is if we're unthrottling the blkg we |
|
* are ok with whatever is happening now, and we can take away more of |
|
* the accumulated delay as we've already throttled enough that |
|
* everybody is happy with their IO latencies. |
|
*/ |
|
if (time_before64(old + NSEC_PER_SEC, now) && |
|
atomic64_cmpxchg(&blkg->delay_start, old, now) == old) { |
|
u64 cur = atomic64_read(&blkg->delay_nsec); |
|
u64 sub = min_t(u64, blkg->last_delay, now - old); |
|
int cur_use = atomic_read(&blkg->use_delay); |
|
|
|
/* |
|
* We've been unthrottled, subtract a larger chunk of our |
|
* accumulated delay. |
|
*/ |
|
if (cur_use < blkg->last_use) |
|
sub = max_t(u64, sub, blkg->last_delay >> 1); |
|
|
|
/* |
|
* This shouldn't happen, but handle it anyway. Our delay_nsec |
|
* should only ever be growing except here where we subtract out |
|
* min(last_delay, 1 second), but lord knows bugs happen and I'd |
|
* rather not end up with negative numbers. |
|
*/ |
|
if (unlikely(cur < sub)) { |
|
atomic64_set(&blkg->delay_nsec, 0); |
|
blkg->last_delay = 0; |
|
} else { |
|
atomic64_sub(sub, &blkg->delay_nsec); |
|
blkg->last_delay = cur - sub; |
|
} |
|
blkg->last_use = cur_use; |
|
} |
|
} |
|
|
|
/* |
|
* This is called when we want to actually walk up the hierarchy and check to |
|
* see if we need to throttle, and then actually throttle if there is some |
|
* accumulated delay. This should only be called upon return to user space so |
|
* we're not holding some lock that would induce a priority inversion. |
|
*/ |
|
static void blkcg_maybe_throttle_blkg(struct blkcg_gq *blkg, bool use_memdelay) |
|
{ |
|
unsigned long pflags; |
|
bool clamp; |
|
u64 now = ktime_to_ns(ktime_get()); |
|
u64 exp; |
|
u64 delay_nsec = 0; |
|
int tok; |
|
|
|
while (blkg->parent) { |
|
int use_delay = atomic_read(&blkg->use_delay); |
|
|
|
if (use_delay) { |
|
u64 this_delay; |
|
|
|
blkcg_scale_delay(blkg, now); |
|
this_delay = atomic64_read(&blkg->delay_nsec); |
|
if (this_delay > delay_nsec) { |
|
delay_nsec = this_delay; |
|
clamp = use_delay > 0; |
|
} |
|
} |
|
blkg = blkg->parent; |
|
} |
|
|
|
if (!delay_nsec) |
|
return; |
|
|
|
/* |
|
* Let's not sleep for all eternity if we've amassed a huge delay. |
|
* Swapping or metadata IO can accumulate 10's of seconds worth of |
|
* delay, and we want userspace to be able to do _something_ so cap the |
|
* delays at 0.25s. If there's 10's of seconds worth of delay then the |
|
* tasks will be delayed for 0.25 second for every syscall. If |
|
* blkcg_set_delay() was used as indicated by negative use_delay, the |
|
* caller is responsible for regulating the range. |
|
*/ |
|
if (clamp) |
|
delay_nsec = min_t(u64, delay_nsec, 250 * NSEC_PER_MSEC); |
|
|
|
if (use_memdelay) |
|
psi_memstall_enter(&pflags); |
|
|
|
exp = ktime_add_ns(now, delay_nsec); |
|
tok = io_schedule_prepare(); |
|
do { |
|
__set_current_state(TASK_KILLABLE); |
|
if (!schedule_hrtimeout(&exp, HRTIMER_MODE_ABS)) |
|
break; |
|
} while (!fatal_signal_pending(current)); |
|
io_schedule_finish(tok); |
|
|
|
if (use_memdelay) |
|
psi_memstall_leave(&pflags); |
|
} |
|
|
|
/** |
|
* blkcg_maybe_throttle_current - throttle the current task if it has been marked |
|
* |
|
* This is only called if we've been marked with set_notify_resume(). Obviously |
|
* we can be set_notify_resume() for reasons other than blkcg throttling, so we |
|
* check to see if current->throttle_queue is set and if not this doesn't do |
|
* anything. This should only ever be called by the resume code, it's not meant |
|
* to be called by people willy-nilly as it will actually do the work to |
|
