linux-stable/fs/io-wq.c
Jens Axboe 3dd1680d14 io-wq: cancel request if it's asking for files and we don't have them
This can't currently happen, but will be possible shortly. Handle missing
files just like we do not being able to grab a needed mm, and mark the
request as needing cancelation.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-11-04 10:22:56 -07:00

1249 lines
30 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Basic worker thread pool for io_uring
*
* Copyright (C) 2019 Jens Axboe
*
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/sched/signal.h>
#include <linux/mm.h>
#include <linux/sched/mm.h>
#include <linux/percpu.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/rculist_nulls.h>
#include <linux/fs_struct.h>
#include <linux/task_work.h>
#include <linux/blk-cgroup.h>
#include <linux/audit.h>
#include <linux/cpu.h>
#include "../kernel/sched/sched.h"
#include "io-wq.h"
#define WORKER_IDLE_TIMEOUT (5 * HZ)
enum {
IO_WORKER_F_UP = 1, /* up and active */
IO_WORKER_F_RUNNING = 2, /* account as running */
IO_WORKER_F_FREE = 4, /* worker on free list */
IO_WORKER_F_FIXED = 8, /* static idle worker */
IO_WORKER_F_BOUND = 16, /* is doing bounded work */
};
enum {
IO_WQ_BIT_EXIT = 0, /* wq exiting */
IO_WQ_BIT_CANCEL = 1, /* cancel work on list */
IO_WQ_BIT_ERROR = 2, /* error on setup */
};
enum {
IO_WQE_FLAG_STALLED = 1, /* stalled on hash */
};
/*
* One for each thread in a wqe pool
*/
struct io_worker {
refcount_t ref;
unsigned flags;
struct hlist_nulls_node nulls_node;
struct list_head all_list;
struct task_struct *task;
struct io_wqe *wqe;
struct io_wq_work *cur_work;
spinlock_t lock;
struct rcu_head rcu;
struct mm_struct *mm;
#ifdef CONFIG_BLK_CGROUP
struct cgroup_subsys_state *blkcg_css;
#endif
const struct cred *cur_creds;
const struct cred *saved_creds;
struct files_struct *restore_files;
struct nsproxy *restore_nsproxy;
struct fs_struct *restore_fs;
};
#if BITS_PER_LONG == 64
#define IO_WQ_HASH_ORDER 6
#else
#define IO_WQ_HASH_ORDER 5
#endif
#define IO_WQ_NR_HASH_BUCKETS (1u << IO_WQ_HASH_ORDER)
struct io_wqe_acct {
unsigned nr_workers;
unsigned max_workers;
atomic_t nr_running;
};
enum {
IO_WQ_ACCT_BOUND,
IO_WQ_ACCT_UNBOUND,
};
/*
* Per-node worker thread pool
*/
struct io_wqe {
struct {
raw_spinlock_t lock;
struct io_wq_work_list work_list;
unsigned long hash_map;
unsigned flags;
} ____cacheline_aligned_in_smp;
int node;
struct io_wqe_acct acct[2];
struct hlist_nulls_head free_list;
struct list_head all_list;
struct io_wq *wq;
struct io_wq_work *hash_tail[IO_WQ_NR_HASH_BUCKETS];
};
/*
* Per io_wq state
*/
struct io_wq {
struct io_wqe **wqes;
unsigned long state;
free_work_fn *free_work;
io_wq_work_fn *do_work;
struct task_struct *manager;
struct user_struct *user;
refcount_t refs;
struct completion done;
struct hlist_node cpuhp_node;
refcount_t use_refs;
};
static enum cpuhp_state io_wq_online;
static bool io_worker_get(struct io_worker *worker)
{
return refcount_inc_not_zero(&worker->ref);
}
static void io_worker_release(struct io_worker *worker)
{
if (refcount_dec_and_test(&worker->ref))
wake_up_process(worker->task);
}
/*
* Note: drops the wqe->lock if returning true! The caller must re-acquire
* the lock in that case. Some callers need to restart handling if this
* happens, so we can't just re-acquire the lock on behalf of the caller.
*/
static bool __io_worker_unuse(struct io_wqe *wqe, struct io_worker *worker)
{
bool dropped_lock = false;
if (worker->saved_creds) {
revert_creds(worker->saved_creds);
worker->cur_creds = worker->saved_creds = NULL;
}
if (current->files != worker->restore_files) {
__acquire(&wqe->lock);
raw_spin_unlock_irq(&wqe->lock);
dropped_lock = true;
task_lock(current);
current->files = worker->restore_files;
current->nsproxy = worker->restore_nsproxy;
task_unlock(current);
}
if (current->fs != worker->restore_fs)
current->fs = worker->restore_fs;
/*
* If we have an active mm, we need to drop the wq lock before unusing
* it. If we do, return true and let the caller retry the idle loop.
