mirror of
https://github.com/torvalds/linux.git
synced 2024-12-05 02:23:16 +00:00
ee89f81252
Pull block IO core bits from Jens Axboe:
"Below are the core block IO bits for 3.9. It was delayed a few days
since my workstation kept crashing every 2-8h after pulling it into
current -git, but turns out it is a bug in the new pstate code (divide
by zero, will report separately). In any case, it contains:
- The big cfq/blkcg update from Tejun and and Vivek.
- Additional block and writeback tracepoints from Tejun.
- Improvement of the should sort (based on queues) logic in the plug
flushing.
- _io() variants of the wait_for_completion() interface, using
io_schedule() instead of schedule() to contribute to io wait
properly.
- Various little fixes.
You'll get two trivial merge conflicts, which should be easy enough to
fix up"
Fix up the trivial conflicts due to hlist traversal cleanups (commit
b67bfe0d42
: "hlist: drop the node parameter from iterators").
* 'for-3.9/core' of git://git.kernel.dk/linux-block: (39 commits)
block: remove redundant check to bd_openers()
block: use i_size_write() in bd_set_size()
cfq: fix lock imbalance with failed allocations
drivers/block/swim3.c: fix null pointer dereference
block: don't select PERCPU_RWSEM
block: account iowait time when waiting for completion of IO request
sched: add wait_for_completion_io[_timeout]
writeback: add more tracepoints
block: add block_{touch|dirty}_buffer tracepoint
buffer: make touch_buffer() an exported function
block: add @req to bio_{front|back}_merge tracepoints
block: add missing block_bio_complete() tracepoint
block: Remove should_sort judgement when flush blk_plug
block,elevator: use new hashtable implementation
cfq-iosched: add hierarchical cfq_group statistics
cfq-iosched: collect stats from dead cfqgs
cfq-iosched: separate out cfqg_stats_reset() from cfq_pd_reset_stats()
blkcg: make blkcg_print_blkgs() grab q locks instead of blkcg lock
block: RCU free request_queue
blkcg: implement blkg_[rw]stat_recursive_sum() and blkg_[rw]stat_merge()
...
1163 lines
30 KiB
C
1163 lines
30 KiB
C
/*
|
|
* Common Block IO controller cgroup interface
|
|
*
|
|
* Based on ideas and code from CFQ, CFS and BFQ:
|
|
* Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
|
|
*
|
|
* Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
|
|
* Paolo Valente <paolo.valente@unimore.it>
|
|
*
|
|
* Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
|
|
* Nauman Rafique <nauman@google.com>
|
|
*/
|
|
#include <linux/ioprio.h>
|
|
#include <linux/kdev_t.h>
|
|
#include <linux/module.h>
|
|
#include <linux/err.h>
|
|
#include <linux/blkdev.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/genhd.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/atomic.h>
|
|
#include "blk-cgroup.h"
|
|
#include "blk.h"
|
|
|
|
#define MAX_KEY_LEN 100
|
|
|
|
static DEFINE_MUTEX(blkcg_pol_mutex);
|
|
|
|
struct blkcg blkcg_root = { .cfq_weight = 2 * CFQ_WEIGHT_DEFAULT,
|
|
.cfq_leaf_weight = 2 * CFQ_WEIGHT_DEFAULT, };
|
|
EXPORT_SYMBOL_GPL(blkcg_root);
|
|
|
|
static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS];
|
|
|
|
static struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg,
|
|
struct request_queue *q, bool update_hint);
|
|
|
|
/**
|
|
* blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
|
|
* @d_blkg: loop cursor pointing to the current descendant
|
|
* @pos_cgrp: used for iteration
|
|
* @p_blkg: target blkg to walk descendants of
|
|
*
|
|
* Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU
|
|
* read locked. If called under either blkcg or queue lock, the iteration
|
|
* is guaranteed to include all and only online blkgs. The caller may
|
|
* update @pos_cgrp by calling cgroup_rightmost_descendant() to skip
|
|
* subtree.
|
|
*/
|
|
#define blkg_for_each_descendant_pre(d_blkg, pos_cgrp, p_blkg) \
|
|
cgroup_for_each_descendant_pre((pos_cgrp), (p_blkg)->blkcg->css.cgroup) \
|
|
if (((d_blkg) = __blkg_lookup(cgroup_to_blkcg(pos_cgrp), \
|
|
(p_blkg)->q, false)))
|
|
|
|
static bool blkcg_policy_enabled(struct request_queue *q,
|
|
const struct blkcg_policy *pol)
|
|
{
|
|
return pol && test_bit(pol->plid, q->blkcg_pols);
|
|
}
|
|
|
|
/**
|
|
* blkg_free - free a blkg
|
|
* @blkg: blkg to free
|
|
*
|
|
* Free @blkg which may be partially allocated.
