linux/block/blk-mq.c
Jens Axboe 7fe311302f blk-mq: update hardware and software queues for sleeping alloc
If we end up sleeping due to running out of requests, we should
update the hardware and software queues in the map ctx structure.
Otherwise we could end up having rq->mq_ctx point to the pre-sleep
context, and risk corrupting ctx->rq_list since we'll be
grabbing the wrong lock when inserting the request.

Reported-by: Dave Jones <davej@codemonkey.org.uk>
Reported-by: Chris Mason <clm@fb.com>
Tested-by: Chris Mason <clm@fb.com>
Fixes: 63581af3f3 ("blk-mq: remove non-blocking pass in blk_mq_map_request")
Signed-off-by: Jens Axboe <axboe@fb.com>
2016-10-27 09:56:03 -06:00

2377 lines
56 KiB
C

/*
* Block multiqueue core code
*
* Copyright (C) 2013-2014 Jens Axboe
* Copyright (C) 2013-2014 Christoph Hellwig
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/backing-dev.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/kmemleak.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/smp.h>
#include <linux/llist.h>
#include <linux/list_sort.h>
#include <linux/cpu.h>
#include <linux/cache.h>
#include <linux/sched/sysctl.h>
#include <linux/delay.h>
#include <linux/crash_dump.h>
#include <linux/prefetch.h>
#include <trace/events/block.h>
#include <linux/blk-mq.h>
#include "blk.h"
#include "blk-mq.h"
#include "blk-mq-tag.h"
static DEFINE_MUTEX(all_q_mutex);
static LIST_HEAD(all_q_list);
/*
* Check if any of the ctx's have pending work in this hardware queue
*/
static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
{
return sbitmap_any_bit_set(&hctx->ctx_map);
}
/*
* Mark this ctx as having pending work in this hardware queue
*/
static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
struct blk_mq_ctx *ctx)
{
if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw))
sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw);
}
static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
struct blk_mq_ctx *ctx)
{
sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
}
void blk_mq_freeze_queue_start(struct request_queue *q)
{
int freeze_depth;
freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
if (freeze_depth == 1) {
percpu_ref_kill(&q->q_usage_counter);
blk_mq_run_hw_queues(q, false);
}
}
EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start);
static void blk_mq_freeze_queue_wait(struct request_queue *q)
{
wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
}
/*
* Guarantee no request is in use, so we can change any data structure of
* the queue afterward.
*/
void blk_freeze_queue(struct request_queue *q)
{
/*
* In the !blk_mq case we are only calling this to kill the
* q_usage_counter, otherwise this increases the freeze depth
* and waits for it to return to zero. For this reason there is
* no blk_unfreeze_queue(), and blk_freeze_queue() is not
* exported to drivers as the only user for unfreeze is blk_mq.
*/
blk_mq_freeze_queue_start(q);
blk_mq_freeze_queue_wait(q);
}
void blk_mq_freeze_queue(struct request_queue *q)
{
/*
* ...just an alias to keep freeze and unfreeze actions balanced
* in the blk_mq_* namespace
*/
blk_freeze_queue(q);
}
EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
void blk_mq_unfreeze_queue(struct request_queue *q)
{
int freeze_depth;
freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
WARN_ON_ONCE(freeze_depth < 0);
if (!freeze_depth) {
percpu_ref_reinit(&q->q_usage_counter);
wake_up_all(&q->mq_freeze_wq);
}
}
EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
void blk_mq_wake_waiters(struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
unsigned int i;
queue_for_each_hw_ctx(q, hctx, i)
if (blk_mq_hw_queue_mapped(hctx))
blk_mq_tag_wakeup_all(hctx->tags, true);
/*
* If we are called because the queue has now been marked as
* dying, we need to ensure that processes currently waiting on
* the queue are notified as well.
*/
wake_up_all(&q->mq_freeze_wq);
}
bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
{
return blk_mq_has_free_tags(hctx->tags);
}
EXPORT_SYMBOL(blk_mq_can_queue);
static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
struct request *rq, int op,
unsigned int op_flags)
{
if (blk_queue_io_stat(q))
op_flags |= REQ_IO_STAT;
INIT_LIST_HEAD(&rq->queuelist);
/* csd/requeue_work/fifo_time is initialized before use */
rq->q = q;
rq->mq_ctx = ctx;
req_set_op_attrs(rq, op, op_flags);
/* do not touch atomic flags, it needs atomic ops against the timer */
rq->cpu = -1;
INIT_HLIST_NODE(&rq->hash);
RB_CLEAR_NODE(&rq->rb_node);
rq->rq_disk = NULL;
rq->part = NULL;
rq->start_time = jiffies;
#ifdef CONFIG_BLK_CGROUP
rq->rl = NULL;
set_start_time_ns(rq);
rq->io_start_time_ns = 0;
#endif
rq->nr_phys_segments = 0;
#if defined(CONFIG_BLK_DEV_INTEGRITY)
rq->nr_integrity_segments = 0;
#endif
rq->special = NULL;
/* tag was already set */
rq->errors = 0;
rq->cmd = rq->__cmd;
rq->extra_len = 0;
rq->sense_len = 0;
rq->resid_len = 0;
rq->sense = NULL;
INIT_LIST_HEAD(&rq->timeout_list);
rq->timeout = 0;
rq->end_io = NULL;
rq->end_io_data = NULL;
rq->next_rq = NULL;
ctx->rq_dispatched[rw_is_sync(op, op_flags)]++;
}
static struct request *
__blk_mq_alloc_request(struct blk_mq_alloc_data *data, int op, int op_flags)
{
struct request *rq;
unsigned int tag;
tag = blk_mq_get_tag(data);
if (tag != BLK_MQ_TAG_FAIL) {
rq = data->hctx->tags->rqs[tag];
if (blk_mq_tag_busy(data->hctx)) {
rq->cmd_flags = REQ_MQ_INFLIGHT;
atomic_inc(&data->hctx->nr_active);
}
rq->tag = tag;
blk_mq_rq_ctx_init(data->q, data->ctx, rq, op, op_flags);
return rq;
}
return NULL;
}
struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
unsigned int flags)
{
struct blk_mq_ctx *ctx;
struct blk_mq_hw_ctx *hctx;
struct request *rq;
struct blk_mq_alloc_data alloc_data;
int ret;
ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT);
if (ret)
return ERR_PTR(ret);
ctx = blk_mq_get_ctx(q);
hctx = blk_mq_map_queue(q, ctx->cpu);
blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx);
rq = __blk_mq_alloc_request(&alloc_data, rw, 0);
blk_mq_put_ctx(ctx);
if (!rq) {
blk_queue_exit(q);
return ERR_PTR(-EWOULDBLOCK);
}
rq->__data_len = 0;
rq->__sector = (sector_t) -1;
rq->bio = rq->biotail = NULL;
return rq;
}
EXPORT_SYMBOL(blk_mq_alloc_request);
struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
unsigned int flags, unsigned int hctx_idx)
{
struct blk_mq_hw_ctx *hctx;
struct blk_mq_ctx *ctx;
struct request *rq;
struct blk_mq_alloc_data alloc_data;
int ret;
/*
* If the tag allocator sleeps we could get an allocation for a
* different hardware context. No need to complicate the low level
* allocator for this for the rare use case of a command tied to
* a specific queue.
*/
if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
return ERR_PTR(-EINVAL);
if (hctx_idx >= q->nr_hw_queues)
return ERR_PTR(-EIO);
ret = blk_queue_enter(q, true);
if (ret)
return ERR_PTR(ret);
/*
* Check if the hardware context is actually mapped to anything.
* If not tell the caller that it should skip this queue.
