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https://github.com/edk2-porting/linux-next.git
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629ed0b102
As with conf/stats file handling code, there's no reason for stat update code to live in blkcg core with policies calling into update them. The current organization is both inflexible and complex. This patch moves stat update code to specific policies. All blkiocg_update_*_stats() functions which deal with BLKIO_POLICY_PROP stats are collapsed into their cfq_blkiocg_update_*_stats() counterparts. blkiocg_update_dispatch_stats() is used by both policies and duplicated as throtl_update_dispatch_stats() and cfq_blkiocg_update_dispatch_stats(). This will be cleaned up later. Signed-off-by: Tejun Heo <tj@kernel.org>
949 lines
24 KiB
C
949 lines
24 KiB
C
/*
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* Common Block IO controller cgroup interface
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*
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* Based on ideas and code from CFQ, CFS and BFQ:
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* Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
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*
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* Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
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* Paolo Valente <paolo.valente@unimore.it>
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*
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* Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
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* Nauman Rafique <nauman@google.com>
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*/
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#include <linux/ioprio.h>
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#include <linux/kdev_t.h>
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#include <linux/module.h>
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#include <linux/err.h>
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#include <linux/blkdev.h>
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#include <linux/slab.h>
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#include <linux/genhd.h>
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#include <linux/delay.h>
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#include <linux/atomic.h>
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#include "blk-cgroup.h"
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#include "blk.h"
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#define MAX_KEY_LEN 100
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static DEFINE_SPINLOCK(blkio_list_lock);
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static LIST_HEAD(blkio_list);
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static DEFINE_MUTEX(all_q_mutex);
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static LIST_HEAD(all_q_list);
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/* List of groups pending per cpu stats allocation */
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static DEFINE_SPINLOCK(alloc_list_lock);
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static LIST_HEAD(alloc_list);
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static void blkio_stat_alloc_fn(struct work_struct *);
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static DECLARE_DELAYED_WORK(blkio_stat_alloc_work, blkio_stat_alloc_fn);
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struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
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EXPORT_SYMBOL_GPL(blkio_root_cgroup);
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static struct blkio_policy_type *blkio_policy[BLKIO_NR_POLICIES];
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struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
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{
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return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
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struct blkio_cgroup, css);
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}
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EXPORT_SYMBOL_GPL(cgroup_to_blkio_cgroup);
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static struct blkio_cgroup *task_blkio_cgroup(struct task_struct *tsk)
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{
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return container_of(task_subsys_state(tsk, blkio_subsys_id),
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struct blkio_cgroup, css);
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}
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struct blkio_cgroup *bio_blkio_cgroup(struct bio *bio)
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{
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if (bio && bio->bi_css)
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return container_of(bio->bi_css, struct blkio_cgroup, css);
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return task_blkio_cgroup(current);
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}
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EXPORT_SYMBOL_GPL(bio_blkio_cgroup);
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/*
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* Worker for allocating per cpu stat for blk groups. This is scheduled on
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* the system_nrt_wq once there are some groups on the alloc_list waiting
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* for allocation.
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*/
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static void blkio_stat_alloc_fn(struct work_struct *work)
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{
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static void *pcpu_stats[BLKIO_NR_POLICIES];
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struct delayed_work *dwork = to_delayed_work(work);
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struct blkio_group *blkg;
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int i;
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bool empty = false;
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alloc_stats:
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for (i = 0; i < BLKIO_NR_POLICIES; i++) {
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if (pcpu_stats[i] != NULL)
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continue;
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pcpu_stats[i] = alloc_percpu(struct blkio_group_stats_cpu);
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/* Allocation failed. Try again after some time. */
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if (pcpu_stats[i] == NULL) {
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queue_delayed_work(system_nrt_wq, dwork,
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msecs_to_jiffies(10));
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return;
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}
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}
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spin_lock_irq(&blkio_list_lock);
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spin_lock(&alloc_list_lock);
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/* cgroup got deleted or queue exited. */
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if (!list_empty(&alloc_list)) {
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blkg = list_first_entry(&alloc_list, struct blkio_group,
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alloc_node);
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for (i = 0; i < BLKIO_NR_POLICIES; i++) {
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struct blkg_policy_data *pd = blkg->pd[i];
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if (blkio_policy[i] && pd && !pd->stats_cpu)
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swap(pd->stats_cpu, pcpu_stats[i]);
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}
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list_del_init(&blkg->alloc_node);
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}
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empty = list_empty(&alloc_list);
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spin_unlock(&alloc_list_lock);
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spin_unlock_irq(&blkio_list_lock);
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if (!empty)
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goto alloc_stats;
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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 blkio_group *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 < BLKIO_NR_POLICIES; i++) {
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struct blkg_policy_data *pd = blkg->pd[i];
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if (pd) {
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free_percpu(pd->stats_cpu);
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kfree(pd);
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}
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}
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kfree(blkg);
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}
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/**
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* blkg_alloc - allocate a blkg
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* @blkcg: block cgroup the new blkg is associated with
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* @q: request_queue the new blkg is associated with
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*
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* Allocate a new blkg assocating @blkcg and @q.