|
|
*/
|
|
static void blkg_free(struct blkcg_gq *blkg)
|
|
{
|
|
int i;
|
|
|
|
if (!blkg)
|
|
return;
|
|
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++) {
|
|
struct blkcg_policy *pol = blkcg_policy[i];
|
|
struct blkg_policy_data *pd = blkg->pd[i];
|
|
|
|
if (!pd)
|
|
continue;
|
|
|
|
if (pol && pol->pd_exit_fn)
|
|
pol->pd_exit_fn(blkg);
|
|
|
|
kfree(pd);
|
|
}
|
|
|
|
blk_exit_rl(&blkg->rl);
|
|
kfree(blkg);
|
|
}
|
|
|
|
/**
|
|
* blkg_alloc - allocate a blkg
|
|
* @blkcg: block cgroup the new blkg is associated with
|
|
* @q: request_queue the new blkg is associated with
|
|
* @gfp_mask: allocation mask to use
|
|
*
|
|
* Allocate a new blkg assocating @blkcg and @q.
|
|
*/
|
|
static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q,
|
|
gfp_t gfp_mask)
|
|
{
|
|
struct blkcg_gq *blkg;
|
|
int i;
|
|
|
|
/* alloc and init base part */
|
|
blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node);
|
|
if (!blkg)
|
|
return NULL;
|
|
|
|
blkg->q = q;
|
|
INIT_LIST_HEAD(&blkg->q_node);
|
|
blkg->blkcg = blkcg;
|
|
blkg->refcnt = 1;
|
|
|
|
/* root blkg uses @q->root_rl, init rl only for !root blkgs */
|
|
if (blkcg != &blkcg_root) {
|
|
if (blk_init_rl(&blkg->rl, q, gfp_mask))
|
|
goto err_free;
|
|
blkg->rl.blkg = blkg;
|
|
}
|
|
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++) {
|
|
struct blkcg_policy *pol = blkcg_policy[i];
|
|
struct blkg_policy_data *pd;
|
|
|
|
if (!blkcg_policy_enabled(q, pol))
|
|
continue;
|
|
|
|
/* alloc per-policy data and attach it to blkg */
|
|
pd = kzalloc_node(pol->pd_size, gfp_mask, q->node);
|
|
if (!pd)
|
|
goto err_free;
|
|
|
|
blkg->pd[i] = pd;
|
|
pd->blkg = blkg;
|
|
pd->plid = i;
|
|
|
|
/* invoke per-policy init */
|
|
if (pol->pd_init_fn)
|
|
pol->pd_init_fn(blkg);
|
|
}
|
|
|
|
return blkg;
|
|
|
|
err_free:
|
|
blkg_free(blkg);
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* __blkg_lookup - internal version of blkg_lookup()
|
|
* @blkcg: blkcg of interest
|
|
* @q: request_queue of interest
|
|
* @update_hint: whether to update lookup hint with the result or not
|
|
*
|
|
* This is internal version and shouldn't be used by policy
|
|
* implementations. Looks up blkgs for the @blkcg - @q pair regardless of
|
|
* @q's bypass state. If @update_hint is %true, the caller should be
|
|
* holding @q->queue_lock and lookup hint is updated on success.
|
|
*/
|
|
static struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg,
|
|
struct request_queue *q, bool update_hint)
|
|
{
|
|
struct blkcg_gq *blkg;
|
|
|
|
blkg = rcu_dereference(blkcg->blkg_hint);
|
|
if (blkg && blkg->q == q)
|
|
return blkg;
|
|
|
|
/*
|
|
* Hint didn't match. Look up from the radix tree. Note that the
|
|
* hint can only be updated under queue_lock as otherwise @blkg
|
|
* could have already been removed from blkg_tree. The caller is
|
|
* responsible for grabbing queue_lock if @update_hint.
|
|
*/
|
|
blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id);
|
|
if (blkg && blkg->q == q) {
|
|
if (update_hint) {
|
|
lockdep_assert_held(q->queue_lock);
|
|
rcu_assign_pointer(blkcg->blkg_hint, blkg);
|
|
}
|
|
return blkg;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* blkg_lookup - lookup blkg for the specified blkcg - q pair
|
|
* @blkcg: blkcg of interest
|
|
* @q: request_queue of interest
|
|
*
|
|
* Lookup blkg for the @blkcg - @q pair. This function should be called
|
|
* under RCU read lock and is guaranteed to return %NULL if @q is bypassing
|
|
* - see blk_queue_bypass_start() for details.
|
|
*/
|
|
struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q)
|
|
{
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
if (unlikely(blk_queue_bypass(q)))
|
|
return NULL;
|
|
return __blkg_lookup(blkcg, q, false);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_lookup);
|
|
|
|
/*
|
|
* If @new_blkg is %NULL, this function tries to allocate a new one as
|
|
* necessary using %GFP_ATOMIC. @new_blkg is always consumed on return.