*/
hctx = q->queue_hw_ctx[hctx_idx];
if (!blk_mq_hw_queue_mapped(hctx)) {
ret = -EXDEV;
goto out_queue_exit;
}
ctx = __blk_mq_get_ctx(q, cpumask_first(hctx->cpumask));
blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx);
rq = __blk_mq_alloc_request(&alloc_data, rw, 0);
if (!rq) {
ret = -EWOULDBLOCK;
goto out_queue_exit;
}
return rq;
out_queue_exit:
blk_queue_exit(q);
return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
struct blk_mq_ctx *ctx, struct request *rq)
{
const int tag = rq->tag;
struct request_queue *q = rq->q;
if (rq->cmd_flags & REQ_MQ_INFLIGHT)
atomic_dec(&hctx->nr_active);
rq->cmd_flags = 0;
clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
blk_mq_put_tag(hctx, ctx, tag);
blk_queue_exit(q);
}
void blk_mq_free_hctx_request(struct blk_mq_hw_ctx *hctx, struct request *rq)
{
struct blk_mq_ctx *ctx = rq->mq_ctx;
ctx->rq_completed[rq_is_sync(rq)]++;
__blk_mq_free_request(hctx, ctx, rq);
}
EXPORT_SYMBOL_GPL(blk_mq_free_hctx_request);
void blk_mq_free_request(struct request *rq)
{
blk_mq_free_hctx_request(blk_mq_map_queue(rq->q, rq->mq_ctx->cpu), rq);
}
EXPORT_SYMBOL_GPL(blk_mq_free_request);
inline void __blk_mq_end_request(struct request *rq, int error)
{
blk_account_io_done(rq);
if (rq->end_io) {
rq->end_io(rq, error);
} else {
if (unlikely(blk_bidi_rq(rq)))
blk_mq_free_request(rq->next_rq);
blk_mq_free_request(rq);
}
}
EXPORT_SYMBOL(__blk_mq_end_request);
void blk_mq_end_request(struct request *rq, int error)
{
if (blk_update_request(rq, error, blk_rq_bytes(rq)))
BUG();
__blk_mq_end_request(rq, error);
}
EXPORT_SYMBOL(blk_mq_end_request);
static void __blk_mq_complete_request_remote(void *data)
{
struct request *rq = data;
rq->q->softirq_done_fn(rq);
}
static void blk_mq_ipi_complete_request(struct request *rq)
{
struct blk_mq_ctx *ctx = rq->mq_ctx;
bool shared = false;
int cpu;
if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
rq->q->softirq_done_fn(rq);
return;
}
cpu = get_cpu();
if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
shared = cpus_share_cache(cpu, ctx->cpu);
if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
rq->csd.func = __blk_mq_complete_request_remote;
rq->csd.info = rq;
rq->csd.flags = 0;
smp_call_function_single_async(ctx->cpu, &rq->csd);
} else {
rq->q->softirq_done_fn(rq);
}
put_cpu();
}
static void __blk_mq_complete_request(struct request *rq)
{
struct request_queue *q = rq->q;
if (!q->softirq_done_fn)
blk_mq_end_request(rq, rq->errors);
else
blk_mq_ipi_complete_request(rq);
}
/**
* blk_mq_complete_request - end I/O on a request
* @rq: the request being processed
*
* Description:
* Ends all I/O on a request. It does not handle partial completions.
* The actual completion happens out-of-order, through a IPI handler.
**/
void blk_mq_complete_request(struct request *rq, int error)
{
struct request_queue *q = rq->q;
if (unlikely(blk_should_fake_timeout(q)))
return;
if (!blk_mark_rq_complete(rq)) {
rq->errors = error;
__blk_mq_complete_request(rq);
}
}
EXPORT_SYMBOL(blk_mq_complete_request);
int blk_mq_request_started(struct request *rq)
{
return test_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
}
EXPORT_SYMBOL_GPL(blk_mq_request_started);
void blk_mq_start_request(struct request *rq)
{
struct request_queue *q = rq->q;
trace_block_rq_issue(q, rq);
rq->resid_len = blk_rq_bytes(rq);
if (unlikely(blk_bidi_rq(rq)))
rq->next_rq->resid_len = blk_rq_bytes(rq->next_rq);
blk_add_timer(rq);
/*
* Ensure that ->deadline is visible before set the started
* flag and clear the completed flag.
*/
smp_mb__before_atomic();
/*
* Mark us as started and clear complete. Complete might have been
* set if requeue raced with timeout, which then marked it as
* complete. So be sure to clear complete again when we start
* the request, otherwise we'll ignore the completion event.
*/
if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
if (q->dma_drain_size && blk_rq_bytes(rq)) {
/*
* Make sure space for the drain appears. We know we can do
* this because max_hw_segments has been adjusted to be one
* fewer than the device can handle.
*/
rq->nr_phys_segments++;
}
}
EXPORT_SYMBOL(blk_mq_start_request);
static void __blk_mq_requeue_request(struct request *rq)
{
struct request_queue *q = rq->q;
trace_block_rq_requeue(q, rq);
if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
if (q->dma_drain_size && blk_rq_bytes(rq))
rq->nr_phys_segments--;
}
}
void blk_mq_requeue_request(struct request *rq)
{
__blk_mq_requeue_request(rq);
BUG_ON(blk_queued_rq(rq));
blk_mq_add_to_requeue_list(rq, true);
}
EXPORT_SYMBOL(blk_mq_requeue_request);
static void blk_mq_requeue_work(struct work_struct *work)
{
struct request_queue *q =
container_of(work, struct request_queue, requeue_work.work);
LIST_HEAD(rq_list);
struct request *rq, *next;
unsigned long flags;
spin_lock_irqsave(&q->requeue_lock, flags);
list_splice_init(&q->requeue_list, &rq_list);
spin_unlock_irqrestore(&q->requeue_lock, flags);
list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
if (!(rq->cmd_flags & REQ_SOFTBARRIER))
continue;
rq->cmd_flags &= ~REQ_SOFTBARRIER;
list_del_init(&rq->queuelist);
blk_mq_insert_request(rq, true, false, false);
}
while (!list_empty(&rq_list)) {
rq = list_entry(rq_list.next, struct request, queuelist);
list_del_init(&rq->queuelist);
blk_mq_insert_request(rq, false, false, false);
}
/*
* Use the start variant of queue running here, so that running
* the requeue work will kick stopped queues.
*/
blk_mq_start_hw_queues(q);
}
void blk_mq_add_to_requeue_list(struct request *rq, bool at_head)
{
struct request_queue *q = rq->q;
unsigned long flags;
/*
* We abuse this flag that is otherwise used by the I/O scheduler to
* request head insertation from the workqueue.
*/
BUG_ON(rq->cmd_flags & REQ_SOFTBARRIER);
spin_lock_irqsave(&q->requeue_lock, flags);
if (at_head) {
rq->cmd_flags |= REQ_SOFTBARRIER;
list_add(&rq->queuelist, &q->requeue_list);
} else {
list_add_tail(&rq->queuelist, &q->requeue_list);
}
spin_unlock_irqrestore(&q->requeue_lock, flags);
}
EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
void blk_mq_cancel_requeue_work(struct request_queue *q)
{
cancel_delayed_work_sync(&q->requeue_work);
}
EXPORT_SYMBOL_GPL(blk_mq_cancel_requeue_work);
void blk_mq_kick_requeue_list(struct request_queue *q)
{
kblockd_schedule_delayed_work(&q->requeue_work, 0);
}
EXPORT_SYMBOL(blk_mq_kick_requeue_list);
void blk_mq_delay_kick_requeue_list(struct request_queue *q,
unsigned long msecs)
{
kblockd_schedule_delayed_work(&q->requeue_work,
msecs_to_jiffies(msecs));
}
EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
void blk_mq_abort_requeue_list(struct request_queue *q)
{
unsigned long flags;
LIST_HEAD(rq_list);
spin_lock_irqsave(&q->requeue_lock, flags);
list_splice_init(&q->requeue_list, &rq_list);
spin_unlock_irqrestore(&q->requeue_lock, flags);
while (!list_empty(&rq_list)) {
struct request *rq;
rq = list_first_entry(&rq_list, struct request, queuelist);
list_del_init(&rq->queuelist);
rq->errors = -EIO;
blk_mq_end_request(rq, rq->errors);
}
}
EXPORT_SYMBOL(blk_mq_abort_requeue_list);
struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
{
if (tag < tags->nr_tags) {
prefetch(tags->rqs[tag]);
return tags->rqs[tag];
}
return NULL;
}
EXPORT_SYMBOL(blk_mq_tag_to_rq);
struct blk_mq_timeout_data {
unsigned long next;
unsigned int next_set;
};
void blk_mq_rq_timed_out(struct request *req, bool reserved)
{
struct blk_mq_ops *ops = req->q->mq_ops;
enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
/*
* We know that complete is set at this point. If STARTED isn't set
* anymore, then the request isn't active and the "timeout" should
* just be ignored. This can happen due to the bitflag ordering.