* throttle the task if it is setup for throttling. |
|
*/ |
|
void blkcg_maybe_throttle_current(void) |
|
{ |
|
struct request_queue *q = current->throttle_queue; |
|
struct cgroup_subsys_state *css; |
|
struct blkcg *blkcg; |
|
struct blkcg_gq *blkg; |
|
bool use_memdelay = current->use_memdelay; |
|
|
|
if (!q) |
|
return; |
|
|
|
current->throttle_queue = NULL; |
|
current->use_memdelay = false; |
|
|
|
rcu_read_lock(); |
|
css = kthread_blkcg(); |
|
if (css) |
|
blkcg = css_to_blkcg(css); |
|
else |
|
blkcg = css_to_blkcg(task_css(current, io_cgrp_id)); |
|
|
|
if (!blkcg) |
|
goto out; |
|
blkg = blkg_lookup(blkcg, q); |
|
if (!blkg) |
|
goto out; |
|
if (!blkg_tryget(blkg)) |
|
goto out; |
|
rcu_read_unlock(); |
|
|
|
blkcg_maybe_throttle_blkg(blkg, use_memdelay); |
|
blkg_put(blkg); |
|
blk_put_queue(q); |
|
return; |
|
out: |
|
rcu_read_unlock(); |
|
blk_put_queue(q); |
|
} |
|
|
|
/** |
|
* blkcg_schedule_throttle - this task needs to check for throttling |
|
* @q: the request queue IO was submitted on |
|
* @use_memdelay: do we charge this to memory delay for PSI |
|
* |
|
* This is called by the IO controller when we know there's delay accumulated |
|
* for the blkg for this task. We do not pass the blkg because there are places |
|
* we call this that may not have that information, the swapping code for |
|
* instance will only have a request_queue at that point. This set's the |
|
* notify_resume for the task to check and see if it requires throttling before |
|
* returning to user space. |
|
* |
|
* We will only schedule once per syscall. You can call this over and over |
|
* again and it will only do the check once upon return to user space, and only |
|
* throttle once. If the task needs to be throttled again it'll need to be |
|
* re-set at the next time we see the task. |
|
*/ |
|
void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay) |
|
{ |
|
if (unlikely(current->flags & PF_KTHREAD)) |
|
return; |
|
|
|
if (current->throttle_queue != q) { |
|
if (!blk_get_queue(q)) |
|
return; |
|
|
|
if (current->throttle_queue) |
|
blk_put_queue(current->throttle_queue); |
|
current->throttle_queue = q; |
|
} |
|
|
|
if (use_memdelay) |
|
current->use_memdelay = use_memdelay; |
|
set_notify_resume(current); |
|
} |
|
|
|
/** |
|
* blkcg_add_delay - add delay to this blkg |
|
* @blkg: blkg of interest |
|
* @now: the current time in nanoseconds |
|
* @delta: how many nanoseconds of delay to add |
|
* |
|
* Charge @delta to the blkg's current delay accumulation. This is used to |
|
* throttle tasks if an IO controller thinks we need more throttling. |
|
*/ |
|
void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta) |
|
{ |
|
if (WARN_ON_ONCE(atomic_read(&blkg->use_delay) < 0)) |
|
return; |
|
blkcg_scale_delay(blkg, now); |
|
atomic64_add(delta, &blkg->delay_nsec); |
|
} |
|
|
|
/** |
|
* blkg_tryget_closest - try and get a blkg ref on the closet blkg |
|
* @bio: target bio |
|
* @css: target css |
|
* |
|
* As the failure mode here is to walk up the blkg tree, this ensure that the |
|
* blkg->parent pointers are always valid. This returns the blkg that it ended |
|
* up taking a reference on or %NULL if no reference was taken. |
|
*/ |
|
static inline struct blkcg_gq *blkg_tryget_closest(struct bio *bio, |
|
struct cgroup_subsys_state *css) |
|
{ |
|
struct blkcg_gq *blkg, *ret_blkg = NULL; |
|
|
|
rcu_read_lock(); |
|
blkg = blkg_lookup_create(css_to_blkcg(css), |
|
bio->bi_bdev->bd_disk->queue); |
|
while (blkg) { |
|
if (blkg_tryget(blkg)) { |
|
ret_blkg = blkg; |
|
break; |
|
} |
|
blkg = blkg->parent; |
|
} |
|
rcu_read_unlock(); |
