linux/block/blk-mq.c
Jens Axboe bccb5f7c8b blk-mq: fix potential stall during CPU unplug with IO pending
When a CPU is unplugged, we move the blk_mq_ctx request entries
to the current queue. The current code forgets to remap the
blk_mq_hw_ctx before marking the software context pending,
which breaks if old-cpu and new-cpu don't map to the same
hardware queue.

Additionally, if we mark entries as pending in the new
hardware queue, then make sure we schedule it for running.
Otherwise request could be sitting there until someone else
queues IO for that hardware queue.

Signed-off-by: Jens Axboe <axboe@fb.com>
2014-04-07 08:17:18 -06:00

1495 lines
33 KiB
C

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/backing-dev.h>
#include <linux/bio.h>
#include <linux/blkdev.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 <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);
static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx);
static struct blk_mq_ctx *__blk_mq_get_ctx(struct request_queue *q,
unsigned int cpu)
{
return per_cpu_ptr(q->queue_ctx, cpu);
}
/*
* This assumes per-cpu software queueing queues. They could be per-node
* as well, for instance. For now this is hardcoded as-is. Note that we don't
* care about preemption, since we know the ctx's are persistent. This does
* mean that we can't rely on ctx always matching the currently running CPU.
*/
static struct blk_mq_ctx *blk_mq_get_ctx(struct request_queue *q)
{
return __blk_mq_get_ctx(q, get_cpu());
}
static void blk_mq_put_ctx(struct blk_mq_ctx *ctx)
{
put_cpu();
}
/*
* 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)
{
unsigned int i;
for (i = 0; i < hctx->nr_ctx_map; i++)
if (hctx->ctx_map[i])
return true;
return false;
}
/*
* 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 (!test_bit(ctx->index_hw, hctx->ctx_map))
set_bit(ctx->index_hw, hctx->ctx_map);
}
static struct request *__blk_mq_alloc_request(struct blk_mq_hw_ctx *hctx,
gfp_t gfp, bool reserved)
{
struct request *rq;
unsigned int tag;
tag = blk_mq_get_tag(hctx->tags, gfp, reserved);
if (tag != BLK_MQ_TAG_FAIL) {
rq = hctx->rqs[tag];
rq->tag = tag;
return rq;
}
return NULL;
}
static int blk_mq_queue_enter(struct request_queue *q)
{
int ret;
__percpu_counter_add(&q->mq_usage_counter, 1, 1000000);
smp_wmb();
/* we have problems to freeze the queue if it's initializing */
if (!blk_queue_bypass(q) || !blk_queue_init_done(q))
return 0;
__percpu_counter_add(&q->mq_usage_counter, -1, 1000000);
spin_lock_irq(q->queue_lock);
ret = wait_event_interruptible_lock_irq(q->mq_freeze_wq,
!blk_queue_bypass(q) || blk_queue_dying(q),
*q->queue_lock);
/* inc usage with lock hold to avoid freeze_queue runs here */
if (!ret && !blk_queue_dying(q))
__percpu_counter_add(&q->mq_usage_counter, 1, 1000000);
else if (blk_queue_dying(q))
ret = -ENODEV;
spin_unlock_irq(q->queue_lock);
return ret;
}
static void blk_mq_queue_exit(struct request_queue *q)
{
__percpu_counter_add(&q->mq_usage_counter, -1, 1000000);
}
static void __blk_mq_drain_queue(struct request_queue *q)
{
while (true) {
s64 count;
spin_lock_irq(q->queue_lock);
count = percpu_counter_sum(&q->mq_usage_counter);
spin_unlock_irq(q->queue_lock);
if (count == 0)
break;
blk_mq_run_queues(q, false);
msleep(10);
}
}
/*
* Guarantee no request is in use, so we can change any data structure of
* the queue afterward.