* Timeout first checks if STARTED is set, and if it is, assumes
* the request is active. But if we race with completion, then
* we both flags will get cleared. So check here again, and ignore
* a timeout event with a request that isn't active.
*/
if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags))
return;
if (ops->timeout)
ret = ops->timeout(req, reserved);
switch (ret) {
case BLK_EH_HANDLED:
__blk_mq_complete_request(req);
break;
case BLK_EH_RESET_TIMER:
blk_add_timer(req);
blk_clear_rq_complete(req);
break;
case BLK_EH_NOT_HANDLED:
break;
default:
printk(KERN_ERR "block: bad eh return: %d\n", ret);
break;
}
}
static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
struct request *rq, void *priv, bool reserved)
{
struct blk_mq_timeout_data *data = priv;
if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
/*
* If a request wasn't started before the queue was
* marked dying, kill it here or it'll go unnoticed.
*/
if (unlikely(blk_queue_dying(rq->q))) {
rq->errors = -EIO;
blk_mq_end_request(rq, rq->errors);
}
return;
}
if (time_after_eq(jiffies, rq->deadline)) {
if (!blk_mark_rq_complete(rq))
blk_mq_rq_timed_out(rq, reserved);
} else if (!data->next_set || time_after(data->next, rq->deadline)) {
data->next = rq->deadline;
data->next_set = 1;
}
}
static void blk_mq_timeout_work(struct work_struct *work)
{
struct request_queue *q =
container_of(work, struct request_queue, timeout_work);
struct blk_mq_timeout_data data = {
.next = 0,
.next_set = 0,
};
int i;
/* A deadlock might occur if a request is stuck requiring a
* timeout at the same time a queue freeze is waiting
* completion, since the timeout code would not be able to
* acquire the queue reference here.
*
* That's why we don't use blk_queue_enter here; instead, we use
* percpu_ref_tryget directly, because we need to be able to
* obtain a reference even in the short window between the queue
* starting to freeze, by dropping the first reference in
* blk_mq_freeze_queue_start, and the moment the last request is
* consumed, marked by the instant q_usage_counter reaches
* zero.
*/
if (!percpu_ref_tryget(&q->q_usage_counter))
return;
blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
if (data.next_set) {
data.next = blk_rq_timeout(round_jiffies_up(data.next));
mod_timer(&q->timeout, data.next);
} else {
struct blk_mq_hw_ctx *hctx;
queue_for_each_hw_ctx(q, hctx, i) {
/* the hctx may be unmapped, so check it here */
if (blk_mq_hw_queue_mapped(hctx))
blk_mq_tag_idle(hctx);
}
}
blk_queue_exit(q);
}
/*
* Reverse check our software queue for entries that we could potentially
* merge with. Currently includes a hand-wavy stop count of 8, to not spend
* too much time checking for merges.
*/
static bool blk_mq_attempt_merge(struct request_queue *q,
struct blk_mq_ctx *ctx, struct bio *bio)
{
struct request *rq;
int checked = 8;
list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
int el_ret;
if (!checked--)
break;
if (!blk_rq_merge_ok(rq, bio))
continue;
el_ret = blk_try_merge(rq, bio);
if (el_ret == ELEVATOR_BACK_MERGE) {
if (bio_attempt_back_merge(q, rq, bio)) {
ctx->rq_merged++;
return true;
}
break;
} else if (el_ret == ELEVATOR_FRONT_MERGE) {
if (bio_attempt_front_merge(q, rq, bio)) {
ctx->rq_merged++;
return true;
}
break;
}
}
return false;
}
struct flush_busy_ctx_data {
struct blk_mq_hw_ctx *hctx;
struct list_head *list;
};
static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
{
struct flush_busy_ctx_data *flush_data = data;
struct blk_mq_hw_ctx *hctx = flush_data->hctx;
struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
sbitmap_clear_bit(sb, bitnr);
spin_lock(&ctx->lock);
list_splice_tail_init(&ctx->rq_list, flush_data->list);
spin_unlock(&ctx->lock);
return true;
}
/*
* Process software queues that have been marked busy, splicing them
* to the for-dispatch
*/
static void flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
{
struct flush_busy_ctx_data data = {
.hctx = hctx,
.list = list,
};
sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
}
static inline unsigned int queued_to_index(unsigned int queued)
{
if (!queued)
return 0;
return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
}
/*
* Run this hardware queue, pulling any software queues mapped to it in.
* Note that this function currently has various problems around ordering
* of IO. In particular, we'd like FIFO behaviour on handling existing
* items on the hctx->dispatch list. Ignore that for now.
*/
static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
{
struct request_queue *q = hctx->queue;
struct request *rq;
LIST_HEAD(rq_list);
LIST_HEAD(driver_list);
struct list_head *dptr;
int queued;
if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
return;
WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
cpu_online(hctx->next_cpu));
hctx->run++;
/*
* Touch any software queue that has pending entries.
*/
flush_busy_ctxs(hctx, &rq_list);
/*
* If we have previous entries on our dispatch list, grab them
* and stuff them at the front for more fair dispatch.
*/
if (!list_empty_careful(&hctx->dispatch)) {
spin_lock(&hctx->lock);
if (!list_empty(&hctx->dispatch))
list_splice_init(&hctx->dispatch, &rq_list);
spin_unlock(&hctx->lock);
}
/*
* Start off with dptr being NULL, so we start the first request
* immediately, even if we have more pending.
*/
dptr = NULL;
/*
* Now process all the entries, sending them to the driver.
*/
queued = 0;
while (!list_empty(&rq_list)) {
struct blk_mq_queue_data bd;
int ret;
rq = list_first_entry(&rq_list, struct request, queuelist);
list_del_init(&rq->queuelist);
bd.rq = rq;
bd.list = dptr;
bd.last = list_empty(&rq_list);
ret = q->mq_ops->queue_rq(hctx, &bd);
switch (ret) {
case BLK_MQ_RQ_QUEUE_OK:
queued++;
break;
case BLK_MQ_RQ_QUEUE_BUSY:
list_add(&rq->queuelist, &rq_list);
__blk_mq_requeue_request(rq);
break;
default:
pr_err("blk-mq: bad return on queue: %d\n", ret);
case BLK_MQ_RQ_QUEUE_ERROR:
rq->errors = -EIO;
blk_mq_end_request(rq, rq->errors);
break;
}
if (ret == BLK_MQ_RQ_QUEUE_BUSY)
break;
/*
* We've done the first request. If we have more than 1
* left in the list, set dptr to defer issue.