*/
if (worker->mm) {
if (!dropped_lock) {
__acquire(&wqe->lock);
raw_spin_unlock_irq(&wqe->lock);
dropped_lock = true;
}
__set_current_state(TASK_RUNNING);
kthread_unuse_mm(worker->mm);
mmput(worker->mm);
worker->mm = NULL;
}
#ifdef CONFIG_BLK_CGROUP
if (worker->blkcg_css) {
kthread_associate_blkcg(NULL);
worker->blkcg_css = NULL;
}
#endif
if (current->signal->rlim[RLIMIT_FSIZE].rlim_cur != RLIM_INFINITY)
current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
return dropped_lock;
}
static inline struct io_wqe_acct *io_work_get_acct(struct io_wqe *wqe,
struct io_wq_work *work)
{
if (work->flags & IO_WQ_WORK_UNBOUND)
return &wqe->acct[IO_WQ_ACCT_UNBOUND];
return &wqe->acct[IO_WQ_ACCT_BOUND];
}
static inline struct io_wqe_acct *io_wqe_get_acct(struct io_wqe *wqe,
struct io_worker *worker)
{
if (worker->flags & IO_WORKER_F_BOUND)
return &wqe->acct[IO_WQ_ACCT_BOUND];
return &wqe->acct[IO_WQ_ACCT_UNBOUND];
}
static void io_worker_exit(struct io_worker *worker)
{
struct io_wqe *wqe = worker->wqe;
struct io_wqe_acct *acct = io_wqe_get_acct(wqe, worker);
/*
* If we're not at zero, someone else is holding a brief reference
* to the worker. Wait for that to go away.
*/
set_current_state(TASK_INTERRUPTIBLE);
if (!refcount_dec_and_test(&worker->ref))
schedule();
__set_current_state(TASK_RUNNING);
preempt_disable();
current->flags &= ~PF_IO_WORKER;
if (worker->flags & IO_WORKER_F_RUNNING)
atomic_dec(&acct->nr_running);
if (!(worker->flags & IO_WORKER_F_BOUND))
atomic_dec(&wqe->wq->user->processes);
worker->flags = 0;
preempt_enable();
raw_spin_lock_irq(&wqe->lock);
hlist_nulls_del_rcu(&worker->nulls_node);
list_del_rcu(&worker->all_list);
if (__io_worker_unuse(wqe, worker)) {
__release(&wqe->lock);
raw_spin_lock_irq(&wqe->lock);
}
acct->nr_workers--;
raw_spin_unlock_irq(&wqe->lock);
kfree_rcu(worker, rcu);
if (refcount_dec_and_test(&wqe->wq->refs))
complete(&wqe->wq->done);
}
static inline bool io_wqe_run_queue(struct io_wqe *wqe)
__must_hold(wqe->lock)
{
if (!wq_list_empty(&wqe->work_list) &&
!(wqe->flags & IO_WQE_FLAG_STALLED))
return true;
return false;
}
/*
* Check head of free list for an available worker. If one isn't available,
* caller must wake up the wq manager to create one.
*/
static bool io_wqe_activate_free_worker(struct io_wqe *wqe)
__must_hold(RCU)
{
struct hlist_nulls_node *n;
struct io_worker *worker;
n = rcu_dereference(hlist_nulls_first_rcu(&wqe->free_list));
if (is_a_nulls(n))
return false;
worker = hlist_nulls_entry(n, struct io_worker, nulls_node);
if (io_worker_get(worker)) {
wake_up_process(worker->task);
io_worker_release(worker);
return true;
}
return false;
}
/*
* We need a worker. If we find a free one, we're good. If not, and we're
* below the max number of workers, wake up the manager to create one.
*/
static void io_wqe_wake_worker(struct io_wqe *wqe, struct io_wqe_acct *acct)
{
bool ret;
/*
* Most likely an attempt to queue unbounded work on an io_wq that
* wasn't setup with any unbounded workers.