|
|
*/
|
|
static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
|
|
struct request_queue *q,
|
|
struct blkcg_gq *new_blkg)
|
|
{
|
|
struct blkcg_gq *blkg;
|
|
int i, ret;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
lockdep_assert_held(q->queue_lock);
|
|
|
|
/* blkg holds a reference to blkcg */
|
|
if (!css_tryget(&blkcg->css)) {
|
|
ret = -EINVAL;
|
|
goto err_free_blkg;
|
|
}
|
|
|
|
/* allocate */
|
|
if (!new_blkg) {
|
|
new_blkg = blkg_alloc(blkcg, q, GFP_ATOMIC);
|
|
if (unlikely(!new_blkg)) {
|
|
ret = -ENOMEM;
|
|
goto err_put_css;
|
|
}
|
|
}
|
|
blkg = new_blkg;
|
|
|
|
/* link parent and insert */
|
|
if (blkcg_parent(blkcg)) {
|
|
blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false);
|
|
if (WARN_ON_ONCE(!blkg->parent)) {
|
|
blkg = ERR_PTR(-EINVAL);
|
|
goto err_put_css;
|
|
}
|
|
blkg_get(blkg->parent);
|
|
}
|
|
|
|
spin_lock(&blkcg->lock);
|
|
ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg);
|
|
if (likely(!ret)) {
|
|
hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
|
|
list_add(&blkg->q_node, &q->blkg_list);
|
|
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++) {
|
|
struct blkcg_policy *pol = blkcg_policy[i];
|
|
|
|
if (blkg->pd[i] && pol->pd_online_fn)
|
|
pol->pd_online_fn(blkg);
|
|
}
|
|
}
|
|
blkg->online = true;
|
|
spin_unlock(&blkcg->lock);
|
|
|
|
if (!ret)
|
|
return blkg;
|
|
|
|
/* @blkg failed fully initialized, use the usual release path */
|
|
blkg_put(blkg);
|
|
return ERR_PTR(ret);
|
|
|
|
err_put_css:
|
|
css_put(&blkcg->css);
|
|
err_free_blkg:
|
|
blkg_free(new_blkg);
|
|
return ERR_PTR(ret);
|
|
}
|
|
|
|
/**
|
|
* blkg_lookup_create - lookup blkg, try to create one if not there
|
|
* @blkcg: blkcg of interest
|
|
* @q: request_queue of interest
|
|
*
|
|
* Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to
|
|
* create one. blkg creation is performed recursively from blkcg_root such
|
|
* that all non-root blkg's have access to the parent blkg. This function
|
|
* should be called under RCU read lock and @q->queue_lock.
|
|
*
|
|
* Returns pointer to the looked up or created blkg on success, ERR_PTR()
|
|
* value on error. If @q is dead, returns ERR_PTR(-EINVAL). If @q is not
|
|
* dead and bypassing, returns ERR_PTR(-EBUSY).
|
|
*/
|
|
struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
|
|
struct request_queue *q)
|
|
{
|
|
struct blkcg_gq *blkg;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
lockdep_assert_held(q->queue_lock);
|
|
|
|
/*
|
|
* This could be the first entry point of blkcg implementation and
|
|
* we shouldn't allow anything to go through for a bypassing queue.
|
|
*/
|
|
if (unlikely(blk_queue_bypass(q)))
|
|
return ERR_PTR(blk_queue_dying(q) ? -EINVAL : -EBUSY);
|
|
|
|
blkg = __blkg_lookup(blkcg, q, true);
|
|
if (blkg)
|
|
return blkg;
|
|
|
|
/*
|
|
* Create blkgs walking down from blkcg_root to @blkcg, so that all
|
|
* non-root blkgs have access to their parents.
|
|
*/
|
|
while (true) {
|
|
struct blkcg *pos = blkcg;
|
|
struct blkcg *parent = blkcg_parent(blkcg);
|
|
|
|
while (parent && !__blkg_lookup(parent, q, false)) {
|
|
pos = parent;
|
|
parent = blkcg_parent(parent);
|
|
}
|
|
|
|
blkg = blkg_create(pos, q, NULL);
|
|
if (pos == blkcg || IS_ERR(blkg))
|
|
return blkg;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_lookup_create);
|
|
|
|
static void blkg_destroy(struct blkcg_gq *blkg)
|
|
{
|
|
struct blkcg *blkcg = blkg->blkcg;
|
|
int i;
|
|
|
|
lockdep_assert_held(blkg->q->queue_lock);
|
|
lockdep_assert_held(&blkcg->lock);
|
|
|
|
/* Something wrong if we are trying to remove same group twice */
|
|
WARN_ON_ONCE(list_empty(&blkg->q_node));
|
|
WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node));
|
|
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++) {
|
|
struct blkcg_policy *pol = blkcg_policy[i];
|
|
|
|
if (blkg->pd[i] && pol->pd_offline_fn)
|
|
pol->pd_offline_fn(blkg);
|
|
}
|
|
blkg->online = false;
|
|
|
|
radix_tree_delete(&blkcg->blkg_tree, blkg->q->id);
|
|
list_del_init(&blkg->q_node);
|
|
hlist_del_init_rcu(&blkg->blkcg_node);
|
|
|
|
/*
|
|
* Both setting lookup hint to and clearing it from @blkg are done
|
|
* under queue_lock. If it's not pointing to @blkg now, it never
|
|
* will. Hint assignment itself can race safely.
|
|
*/
|
|
if (rcu_dereference_raw(blkcg->blkg_hint) == blkg)
|
|
rcu_assign_pointer(blkcg->blkg_hint, NULL);
|
|
|
|
/*
|
|
* Put the reference taken at the time of creation so that when all
|
|
* queues are gone, group can be destroyed.