*/
if (!dptr && rq_list.next != rq_list.prev)
dptr = &driver_list;
}
hctx->dispatched[queued_to_index(queued)]++;
/*
* Any items that need requeuing? Stuff them into hctx->dispatch,
* that is where we will continue on next queue run.
*/
if (!list_empty(&rq_list)) {
spin_lock(&hctx->lock);
list_splice(&rq_list, &hctx->dispatch);
spin_unlock(&hctx->lock);
/*
* the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
* it's possible the queue is stopped and restarted again
* before this. Queue restart will dispatch requests. And since
* requests in rq_list aren't added into hctx->dispatch yet,
* the requests in rq_list might get lost.
*
* blk_mq_run_hw_queue() already checks the STOPPED bit
**/
blk_mq_run_hw_queue(hctx, true);
}
}
/*
* It'd be great if the workqueue API had a way to pass
* in a mask and had some smarts for more clever placement.
* For now we just round-robin here, switching for every
* BLK_MQ_CPU_WORK_BATCH queued items.
*/
static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
{
if (hctx->queue->nr_hw_queues == 1)
return WORK_CPU_UNBOUND;
if (--hctx->next_cpu_batch <= 0) {
int cpu = hctx->next_cpu, next_cpu;
next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
if (next_cpu >= nr_cpu_ids)
next_cpu = cpumask_first(hctx->cpumask);
hctx->next_cpu = next_cpu;
hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
return cpu;
}
return hctx->next_cpu;
}
void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
{
if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state) ||
!blk_mq_hw_queue_mapped(hctx)))
return;
if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
int cpu = get_cpu();
if (cpumask_test_cpu(cpu, hctx->cpumask)) {
__blk_mq_run_hw_queue(hctx);
put_cpu();
return;
}
put_cpu();
}
kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work);
}
void blk_mq_run_hw_queues(struct request_queue *q, bool async)
{
struct blk_mq_hw_ctx *hctx;
int i;
queue_for_each_hw_ctx(q, hctx, i) {
if ((!blk_mq_hctx_has_pending(hctx) &&
list_empty_careful(&hctx->dispatch)) ||
test_bit(BLK_MQ_S_STOPPED, &hctx->state))
continue;
blk_mq_run_hw_queue(hctx, async);
}
}
EXPORT_SYMBOL(blk_mq_run_hw_queues);
void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
{
cancel_work(&hctx->run_work);
cancel_delayed_work(&hctx->delay_work);
set_bit(BLK_MQ_S_STOPPED, &hctx->state);
}
EXPORT_SYMBOL(blk_mq_stop_hw_queue);
void blk_mq_stop_hw_queues(struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
int i;
queue_for_each_hw_ctx(q, hctx, i)
blk_mq_stop_hw_queue(hctx);
}
EXPORT_SYMBOL(blk_mq_stop_hw_queues);
void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
{
clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
blk_mq_run_hw_queue(hctx, false);
}
EXPORT_SYMBOL(blk_mq_start_hw_queue);
void blk_mq_start_hw_queues(struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
int i;
queue_for_each_hw_ctx(q, hctx, i)
blk_mq_start_hw_queue(hctx);
}
EXPORT_SYMBOL(blk_mq_start_hw_queues);
void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
{
struct blk_mq_hw_ctx *hctx;
int i;
queue_for_each_hw_ctx(q, hctx, i) {
if (!test_bit(BLK_MQ_S_STOPPED, &hctx->state))
continue;
clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
blk_mq_run_hw_queue(hctx, async);
}
}
EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
static void blk_mq_run_work_fn(struct work_struct *work)
{
struct blk_mq_hw_ctx *hctx;
hctx = container_of(work, struct blk_mq_hw_ctx, run_work);
__blk_mq_run_hw_queue(hctx);
}
static void blk_mq_delay_work_fn(struct work_struct *work)
{
struct blk_mq_hw_ctx *hctx;
hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work);
if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state))
__blk_mq_run_hw_queue(hctx);
}
void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
{
if (unlikely(!blk_mq_hw_queue_mapped(hctx)))
return;
kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
&hctx->delay_work, msecs_to_jiffies(msecs));
}
EXPORT_SYMBOL(blk_mq_delay_queue);
static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
struct request *rq,
bool at_head)
{
struct blk_mq_ctx *ctx = rq->mq_ctx;
trace_block_rq_insert(hctx->queue, rq);
if (at_head)
list_add(&rq->queuelist, &ctx->rq_list);
else
list_add_tail(&rq->queuelist, &ctx->rq_list);
}
static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
struct request *rq, bool at_head)
{
struct blk_mq_ctx *ctx = rq->mq_ctx;
__blk_mq_insert_req_list(hctx, rq, at_head);
blk_mq_hctx_mark_pending(hctx, ctx);
}
void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
bool async)
{
struct blk_mq_ctx *ctx = rq->mq_ctx;
struct request_queue *q = rq->q;
struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
spin_lock(&ctx->lock);
__blk_mq_insert_request(hctx, rq, at_head);
spin_unlock(&ctx->lock);
if (run_queue)
blk_mq_run_hw_queue(hctx, async);
}
static void blk_mq_insert_requests(struct request_queue *q,
struct blk_mq_ctx *ctx,
struct list_head *list,
int depth,
bool from_schedule)
{
struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
trace_block_unplug(q, depth, !from_schedule);
/*
* preemption doesn't flush plug list, so it's possible ctx->cpu is
* offline now
*/
spin_lock(&ctx->lock);
while (!list_empty(list)) {
struct request *rq;
rq = list_first_entry(list, struct request, queuelist);
BUG_ON(rq->mq_ctx != ctx);
list_del_init(&rq->queuelist);
__blk_mq_insert_req_list(hctx, rq, false);
}
blk_mq_hctx_mark_pending(hctx, ctx);
spin_unlock(&ctx->lock);
blk_mq_run_hw_queue(hctx, from_schedule);
}
static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
{
struct request *rqa = container_of(a, struct request, queuelist);
struct request *rqb = container_of(b, struct request, queuelist);
return !(rqa->mq_ctx < rqb->mq_ctx ||
(rqa->mq_ctx == rqb->mq_ctx &&
blk_rq_pos(rqa) < blk_rq_pos(rqb)));
}
void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
{
struct blk_mq_ctx *this_ctx;
struct request_queue *this_q;
struct request *rq;
LIST_HEAD(list);
LIST_HEAD(ctx_list);
unsigned int depth;
list_splice_init(&plug->mq_list, &list);
list_sort(NULL, &list, plug_ctx_cmp);
this_q = NULL;
this_ctx = NULL;
depth = 0;
while (!list_empty(&list)) {
rq = list_entry_rq(list.next);
list_del_init(&rq->queuelist);
BUG_ON(!rq->q);
if (rq->mq_ctx != this_ctx) {
if (this_ctx) {
blk_mq_insert_requests(this_q, this_ctx,
&ctx_list, depth,
from_schedule);
}
this_ctx = rq->mq_ctx;
this_q = rq->q;
depth = 0;
}
depth++;
list_add_tail(&rq->queuelist, &ctx_list);
}
/*
* If 'this_ctx' is set, we know we have entries to complete
* on 'ctx_list'. Do those.