*/
WARN_ON_ONCE(!acct->max_workers);
rcu_read_lock();
ret = io_wqe_activate_free_worker(wqe);
rcu_read_unlock();
if (!ret && acct->nr_workers < acct->max_workers)
wake_up_process(wqe->wq->manager);
}
static void io_wqe_inc_running(struct io_wqe *wqe, struct io_worker *worker)
{
struct io_wqe_acct *acct = io_wqe_get_acct(wqe, worker);
atomic_inc(&acct->nr_running);
}
static void io_wqe_dec_running(struct io_wqe *wqe, struct io_worker *worker)
__must_hold(wqe->lock)
{
struct io_wqe_acct *acct = io_wqe_get_acct(wqe, worker);
if (atomic_dec_and_test(&acct->nr_running) && io_wqe_run_queue(wqe))
io_wqe_wake_worker(wqe, acct);
}
static void io_worker_start(struct io_wqe *wqe, struct io_worker *worker)
{
allow_kernel_signal(SIGINT);
current->flags |= PF_IO_WORKER;
worker->flags |= (IO_WORKER_F_UP | IO_WORKER_F_RUNNING);
worker->restore_files = current->files;
worker->restore_nsproxy = current->nsproxy;
worker->restore_fs = current->fs;
io_wqe_inc_running(wqe, worker);
}
/*
* Worker will start processing some work. Move it to the busy list, if
* it's currently on the freelist
*/
static void __io_worker_busy(struct io_wqe *wqe, struct io_worker *worker,
struct io_wq_work *work)
__must_hold(wqe->lock)
{
bool worker_bound, work_bound;
if (worker->flags & IO_WORKER_F_FREE) {
worker->flags &= ~IO_WORKER_F_FREE;
hlist_nulls_del_init_rcu(&worker->nulls_node);
}
/*
* If worker is moving from bound to unbound (or vice versa), then
* ensure we update the running accounting.
*/
worker_bound = (worker->flags & IO_WORKER_F_BOUND) != 0;
work_bound = (work->flags & IO_WQ_WORK_UNBOUND) == 0;
if (worker_bound != work_bound) {
io_wqe_dec_running(wqe, worker);
if (work_bound) {
worker->flags |= IO_WORKER_F_BOUND;
wqe->acct[IO_WQ_ACCT_UNBOUND].nr_workers--;
wqe->acct[IO_WQ_ACCT_BOUND].nr_workers++;
atomic_dec(&wqe->wq->user->processes);
} else {
worker->flags &= ~IO_WORKER_F_BOUND;
wqe->acct[IO_WQ_ACCT_UNBOUND].nr_workers++;
wqe->acct[IO_WQ_ACCT_BOUND].nr_workers--;
atomic_inc(&wqe->wq->user->processes);
}
io_wqe_inc_running(wqe, worker);
}
}
/*
* No work, worker going to sleep. Move to freelist, and unuse mm if we
* have one attached. Dropping the mm may potentially sleep, so we drop
* the lock in that case and return success. Since the caller has to
* retry the loop in that case (we changed task state), we don't regrab
* the lock if we return success.
*/
static bool __io_worker_idle(struct io_wqe *wqe, struct io_worker *worker)
__must_hold(wqe->lock)
{
if (!(worker->flags & IO_WORKER_F_FREE)) {
worker->flags |= IO_WORKER_F_FREE;
hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list);
}
return __io_worker_unuse(wqe, worker);
}
static inline unsigned int io_get_work_hash(struct io_wq_work *work)
{
return work->flags >> IO_WQ_HASH_SHIFT;
}
static struct io_wq_work *io_get_next_work(struct io_wqe *wqe)
__must_hold(wqe->lock)
{
struct io_wq_work_node *node, *prev;
struct io_wq_work *work, *tail;
unsigned int hash;
wq_list_for_each(node, prev, &wqe->work_list) {
work = container_of(node, struct io_wq_work, list);
/* not hashed, can run anytime */
if (!io_wq_is_hashed(work)) {
wq_list_del(&wqe->work_list, node, prev);
return work;
}
/* hashed, can run if not already running */
hash = io_get_work_hash(work);
if (!(wqe->hash_map & BIT(hash))) {
wqe->hash_map |= BIT(hash);
/* all items with this hash lie in [work, tail] */
tail = wqe->hash_tail[hash];
wqe->hash_tail[hash] = NULL;
wq_list_cut(&wqe->work_list, &tail->list, prev);
return work;
}
}
return NULL;
}
static void io_wq_switch_mm(struct io_worker *worker, struct io_wq_work *work)
{
if (worker->mm) {
kthread_unuse_mm(worker->mm);
mmput(worker->mm);
worker->mm = NULL;
}
if (mmget_not_zero(work->identity->mm)) {
kthread_use_mm(work->identity->mm);
worker->mm = work->identity->mm;
return;
}
/* failed grabbing mm, ensure work gets cancelled */
work->flags |= IO_WQ_WORK_CANCEL;
}
static inline void io_wq_switch_blkcg(struct io_worker *worker,
struct io_wq_work *work)
{
#ifdef CONFIG_BLK_CGROUP
if (!(work->flags & IO_WQ_WORK_BLKCG))
return;
if (work->identity->blkcg_css != worker->blkcg_css) {
kthread_associate_blkcg(work->identity->blkcg_css);
worker->blkcg_css = work->identity->blkcg_css;
}
#endif
}
static void io_wq_switch_creds(struct io_worker *worker,
struct io_wq_work *work)
{
const struct cred *old_creds = override_creds(work->identity->creds);
worker->cur_creds = work->identity->creds;
if (worker->saved_creds)
put_cred(old_creds); /* creds set by previous switch */