*/
static void blk_mq_freeze_queue(struct request_queue *q)
{
bool drain;
spin_lock_irq(q->queue_lock);
drain = !q->bypass_depth++;
queue_flag_set(QUEUE_FLAG_BYPASS, q);
spin_unlock_irq(q->queue_lock);
if (drain)
__blk_mq_drain_queue(q);
}
void blk_mq_drain_queue(struct request_queue *q)
{
__blk_mq_drain_queue(q);
}
static void blk_mq_unfreeze_queue(struct request_queue *q)
{
bool wake = false;
spin_lock_irq(q->queue_lock);
if (!--q->bypass_depth) {
queue_flag_clear(QUEUE_FLAG_BYPASS, q);
wake = true;
}
WARN_ON_ONCE(q->bypass_depth < 0);
spin_unlock_irq(q->queue_lock);
if (wake)
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, unsigned int rw_flags)
{
if (blk_queue_io_stat(q))
rw_flags |= REQ_IO_STAT;
rq->mq_ctx = ctx;
rq->cmd_flags = rw_flags;
rq->start_time = jiffies;
set_start_time_ns(rq);
ctx->rq_dispatched[rw_is_sync(rw_flags)]++;
}
static struct request *blk_mq_alloc_request_pinned(struct request_queue *q,
int rw, gfp_t gfp,
bool reserved)
{
struct request *rq;
do {
struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
struct blk_mq_hw_ctx *hctx = q->mq_ops->map_queue(q, ctx->cpu);
rq = __blk_mq_alloc_request(hctx, gfp & ~__GFP_WAIT, reserved);
if (rq) {
blk_mq_rq_ctx_init(q, ctx, rq, rw);
break;
}
blk_mq_put_ctx(ctx);
if (!(gfp & __GFP_WAIT))
break;
__blk_mq_run_hw_queue(hctx);
blk_mq_wait_for_tags(hctx->tags);
} while (1);
return rq;
}
struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp)
{
struct request *rq;
if (blk_mq_queue_enter(q))
return NULL;
rq = blk_mq_alloc_request_pinned(q, rw, gfp, false);
if (rq)
blk_mq_put_ctx(rq->mq_ctx);
return rq;
}
struct request *blk_mq_alloc_reserved_request(struct request_queue *q, int rw,
gfp_t gfp)
{
struct request *rq;
if (blk_mq_queue_enter(q))
return NULL;
rq = blk_mq_alloc_request_pinned(q, rw, gfp, true);
if (rq)
blk_mq_put_ctx(rq->mq_ctx);
return rq;
}
EXPORT_SYMBOL(blk_mq_alloc_reserved_request);
/*
* Re-init and set pdu, if we have it
*/
void blk_mq_rq_init(struct blk_mq_hw_ctx *hctx, struct request *rq)
{
blk_rq_init(hctx->queue, rq);
if (hctx->cmd_size)
rq->special = blk_mq_rq_to_pdu(rq);
}
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;
blk_mq_rq_init(hctx, rq);
blk_mq_put_tag(hctx->tags, tag);
blk_mq_queue_exit(q);
}
void blk_mq_free_request(struct request *rq)
{
struct blk_mq_ctx *ctx = rq->mq_ctx;
struct blk_mq_hw_ctx *hctx;
struct request_queue *q = rq->q;
ctx->rq_completed[rq_is_sync(rq)]++;
hctx = q->mq_ops->map_queue(q, ctx->cpu);
__blk_mq_free_request(hctx, ctx, rq);
}
bool blk_mq_end_io_partial(struct request *rq, int error, unsigned int nr_bytes)
{
if (blk_update_request(rq, error, blk_rq_bytes(rq)))
return true;
blk_account_io_done(rq);
if (rq->end_io)
rq->end_io(rq, error);
else
blk_mq_free_request(rq);
return false;
}
EXPORT_SYMBOL(blk_mq_end_io_partial);
static void __blk_mq_complete_request_remote(void *data)
{
struct request *rq = data;
rq->q->softirq_done_fn(rq);
}
void __blk_mq_complete_request(struct request *rq)
{
struct blk_mq_ctx *ctx = rq->mq_ctx;
int cpu;
if (!ctx->ipi_redirect) {
rq->q->softirq_done_fn(rq);
return;
}
cpu = get_cpu();
if (cpu != ctx->cpu && 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();
}
/**
* 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)
{
if (unlikely(blk_should_fake_timeout(rq->q)))
return;
if (!blk_mark_rq_complete(rq))
__blk_mq_complete_request(rq);
}
EXPORT_SYMBOL(blk_mq_complete_request);
static void blk_mq_start_request(struct request *rq, bool last)
{
struct request_queue *q = rq->q;
trace_block_rq_issue(q, rq);
/*
* Just mark start time and set the started bit. Due to memory
* ordering, we know we'll see the correct deadline as long as
* REQ_ATOMIC_STARTED is seen.