*/
if (this_ctx) {
blk_mq_insert_requests(this_q, this_ctx, &ctx_list, depth,
from_schedule);
}
}
static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
{
init_request_from_bio(rq, bio);
blk_account_io_start(rq, 1);
}
static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
{
return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
!blk_queue_nomerges(hctx->queue);
}
static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
struct blk_mq_ctx *ctx,
struct request *rq, struct bio *bio)
{
if (!hctx_allow_merges(hctx) || !bio_mergeable(bio)) {
blk_mq_bio_to_request(rq, bio);
spin_lock(&ctx->lock);
insert_rq:
__blk_mq_insert_request(hctx, rq, false);
spin_unlock(&ctx->lock);
return false;
} else {
struct request_queue *q = hctx->queue;
spin_lock(&ctx->lock);
if (!blk_mq_attempt_merge(q, ctx, bio)) {
blk_mq_bio_to_request(rq, bio);
goto insert_rq;
}
spin_unlock(&ctx->lock);
__blk_mq_free_request(hctx, ctx, rq);
return true;
}
}
struct blk_map_ctx {
struct blk_mq_hw_ctx *hctx;
struct blk_mq_ctx *ctx;
};
static struct request *blk_mq_map_request(struct request_queue *q,
struct bio *bio,
struct blk_map_ctx *data)
{
struct blk_mq_hw_ctx *hctx;
struct blk_mq_ctx *ctx;
struct request *rq;
int op = bio_data_dir(bio);
int op_flags = 0;
struct blk_mq_alloc_data alloc_data;
blk_queue_enter_live(q);
ctx = blk_mq_get_ctx(q);
hctx = blk_mq_map_queue(q, ctx->cpu);
if (rw_is_sync(bio_op(bio), bio->bi_opf))
op_flags |= REQ_SYNC;
trace_block_getrq(q, bio, op);
blk_mq_set_alloc_data(&alloc_data, q, 0, ctx, hctx);
rq = __blk_mq_alloc_request(&alloc_data, op, op_flags);
data->hctx = alloc_data.hctx;
data->ctx = alloc_data.ctx;
data->hctx->queued++;
return rq;
}
static int blk_mq_direct_issue_request(struct request *rq, blk_qc_t *cookie)
{
int ret;
struct request_queue *q = rq->q;
struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu);
struct blk_mq_queue_data bd = {
.rq = rq,
.list = NULL,
.last = 1
};
blk_qc_t new_cookie = blk_tag_to_qc_t(rq->tag, hctx->queue_num);
/*
* For OK queue, we are done. For error, kill it. Any other
* error (busy), just add it to our list as we previously
* would have done
*/
ret = q->mq_ops->queue_rq(hctx, &bd);
if (ret == BLK_MQ_RQ_QUEUE_OK) {
*cookie = new_cookie;
return 0;
}
__blk_mq_requeue_request(rq);
if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
*cookie = BLK_QC_T_NONE;
rq->errors = -EIO;
blk_mq_end_request(rq, rq->errors);
return 0;
}
return -1;
}
/*
* Multiple hardware queue variant. This will not use per-process plugs,
* but will attempt to bypass the hctx queueing if we can go straight to
* hardware for SYNC IO.
*/
static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
{
const int is_sync = rw_is_sync(bio_op(bio), bio->bi_opf);
const int is_flush_fua = bio->bi_opf & (REQ_PREFLUSH | REQ_FUA);
struct blk_map_ctx data;
struct request *rq;
unsigned int request_count = 0;
struct blk_plug *plug;
struct request *same_queue_rq = NULL;
blk_qc_t cookie;
blk_queue_bounce(q, &bio);
if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
bio_io_error(bio);
return BLK_QC_T_NONE;
}
blk_queue_split(q, &bio, q->bio_split);
if (!is_flush_fua && !blk_queue_nomerges(q) &&
blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))
return BLK_QC_T_NONE;
rq = blk_mq_map_request(q, bio, &data);
if (unlikely(!rq))
return BLK_QC_T_NONE;
cookie = blk_tag_to_qc_t(rq->tag, data.hctx->queue_num);
if (unlikely(is_flush_fua)) {
blk_mq_bio_to_request(rq, bio);
blk_insert_flush(rq);
goto run_queue;
}
plug = current->plug;
/*
* If the driver supports defer issued based on 'last', then
* queue it up like normal since we can potentially save some
* CPU this way.
*/
if (((plug && !blk_queue_nomerges(q)) || is_sync) &&
!(data.hctx->flags & BLK_MQ_F_DEFER_ISSUE)) {
struct request *old_rq = NULL;
blk_mq_bio_to_request(rq, bio);
/*
* We do limited pluging. If the bio can be merged, do that.
* Otherwise the existing request in the plug list will be
* issued. So the plug list will have one request at most
*/
if (plug) {
/*
* The plug list might get flushed before this. If that
* happens, same_queue_rq is invalid and plug list is
* empty
*/
if (same_queue_rq && !list_empty(&plug->mq_list)) {
old_rq = same_queue_rq;
list_del_init(&old_rq->queuelist);
}
list_add_tail(&rq->queuelist, &plug->mq_list);
} else /* is_sync */
old_rq = rq;
blk_mq_put_ctx(data.ctx);
if (!old_rq)
goto done;
if (!blk_mq_direct_issue_request(old_rq, &cookie))
goto done;
blk_mq_insert_request(old_rq, false, true, true);
goto done;
}
if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
/*
* For a SYNC request, send it to the hardware immediately. For
* an ASYNC request, just ensure that we run it later on. The
* latter allows for merging opportunities and more efficient
* dispatching.
*/
run_queue:
blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
}
blk_mq_put_ctx(data.ctx);
done:
return cookie;
}
/*
* Single hardware queue variant. This will attempt to use any per-process
* plug for merging and IO deferral.
*/
static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
{
const int is_sync = rw_is_sync(bio_op(bio), bio->bi_opf);
const int is_flush_fua = bio->bi_opf & (REQ_PREFLUSH | REQ_FUA);
struct blk_plug *plug;
unsigned int request_count = 0;
struct blk_map_ctx data;
struct request *rq;
blk_qc_t cookie;
blk_queue_bounce(q, &bio);
if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
bio_io_error(bio);
return BLK_QC_T_NONE;
}
blk_queue_split(q, &bio, q->bio_split);
if (!is_flush_fua && !blk_queue_nomerges(q)) {
if (blk_attempt_plug_merge(q, bio, &request_count, NULL))
return BLK_QC_T_NONE;
} else
request_count = blk_plug_queued_count(q);
rq = blk_mq_map_request(q, bio, &data);
if (unlikely(!rq))
return BLK_QC_T_NONE;
cookie = blk_tag_to_qc_t(rq->tag, data.hctx->queue_num);
if (unlikely(is_flush_fua)) {
blk_mq_bio_to_request(rq, bio);
blk_insert_flush(rq);
goto run_queue;
}
/*
* A task plug currently exists. Since this is completely lockless,
* utilize that to temporarily store requests until the task is
* either done or scheduled away.
*/
plug = current->plug;
if (plug) {
blk_mq_bio_to_request(rq, bio);
if (!request_count)
trace_block_plug(q);
blk_mq_put_ctx(data.ctx);
if (request_count >= BLK_MAX_REQUEST_COUNT) {
blk_flush_plug_list(plug, false);
trace_block_plug(q);
}
list_add_tail(&rq->queuelist, &plug->mq_list);
return cookie;
}
if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
/*
* For a SYNC request, send it to the hardware immediately. For
* an ASYNC request, just ensure that we run it later on. The
* latter allows for merging opportunities and more efficient
* dispatching.
*/
run_queue:
blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
}
blk_mq_put_ctx(data.ctx);
return cookie;
}
static void blk_mq_free_rq_map(struct blk_mq_tag_set *set,
struct blk_mq_tags *tags, unsigned int hctx_idx)
{
struct page *page;
if (tags->rqs && set->ops->exit_request) {
int i;
for (i = 0; i < tags->nr_tags; i++) {
if (!tags->rqs[i])
continue;
set->ops->exit_request(set->driver_data, tags->rqs[i],
hctx_idx, i);
tags->rqs[i] = NULL;
}
}
while (!list_empty(&tags->page_list)) {
page = list_first_entry(&tags->page_list, struct page, lru);
list_del_init(&page->lru);
/*
* Remove kmemleak object previously allocated in
* blk_mq_init_rq_map().