else
worker->saved_creds = old_creds;
}
static void io_impersonate_work(struct io_worker *worker,
struct io_wq_work *work)
{
if ((work->flags & IO_WQ_WORK_FILES) &&
current->files != work->identity->files) {
task_lock(current);
current->files = work->identity->files;
current->nsproxy = work->identity->nsproxy;
task_unlock(current);
if (!work->identity->files) {
/* failed grabbing files, ensure work gets cancelled */
work->flags |= IO_WQ_WORK_CANCEL;
}
}
if ((work->flags & IO_WQ_WORK_FS) && current->fs != work->identity->fs)
current->fs = work->identity->fs;
if ((work->flags & IO_WQ_WORK_MM) && work->identity->mm != worker->mm)
io_wq_switch_mm(worker, work);
if ((work->flags & IO_WQ_WORK_CREDS) &&
worker->cur_creds != work->identity->creds)
io_wq_switch_creds(worker, work);
if (work->flags & IO_WQ_WORK_FSIZE)
current->signal->rlim[RLIMIT_FSIZE].rlim_cur = work->identity->fsize;
else if (current->signal->rlim[RLIMIT_FSIZE].rlim_cur != RLIM_INFINITY)
current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
io_wq_switch_blkcg(worker, work);
#ifdef CONFIG_AUDIT
current->loginuid = work->identity->loginuid;
current->sessionid = work->identity->sessionid;
#endif
}
static void io_assign_current_work(struct io_worker *worker,
struct io_wq_work *work)
{
if (work) {
/* flush pending signals before assigning new work */
if (signal_pending(current))
flush_signals(current);
cond_resched();
}
#ifdef CONFIG_AUDIT
current->loginuid = KUIDT_INIT(AUDIT_UID_UNSET);
current->sessionid = AUDIT_SID_UNSET;
#endif
spin_lock_irq(&worker->lock);
worker->cur_work = work;
spin_unlock_irq(&worker->lock);
}
static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work);
static void io_worker_handle_work(struct io_worker *worker)
__releases(wqe->lock)
{
struct io_wqe *wqe = worker->wqe;
struct io_wq *wq = wqe->wq;
do {
struct io_wq_work *work;
get_next:
/*
* If we got some work, mark us as busy. If we didn't, but
* the list isn't empty, it means we stalled on hashed work.
* Mark us stalled so we don't keep looking for work when we
* can't make progress, any work completion or insertion will
* clear the stalled flag.
*/
work = io_get_next_work(wqe);
if (work)
__io_worker_busy(wqe, worker, work);
else if (!wq_list_empty(&wqe->work_list))
wqe->flags |= IO_WQE_FLAG_STALLED;
raw_spin_unlock_irq(&wqe->lock);
if (!work)
break;
io_assign_current_work(worker, work);
/* handle a whole dependent link */
do {
struct io_wq_work *old_work, *next_hashed, *linked;
unsigned int hash = io_get_work_hash(work);
next_hashed = wq_next_work(work);
io_impersonate_work(worker, work);
/*
* OK to set IO_WQ_WORK_CANCEL even for uncancellable
* work, the worker function will do the right thing.
*/
if (test_bit(IO_WQ_BIT_CANCEL, &wq->state))
work->flags |= IO_WQ_WORK_CANCEL;
old_work = work;
linked = wq->do_work(work);
work = next_hashed;
if (!work && linked && !io_wq_is_hashed(linked)) {
work = linked;
linked = NULL;
}
io_assign_current_work(worker, work);
wq->free_work(old_work);
if (linked)
io_wqe_enqueue(wqe, linked);
if (hash != -1U && !next_hashed) {
raw_spin_lock_irq(&wqe->lock);
wqe->hash_map &= ~BIT_ULL(hash);
wqe->flags &= ~IO_WQE_FLAG_STALLED;
/* skip unnecessary unlock-lock wqe->lock */
if (!work)
goto get_next;
raw_spin_unlock_irq(&wqe->lock);
}
} while (work);
raw_spin_lock_irq(&wqe->lock);
} while (1);
}
static int io_wqe_worker(void *data)
{
struct io_worker *worker = data;
struct io_wqe *wqe = worker->wqe;
struct io_wq *wq = wqe->wq;
io_worker_start(wqe, worker);
while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
set_current_state(TASK_INTERRUPTIBLE);
loop:
raw_spin_lock_irq(&wqe->lock);
if (io_wqe_run_queue(wqe)) {
__set_current_state(TASK_RUNNING);
io_worker_handle_work(worker);
goto loop;
}
/* drops the lock on success, retry */
if (__io_worker_idle(wqe, worker)) {
__release(&wqe->lock);
goto loop;
}
raw_spin_unlock_irq(&wqe->lock);
if (signal_pending(current))
flush_signals(current);
if (schedule_timeout(WORKER_IDLE_TIMEOUT))
continue;
/* timed out, exit unless we're the fixed worker */
if (test_bit(IO_WQ_BIT_EXIT, &wq->state) ||
!(worker->flags & IO_WORKER_F_FIXED))
break;
}
if (test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
raw_spin_lock_irq(&wqe->lock);
if (!wq_list_empty(&wqe->work_list))
io_worker_handle_work(worker);
else
raw_spin_unlock_irq(&wqe->lock);
}
io_worker_exit(worker);
return 0;
}
/*
* Called when a worker is scheduled in. Mark us as currently running.