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*/
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static struct blkio_group *blkg_alloc(struct blkio_cgroup *blkcg,
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struct request_queue *q)
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{
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struct blkio_group *blkg;
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int i;
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/* alloc and init base part */
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blkg = kzalloc_node(sizeof(*blkg), GFP_ATOMIC, q->node);
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if (!blkg)
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return NULL;
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blkg->q = q;
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INIT_LIST_HEAD(&blkg->q_node);
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INIT_LIST_HEAD(&blkg->alloc_node);
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blkg->blkcg = blkcg;
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blkg->refcnt = 1;
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cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
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for (i = 0; i < BLKIO_NR_POLICIES; i++) {
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struct blkio_policy_type *pol = blkio_policy[i];
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struct blkg_policy_data *pd;
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if (!pol)
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continue;
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/* alloc per-policy data and attach it to blkg */
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pd = kzalloc_node(sizeof(*pd) + pol->pdata_size, GFP_ATOMIC,
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q->node);
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if (!pd) {
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blkg_free(blkg);
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return NULL;
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}
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blkg->pd[i] = pd;
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pd->blkg = blkg;
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}
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/* invoke per-policy init */
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for (i = 0; i < BLKIO_NR_POLICIES; i++) {
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struct blkio_policy_type *pol = blkio_policy[i];
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if (pol)
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pol->ops.blkio_init_group_fn(blkg);
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}
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return blkg;
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}
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struct blkio_group *blkg_lookup_create(struct blkio_cgroup *blkcg,
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struct request_queue *q,
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bool for_root)
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__releases(q->queue_lock) __acquires(q->queue_lock)
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{
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struct blkio_group *blkg;
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WARN_ON_ONCE(!rcu_read_lock_held());
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lockdep_assert_held(q->queue_lock);
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/*
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* This could be the first entry point of blkcg implementation and
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* we shouldn't allow anything to go through for a bypassing queue.
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* The following can be removed if blkg lookup is guaranteed to
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* fail on a bypassing queue.
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*/
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if (unlikely(blk_queue_bypass(q)) && !for_root)
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return ERR_PTR(blk_queue_dead(q) ? -EINVAL : -EBUSY);
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blkg = blkg_lookup(blkcg, q);
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if (blkg)
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return blkg;
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/* blkg holds a reference to blkcg */
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if (!css_tryget(&blkcg->css))
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return ERR_PTR(-EINVAL);
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/*
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* Allocate and initialize.