|
|
*/
|
|
blkg_put(blkg);
|
|
}
|
|
|
|
/**
|
|
* blkg_destroy_all - destroy all blkgs associated with a request_queue
|
|
* @q: request_queue of interest
|
|
*
|
|
* Destroy all blkgs associated with @q.
|
|
*/
|
|
static void blkg_destroy_all(struct request_queue *q)
|
|
{
|
|
struct blkcg_gq *blkg, *n;
|
|
|
|
lockdep_assert_held(q->queue_lock);
|
|
|
|
list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
|
|
struct blkcg *blkcg = blkg->blkcg;
|
|
|
|
spin_lock(&blkcg->lock);
|
|
blkg_destroy(blkg);
|
|
spin_unlock(&blkcg->lock);
|
|
}
|
|
|
|
/*
|
|
* root blkg is destroyed. Just clear the pointer since
|
|
* root_rl does not take reference on root blkg.
|
|
*/
|
|
q->root_blkg = NULL;
|
|
q->root_rl.blkg = NULL;
|
|
}
|
|
|
|
static void blkg_rcu_free(struct rcu_head *rcu_head)
|
|
{
|
|
blkg_free(container_of(rcu_head, struct blkcg_gq, rcu_head));
|
|
}
|
|
|
|
void __blkg_release(struct blkcg_gq *blkg)
|
|
{
|
|
/* release the blkcg and parent blkg refs this blkg has been holding */
|
|
css_put(&blkg->blkcg->css);
|
|
if (blkg->parent)
|
|
blkg_put(blkg->parent);
|
|
|
|
/*
|
|
* A group is freed in rcu manner. But having an rcu lock does not
|
|
* mean that one can access all the fields of blkg and assume these
|
|
* are valid. For example, don't try to follow throtl_data and
|
|
* request queue links.
|
|
*
|
|
* Having a reference to blkg under an rcu allows acess to only
|
|
* values local to groups like group stats and group rate limits
|
|
*/
|
|
call_rcu(&blkg->rcu_head, blkg_rcu_free);
|
|
}
|
|
EXPORT_SYMBOL_GPL(__blkg_release);
|
|
|
|
/*
|
|
* The next function used by blk_queue_for_each_rl(). It's a bit tricky
|
|
* because the root blkg uses @q->root_rl instead of its own rl.
|
|
*/
|
|
struct request_list *__blk_queue_next_rl(struct request_list *rl,
|
|
struct request_queue *q)
|
|
{
|
|
struct list_head *ent;
|
|
struct blkcg_gq *blkg;
|
|
|
|
/*
|
|
* Determine the current blkg list_head. The first entry is
|
|
* root_rl which is off @q->blkg_list and mapped to the head.
|
|
*/
|
|
if (rl == &q->root_rl) {
|
|
ent = &q->blkg_list;
|
|
/* There are no more block groups, hence no request lists */
|
|
if (list_empty(ent))
|
|
return NULL;
|
|
} else {
|
|
blkg = container_of(rl, struct blkcg_gq, rl);
|
|
ent = &blkg->q_node;
|
|
}
|
|
|
|
/* walk to the next list_head, skip root blkcg */
|
|
ent = ent->next;
|
|
if (ent == &q->root_blkg->q_node)
|
|
ent = ent->next;
|
|
if (ent == &q->blkg_list)
|
|
return NULL;
|
|
|
|
blkg = container_of(ent, struct blkcg_gq, q_node);
|
|
return &blkg->rl;
|
|
}
|
|
|
|
static int blkcg_reset_stats(struct cgroup *cgroup, struct cftype *cftype,
|
|
u64 val)
|
|
{
|
|
struct blkcg *blkcg = cgroup_to_blkcg(cgroup);
|
|
struct blkcg_gq *blkg;
|
|
int i;
|
|
|
|
mutex_lock(&blkcg_pol_mutex);
|
|
spin_lock_irq(&blkcg->lock);
|
|
|
|
/*
|
|
* Note that stat reset is racy - it doesn't synchronize against
|
|
* stat updates. This is a debug feature which shouldn't exist
|
|
* anyway. If you get hit by a race, retry.
|
|
*/
|
|
hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++) {
|
|
struct blkcg_policy *pol = blkcg_policy[i];
|
|
|
|
if (blkcg_policy_enabled(blkg->q, pol) &&
|
|
pol->pd_reset_stats_fn)
|
|
pol->pd_reset_stats_fn(blkg);
|
|
}
|
|
}
|
|
|
|
spin_unlock_irq(&blkcg->lock);
|
|
mutex_unlock(&blkcg_pol_mutex);
|
|
return 0;
|
|
}
|
|
|
|
static const char *blkg_dev_name(struct blkcg_gq *blkg)
|
|
{
|
|
/* some drivers (floppy) instantiate a queue w/o disk registered */
|
|
if (blkg->q->backing_dev_info.dev)
|
|
return dev_name(blkg->q->backing_dev_info.dev);
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* blkcg_print_blkgs - helper for printing per-blkg data
|
|
* @sf: seq_file to print to
|
|
* @blkcg: blkcg of interest
|
|
* @prfill: fill function to print out a blkg
|
|
* @pol: policy in question
|
|
* @data: data to be passed to @prfill
|
|
* @show_total: to print out sum of prfill return values or not
|
|
*
|
|
* This function invokes @prfill on each blkg of @blkcg if pd for the
|
|
* policy specified by @pol exists. @prfill is invoked with @sf, the
|
|
* policy data and @data and the matching queue lock held. If @show_total
|
|
* is %true, the sum of the return values from @prfill is printed with
|
|
* "Total" label at the end.