*/
rq->deadline = jiffies + q->rq_timeout;
set_bit(REQ_ATOM_STARTED, &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++;
}
/*
* Flag the last request in the series so that drivers know when IO
* should be kicked off, if they don't do it on a per-request basis.
*
* Note: the flag isn't the only condition drivers should do kick off.
* If drive is busy, the last request might not have the bit set.
*/
if (last)
rq->cmd_flags |= REQ_END;
}
static void blk_mq_requeue_request(struct request *rq)
{
struct request_queue *q = rq->q;
trace_block_rq_requeue(q, rq);
clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
rq->cmd_flags &= ~REQ_END;
if (q->dma_drain_size && blk_rq_bytes(rq))
rq->nr_phys_segments--;
}
struct blk_mq_timeout_data {
struct blk_mq_hw_ctx *hctx;
unsigned long *next;
unsigned int *next_set;
};
static void blk_mq_timeout_check(void *__data, unsigned long *free_tags)
{
struct blk_mq_timeout_data *data = __data;
struct blk_mq_hw_ctx *hctx = data->hctx;
unsigned int tag;
/* It may not be in flight yet (this is where
* the REQ_ATOMIC_STARTED flag comes in). The requests are
* statically allocated, so we know it's always safe to access the
* memory associated with a bit offset into ->rqs[].
*/
tag = 0;
do {
struct request *rq;
tag = find_next_zero_bit(free_tags, hctx->queue_depth, tag);
if (tag >= hctx->queue_depth)
break;
rq = hctx->rqs[tag++];
if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
continue;
blk_rq_check_expired(rq, data->next, data->next_set);
} while (1);
}
static void blk_mq_hw_ctx_check_timeout(struct blk_mq_hw_ctx *hctx,
unsigned long *next,
unsigned int *next_set)
{
struct blk_mq_timeout_data data = {
.hctx = hctx,
.next = next,
.next_set = next_set,
};
/*
* Ask the tagging code to iterate busy requests, so we can
* check them for timeout.
*/
blk_mq_tag_busy_iter(hctx->tags, blk_mq_timeout_check, &data);
}
static void blk_mq_rq_timer(unsigned long data)
{
struct request_queue *q = (struct request_queue *) data;
struct blk_mq_hw_ctx *hctx;
unsigned long next = 0;
int i, next_set = 0;
queue_for_each_hw_ctx(q, hctx, i)
blk_mq_hw_ctx_check_timeout(hctx, &next, &next_set);
if (next_set)
mod_timer(&q->timeout, round_jiffies_up(next));
}
/*
* 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;
}
void blk_mq_add_timer(struct request *rq)
{
__blk_add_timer(rq, NULL);
}
/*
* 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 blk_mq_ctx *ctx;
struct request *rq;
LIST_HEAD(rq_list);
int bit, queued;
if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
return;
hctx->run++;
/*
* Touch any software queue that has pending entries.
*/
for_each_set_bit(bit, hctx->ctx_map, hctx->nr_ctx) {
clear_bit(bit, hctx->ctx_map);
ctx = hctx->ctxs[bit];
BUG_ON(bit != ctx->index_hw);
spin_lock(&ctx->lock);
list_splice_tail_init(&ctx->rq_list, &rq_list);
spin_unlock(&ctx->lock);
}
/*
* 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);
}
/*
* Delete and return all entries from our dispatch list
*/
queued = 0;
/*
* Now process all the entries, sending them to the driver.