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*/
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blkg = blkg_alloc(blkcg, q);
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/* did alloc fail? */
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if (unlikely(!blkg)) {
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blkg = ERR_PTR(-ENOMEM);
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goto out;
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}
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/* insert */
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spin_lock(&blkcg->lock);
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hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
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list_add(&blkg->q_node, &q->blkg_list);
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spin_unlock(&blkcg->lock);
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spin_lock(&alloc_list_lock);
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list_add(&blkg->alloc_node, &alloc_list);
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/* Queue per cpu stat allocation from worker thread. */
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queue_delayed_work(system_nrt_wq, &blkio_stat_alloc_work, 0);
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spin_unlock(&alloc_list_lock);
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out:
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return blkg;
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}
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EXPORT_SYMBOL_GPL(blkg_lookup_create);
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/* called under rcu_read_lock(). */
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struct blkio_group *blkg_lookup(struct blkio_cgroup *blkcg,
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struct request_queue *q)
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{
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struct blkio_group *blkg;
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struct hlist_node *n;
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hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node)
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if (blkg->q == q)
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return blkg;
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return NULL;
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}
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EXPORT_SYMBOL_GPL(blkg_lookup);
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static void blkg_destroy(struct blkio_group *blkg)
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{
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struct request_queue *q = blkg->q;
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struct blkio_cgroup *blkcg = blkg->blkcg;
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lockdep_assert_held(q->queue_lock);
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lockdep_assert_held(&blkcg->lock);
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/* Something wrong if we are trying to remove same group twice */
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WARN_ON_ONCE(list_empty(&blkg->q_node));
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WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node));
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list_del_init(&blkg->q_node);
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hlist_del_init_rcu(&blkg->blkcg_node);
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spin_lock(&alloc_list_lock);
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list_del_init(&blkg->alloc_node);
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spin_unlock(&alloc_list_lock);
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/*
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* Put the reference taken at the time of creation so that when all
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* queues are gone, group can be destroyed.
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*/
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blkg_put(blkg);
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}
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/*
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* XXX: This updates blkg policy data in-place for root blkg, which is
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* necessary across elevator switch and policy registration as root blkgs
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* aren't shot down. This broken and racy implementation is temporary.
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* Eventually, blkg shoot down will be replaced by proper in-place update.
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*/
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void update_root_blkg_pd(struct request_queue *q, enum blkio_policy_id plid)
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{
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struct blkio_policy_type *pol = blkio_policy[plid];
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struct blkio_group *blkg = blkg_lookup(&blkio_root_cgroup, q);
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struct blkg_policy_data *pd;
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if (!blkg)
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return;
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kfree(blkg->pd[plid]);
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blkg->pd[plid] = NULL;
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if (!pol)
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return;
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pd = kzalloc(sizeof(*pd) + pol->pdata_size, GFP_KERNEL);
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WARN_ON_ONCE(!pd);
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pd->stats_cpu = alloc_percpu(struct blkio_group_stats_cpu);
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WARN_ON_ONCE(!pd->stats_cpu);
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blkg->pd[plid] = pd;
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pd->blkg = blkg;
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pol->ops.blkio_init_group_fn(blkg);
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}
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EXPORT_SYMBOL_GPL(update_root_blkg_pd);
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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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* @destroy_root: whether to destroy root blkg or not
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*
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* Destroy blkgs associated with @q. If @destroy_root is %true, all are
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* destroyed; otherwise, root blkg is left alone.
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*/
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void blkg_destroy_all(struct request_queue *q, bool destroy_root)
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{
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struct blkio_group *blkg, *n;
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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 blkio_cgroup *blkcg = blkg->blkcg;
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/* skip root? */
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if (!destroy_root && blkg->blkcg == &blkio_root_cgroup)
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continue;
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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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spin_unlock_irq(q->queue_lock);
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}
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EXPORT_SYMBOL_GPL(blkg_destroy_all);
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static void blkg_rcu_free(struct rcu_head *rcu_head)
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{
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blkg_free(container_of(rcu_head, struct blkio_group, rcu_head));
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}
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void __blkg_release(struct blkio_group *blkg)
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{
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/* release the extra blkcg reference this blkg has been holding */
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css_put(&blkg->blkcg->css);
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/*
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* A group is freed in rcu manner. But having an rcu lock does not
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* mean that one can access all the fields of blkg and assume these
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* are valid. For example, don't try to follow throtl_data and
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* request queue links.