|
|
*
|
|
* This is to be used to construct print functions for
|
|
* cftype->read_seq_string method.
|
|
*/
|
|
void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
|
|
u64 (*prfill)(struct seq_file *,
|
|
struct blkg_policy_data *, int),
|
|
const struct blkcg_policy *pol, int data,
|
|
bool show_total)
|
|
{
|
|
struct blkcg_gq *blkg;
|
|
u64 total = 0;
|
|
|
|
rcu_read_lock();
|
|
hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) {
|
|
spin_lock_irq(blkg->q->queue_lock);
|
|
if (blkcg_policy_enabled(blkg->q, pol))
|
|
total += prfill(sf, blkg->pd[pol->plid], data);
|
|
spin_unlock_irq(blkg->q->queue_lock);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
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 private 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 private 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;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat);
|
|
|
|
/**
|
|
* blkg_prfill_stat - prfill callback for blkg_stat
|
|
* @sf: seq_file to print to
|
|
* @pd: policy private data of interest
|
|
* @off: offset to the blkg_stat in @pd
|
|
*
|
|
* prfill callback for printing a blkg_stat.
|
|
*/
|
|
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 + off));
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_prfill_stat);
|
|
|
|
/**
|
|
* blkg_prfill_rwstat - prfill callback for blkg_rwstat
|
|
* @sf: seq_file to print to
|
|
* @pd: policy private data of interest
|
|
* @off: offset to the blkg_rwstat in @pd
|
|
*
|
|
* prfill callback for printing a blkg_rwstat.
|
|
*/
|
|
u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
|
|
int off)
|
|
{
|
|
struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd + off);
|
|
|
|
return __blkg_prfill_rwstat(sf, pd, &rwstat);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_prfill_rwstat);
|
|
|
|
/**
|
|
* blkg_stat_recursive_sum - collect hierarchical blkg_stat
|
|
* @pd: policy private data of interest
|
|
* @off: offset to the blkg_stat in @pd
|
|
*
|
|
* Collect the blkg_stat specified by @off from @pd and all its online
|
|
* descendants and return the sum. The caller must be holding the queue
|
|
* lock for online tests.
|
|
*/
|
|
u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off)
|
|
{
|
|
struct blkcg_policy *pol = blkcg_policy[pd->plid];
|
|
struct blkcg_gq *pos_blkg;
|
|
struct cgroup *pos_cgrp;
|
|
u64 sum;
|
|
|
|
lockdep_assert_held(pd->blkg->q->queue_lock);
|
|
|
|
sum = blkg_stat_read((void *)pd + off);
|
|
|
|
rcu_read_lock();
|
|
blkg_for_each_descendant_pre(pos_blkg, pos_cgrp, pd_to_blkg(pd)) {
|
|
struct blkg_policy_data *pos_pd = blkg_to_pd(pos_blkg, pol);
|
|
struct blkg_stat *stat = (void *)pos_pd + off;
|
|
|
|
if (pos_blkg->online)
|
|
sum += blkg_stat_read(stat);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
return sum;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum);
|
|
|
|
/**
|
|
* blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat
|
|
* @pd: policy private data of interest
|
|
* @off: offset to the blkg_stat in @pd
|
|
*
|
|
* Collect the blkg_rwstat specified by @off from @pd and all its online
|
|
* descendants and return the sum. The caller must be holding the queue
|
|
* lock for online tests.