*/
while (!list_empty(&rq_list)) {
int ret;
rq = list_first_entry(&rq_list, struct request, queuelist);
list_del_init(&rq->queuelist);
blk_mq_start_request(rq, list_empty(&rq_list));
ret = q->mq_ops->queue_rq(hctx, rq);
switch (ret) {
case BLK_MQ_RQ_QUEUE_OK:
queued++;
continue;
case BLK_MQ_RQ_QUEUE_BUSY:
/*
* FIXME: we should have a mechanism to stop the queue
* like blk_stop_queue, otherwise we will waste cpu
* time
*/
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_io(rq, rq->errors);
break;
}
if (ret == BLK_MQ_RQ_QUEUE_BUSY)
break;
}
if (!queued)
hctx->dispatched[0]++;
else if (queued < (1 << (BLK_MQ_MAX_DISPATCH_ORDER - 1)))
hctx->dispatched[ilog2(queued) + 1]++;
/*
* 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);
}
}
void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
{
if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
return;
if (!async)
__blk_mq_run_hw_queue(hctx);
else {
struct request_queue *q = hctx->queue;
kblockd_schedule_delayed_work(q, &hctx->delayed_work, 0);
}
}
void blk_mq_run_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_queues);
void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
{
cancel_delayed_work(&hctx->delayed_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);
}
EXPORT_SYMBOL(blk_mq_start_hw_queue);
void blk_mq_start_stopped_hw_queues(struct request_queue *q)
{
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, true);
}
}
EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
static void blk_mq_work_fn(struct work_struct *work)
{
struct blk_mq_hw_ctx *hctx;
hctx = container_of(work, struct blk_mq_hw_ctx, delayed_work.work);
__blk_mq_run_hw_queue(hctx);
}
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;
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);
blk_mq_hctx_mark_pending(hctx, ctx);
/*
* We do this early, to ensure we are on the right CPU.
*/
blk_mq_add_timer(rq);
}
void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
bool async)
{
struct request_queue *q = rq->q;
struct blk_mq_hw_ctx *hctx;
struct blk_mq_ctx *ctx = rq->mq_ctx, *current_ctx;
current_ctx = blk_mq_get_ctx(q);
if (!cpu_online(ctx->cpu))
rq->mq_ctx = ctx = current_ctx;
hctx = q->mq_ops->map_queue(q, ctx->cpu);
if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA) &&
!(rq->cmd_flags & (REQ_FLUSH_SEQ))) {
blk_insert_flush(rq);
} else {
spin_lock(&ctx->lock);
__blk_mq_insert_request(hctx, rq, at_head);
spin_unlock(&ctx->lock);
}
blk_mq_put_ctx(current_ctx);
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;
struct blk_mq_ctx *current_ctx;
trace_block_unplug(q, depth, !from_schedule);
current_ctx = blk_mq_get_ctx(q);
if (!cpu_online(ctx->cpu))
ctx = current_ctx;
hctx = q->mq_ops->map_queue(q, ctx->cpu);
/*
* 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);
list_del_init(&rq->queuelist);
rq->mq_ctx = ctx;
__blk_mq_insert_request(hctx, rq, false);
}
spin_unlock(&ctx->lock);
blk_mq_put_ctx(current_ctx);
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 void blk_mq_make_request(struct request_queue *q, struct bio *bio)
{
struct blk_mq_hw_ctx *hctx;
struct blk_mq_ctx *ctx;
const int is_sync = rw_is_sync(bio->bi_rw);
const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
int rw = bio_data_dir(bio);
struct request *rq;
unsigned int use_plug, request_count = 0;
/*
* If we have multiple hardware queues, just go directly to
* one of those for sync IO.
*/
use_plug = !is_flush_fua && ((q->nr_hw_queues == 1) || !is_sync);
blk_queue_bounce(q, &bio);
if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
bio_endio(bio, -EIO);
return;
}
if (use_plug && blk_attempt_plug_merge(q, bio, &request_count))
return;
if (blk_mq_queue_enter(q)) {
bio_endio(bio, -EIO);
return;
}
ctx = blk_mq_get_ctx(q);
hctx = q->mq_ops->map_queue(q, ctx->cpu);
if (is_sync)
rw |= REQ_SYNC;
trace_block_getrq(q, bio, rw);
rq = __blk_mq_alloc_request(hctx, GFP_ATOMIC, false);
if (likely(rq))
blk_mq_rq_ctx_init(q, ctx, rq, rw);
else {
blk_mq_put_ctx(ctx);
trace_block_sleeprq(q, bio, rw);
rq = blk_mq_alloc_request_pinned(q, rw, __GFP_WAIT|GFP_ATOMIC,
false);
ctx = rq->mq_ctx;
hctx = q->mq_ops->map_queue(q, ctx->cpu);
}
hctx->queued++;
if (unlikely(is_flush_fua)) {
blk_mq_bio_to_request(rq, bio);
blk_mq_put_ctx(ctx);
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.