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*
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* Having a reference to blkg under an rcu allows acess to only
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* values local to groups like group stats and group rate limits
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*/
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call_rcu(&blkg->rcu_head, blkg_rcu_free);
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}
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EXPORT_SYMBOL_GPL(__blkg_release);
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static void blkio_reset_stats_cpu(struct blkio_group *blkg, int plid)
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{
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struct blkg_policy_data *pd = blkg->pd[plid];
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int cpu;
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if (pd->stats_cpu == NULL)
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return;
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for_each_possible_cpu(cpu) {
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struct blkio_group_stats_cpu *sc =
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per_cpu_ptr(pd->stats_cpu, cpu);
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blkg_rwstat_reset(&sc->service_bytes);
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blkg_rwstat_reset(&sc->serviced);
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blkg_stat_reset(&sc->sectors);
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}
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}
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static int
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blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
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{
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struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
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struct blkio_group *blkg;
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struct hlist_node *n;
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spin_lock(&blkio_list_lock);
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spin_lock_irq(&blkcg->lock);
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/*
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* Note that stat reset is racy - it doesn't synchronize against
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* stat updates. This is a debug feature which shouldn't exist
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* anyway. If you get hit by a race, retry.
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*/
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hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
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struct blkio_policy_type *pol;
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list_for_each_entry(pol, &blkio_list, list) {
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struct blkg_policy_data *pd = blkg->pd[pol->plid];
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struct blkio_group_stats *stats = &pd->stats;
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/* queued stats shouldn't be cleared */
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blkg_rwstat_reset(&stats->merged);
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blkg_rwstat_reset(&stats->service_time);
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blkg_rwstat_reset(&stats->wait_time);
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blkg_stat_reset(&stats->time);
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#ifdef CONFIG_DEBUG_BLK_CGROUP
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blkg_stat_reset(&stats->unaccounted_time);
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blkg_stat_reset(&stats->avg_queue_size_sum);
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blkg_stat_reset(&stats->avg_queue_size_samples);
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blkg_stat_reset(&stats->dequeue);
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blkg_stat_reset(&stats->group_wait_time);
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blkg_stat_reset(&stats->idle_time);
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blkg_stat_reset(&stats->empty_time);
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#endif
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blkio_reset_stats_cpu(blkg, pol->plid);
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}
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}
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spin_unlock_irq(&blkcg->lock);
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spin_unlock(&blkio_list_lock);
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return 0;
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}
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static const char *blkg_dev_name(struct blkio_group *blkg)
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{
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/* some drivers (floppy) instantiate a queue w/o disk registered */
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if (blkg->q->backing_dev_info.dev)
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return dev_name(blkg->q->backing_dev_info.dev);
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return NULL;
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}
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/**
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* blkcg_print_blkgs - helper for printing per-blkg data
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* @sf: seq_file to print to
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* @blkcg: blkcg of interest
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* @prfill: fill function to print out a blkg
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* @pol: policy in question
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* @data: data to be passed to @prfill
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* @show_total: to print out sum of prfill return values or not
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*
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* This function invokes @prfill on each blkg of @blkcg if pd for the
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* policy specified by @pol exists. @prfill is invoked with @sf, the
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* policy data and @data. If @show_total is %true, the sum of the return
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* values from @prfill is printed with "Total" label at the end.
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*
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* This is to be used to construct print functions for
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* cftype->read_seq_string method.
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*/
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void blkcg_print_blkgs(struct seq_file *sf, struct blkio_cgroup *blkcg,
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u64 (*prfill)(struct seq_file *, struct blkg_policy_data *, int),
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int pol, int data, bool show_total)
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{
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struct blkio_group *blkg;
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struct hlist_node *n;
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u64 total = 0;
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|
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spin_lock_irq(&blkcg->lock);
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hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node)
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if (blkg->pd[pol])
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total += prfill(sf, blkg->pd[pol], data);
|
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spin_unlock_irq(&blkcg->lock);
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|
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if (show_total)
|
|
seq_printf(sf, "Total %llu\n", (unsigned long long)total);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_print_blkgs);
|
|
|
|
/**
|
|
* __blkg_prfill_u64 - prfill helper for a single u64 value
|
|
* @sf: seq_file to print to
|
|
* @pd: policy data of interest
|
|
* @v: value to print
|
|
*
|
|
* Print @v to @sf for the device assocaited with @pd.