*/
kmemleak_free(page_address(page));
__free_pages(page, page->private);
}
kfree(tags->rqs);
blk_mq_free_tags(tags);
}
static size_t order_to_size(unsigned int order)
{
return (size_t)PAGE_SIZE << order;
}
static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
unsigned int hctx_idx)
{
struct blk_mq_tags *tags;
unsigned int i, j, entries_per_page, max_order = 4;
size_t rq_size, left;
tags = blk_mq_init_tags(set->queue_depth, set->reserved_tags,
set->numa_node,
BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
if (!tags)
return NULL;
INIT_LIST_HEAD(&tags->page_list);
tags->rqs = kzalloc_node(set->queue_depth * sizeof(struct request *),
GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY,
set->numa_node);
if (!tags->rqs) {
blk_mq_free_tags(tags);
return NULL;
}
/*
* rq_size is the size of the request plus driver payload, rounded
* to the cacheline size
*/
rq_size = round_up(sizeof(struct request) + set->cmd_size,
cache_line_size());
left = rq_size * set->queue_depth;
for (i = 0; i < set->queue_depth; ) {
int this_order = max_order;
struct page *page;
int to_do;
void *p;
while (this_order && left < order_to_size(this_order - 1))
this_order--;
do {
page = alloc_pages_node(set->numa_node,
GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
this_order);
if (page)
break;
if (!this_order--)
break;
if (order_to_size(this_order) < rq_size)
break;
} while (1);
if (!page)
goto fail;
page->private = this_order;
list_add_tail(&page->lru, &tags->page_list);
p = page_address(page);
/*
* Allow kmemleak to scan these pages as they contain pointers
* to additional allocations like via ops->init_request().
*/
kmemleak_alloc(p, order_to_size(this_order), 1, GFP_KERNEL);
entries_per_page = order_to_size(this_order) / rq_size;
to_do = min(entries_per_page, set->queue_depth - i);
left -= to_do * rq_size;
for (j = 0; j < to_do; j++) {
tags->rqs[i] = p;
if (set->ops->init_request) {
if (set->ops->init_request(set->driver_data,
tags->rqs[i], hctx_idx, i,
set->numa_node)) {
tags->rqs[i] = NULL;
goto fail;
}
}
p += rq_size;
i++;
}
}
return tags;
fail:
blk_mq_free_rq_map(set, tags, hctx_idx);
return NULL;
}
/*
* 'cpu' is going away. splice any existing rq_list entries from this
* software queue to the hw queue dispatch list, and ensure that it
* gets run.
*/
static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
{
struct blk_mq_hw_ctx *hctx;
struct blk_mq_ctx *ctx;
LIST_HEAD(tmp);
hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
ctx = __blk_mq_get_ctx(hctx->queue, cpu);
spin_lock(&ctx->lock);
if (!list_empty(&ctx->rq_list)) {
list_splice_init(&ctx->rq_list, &tmp);
blk_mq_hctx_clear_pending(hctx, ctx);
}
spin_unlock(&ctx->lock);
if (list_empty(&tmp))
return 0;
spin_lock(&hctx->lock);
list_splice_tail_init(&tmp, &hctx->dispatch);
spin_unlock(&hctx->lock);
blk_mq_run_hw_queue(hctx, true);
return 0;
}
static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
{
cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
&hctx->cpuhp_dead);
}
/* hctx->ctxs will be freed in queue's release handler */
static void blk_mq_exit_hctx(struct request_queue *q,
struct blk_mq_tag_set *set,
struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
{
unsigned flush_start_tag = set->queue_depth;
blk_mq_tag_idle(hctx);
if (set->ops->exit_request)
set->ops->exit_request(set->driver_data,
hctx->fq->flush_rq, hctx_idx,
flush_start_tag + hctx_idx);
if (set->ops->exit_hctx)
set->ops->exit_hctx(hctx, hctx_idx);
blk_mq_remove_cpuhp(hctx);
blk_free_flush_queue(hctx->fq);
sbitmap_free(&hctx->ctx_map);
}
static void blk_mq_exit_hw_queues(struct request_queue *q,
struct blk_mq_tag_set *set, int nr_queue)
{
struct blk_mq_hw_ctx *hctx;
unsigned int i;
queue_for_each_hw_ctx(q, hctx, i) {
if (i == nr_queue)
break;
blk_mq_exit_hctx(q, set, hctx, i);
}
}
static void blk_mq_free_hw_queues(struct request_queue *q,
struct blk_mq_tag_set *set)
{
struct blk_mq_hw_ctx *hctx;
unsigned int i;
queue_for_each_hw_ctx(q, hctx, i)
free_cpumask_var(hctx->cpumask);
}
static int blk_mq_init_hctx(struct request_queue *q,
struct blk_mq_tag_set *set,
struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
{
int node;
unsigned flush_start_tag = set->queue_depth;
node = hctx->numa_node;
if (node == NUMA_NO_NODE)
node = hctx->numa_node = set->numa_node;
INIT_WORK(&hctx->run_work, blk_mq_run_work_fn);
INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
spin_lock_init(&hctx->lock);
INIT_LIST_HEAD(&hctx->dispatch);
hctx->queue = q;
hctx->queue_num = hctx_idx;
hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
hctx->tags = set->tags[hctx_idx];
/*
* Allocate space for all possible cpus to avoid allocation at
* runtime
*/
hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
GFP_KERNEL, node);
if (!hctx->ctxs)
goto unregister_cpu_notifier;
if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL,
node))
goto free_ctxs;
hctx->nr_ctx = 0;
if (set->ops->init_hctx &&
set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
goto free_bitmap;
hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
if (!hctx->fq)
goto exit_hctx;
if (set->ops->init_request &&
set->ops->init_request(set->driver_data,
hctx->fq->flush_rq, hctx_idx,
flush_start_tag + hctx_idx, node))
goto free_fq;
return 0;
free_fq:
kfree(hctx->fq);
exit_hctx:
if (set->ops->exit_hctx)
set->ops->exit_hctx(hctx, hctx_idx);
free_bitmap:
sbitmap_free(&hctx->ctx_map);
free_ctxs:
kfree(hctx->ctxs);
unregister_cpu_notifier:
blk_mq_remove_cpuhp(hctx);
return -1;
}
static void blk_mq_init_cpu_queues(struct request_queue *q,
unsigned int nr_hw_queues)
{
unsigned int i;
for_each_possible_cpu(i) {
struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
struct blk_mq_hw_ctx *hctx;
memset(__ctx, 0, sizeof(*__ctx));
__ctx->cpu = i;
spin_lock_init(&__ctx->lock);
INIT_LIST_HEAD(&__ctx->rq_list);
__ctx->queue = q;
/* If the cpu isn't online, the cpu is mapped to first hctx */
if (!cpu_online(i))
continue;
hctx = blk_mq_map_queue(q, i);
/*
* Set local node, IFF we have more than one hw queue. If
* not, we remain on the home node of the device
*/
if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
hctx->numa_node = local_memory_node(cpu_to_node(i));
}
}
static void blk_mq_map_swqueue(struct request_queue *q,
const struct cpumask *online_mask)
{
unsigned int i;
struct blk_mq_hw_ctx *hctx;
struct blk_mq_ctx *ctx;
struct blk_mq_tag_set *set = q->tag_set;
/*
* Avoid others reading imcomplete hctx->cpumask through sysfs
*/
mutex_lock(&q->sysfs_lock);
queue_for_each_hw_ctx(q, hctx, i) {
cpumask_clear(hctx->cpumask);
hctx->nr_ctx = 0;
}
/*
* Map software to hardware queues
*/
for_each_possible_cpu(i) {
/* If the cpu isn't online, the cpu is mapped to first hctx */
if (!cpumask_test_cpu(i, online_mask))
continue;
ctx = per_cpu_ptr(q->queue_ctx, i);
hctx = blk_mq_map_queue(q, i);
cpumask_set_cpu(i, hctx->cpumask);
ctx->index_hw = hctx->nr_ctx;
hctx->ctxs[hctx->nr_ctx++] = ctx;
}
mutex_unlock(&q->sysfs_lock);
queue_for_each_hw_ctx(q, hctx, i) {
/*
* If no software queues are mapped to this hardware queue,
* disable it and free the request entries.