*/
void io_wq_worker_running(struct task_struct *tsk)
{
struct io_worker *worker = kthread_data(tsk);
struct io_wqe *wqe = worker->wqe;
if (!(worker->flags & IO_WORKER_F_UP))
return;
if (worker->flags & IO_WORKER_F_RUNNING)
return;
worker->flags |= IO_WORKER_F_RUNNING;
io_wqe_inc_running(wqe, worker);
}
/*
* Called when worker is going to sleep. If there are no workers currently
* running and we have work pending, wake up a free one or have the manager
* set one up.
*/
void io_wq_worker_sleeping(struct task_struct *tsk)
{
struct io_worker *worker = kthread_data(tsk);
struct io_wqe *wqe = worker->wqe;
if (!(worker->flags & IO_WORKER_F_UP))
return;
if (!(worker->flags & IO_WORKER_F_RUNNING))
return;
worker->flags &= ~IO_WORKER_F_RUNNING;
raw_spin_lock_irq(&wqe->lock);
io_wqe_dec_running(wqe, worker);
raw_spin_unlock_irq(&wqe->lock);
}
static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)
{
struct io_wqe_acct *acct = &wqe->acct[index];
struct io_worker *worker;
worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, wqe->node);
if (!worker)
return false;
refcount_set(&worker->ref, 1);
worker->nulls_node.pprev = NULL;
worker->wqe = wqe;
spin_lock_init(&worker->lock);
worker->task = kthread_create_on_node(io_wqe_worker, worker, wqe->node,
"io_wqe_worker-%d/%d", index, wqe->node);
if (IS_ERR(worker->task)) {
kfree(worker);
return false;
}
kthread_bind_mask(worker->task, cpumask_of_node(wqe->node));
raw_spin_lock_irq(&wqe->lock);
hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list);
list_add_tail_rcu(&worker->all_list, &wqe->all_list);
worker->flags |= IO_WORKER_F_FREE;
if (index == IO_WQ_ACCT_BOUND)
worker->flags |= IO_WORKER_F_BOUND;
if (!acct->nr_workers && (worker->flags & IO_WORKER_F_BOUND))
worker->flags |= IO_WORKER_F_FIXED;
acct->nr_workers++;
raw_spin_unlock_irq(&wqe->lock);
if (index == IO_WQ_ACCT_UNBOUND)
atomic_inc(&wq->user->processes);
refcount_inc(&wq->refs);
wake_up_process(worker->task);
return true;
}
static inline bool io_wqe_need_worker(struct io_wqe *wqe, int index)
__must_hold(wqe->lock)
{
struct io_wqe_acct *acct = &wqe->acct[index];
/* if we have available workers or no work, no need */
if (!hlist_nulls_empty(&wqe->free_list) || !io_wqe_run_queue(wqe))
return false;
return acct->nr_workers < acct->max_workers;
}
static bool io_wqe_worker_send_sig(struct io_worker *worker, void *data)
{
send_sig(SIGINT, worker->task, 1);
return false;
}
/*
* Iterate the passed in list and call the specific function for each
* worker that isn't exiting
*/
static bool io_wq_for_each_worker(struct io_wqe *wqe,
bool (*func)(struct io_worker *, void *),
void *data)
{
struct io_worker *worker;
bool ret = false;
list_for_each_entry_rcu(worker, &wqe->all_list, all_list) {
if (io_worker_get(worker)) {
/* no task if node is/was offline */
if (worker->task)
ret = func(worker, data);
io_worker_release(worker);
if (ret)
break;
}
}
return ret;
}
static bool io_wq_worker_wake(struct io_worker *worker, void *data)
{
wake_up_process(worker->task);
return false;
}
/*
* Manager thread. Tasked with creating new workers, if we need them.