|
|
*/
|
|
struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd,
|
|
int off)
|
|
{
|
|
struct blkcg_policy *pol = blkcg_policy[pd->plid];
|
|
struct blkcg_gq *pos_blkg;
|
|
struct cgroup *pos_cgrp;
|
|
struct blkg_rwstat sum;
|
|
int i;
|
|
|
|
lockdep_assert_held(pd->blkg->q->queue_lock);
|
|
|
|
sum = blkg_rwstat_read((void *)pd + off);
|
|
|
|
rcu_read_lock();
|
|
blkg_for_each_descendant_pre(pos_blkg, pos_cgrp, pd_to_blkg(pd)) {
|
|
struct blkg_policy_data *pos_pd = blkg_to_pd(pos_blkg, pol);
|
|
struct blkg_rwstat *rwstat = (void *)pos_pd + off;
|
|
struct blkg_rwstat tmp;
|
|
|
|
if (!pos_blkg->online)
|
|
continue;
|
|
|
|
tmp = blkg_rwstat_read(rwstat);
|
|
|
|
for (i = 0; i < BLKG_RWSTAT_NR; i++)
|
|
sum.cnt[i] += tmp.cnt[i];
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
return sum;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum);
|
|
|
|
/**
|
|
* blkg_conf_prep - parse and prepare for per-blkg config update
|
|
* @blkcg: target block cgroup
|
|
* @pol: target policy
|
|
* @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 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,
|
|
const char *input, struct blkg_conf_ctx *ctx)
|
|
__acquires(rcu) __acquires(disk->queue->queue_lock)
|
|
{
|
|
struct gendisk *disk;
|
|
struct blkcg_gq *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);
|
|
|
|
if (blkcg_policy_enabled(disk->queue, pol))
|
|
blkg = blkg_lookup_create(blkcg, disk->queue);
|
|
else
|
|
blkg = ERR_PTR(-EINVAL);
|
|
|
|
if (IS_ERR(blkg)) {
|
|
ret = PTR_ERR(blkg);
|
|
rcu_read_unlock();
|
|
spin_unlock_irq(disk->queue->queue_lock);
|
|
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(ctx->disk->queue->queue_lock) __releases(rcu)
|
|
{
|
|
spin_unlock_irq(ctx->disk->queue->queue_lock);
|
|
rcu_read_unlock();
|
|
put_disk(ctx->disk);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_conf_finish);
|
|
|
|
struct cftype blkcg_files[] = {
|
|
{
|
|
.name = "reset_stats",
|
|
.write_u64 = blkcg_reset_stats,
|
|
},
|
|
{ } /* terminate */
|
|
};
|
|
|
|
/**
|
|
* blkcg_css_offline - cgroup css_offline 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 void blkcg_css_offline(struct cgroup *cgroup)
|
|
{
|
|
struct blkcg *blkcg = cgroup_to_blkcg(cgroup);
|
|
|
|
spin_lock_irq(&blkcg->lock);
|
|
|
|
while (!hlist_empty(&blkcg->blkg_list)) {
|
|
struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first,
|
|
struct blkcg_gq, blkcg_node);
|
|
struct request_queue *q = blkg->q;
|
|
|
|
if (spin_trylock(q->queue_lock)) {
|
|
blkg_destroy(blkg);
|
|
spin_unlock(q->queue_lock);
|
|
} else {
|
|
spin_unlock_irq(&blkcg->lock);
|
|
cpu_relax();
|
|
spin_lock_irq(&blkcg->lock);
|
|
}
|
|
}
|
|
|
|
spin_unlock_irq(&blkcg->lock);
|
|
}
|
|
|
|
static void blkcg_css_free(struct cgroup *cgroup)
|
|
{
|
|
struct blkcg *blkcg = cgroup_to_blkcg(cgroup);
|
|
|
|
if (blkcg != &blkcg_root)
|
|
kfree(blkcg);
|
|
}
|
|
|
|
static struct cgroup_subsys_state *blkcg_css_alloc(struct cgroup *cgroup)
|
|
{
|
|
static atomic64_t id_seq = ATOMIC64_INIT(0);
|
|
struct blkcg *blkcg;
|
|
struct cgroup *parent = cgroup->parent;
|
|
|
|
if (!parent) {
|
|
blkcg = &blkcg_root;
|
|
goto done;
|
|
}
|
|
|
|
blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
|
|
if (!blkcg)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
blkcg->cfq_weight = CFQ_WEIGHT_DEFAULT;
|
|
blkcg->cfq_leaf_weight = CFQ_WEIGHT_DEFAULT;
|
|
blkcg->id = atomic64_inc_return(&id_seq); /* root is 0, start from 1 */
|
|
done:
|
|
spin_lock_init(&blkcg->lock);
|
|
INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_ATOMIC);
|
|
INIT_HLIST_HEAD(&blkcg->blkg_list);
|
|
|
|
return &blkcg->css;
|
|
}
|
|
|
|
/**
|
|
* blkcg_init_queue - initialize blkcg part of request queue
|
|
* @q: request_queue to initialize
|
|
*
|
|
* Called from blk_alloc_queue_node(). Responsible for initializing blkcg
|
|
* part of new request_queue @q.
|
|
*
|
|
* RETURNS:
|
|
* 0 on success, -errno on failure.
|
|
*/
|
|
int blkcg_init_queue(struct request_queue *q)
|
|
{
|
|
might_sleep();
|
|
|
|
return blk_throtl_init(q);
|
|
}
|
|
|
|
/**
|
|
* blkcg_drain_queue - drain blkcg part of request_queue
|
|
* @q: request_queue to drain
|
|
*
|
|
* Called from blk_drain_queue(). Responsible for draining blkcg part.
|
|
*/
|
|
void blkcg_drain_queue(struct request_queue *q)
|
|
{
|
|
lockdep_assert_held(q->queue_lock);
|
|
|
|
blk_throtl_drain(q);
|
|
}
|
|
|
|
/**
|
|
* blkcg_exit_queue - exit and release blkcg part of request_queue
|
|
* @q: request_queue being released
|
|
*
|
|
* Called from blk_release_queue(). Responsible for exiting blkcg part.