*/
if (!hctx->nr_ctx) {
if (set->tags[i]) {
blk_mq_free_rq_map(set, set->tags[i], i);
set->tags[i] = NULL;
}
hctx->tags = NULL;
continue;
}
/* unmapped hw queue can be remapped after CPU topo changed */
if (!set->tags[i])
set->tags[i] = blk_mq_init_rq_map(set, i);
hctx->tags = set->tags[i];
WARN_ON(!hctx->tags);
/*
* Set the map size to the number of mapped software queues.
* This is more accurate and more efficient than looping
* over all possibly mapped software queues.
*/
sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
/*
* Initialize batch roundrobin counts
*/
hctx->next_cpu = cpumask_first(hctx->cpumask);
hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
}
}
static void queue_set_hctx_shared(struct request_queue *q, bool shared)
{
struct blk_mq_hw_ctx *hctx;
int i;
queue_for_each_hw_ctx(q, hctx, i) {
if (shared)
hctx->flags |= BLK_MQ_F_TAG_SHARED;
else
hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
}
}
static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, bool shared)
{
struct request_queue *q;
list_for_each_entry(q, &set->tag_list, tag_set_list) {
blk_mq_freeze_queue(q);
queue_set_hctx_shared(q, shared);
blk_mq_unfreeze_queue(q);
}
}
static void blk_mq_del_queue_tag_set(struct request_queue *q)
{
struct blk_mq_tag_set *set = q->tag_set;
mutex_lock(&set->tag_list_lock);
list_del_init(&q->tag_set_list);
if (list_is_singular(&set->tag_list)) {
/* just transitioned to unshared */
set->flags &= ~BLK_MQ_F_TAG_SHARED;
/* update existing queue */
blk_mq_update_tag_set_depth(set, false);
}
mutex_unlock(&set->tag_list_lock);
}
static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
struct request_queue *q)
{
q->tag_set = set;
mutex_lock(&set->tag_list_lock);
/* Check to see if we're transitioning to shared (from 1 to 2 queues). */
if (!list_empty(&set->tag_list) && !(set->flags & BLK_MQ_F_TAG_SHARED)) {
set->flags |= BLK_MQ_F_TAG_SHARED;
/* update existing queue */
blk_mq_update_tag_set_depth(set, true);
}
if (set->flags & BLK_MQ_F_TAG_SHARED)
queue_set_hctx_shared(q, true);
list_add_tail(&q->tag_set_list, &set->tag_list);
mutex_unlock(&set->tag_list_lock);
}
/*
* It is the actual release handler for mq, but we do it from
* request queue's release handler for avoiding use-after-free
* and headache because q->mq_kobj shouldn't have been introduced,
* but we can't group ctx/kctx kobj without it.
*/
void blk_mq_release(struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
unsigned int i;
/* hctx kobj stays in hctx */
queue_for_each_hw_ctx(q, hctx, i) {
if (!hctx)
continue;
kfree(hctx->ctxs);
kfree(hctx);
}
q->mq_map = NULL;
kfree(q->queue_hw_ctx);
/* ctx kobj stays in queue_ctx */
free_percpu(q->queue_ctx);
}
struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
{
struct request_queue *uninit_q, *q;
uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
if (!uninit_q)
return ERR_PTR(-ENOMEM);
q = blk_mq_init_allocated_queue(set, uninit_q);
if (IS_ERR(q))
blk_cleanup_queue(uninit_q);
return q;
}
EXPORT_SYMBOL(blk_mq_init_queue);
static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
struct request_queue *q)
{
int i, j;
struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
blk_mq_sysfs_unregister(q);
for (i = 0; i < set->nr_hw_queues; i++) {
int node;
if (hctxs[i])
continue;
node = blk_mq_hw_queue_to_node(q->mq_map, i);
hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
GFP_KERNEL, node);
if (!hctxs[i])
break;
if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
node)) {
kfree(hctxs[i]);
hctxs[i] = NULL;
break;
}
atomic_set(&hctxs[i]->nr_active, 0);
hctxs[i]->numa_node = node;
hctxs[i]->queue_num = i;
if (blk_mq_init_hctx(q, set, hctxs[i], i)) {
free_cpumask_var(hctxs[i]->cpumask);
kfree(hctxs[i]);
hctxs[i] = NULL;
break;
}
blk_mq_hctx_kobj_init(hctxs[i]);
}
for (j = i; j < q->nr_hw_queues; j++) {
struct blk_mq_hw_ctx *hctx = hctxs[j];
if (hctx) {
if (hctx->tags) {
blk_mq_free_rq_map(set, hctx->tags, j);
set->tags[j] = NULL;
}
blk_mq_exit_hctx(q, set, hctx, j);
free_cpumask_var(hctx->cpumask);
kobject_put(&hctx->kobj);
kfree(hctx->ctxs);
kfree(hctx);
hctxs[j] = NULL;
}
}
q->nr_hw_queues = i;
blk_mq_sysfs_register(q);
}
struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
struct request_queue *q)
{
/* mark the queue as mq asap */
q->mq_ops = set->ops;
q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
if (!q->queue_ctx)
goto err_exit;
q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
GFP_KERNEL, set->numa_node);
if (!q->queue_hw_ctx)
goto err_percpu;
q->mq_map = set->mq_map;
blk_mq_realloc_hw_ctxs(set, q);
if (!q->nr_hw_queues)
goto err_hctxs;
INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
q->nr_queues = nr_cpu_ids;
q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
if (!(set->flags & BLK_MQ_F_SG_MERGE))
q->queue_flags |= 1 << QUEUE_FLAG_NO_SG_MERGE;
q->sg_reserved_size = INT_MAX;
INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
INIT_LIST_HEAD(&q->requeue_list);
spin_lock_init(&q->requeue_lock);
if (q->nr_hw_queues > 1)
blk_queue_make_request(q, blk_mq_make_request);
else
blk_queue_make_request(q, blk_sq_make_request);
/*
* Do this after blk_queue_make_request() overrides it...
*/
q->nr_requests = set->queue_depth;
if (set->ops->complete)
blk_queue_softirq_done(q, set->ops->complete);
blk_mq_init_cpu_queues(q, set->nr_hw_queues);
get_online_cpus();
mutex_lock(&all_q_mutex);
list_add_tail(&q->all_q_node, &all_q_list);
blk_mq_add_queue_tag_set(set, q);
blk_mq_map_swqueue(q, cpu_online_mask);
mutex_unlock(&all_q_mutex);
put_online_cpus();
return q;
err_hctxs:
kfree(q->queue_hw_ctx);
err_percpu:
free_percpu(q->queue_ctx);
err_exit:
q->mq_ops = NULL;
return ERR_PTR(-ENOMEM);
}
EXPORT_SYMBOL(blk_mq_init_allocated_queue);
void blk_mq_free_queue(struct request_queue *q)
{
struct blk_mq_tag_set *set = q->tag_set;
mutex_lock(&all_q_mutex);
list_del_init(&q->all_q_node);
mutex_unlock(&all_q_mutex);
blk_mq_del_queue_tag_set(q);
blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
blk_mq_free_hw_queues(q, set);
}
/* Basically redo blk_mq_init_queue with queue frozen */
static void blk_mq_queue_reinit(struct request_queue *q,
const struct cpumask *online_mask)
{
WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
blk_mq_sysfs_unregister(q);
/*
* redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
* we should change hctx numa_node according to new topology (this
* involves free and re-allocate memory, worthy doing?)