*/
if (use_plug) {
struct blk_plug *plug = current->plug;
if (plug) {
blk_mq_bio_to_request(rq, bio);
if (list_empty(&plug->mq_list))
trace_block_plug(q);
else 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);
blk_mq_put_ctx(ctx);
return;
}
}
spin_lock(&ctx->lock);
if ((hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
blk_mq_attempt_merge(q, ctx, bio))
__blk_mq_free_request(hctx, ctx, rq);
else {
blk_mq_bio_to_request(rq, bio);
__blk_mq_insert_request(hctx, rq, false);
}
spin_unlock(&ctx->lock);
blk_mq_put_ctx(ctx);
/*
* 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(hctx, !is_sync || is_flush_fua);
}
/*
* Default mapping to a software queue, since we use one per CPU.
*/
struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q, const int cpu)
{
return q->queue_hw_ctx[q->mq_map[cpu]];
}
EXPORT_SYMBOL(blk_mq_map_queue);
struct blk_mq_hw_ctx *blk_mq_alloc_single_hw_queue(struct blk_mq_reg *reg,
unsigned int hctx_index)
{
return kmalloc_node(sizeof(struct blk_mq_hw_ctx),
GFP_KERNEL | __GFP_ZERO, reg->numa_node);
}
EXPORT_SYMBOL(blk_mq_alloc_single_hw_queue);
void blk_mq_free_single_hw_queue(struct blk_mq_hw_ctx *hctx,
unsigned int hctx_index)
{
kfree(hctx);
}
EXPORT_SYMBOL(blk_mq_free_single_hw_queue);
static void blk_mq_hctx_notify(void *data, unsigned long action,
unsigned int cpu)
{
struct blk_mq_hw_ctx *hctx = data;
struct request_queue *q = hctx->queue;
struct blk_mq_ctx *ctx;
LIST_HEAD(tmp);
if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
return;
/*
* Move ctx entries to new CPU, if this one is going away.
*/
ctx = __blk_mq_get_ctx(q, cpu);
spin_lock(&ctx->lock);
if (!list_empty(&ctx->rq_list)) {
list_splice_init(&ctx->rq_list, &tmp);
clear_bit(ctx->index_hw, hctx->ctx_map);
}
spin_unlock(&ctx->lock);
if (list_empty(&tmp))
return;
ctx = blk_mq_get_ctx(q);
spin_lock(&ctx->lock);
while (!list_empty(&tmp)) {
struct request *rq;
rq = list_first_entry(&tmp, struct request, queuelist);
rq->mq_ctx = ctx;
list_move_tail(&rq->queuelist, &ctx->rq_list);
}
hctx = q->mq_ops->map_queue(q, ctx->cpu);
blk_mq_hctx_mark_pending(hctx, ctx);
spin_unlock(&ctx->lock);
blk_mq_put_ctx(ctx);
blk_mq_run_hw_queue(hctx, true);
}
static int blk_mq_init_hw_commands(struct blk_mq_hw_ctx *hctx,
int (*init)(void *, struct blk_mq_hw_ctx *,
struct request *, unsigned int),
void *data)
{
unsigned int i;
int ret = 0;
for (i = 0; i < hctx->queue_depth; i++) {
struct request *rq = hctx->rqs[i];
ret = init(data, hctx, rq, i);
if (ret)
break;
}
return ret;
}
int blk_mq_init_commands(struct request_queue *q,
int (*init)(void *, struct blk_mq_hw_ctx *,
struct request *, unsigned int),
void *data)
{
struct blk_mq_hw_ctx *hctx;
unsigned int i;
int ret = 0;
queue_for_each_hw_ctx(q, hctx, i) {
ret = blk_mq_init_hw_commands(hctx, init, data);
if (ret)
break;
}
return ret;
}
EXPORT_SYMBOL(blk_mq_init_commands);
static void blk_mq_free_hw_commands(struct blk_mq_hw_ctx *hctx,
void (*free)(void *, struct blk_mq_hw_ctx *,
struct request *, unsigned int),
void *data)
{
unsigned int i;
for (i = 0; i < hctx->queue_depth; i++) {
struct request *rq = hctx->rqs[i];
free(data, hctx, rq, i);
}
}
void blk_mq_free_commands(struct request_queue *q,
void (*free)(void *, struct blk_mq_hw_ctx *,
struct request *, unsigned int),