|
|
*/
|
|
void blkcg_exit_queue(struct request_queue *q)
|
|
{
|
|
spin_lock_irq(q->queue_lock);
|
|
blkg_destroy_all(q);
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
blk_throtl_exit(q);
|
|
}
|
|
|
|
/*
|
|
* We cannot support shared io contexts, as we have no mean to support
|
|
* two tasks with the same ioc in two different groups without major rework
|
|
* of the main cic data structures. For now we allow a task to change
|
|
* its cgroup only if it's the only owner of its ioc.
|
|
*/
|
|
static int blkcg_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
|
|
{
|
|
struct task_struct *task;
|
|
struct io_context *ioc;
|
|
int ret = 0;
|
|
|
|
/* task_lock() is needed to avoid races with exit_io_context() */
|
|
cgroup_taskset_for_each(task, cgrp, tset) {
|
|
task_lock(task);
|
|
ioc = task->io_context;
|
|
if (ioc && atomic_read(&ioc->nr_tasks) > 1)
|
|
ret = -EINVAL;
|
|
task_unlock(task);
|
|
if (ret)
|
|
break;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
struct cgroup_subsys blkio_subsys = {
|
|
.name = "blkio",
|
|
.css_alloc = blkcg_css_alloc,
|
|
.css_offline = blkcg_css_offline,
|
|
.css_free = blkcg_css_free,
|
|
.can_attach = blkcg_can_attach,
|
|
.subsys_id = blkio_subsys_id,
|
|
.base_cftypes = blkcg_files,
|
|
.module = THIS_MODULE,
|
|
|
|
/*
|
|
* blkio subsystem is utterly broken in terms of hierarchy support.
|
|
* It treats all cgroups equally regardless of where they're
|
|
* located in the hierarchy - all cgroups are treated as if they're
|
|
* right below the root. Fix it and remove the following.
|
|
*/
|
|
.broken_hierarchy = true,
|
|
};
|
|
EXPORT_SYMBOL_GPL(blkio_subsys);
|
|
|
|
/**
|
|
* blkcg_activate_policy - activate a blkcg policy on a request_queue
|
|
* @q: request_queue of interest
|
|
* @pol: blkcg policy to activate
|
|
*
|
|
* Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through
|
|
* bypass mode to populate its blkgs with policy_data for @pol.
|
|
*
|
|
* Activation happens with @q bypassed, so nobody would be accessing blkgs
|
|
* from IO path. Update of each blkg is protected by both queue and blkcg
|
|
* locks so that holding either lock and testing blkcg_policy_enabled() is
|
|
* always enough for dereferencing policy data.
|
|
*
|
|
* The caller is responsible for synchronizing [de]activations and policy
|
|
* [un]registerations. Returns 0 on success, -errno on failure.
|
|
*/
|
|
int blkcg_activate_policy(struct request_queue *q,
|
|
const struct blkcg_policy *pol)
|
|
{
|
|
LIST_HEAD(pds);
|
|
struct blkcg_gq *blkg, *new_blkg;
|
|
struct blkg_policy_data *pd, *n;
|
|
int cnt = 0, ret;
|
|
bool preloaded;
|
|
|
|
if (blkcg_policy_enabled(q, pol))
|
|
return 0;
|
|
|
|
/* preallocations for root blkg */
|
|
new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL);
|
|
if (!new_blkg)
|
|
return -ENOMEM;
|
|
|
|
preloaded = !radix_tree_preload(GFP_KERNEL);
|
|
|
|
blk_queue_bypass_start(q);
|
|
|
|
/*
|
|
* Make sure the root blkg exists and count the existing blkgs. As
|
|
* @q is bypassing at this point, blkg_lookup_create() can't be
|
|
* used. Open code it.
|
|
*/
|
|
spin_lock_irq(q->queue_lock);
|
|
|
|
rcu_read_lock();
|
|
blkg = __blkg_lookup(&blkcg_root, q, false);
|
|
if (blkg)
|
|
blkg_free(new_blkg);
|
|
else
|
|
blkg = blkg_create(&blkcg_root, q, new_blkg);
|
|
rcu_read_unlock();
|
|
|
|
if (preloaded)
|
|
radix_tree_preload_end();
|
|
|
|
if (IS_ERR(blkg)) {
|
|
ret = PTR_ERR(blkg);
|
|
goto out_unlock;
|
|
}
|
|
q->root_blkg = blkg;
|
|
q->root_rl.blkg = blkg;
|
|
|
|
list_for_each_entry(blkg, &q->blkg_list, q_node)
|
|
cnt++;
|
|
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
/* allocate policy_data for all existing blkgs */
|
|
while (cnt--) {
|
|
pd = kzalloc_node(pol->pd_size, GFP_KERNEL, q->node);
|
|
if (!pd) {
|
|
ret = -ENOMEM;
|
|
goto out_free;
|
|
}
|
|
list_add_tail(&pd->alloc_node, &pds);
|
|
}
|
|
|
|
/*
|
|
* Install the allocated pds. With @q bypassing, no new blkg
|
|
* should have been created while the queue lock was dropped.