*/
blk_mq_map_swqueue(q, online_mask);
blk_mq_sysfs_register(q);
}
/*
* New online cpumask which is going to be set in this hotplug event.
* Declare this cpumasks as global as cpu-hotplug operation is invoked
* one-by-one and dynamically allocating this could result in a failure.
*/
static struct cpumask cpuhp_online_new;
static void blk_mq_queue_reinit_work(void)
{
struct request_queue *q;
mutex_lock(&all_q_mutex);
/*
* We need to freeze and reinit all existing queues. Freezing
* involves synchronous wait for an RCU grace period and doing it
* one by one may take a long time. Start freezing all queues in
* one swoop and then wait for the completions so that freezing can
* take place in parallel.
*/
list_for_each_entry(q, &all_q_list, all_q_node)
blk_mq_freeze_queue_start(q);
list_for_each_entry(q, &all_q_list, all_q_node) {
blk_mq_freeze_queue_wait(q);
/*
* timeout handler can't touch hw queue during the
* reinitialization
*/
del_timer_sync(&q->timeout);
}
list_for_each_entry(q, &all_q_list, all_q_node)
blk_mq_queue_reinit(q, &cpuhp_online_new);
list_for_each_entry(q, &all_q_list, all_q_node)
blk_mq_unfreeze_queue(q);
mutex_unlock(&all_q_mutex);
}
static int blk_mq_queue_reinit_dead(unsigned int cpu)
{
cpumask_copy(&cpuhp_online_new, cpu_online_mask);
blk_mq_queue_reinit_work();
return 0;
}
/*
* Before hotadded cpu starts handling requests, new mappings must be
* established. Otherwise, these requests in hw queue might never be
* dispatched.
*
* For example, there is a single hw queue (hctx) and two CPU queues (ctx0
* for CPU0, and ctx1 for CPU1).
*
* Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
* and set bit0 in pending bitmap as ctx1->index_hw is still zero.
*
* And then while running hw queue, flush_busy_ctxs() finds bit0 is set in
* pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
* But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list
* is ignored.
*/
static int blk_mq_queue_reinit_prepare(unsigned int cpu)
{
cpumask_copy(&cpuhp_online_new, cpu_online_mask);
cpumask_set_cpu(cpu, &cpuhp_online_new);
blk_mq_queue_reinit_work();
return 0;
}
static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
{
int i;
for (i = 0; i < set->nr_hw_queues; i++) {
set->tags[i] = blk_mq_init_rq_map(set, i);
if (!set->tags[i])
goto out_unwind;
}
return 0;
out_unwind:
while (--i >= 0)
blk_mq_free_rq_map(set, set->tags[i], i);
return -ENOMEM;
}
/*
* Allocate the request maps associated with this tag_set. Note that this
* may reduce the depth asked for, if memory is tight. set->queue_depth
* will be updated to reflect the allocated depth.
*/
static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
{
unsigned int depth;
int err;
depth = set->queue_depth;
do {
err = __blk_mq_alloc_rq_maps(set);
if (!err)
break;
set->queue_depth >>= 1;
if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
err = -ENOMEM;
break;
}
} while (set->queue_depth);
if (!set->queue_depth || err) {
pr_err("blk-mq: failed to allocate request map\n");
return -ENOMEM;
}
if (depth != set->queue_depth)
pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
depth, set->queue_depth);
return 0;
}
/*
* Alloc a tag set to be associated with one or more request queues.
* May fail with EINVAL for various error conditions. May adjust the
* requested depth down, if if it too large. In that case, the set
* value will be stored in set->queue_depth.
*/
int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
{
int ret;
BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
if (!set->nr_hw_queues)
return -EINVAL;
if (!set->queue_depth)
return -EINVAL;
if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
return -EINVAL;
if (!set->ops->queue_rq)
return -EINVAL;
if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
pr_info("blk-mq: reduced tag depth to %u\n",
BLK_MQ_MAX_DEPTH);
set->queue_depth = BLK_MQ_MAX_DEPTH;
}
/*
* If a crashdump is active, then we are potentially in a very
* memory constrained environment. Limit us to 1 queue and
* 64 tags to prevent using too much memory.
*/
if (is_kdump_kernel()) {
set->nr_hw_queues = 1;
set->queue_depth = min(64U, set->queue_depth);
}
/*
* There is no use for more h/w queues than cpus.
*/
if (set->nr_hw_queues > nr_cpu_ids)
set->nr_hw_queues = nr_cpu_ids;
set->tags = kzalloc_node(nr_cpu_ids * sizeof(struct blk_mq_tags *),
GFP_KERNEL, set->numa_node);
if (!set->tags)
return -ENOMEM;
ret = -ENOMEM;
set->mq_map = kzalloc_node(sizeof(*set->mq_map) * nr_cpu_ids,
GFP_KERNEL, set->numa_node);
if (!set->mq_map)
goto out_free_tags;
if (set->ops->map_queues)
ret = set->ops->map_queues(set);
else
ret = blk_mq_map_queues(set);
if (ret)
goto out_free_mq_map;
ret = blk_mq_alloc_rq_maps(set);
if (ret)
goto out_free_mq_map;
mutex_init(&set->tag_list_lock);
INIT_LIST_HEAD(&set->tag_list);
return 0;
out_free_mq_map:
kfree(set->mq_map);
set->mq_map = NULL;
out_free_tags:
kfree(set->tags);
set->tags = NULL;
return ret;
}
EXPORT_SYMBOL(blk_mq_alloc_tag_set);
void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
{
int i;
for (i = 0; i < nr_cpu_ids; i++) {
if (set->tags[i])
blk_mq_free_rq_map(set, set->tags[i], i);
}
kfree(set->mq_map);
set->mq_map = NULL;
kfree(set->tags);
set->tags = NULL;
}
EXPORT_SYMBOL(blk_mq_free_tag_set);
int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
{
struct blk_mq_tag_set *set = q->tag_set;
struct blk_mq_hw_ctx *hctx;
int i, ret;
if (!set || nr > set->queue_depth)
return -EINVAL;
ret = 0;
queue_for_each_hw_ctx(q, hctx, i) {
if (!hctx->tags)
continue;
ret = blk_mq_tag_update_depth(hctx->tags, nr);
if (ret)
break;
}
if (!ret)
q->nr_requests = nr;
return ret;
}
void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
{
struct request_queue *q;
if (nr_hw_queues > nr_cpu_ids)
nr_hw_queues = nr_cpu_ids;
if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
return;
list_for_each_entry(q, &set->tag_list, tag_set_list)
blk_mq_freeze_queue(q);
set->nr_hw_queues = nr_hw_queues;
list_for_each_entry(q, &set->tag_list, tag_set_list) {
blk_mq_realloc_hw_ctxs(set, q);
if (q->nr_hw_queues > 1)
blk_queue_make_request(q, blk_mq_make_request);
else
blk_queue_make_request(q, blk_sq_make_request);
blk_mq_queue_reinit(q, cpu_online_mask);
}
list_for_each_entry(q, &set->tag_list, tag_set_list)
blk_mq_unfreeze_queue(q);
}
EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
void blk_mq_disable_hotplug(void)
{
mutex_lock(&all_q_mutex);
}
void blk_mq_enable_hotplug(void)
{
mutex_unlock(&all_q_mutex);
}
static int __init blk_mq_init(void)
{
cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
blk_mq_hctx_notify_dead);
cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE, "block/mq:prepare",
blk_mq_queue_reinit_prepare,
blk_mq_queue_reinit_dead);
return 0;
}
subsys_initcall(blk_mq_init);