|
|
*/
|
|
u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v)
|
|
{
|
|
const char *dname = blkg_dev_name(pd->blkg);
|
|
|
|
if (!dname)
|
|
return 0;
|
|
|
|
seq_printf(sf, "%s %llu\n", dname, (unsigned long long)v);
|
|
return v;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__blkg_prfill_u64);
|
|
|
|
/**
|
|
* __blkg_prfill_rwstat - prfill helper for a blkg_rwstat
|
|
* @sf: seq_file to print to
|
|
* @pd: policy data of interest
|
|
* @rwstat: rwstat to print
|
|
*
|
|
* Print @rwstat to @sf for the device assocaited with @pd.
|
|
*/
|
|
u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
|
|
const struct blkg_rwstat *rwstat)
|
|
{
|
|
static const char *rwstr[] = {
|
|
[BLKG_RWSTAT_READ] = "Read",
|
|
[BLKG_RWSTAT_WRITE] = "Write",
|
|
[BLKG_RWSTAT_SYNC] = "Sync",
|
|
[BLKG_RWSTAT_ASYNC] = "Async",
|
|
};
|
|
const char *dname = blkg_dev_name(pd->blkg);
|
|
u64 v;
|
|
int i;
|
|
|
|
if (!dname)
|
|
return 0;
|
|
|
|
for (i = 0; i < BLKG_RWSTAT_NR; i++)
|
|
seq_printf(sf, "%s %s %llu\n", dname, rwstr[i],
|
|
(unsigned long long)rwstat->cnt[i]);
|
|
|
|
v = rwstat->cnt[BLKG_RWSTAT_READ] + rwstat->cnt[BLKG_RWSTAT_WRITE];
|
|
seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v);
|
|
return v;
|
|
}
|
|
|
|
static u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd,
|
|
int off)
|
|
{
|
|
return __blkg_prfill_u64(sf, pd,
|
|
blkg_stat_read((void *)&pd->stats + off));
|
|
}
|
|
|
|
static u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
|
|
int off)
|
|
{
|
|
struct blkg_rwstat rwstat = blkg_rwstat_read((void *)&pd->stats + off);
|
|
|
|
return __blkg_prfill_rwstat(sf, pd, &rwstat);
|
|
}
|
|
|
|
/* print blkg_stat specified by BLKCG_STAT_PRIV() */
|
|
int blkcg_print_stat(struct cgroup *cgrp, struct cftype *cft,
|
|
struct seq_file *sf)
|
|
{
|
|
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
|
|
|
|
blkcg_print_blkgs(sf, blkcg, blkg_prfill_stat,
|
|
BLKCG_STAT_POL(cft->private),
|
|
BLKCG_STAT_OFF(cft->private), false);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_print_stat);
|
|
|
|
/* print blkg_rwstat specified by BLKCG_STAT_PRIV() */
|
|
int blkcg_print_rwstat(struct cgroup *cgrp, struct cftype *cft,
|
|
struct seq_file *sf)
|
|
{
|
|
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
|
|
|
|
blkcg_print_blkgs(sf, blkcg, blkg_prfill_rwstat,
|
|
BLKCG_STAT_POL(cft->private),
|
|
BLKCG_STAT_OFF(cft->private), true);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_print_rwstat);
|
|
|
|
static u64 blkg_prfill_cpu_stat(struct seq_file *sf,
|
|
struct blkg_policy_data *pd, int off)
|
|
{
|
|
u64 v = 0;
|
|
int cpu;
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
struct blkio_group_stats_cpu *sc =
|
|
per_cpu_ptr(pd->stats_cpu, cpu);
|
|
|
|
v += blkg_stat_read((void *)sc + off);
|
|
}
|
|
|
|
return __blkg_prfill_u64(sf, pd, v);
|
|
}
|
|
|
|
static u64 blkg_prfill_cpu_rwstat(struct seq_file *sf,
|
|
struct blkg_policy_data *pd, int off)
|
|
{
|
|
struct blkg_rwstat rwstat = { }, tmp;
|
|
int i, cpu;
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
struct blkio_group_stats_cpu *sc =
|
|
per_cpu_ptr(pd->stats_cpu, cpu);
|
|
|
|
tmp = blkg_rwstat_read((void *)sc + off);
|
|