|
|
*/
|
|
spin_lock_irq(q->queue_lock);
|
|
|
|
list_for_each_entry(blkg, &q->blkg_list, q_node) {
|
|
if (WARN_ON(list_empty(&pds))) {
|
|
/* umm... this shouldn't happen, just abort */
|
|
ret = -ENOMEM;
|
|
goto out_unlock;
|
|
}
|
|
pd = list_first_entry(&pds, struct blkg_policy_data, alloc_node);
|
|
list_del_init(&pd->alloc_node);
|
|
|
|
/* grab blkcg lock too while installing @pd on @blkg */
|
|
spin_lock(&blkg->blkcg->lock);
|
|
|
|
blkg->pd[pol->plid] = pd;
|
|
pd->blkg = blkg;
|
|
pd->plid = pol->plid;
|
|
pol->pd_init_fn(blkg);
|
|
|
|
spin_unlock(&blkg->blkcg->lock);
|
|
}
|
|
|
|
__set_bit(pol->plid, q->blkcg_pols);
|
|
ret = 0;
|
|
out_unlock:
|
|
spin_unlock_irq(q->queue_lock);
|
|
out_free:
|
|
blk_queue_bypass_end(q);
|
|
list_for_each_entry_safe(pd, n, &pds, alloc_node)
|
|
kfree(pd);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_activate_policy);
|
|
|
|
/**
|
|
* blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue
|
|
* @q: request_queue of interest
|
|
* @pol: blkcg policy to deactivate
|
|
*
|
|
* Deactivate @pol on @q. Follows the same synchronization rules as
|
|
* blkcg_activate_policy().
|
|
*/
|
|
void blkcg_deactivate_policy(struct request_queue *q,
|
|
const struct blkcg_policy *pol)
|
|
{
|
|
struct blkcg_gq *blkg;
|
|
|
|
if (!blkcg_policy_enabled(q, pol))
|
|
return;
|
|
|
|
blk_queue_bypass_start(q);
|
|
spin_lock_irq(q->queue_lock);
|
|
|
|
__clear_bit(pol->plid, q->blkcg_pols);
|
|
|
|
/* if no policy is left, no need for blkgs - shoot them down */
|
|
if (bitmap_empty(q->blkcg_pols, BLKCG_MAX_POLS))
|
|
blkg_destroy_all(q);
|
|
|
|
list_for_each_entry(blkg, &q->blkg_list, q_node) {
|
|
/* grab blkcg lock too while removing @pd from @blkg */
|
|
spin_lock(&blkg->blkcg->lock);
|
|
|
|
if (pol->pd_offline_fn)
|
|
pol->pd_offline_fn(blkg);
|
|
if (pol->pd_exit_fn)
|
|
pol->pd_exit_fn(blkg);
|
|
|
|
kfree(blkg->pd[pol->plid]);
|
|
blkg->pd[pol->plid] = NULL;
|
|
|
|
spin_unlock(&blkg->blkcg->lock);
|
|
}
|
|
|
|
spin_unlock_irq(q->queue_lock);
|
|
blk_queue_bypass_end(q);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_deactivate_policy);
|
|
|
|
/**
|
|
* blkcg_policy_register - register a blkcg policy
|
|
* @pol: blkcg policy to register
|
|
*
|
|
* Register @pol with blkcg core. Might sleep and @pol may be modified on
|
|
* successful registration. Returns 0 on success and -errno on failure.
|
|
*/
|
|
int blkcg_policy_register(struct blkcg_policy *pol)
|
|
{
|
|
int i, ret;
|
|
|
|
if (WARN_ON(pol->pd_size < sizeof(struct blkg_policy_data)))
|
|
return -EINVAL;
|
|
|
|
mutex_lock(&blkcg_pol_mutex);
|
|
|
|
/* find an empty slot */
|
|
ret = -ENOSPC;
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++)
|
|
if (!blkcg_policy[i])
|
|
break;
|
|
if (i >= BLKCG_MAX_POLS)
|
|
goto out_unlock;
|
|
|
|
/* register and update blkgs */
|
|
pol->plid = i;
|
|
blkcg_policy[i] = pol;
|
|
|
|
/* everything is in place, add intf files for the new policy */
|
|
if (pol->cftypes)
|
|
WARN_ON(cgroup_add_cftypes(&blkio_subsys, pol->cftypes));
|
|
ret = 0;
|
|
out_unlock:
|
|
mutex_unlock(&blkcg_pol_mutex);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_policy_register);
|
|
|
|
/**
|
|
* blkcg_policy_unregister - unregister a blkcg policy
|
|
* @pol: blkcg policy to unregister
|
|
*
|
|
* Undo blkcg_policy_register(@pol). Might sleep.
|
|
*/
|
|
void blkcg_policy_unregister(struct blkcg_policy *pol)
|
|
{
|
|
mutex_lock(&blkcg_pol_mutex);
|
|
|
|
if (WARN_ON(blkcg_policy[pol->plid] != pol))
|
|
goto out_unlock;
|
|
|
|
/* kill the intf files first */
|
|
if (pol->cftypes)
|
|
cgroup_rm_cftypes(&blkio_subsys, pol->cftypes);
|
|
|
|
/* unregister and update blkgs */
|
|
blkcg_policy[pol->plid] = NULL;
|
|
out_unlock:
|
|
mutex_unlock(&blkcg_pol_mutex);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_policy_unregister);
|