void *data)
{
struct blk_mq_hw_ctx *hctx;
unsigned int i;
queue_for_each_hw_ctx(q, hctx, i)
blk_mq_free_hw_commands(hctx, free, data);
}
EXPORT_SYMBOL(blk_mq_free_commands);
static void blk_mq_free_rq_map(struct blk_mq_hw_ctx *hctx)
{
struct page *page;
while (!list_empty(&hctx->page_list)) {
page = list_first_entry(&hctx->page_list, struct page, lru);
list_del_init(&page->lru);
__free_pages(page, page->private);
}
kfree(hctx->rqs);
if (hctx->tags)
blk_mq_free_tags(hctx->tags);
}
static size_t order_to_size(unsigned int order)
{
size_t ret = PAGE_SIZE;
while (order--)
ret *= 2;
return ret;
}
static int blk_mq_init_rq_map(struct blk_mq_hw_ctx *hctx,
unsigned int reserved_tags, int node)
{
unsigned int i, j, entries_per_page, max_order = 4;
size_t rq_size, left;
INIT_LIST_HEAD(&hctx->page_list);
hctx->rqs = kmalloc_node(hctx->queue_depth * sizeof(struct request *),
GFP_KERNEL, node);
if (!hctx->rqs)
return -ENOMEM;
/*
* rq_size is the size of the request plus driver payload, rounded
* to the cacheline size
*/
rq_size = round_up(sizeof(struct request) + hctx->cmd_size,
cache_line_size());
left = rq_size * hctx->queue_depth;
for (i = 0; i < hctx->queue_depth;) {
int this_order = max_order;
struct page *page;
int to_do;
void *p;
while (left < order_to_size(this_order - 1) && this_order)
this_order--;
do {
page = alloc_pages_node(node, GFP_KERNEL, this_order);
if (page)
break;
if (!this_order--)
break;
if (order_to_size(this_order) < rq_size)
break;
} while (1);
if (!page)
break;
page->private = this_order;
list_add_tail(&page->lru, &hctx->page_list);
p = page_address(page);
entries_per_page = order_to_size(this_order) / rq_size;
to_do = min(entries_per_page, hctx->queue_depth - i);
left -= to_do * rq_size;
for (j = 0; j < to_do; j++) {
hctx->rqs[i] = p;
blk_mq_rq_init(hctx, hctx->rqs[i]);
p += rq_size;
i++;
}
}
if (i < (reserved_tags + BLK_MQ_TAG_MIN))
goto err_rq_map;
else if (i != hctx->queue_depth) {
hctx->queue_depth = i;
pr_warn("%s: queue depth set to %u because of low memory\n",
__func__, i);
}
hctx->tags = blk_mq_init_tags(hctx->queue_depth, reserved_tags, node);
if (!hctx->tags) {
err_rq_map:
blk_mq_free_rq_map(hctx);
return -ENOMEM;
}
return 0;
}
static int blk_mq_init_hw_queues(struct request_queue *q,
struct blk_mq_reg *reg, void *driver_data)
{
struct blk_mq_hw_ctx *hctx;
unsigned int i, j;
/*
* Initialize hardware queues
*/
queue_for_each_hw_ctx(q, hctx, i) {
unsigned int num_maps;
int node;
node = hctx->numa_node;
if (node == NUMA_NO_NODE)
node = hctx->numa_node = reg->numa_node;
INIT_DELAYED_WORK(&hctx->delayed_work, blk_mq_work_fn);
spin_lock_init(&hctx->lock);
INIT_LIST_HEAD(&hctx->dispatch);
hctx->queue = q;
hctx->queue_num = i;
hctx->flags = reg->flags;
hctx->queue_depth = reg->queue_depth;
hctx->cmd_size = reg->cmd_size;
blk_mq_init_cpu_notifier(&hctx->cpu_notifier,
blk_mq_hctx_notify, hctx);
blk_mq_register_cpu_notifier(&hctx->cpu_notifier);
if (blk_mq_init_rq_map(hctx, reg->reserved_tags, node))
break;
/*
* Allocate space for all possible cpus to avoid allocation in
* runtime
*/
hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
GFP_KERNEL, node);
if (!hctx->ctxs)
break;
num_maps = ALIGN(nr_cpu_ids, BITS_PER_LONG) / BITS_PER_LONG;
hctx->ctx_map = kzalloc_node(num_maps * sizeof(unsigned long),