*/
static int io_wq_manager(void *data)
{
struct io_wq *wq = data;
int node;
/* create fixed workers */
refcount_set(&wq->refs, 1);
for_each_node(node) {
if (!node_online(node))
continue;
if (create_io_worker(wq, wq->wqes[node], IO_WQ_ACCT_BOUND))
continue;
set_bit(IO_WQ_BIT_ERROR, &wq->state);
set_bit(IO_WQ_BIT_EXIT, &wq->state);
goto out;
}
complete(&wq->done);
while (!kthread_should_stop()) {
if (current->task_works)
task_work_run();
for_each_node(node) {
struct io_wqe *wqe = wq->wqes[node];
bool fork_worker[2] = { false, false };
if (!node_online(node))
continue;
raw_spin_lock_irq(&wqe->lock);
if (io_wqe_need_worker(wqe, IO_WQ_ACCT_BOUND))
fork_worker[IO_WQ_ACCT_BOUND] = true;
if (io_wqe_need_worker(wqe, IO_WQ_ACCT_UNBOUND))
fork_worker[IO_WQ_ACCT_UNBOUND] = true;
raw_spin_unlock_irq(&wqe->lock);
if (fork_worker[IO_WQ_ACCT_BOUND])
create_io_worker(wq, wqe, IO_WQ_ACCT_BOUND);
if (fork_worker[IO_WQ_ACCT_UNBOUND])
create_io_worker(wq, wqe, IO_WQ_ACCT_UNBOUND);
}
set_current_state(TASK_INTERRUPTIBLE);
schedule_timeout(HZ);
}
if (current->task_works)
task_work_run();
out:
if (refcount_dec_and_test(&wq->refs)) {
complete(&wq->done);
return 0;
}
/* if ERROR is set and we get here, we have workers to wake */
if (test_bit(IO_WQ_BIT_ERROR, &wq->state)) {
rcu_read_lock();
for_each_node(node)
io_wq_for_each_worker(wq->wqes[node], io_wq_worker_wake, NULL);
rcu_read_unlock();
}
return 0;
}
static bool io_wq_can_queue(struct io_wqe *wqe, struct io_wqe_acct *acct,
struct io_wq_work *work)
{
bool free_worker;
if (!(work->flags & IO_WQ_WORK_UNBOUND))
return true;
if (atomic_read(&acct->nr_running))
return true;
rcu_read_lock();
free_worker = !hlist_nulls_empty(&wqe->free_list);
rcu_read_unlock();
if (free_worker)
return true;
if (atomic_read(&wqe->wq->user->processes) >= acct->max_workers &&
!(capable(CAP_SYS_RESOURCE) || capable(CAP_SYS_ADMIN)))
return false;
return true;
}
static void io_run_cancel(struct io_wq_work *work, struct io_wqe *wqe)
{
struct io_wq *wq = wqe->wq;
do {
struct io_wq_work *old_work = work;
work->flags |= IO_WQ_WORK_CANCEL;
work = wq->do_work(work);
wq->free_work(old_work);
} while (work);
}
static void io_wqe_insert_work(struct io_wqe *wqe, struct io_wq_work *work)
{
unsigned int hash;
struct io_wq_work *tail;
if (!io_wq_is_hashed(work)) {
append:
wq_list_add_tail(&work->list, &wqe->work_list);
return;
}
hash = io_get_work_hash(work);
tail = wqe->hash_tail[hash];
wqe->hash_tail[hash] = work;
if (!tail)
goto append;
wq_list_add_after(&work->list, &tail->list, &wqe->work_list);
}
static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work)
{
struct io_wqe_acct *acct = io_work_get_acct(wqe, work);
int work_flags;
unsigned long flags;
/*
* Do early check to see if we need a new unbound worker, and if we do,
* if we're allowed to do so. This isn't 100% accurate as there's a
* gap between this check and incrementing the value, but that's OK.
* It's close enough to not be an issue, fork() has the same delay.
*/
if (unlikely(!io_wq_can_queue(wqe, acct, work))) {
io_run_cancel(work, wqe);
return;
}
work_flags = work->flags;
raw_spin_lock_irqsave(&wqe->lock, flags);
io_wqe_insert_work(wqe, work);
wqe->flags &= ~IO_WQE_FLAG_STALLED;
raw_spin_unlock_irqrestore(&wqe->lock, flags);
if ((work_flags & IO_WQ_WORK_CONCURRENT) ||
!atomic_read(&acct->nr_running))
io_wqe_wake_worker(wqe, acct);
}
void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work)
{
struct io_wqe *wqe = wq->wqes[numa_node_id()];
io_wqe_enqueue(wqe, work);
}
/*
* Work items that hash to the same value will not be done in parallel.
* Used to limit concurrent writes, generally hashed by inode.