for (i = 0; i < BLKG_RWSTAT_NR; i++)
|
|
rwstat.cnt[i] += tmp.cnt[i];
|
|
}
|
|
|
|
return __blkg_prfill_rwstat(sf, pd, &rwstat);
|
|
}
|
|
|
|
/* print per-cpu blkg_stat specified by BLKCG_STAT_PRIV() */
|
|
int blkcg_print_cpu_stat(struct cgroup *cgrp, struct cftype *cft,
|
|
struct seq_file *sf)
|
|
{
|
|
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
|
|
|
|
blkcg_print_blkgs(sf, blkcg, blkg_prfill_cpu_stat,
|
|
BLKCG_STAT_POL(cft->private),
|
|
BLKCG_STAT_OFF(cft->private), false);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_print_cpu_stat);
|
|
|
|
/* print per-cpu blkg_rwstat specified by BLKCG_STAT_PRIV() */
|
|
int blkcg_print_cpu_rwstat(struct cgroup *cgrp, struct cftype *cft,
|
|
struct seq_file *sf)
|
|
{
|
|
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
|
|
|
|
blkcg_print_blkgs(sf, blkcg, blkg_prfill_cpu_rwstat,
|
|
BLKCG_STAT_POL(cft->private),
|
|
BLKCG_STAT_OFF(cft->private), true);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_print_cpu_rwstat);
|
|
|
|
/**
|
|
* blkg_conf_prep - parse and prepare for per-blkg config update
|
|
* @blkcg: target block cgroup
|
|
* @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->v the new
|
|
* value. This function returns with RCU read locked and must be paired
|
|
* with blkg_conf_finish().
|
|
*/
|
|
int blkg_conf_prep(struct blkio_cgroup *blkcg, const char *input,
|
|
struct blkg_conf_ctx *ctx)
|
|
__acquires(rcu)
|
|
{
|
|
struct gendisk *disk;
|
|
struct blkio_group *blkg;
|
|
unsigned int major, minor;
|
|
unsigned long long v;
|
|
int part, ret;
|
|
|
|
if (sscanf(input, "%u:%u %llu", &major, &minor, &v) != 3)
|
|
return -EINVAL;
|
|
|
|
disk = get_gendisk(MKDEV(major, minor), &part);
|
|
if (!disk || part)
|
|
return -EINVAL;
|
|
|
|
rcu_read_lock();
|
|
|
|
spin_lock_irq(disk->queue->queue_lock);
|
|
blkg = blkg_lookup_create(blkcg, disk->queue, false);
|
|
spin_unlock_irq(disk->queue->queue_lock);
|
|
|
|
if (IS_ERR(blkg)) {
|
|
ret = PTR_ERR(blkg);
|
|
rcu_read_unlock();
|
|
put_disk(disk);
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
ctx->disk = disk;
|
|
ctx->blkg = blkg;
|
|
ctx->v = v;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_conf_prep);
|
|
|
|
/**
|
|
* blkg_conf_finish - finish up per-blkg config update
|
|
* @ctx: blkg_conf_ctx intiailized by blkg_conf_prep()
|
|
*
|
|
* Finish up after per-blkg config update. This function must be paired
|
|
* with blkg_conf_prep().
|
|
*/
|
|
void blkg_conf_finish(struct blkg_conf_ctx *ctx)
|
|
__releases(rcu)
|
|
{
|
|
rcu_read_unlock();
|
|
put_disk(ctx->disk);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_conf_finish);
|
|
|
|
struct cftype blkio_files[] = {
|
|
{
|
|
.name = "reset_stats",
|
|
.write_u64 = blkiocg_reset_stats,
|
|
},
|
|
{ } /* terminate */
|
|
};
|
|
|
|
/**
|
|
* blkiocg_pre_destroy - cgroup pre_destroy callback
|
|
* @cgroup: cgroup of interest
|
|
*
|
|
* This function is called when @cgroup is about to go away and responsible
|
|
* for shooting down all blkgs associated with @cgroup. blkgs should be
|
|
* removed while holding both q and blkcg locks. As blkcg lock is nested
|
|
* inside q lock, this function performs reverse double lock dancing.