|
|
|
return ret_blkg; |
|
} |
|
|
|
/** |
|
* bio_associate_blkg_from_css - associate a bio with a specified css |
|
* @bio: target bio |
|
* @css: target css |
|
* |
|
* Associate @bio with the blkg found by combining the css's blkg and the |
|
* request_queue of the @bio. An association failure is handled by walking up |
|
* the blkg tree. Therefore, the blkg associated can be anything between @blkg |
|
* and q->root_blkg. This situation only happens when a cgroup is dying and |
|
* then the remaining bios will spill to the closest alive blkg. |
|
* |
|
* A reference will be taken on the blkg and will be released when @bio is |
|
* freed. |
|
*/ |
|
void bio_associate_blkg_from_css(struct bio *bio, |
|
struct cgroup_subsys_state *css) |
|
{ |
|
if (bio->bi_blkg) |
|
blkg_put(bio->bi_blkg); |
|
|
|
if (css && css->parent) { |
|
bio->bi_blkg = blkg_tryget_closest(bio, css); |
|
} else { |
|
blkg_get(bio->bi_bdev->bd_disk->queue->root_blkg); |
|
bio->bi_blkg = bio->bi_bdev->bd_disk->queue->root_blkg; |
|
} |
|
} |
|
EXPORT_SYMBOL_GPL(bio_associate_blkg_from_css); |
|
|
|
/** |
|
* bio_associate_blkg - associate a bio with a blkg |
|
* @bio: target bio |
|
* |
|
* Associate @bio with the blkg found from the bio's css and request_queue. |
|
* If one is not found, bio_lookup_blkg() creates the blkg. If a blkg is |
|
* already associated, the css is reused and association redone as the |
|
* request_queue may have changed. |
|
*/ |
|
void bio_associate_blkg(struct bio *bio) |
|
{ |
|
struct cgroup_subsys_state *css; |
|
|
|
rcu_read_lock(); |
|
|
|
if (bio->bi_blkg) |
|
css = &bio_blkcg(bio)->css; |
|
else |
|
css = blkcg_css(); |
|
|
|
bio_associate_blkg_from_css(bio, css); |
|
|
|
rcu_read_unlock(); |
|
} |
|
EXPORT_SYMBOL_GPL(bio_associate_blkg); |
|
|
|
/** |
|
* bio_clone_blkg_association - clone blkg association from src to dst bio |
|
* @dst: destination bio |
|
* @src: source bio |
|
*/ |
|
void bio_clone_blkg_association(struct bio *dst, struct bio *src) |
|
{ |
|
if (src->bi_blkg) { |
|
if (dst->bi_blkg) |
|
blkg_put(dst->bi_blkg); |
|
blkg_get(src->bi_blkg); |
|
dst->bi_blkg = src->bi_blkg; |
|
} |
|
} |
|
EXPORT_SYMBOL_GPL(bio_clone_blkg_association); |
|
|
|
static int blk_cgroup_io_type(struct bio *bio) |
|
{ |
|
if (op_is_discard(bio->bi_opf)) |
|
return BLKG_IOSTAT_DISCARD; |
|
if (op_is_write(bio->bi_opf)) |
|
return BLKG_IOSTAT_WRITE; |
|
return BLKG_IOSTAT_READ; |
|
} |
|
|
|
void blk_cgroup_bio_start(struct bio *bio) |
|
{ |
|
int rwd = blk_cgroup_io_type(bio), cpu; |
|
struct blkg_iostat_set *bis; |
|
|
|
cpu = get_cpu(); |
|
bis = per_cpu_ptr(bio->bi_blkg->iostat_cpu, cpu); |
|
u64_stats_update_begin(&bis->sync); |
|
|
|
/* |
|
* If the bio is flagged with BIO_CGROUP_ACCT it means this is a split |
|
* bio and we would have already accounted for the size of the bio. |
|
*/ |
|
if (!bio_flagged(bio, BIO_CGROUP_ACCT)) { |
|
bio_set_flag(bio, BIO_CGROUP_ACCT); |
|
bis->cur.bytes[rwd] += bio->bi_iter.bi_size; |
|
} |
|
bis->cur.ios[rwd]++; |
|
|
|
u64_stats_update_end(&bis->sync); |
|
if (cgroup_subsys_on_dfl(io_cgrp_subsys)) |
|
cgroup_rstat_updated(bio->bi_blkg->blkcg->css.cgroup, cpu); |
|
put_cpu(); |
|
} |
|
|
|
static int __init blkcg_init(void) |
|
{ |
|
blkcg_punt_bio_wq = alloc_workqueue("blkcg_punt_bio", |
|
WQ_MEM_RECLAIM | WQ_FREEZABLE | |
|
WQ_UNBOUND | WQ_SYSFS, 0); |
|
if (!blkcg_punt_bio_wq) |
|
return -ENOMEM; |
|
return 0; |
|
} |
|
subsys_initcall(blkcg_init); |
|
|
|
module_param(blkcg_debug_stats, bool, 0644); |
|
MODULE_PARM_DESC(blkcg_debug_stats, "True if you want debug stats, false if not");
|
|
|