*/
void io_wq_hash_work(struct io_wq_work *work, void *val)
{
unsigned int bit;
bit = hash_ptr(val, IO_WQ_HASH_ORDER);
work->flags |= (IO_WQ_WORK_HASHED | (bit << IO_WQ_HASH_SHIFT));
}
void io_wq_cancel_all(struct io_wq *wq)
{
int node;
set_bit(IO_WQ_BIT_CANCEL, &wq->state);
rcu_read_lock();
for_each_node(node) {
struct io_wqe *wqe = wq->wqes[node];
io_wq_for_each_worker(wqe, io_wqe_worker_send_sig, NULL);
}
rcu_read_unlock();
}
struct io_cb_cancel_data {
work_cancel_fn *fn;
void *data;
int nr_running;
int nr_pending;
bool cancel_all;
};
static bool io_wq_worker_cancel(struct io_worker *worker, void *data)
{
struct io_cb_cancel_data *match = data;
unsigned long flags;
/*
* Hold the lock to avoid ->cur_work going out of scope, caller
* may dereference the passed in work.
*/
spin_lock_irqsave(&worker->lock, flags);
if (worker->cur_work &&
!(worker->cur_work->flags & IO_WQ_WORK_NO_CANCEL) &&
match->fn(worker->cur_work, match->data)) {
send_sig(SIGINT, worker->task, 1);
match->nr_running++;
}
spin_unlock_irqrestore(&worker->lock, flags);
return match->nr_running && !match->cancel_all;
}
static inline void io_wqe_remove_pending(struct io_wqe *wqe,
struct io_wq_work *work,
struct io_wq_work_node *prev)
{
unsigned int hash = io_get_work_hash(work);
struct io_wq_work *prev_work = NULL;
if (io_wq_is_hashed(work) && work == wqe->hash_tail[hash]) {
if (prev)
prev_work = container_of(prev, struct io_wq_work, list);
if (prev_work && io_get_work_hash(prev_work) == hash)
wqe->hash_tail[hash] = prev_work;
else
wqe->hash_tail[hash] = NULL;
}
wq_list_del(&wqe->work_list, &work->list, prev);
}
static void io_wqe_cancel_pending_work(struct io_wqe *wqe,
struct io_cb_cancel_data *match)
{
struct io_wq_work_node *node, *prev;
struct io_wq_work *work;
unsigned long flags;
retry:
raw_spin_lock_irqsave(&wqe->lock, flags);
wq_list_for_each(node, prev, &wqe->work_list) {
work = container_of(node, struct io_wq_work, list);
if (!match->fn(work, match->data))
continue;
io_wqe_remove_pending(wqe, work, prev);
raw_spin_unlock_irqrestore(&wqe->lock, flags);
io_run_cancel(work, wqe);
match->nr_pending++;
if (!match->cancel_all)
return;
/* not safe to continue after unlock */
goto retry;
}
raw_spin_unlock_irqrestore(&wqe->lock, flags);
}
static void io_wqe_cancel_running_work(struct io_wqe *wqe,
struct io_cb_cancel_data *match)
{
rcu_read_lock();
io_wq_for_each_worker(wqe, io_wq_worker_cancel, match);
rcu_read_unlock();
}
enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
void *data, bool cancel_all)
{
struct io_cb_cancel_data match = {
.fn = cancel,
.data = data,
.cancel_all = cancel_all,
};
int node;
/*
* First check pending list, if we're lucky we can just remove it
* from there. CANCEL_OK means that the work is returned as-new,
* no completion will be posted for it.
*/
for_each_node(node) {
struct io_wqe *wqe = wq->wqes[node];
io_wqe_cancel_pending_work(wqe, &match);
if (match.nr_pending && !match.cancel_all)
return IO_WQ_CANCEL_OK;
}
/*
* Now check if a free (going busy) or busy worker has the work
* currently running. If we find it there, we'll return CANCEL_RUNNING
* as an indication that we attempt to signal cancellation. The
* completion will run normally in this case.