|
|
*
|
|
* This is the blkcg counterpart of ioc_release_fn().
|
|
*/
|
|
static int blkiocg_pre_destroy(struct cgroup *cgroup)
|
|
{
|
|
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
|
|
|
|
spin_lock_irq(&blkcg->lock);
|
|
|
|
while (!hlist_empty(&blkcg->blkg_list)) {
|
|
struct blkio_group *blkg = hlist_entry(blkcg->blkg_list.first,
|
|
struct blkio_group, blkcg_node);
|
|
struct request_queue *q = blkg->q;
|
|
|
|
if (spin_trylock(q->queue_lock)) {
|
|
blkg_destroy(blkg);
|
|
spin_unlock(q->queue_lock);
|
|
} else {
|
|
spin_unlock_irq(&blkcg->lock);
|
|
cpu_relax();
|
|
spin_lock_irq(&blkcg->lock);
|
|
}
|
|
}
|
|
|
|
spin_unlock_irq(&blkcg->lock);
|
|
return 0;
|
|
}
|
|
|
|
static void blkiocg_destroy(struct cgroup *cgroup)
|
|
{
|
|
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
|
|
|
|
if (blkcg != &blkio_root_cgroup)
|
|
kfree(blkcg);
|
|
}
|
|
|
|
static struct cgroup_subsys_state *blkiocg_create(struct cgroup *cgroup)
|
|
{
|
|
static atomic64_t id_seq = ATOMIC64_INIT(0);
|
|
struct blkio_cgroup *blkcg;
|
|
struct cgroup *parent = cgroup->parent;
|
|
|
|
if (!parent) {
|
|
blkcg = &blkio_root_cgroup;
|
|
goto done;
|
|
}
|
|
|
|
blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
|
|
if (!blkcg)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
blkcg->weight = BLKIO_WEIGHT_DEFAULT;
|
|
blkcg->id = atomic64_inc_return(&id_seq); /* root is 0, start from 1 */
|
|
done:
|
|
spin_lock_init(&blkcg->lock);
|
|
INIT_HLIST_HEAD(&blkcg->blkg_list);
|
|
|
|
return &blkcg->css;
|
|
}
|
|
|
|
/**
|
|
* blkcg_init_queue - initialize blkcg part of request queue
|
|
* @q: request_queue to initialize
|
|
*
|
|
* Called from blk_alloc_queue_node(). Responsible for initializing blkcg
|
|
* part of new request_queue @q.
|
|
*
|
|
* RETURNS:
|
|
* 0 on success, -errno on failure.
|
|
*/
|
|
int blkcg_init_queue(struct request_queue *q)
|
|
{
|
|
int ret;
|
|
|
|
might_sleep();
|
|
|
|
ret = blk_throtl_init(q);
|
|
if (ret)
|
|
return ret;
|
|
|
|
mutex_lock(&all_q_mutex);
|
|
INIT_LIST_HEAD(&q->all_q_node);
|
|
list_add_tail(&q->all_q_node, &all_q_list);
|
|
mutex_unlock(&all_q_mutex);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* blkcg_drain_queue - drain blkcg part of request_queue
|
|
* @q: request_queue to drain
|
|
*
|
|
* Called from blk_drain_queue(). Responsible for draining blkcg part.
|
|
*/
|
|
void blkcg_drain_queue(struct request_queue *q)
|
|
{
|
|
lockdep_assert_held(q->queue_lock);
|
|
|
|
blk_throtl_drain(q);
|
|
}
|
|
|
|
/**
|
|
* blkcg_exit_queue - exit and release blkcg part of request_queue
|
|
* @q: request_queue being released
|
|
*
|
|
* Called from blk_release_queue(). Responsible for exiting blkcg part.