*/
for_each_node(node) {
struct io_wqe *wqe = wq->wqes[node];
io_wqe_cancel_running_work(wqe, &match);
if (match.nr_running && !match.cancel_all)
return IO_WQ_CANCEL_RUNNING;
}
if (match.nr_running)
return IO_WQ_CANCEL_RUNNING;
if (match.nr_pending)
return IO_WQ_CANCEL_OK;
return IO_WQ_CANCEL_NOTFOUND;
}
static bool io_wq_io_cb_cancel_data(struct io_wq_work *work, void *data)
{
return work == data;
}
enum io_wq_cancel io_wq_cancel_work(struct io_wq *wq, struct io_wq_work *cwork)
{
return io_wq_cancel_cb(wq, io_wq_io_cb_cancel_data, (void *)cwork, false);
}
struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
{
int ret = -ENOMEM, node;
struct io_wq *wq;
if (WARN_ON_ONCE(!data->free_work || !data->do_work))
return ERR_PTR(-EINVAL);
wq = kzalloc(sizeof(*wq), GFP_KERNEL);
if (!wq)
return ERR_PTR(-ENOMEM);
wq->wqes = kcalloc(nr_node_ids, sizeof(struct io_wqe *), GFP_KERNEL);
if (!wq->wqes)
goto err_wq;
ret = cpuhp_state_add_instance_nocalls(io_wq_online, &wq->cpuhp_node);
if (ret)
goto err_wqes;
wq->free_work = data->free_work;
wq->do_work = data->do_work;
/* caller must already hold a reference to this */
wq->user = data->user;
ret = -ENOMEM;
for_each_node(node) {
struct io_wqe *wqe;
int alloc_node = node;
if (!node_online(alloc_node))
alloc_node = NUMA_NO_NODE;
wqe = kzalloc_node(sizeof(struct io_wqe), GFP_KERNEL, alloc_node);
if (!wqe)
goto err;
wq->wqes[node] = wqe;
wqe->node = alloc_node;
wqe->acct[IO_WQ_ACCT_BOUND].max_workers = bounded;
atomic_set(&wqe->acct[IO_WQ_ACCT_BOUND].nr_running, 0);
if (wq->user) {
wqe->acct[IO_WQ_ACCT_UNBOUND].max_workers =
task_rlimit(current, RLIMIT_NPROC);
}
atomic_set(&wqe->acct[IO_WQ_ACCT_UNBOUND].nr_running, 0);
wqe->wq = wq;
raw_spin_lock_init(&wqe->lock);
INIT_WQ_LIST(&wqe->work_list);
INIT_HLIST_NULLS_HEAD(&wqe->free_list, 0);
INIT_LIST_HEAD(&wqe->all_list);
}
init_completion(&wq->done);
wq->manager = kthread_create(io_wq_manager, wq, "io_wq_manager");
if (!IS_ERR(wq->manager)) {
wake_up_process(wq->manager);
wait_for_completion(&wq->done);
if (test_bit(IO_WQ_BIT_ERROR, &wq->state)) {
ret = -ENOMEM;
goto err;
}
refcount_set(&wq->use_refs, 1);
reinit_completion(&wq->done);
return wq;
}
ret = PTR_ERR(wq->manager);
complete(&wq->done);
err:
cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node);
for_each_node(node)
kfree(wq->wqes[node]);
err_wqes:
kfree(wq->wqes);
err_wq:
kfree(wq);
return ERR_PTR(ret);
}
bool io_wq_get(struct io_wq *wq, struct io_wq_data *data)
{
if (data->free_work != wq->free_work || data->do_work != wq->do_work)
return false;
return refcount_inc_not_zero(&wq->use_refs);
}
static void __io_wq_destroy(struct io_wq *wq)
{
int node;
cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node);
set_bit(IO_WQ_BIT_EXIT, &wq->state);
if (wq->manager)
kthread_stop(wq->manager);
rcu_read_lock();
for_each_node(node)
io_wq_for_each_worker(wq->wqes[node], io_wq_worker_wake, NULL);
rcu_read_unlock();
wait_for_completion(&wq->done);
for_each_node(node)
kfree(wq->wqes[node]);
kfree(wq->wqes);
kfree(wq);
}
void io_wq_destroy(struct io_wq *wq)
{
if (refcount_dec_and_test(&wq->use_refs))
__io_wq_destroy(wq);
}
struct task_struct *io_wq_get_task(struct io_wq *wq)
{
return wq->manager;
}
static bool io_wq_worker_affinity(struct io_worker *worker, void *data)
{
struct task_struct *task = worker->task;
struct rq_flags rf;
struct rq *rq;
rq = task_rq_lock(task, &rf);
do_set_cpus_allowed(task, cpumask_of_node(worker->wqe->node));
task->flags |= PF_NO_SETAFFINITY;
task_rq_unlock(rq, task, &rf);
return false;
}
static int io_wq_cpu_online(unsigned int cpu, struct hlist_node *node)
{
struct io_wq *wq = hlist_entry_safe(node, struct io_wq, cpuhp_node);
int i;
rcu_read_lock();
for_each_node(i)
io_wq_for_each_worker(wq->wqes[i], io_wq_worker_affinity, NULL);
rcu_read_unlock();
return 0;
}
static __init int io_wq_init(void)
{
int ret;
ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "io-wq/online",
io_wq_cpu_online, NULL);
if (ret < 0)
return ret;
io_wq_online = ret;
return 0;
}
subsys_initcall(io_wq_init);