|
|
*/
|
|
void blkcg_exit_queue(struct request_queue *q)
|
|
{
|
|
mutex_lock(&all_q_mutex);
|
|
list_del_init(&q->all_q_node);
|
|
mutex_unlock(&all_q_mutex);
|
|
|
|
blkg_destroy_all(q, true);
|
|
|
|
blk_throtl_exit(q);
|
|
}
|
|
|
|
/*
|
|
* We cannot support shared io contexts, as we have no mean to support
|
|
* two tasks with the same ioc in two different groups without major rework
|
|
* of the main cic data structures. For now we allow a task to change
|
|
* its cgroup only if it's the only owner of its ioc.
|
|
*/
|
|
static int blkiocg_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
|
|
{
|
|
struct task_struct *task;
|
|
struct io_context *ioc;
|
|
int ret = 0;
|
|
|
|
/* task_lock() is needed to avoid races with exit_io_context() */
|
|
cgroup_taskset_for_each(task, cgrp, tset) {
|
|
task_lock(task);
|
|
ioc = task->io_context;
|
|
if (ioc && atomic_read(&ioc->nr_tasks) > 1)
|
|
ret = -EINVAL;
|
|
task_unlock(task);
|
|
if (ret)
|
|
break;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static void blkcg_bypass_start(void)
|
|
__acquires(&all_q_mutex)
|
|
{
|
|
struct request_queue *q;
|
|
|
|
mutex_lock(&all_q_mutex);
|
|
|
|
list_for_each_entry(q, &all_q_list, all_q_node) {
|
|
blk_queue_bypass_start(q);
|
|
blkg_destroy_all(q, false);
|
|
}
|
|
}
|
|
|
|
static void blkcg_bypass_end(void)
|
|
__releases(&all_q_mutex)
|
|
{
|
|
struct request_queue *q;
|
|
|
|
list_for_each_entry(q, &all_q_list, all_q_node)
|
|
blk_queue_bypass_end(q);
|
|
|
|
mutex_unlock(&all_q_mutex);
|
|
}
|
|
|
|
struct cgroup_subsys blkio_subsys = {
|
|
.name = "blkio",
|
|
.create = blkiocg_create,
|
|
.can_attach = blkiocg_can_attach,
|
|
.pre_destroy = blkiocg_pre_destroy,
|
|
.destroy = blkiocg_destroy,
|
|
.subsys_id = blkio_subsys_id,
|
|
.base_cftypes = blkio_files,
|
|
.module = THIS_MODULE,
|
|
};
|
|
EXPORT_SYMBOL_GPL(blkio_subsys);
|
|
|
|
void blkio_policy_register(struct blkio_policy_type *blkiop)
|
|
{
|
|
struct request_queue *q;
|
|
|
|
blkcg_bypass_start();
|
|
spin_lock(&blkio_list_lock);
|
|
|
|
BUG_ON(blkio_policy[blkiop->plid]);
|
|
blkio_policy[blkiop->plid] = blkiop;
|
|
list_add_tail(&blkiop->list, &blkio_list);
|
|
|
|
spin_unlock(&blkio_list_lock);
|
|
list_for_each_entry(q, &all_q_list, all_q_node)
|
|
update_root_blkg_pd(q, blkiop->plid);
|
|
blkcg_bypass_end();
|
|
|
|
if (blkiop->cftypes)
|
|
WARN_ON(cgroup_add_cftypes(&blkio_subsys, blkiop->cftypes));
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkio_policy_register);
|
|
|
|
void blkio_policy_unregister(struct blkio_policy_type *blkiop)
|
|
{
|
|
struct request_queue *q;
|
|
|
|
if (blkiop->cftypes)
|
|
cgroup_rm_cftypes(&blkio_subsys, blkiop->cftypes);
|
|
|
|
blkcg_bypass_start();
|
|
spin_lock(&blkio_list_lock);
|
|
|
|
BUG_ON(blkio_policy[blkiop->plid] != blkiop);
|
|
blkio_policy[blkiop->plid] = NULL;
|
|
list_del_init(&blkiop->list);
|
|
|
|
spin_unlock(&blkio_list_lock);
|
|
list_for_each_entry(q, &all_q_list, all_q_node)
|
|
update_root_blkg_pd(q, blkiop->plid);
|
|
blkcg_bypass_end();
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkio_policy_unregister);
|