GFP_KERNEL, node);
if (!hctx->ctx_map)
break;
hctx->nr_ctx_map = num_maps;
hctx->nr_ctx = 0;
if (reg->ops->init_hctx &&
reg->ops->init_hctx(hctx, driver_data, i))
break;
}
if (i == q->nr_hw_queues)
return 0;
/*
* Init failed
*/
queue_for_each_hw_ctx(q, hctx, j) {
if (i == j)
break;
if (reg->ops->exit_hctx)
reg->ops->exit_hctx(hctx, j);
blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
blk_mq_free_rq_map(hctx);
kfree(hctx->ctxs);
}
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 */
hctx = q->mq_ops->map_queue(q, i);
hctx->nr_ctx++;
if (!cpu_online(i))
continue;
/*
* 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 = cpu_to_node(i);
}
}
static void blk_mq_map_swqueue(struct request_queue *q)
{
unsigned int i;
struct blk_mq_hw_ctx *hctx;
struct blk_mq_ctx *ctx;
queue_for_each_hw_ctx(q, hctx, i) {
hctx->nr_ctx = 0;
}
/*
* Map software to hardware queues
*/
queue_for_each_ctx(q, ctx, i) {
/* If the cpu isn't online, the cpu is mapped to first hctx */
hctx = q->mq_ops->map_queue(q, i);
ctx->index_hw = hctx->nr_ctx;
hctx->ctxs[hctx->nr_ctx++] = ctx;
}
}
struct request_queue *blk_mq_init_queue(struct blk_mq_reg *reg,
void *driver_data)
{
struct blk_mq_hw_ctx **hctxs;
struct blk_mq_ctx *ctx;
struct request_queue *q;
int i;
if (!reg->nr_hw_queues ||
!reg->ops->queue_rq || !reg->ops->map_queue ||
!reg->ops->alloc_hctx || !reg->ops->free_hctx)
return ERR_PTR(-EINVAL);
if (!reg->queue_depth)
reg->queue_depth = BLK_MQ_MAX_DEPTH;
else if (reg->queue_depth > BLK_MQ_MAX_DEPTH) {
pr_err("blk-mq: queuedepth too large (%u)\n", reg->queue_depth);
reg->queue_depth = BLK_MQ_MAX_DEPTH;
}
if (reg->queue_depth < (reg->reserved_tags + BLK_MQ_TAG_MIN))
return ERR_PTR(-EINVAL);
ctx = alloc_percpu(struct blk_mq_ctx);
if (!ctx)
return ERR_PTR(-ENOMEM);
hctxs = kmalloc_node(reg->nr_hw_queues * sizeof(*hctxs), GFP_KERNEL,
reg->numa_node);
if (!hctxs)
goto err_percpu;
for (i = 0; i < reg->nr_hw_queues; i++) {
hctxs[i] = reg->ops->alloc_hctx(reg, i);
if (!hctxs[i])
goto err_hctxs;
hctxs[i]->numa_node = NUMA_NO_NODE;
hctxs[i]->queue_num = i;
}
q = blk_alloc_queue_node(GFP_KERNEL, reg->numa_node);
if (!q)
goto err_hctxs;
q->mq_map = blk_mq_make_queue_map(reg);
if (!q->mq_map)
goto err_map;
setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q);
blk_queue_rq_timeout(q, 30000);
q->nr_queues = nr_cpu_ids;
q->nr_hw_queues = reg->nr_hw_queues;
q->queue_ctx = ctx;
q->queue_hw_ctx = hctxs;
q->mq_ops = reg->ops;
q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
q->sg_reserved_size = INT_MAX;
blk_queue_make_request(q, blk_mq_make_request);
blk_queue_rq_timed_out(q, reg->ops->timeout);
if (reg->timeout)
blk_queue_rq_timeout(q, reg->timeout);
if (reg->ops->complete)
blk_queue_softirq_done(q, reg->ops->complete);
blk_mq_init_flush(q);
blk_mq_init_cpu_queues(q, reg->nr_hw_queues);
q->flush_rq = kzalloc(round_up(sizeof(struct request) + reg->cmd_size,
cache_line_size()), GFP_KERNEL);
if (!q->flush_rq)
goto err_hw;
if (blk_mq_init_hw_queues(q, reg, driver_data))
goto err_flush_rq;
blk_mq_map_swqueue(q);
mutex_lock(&all_q_mutex);
list_add_tail(&q->all_q_node, &all_q_list);
mutex_unlock(&all_q_mutex);
return q;
err_flush_rq:
kfree(q->flush_rq);
err_hw:
kfree(q->mq_map);
err_map:
blk_cleanup_queue(q);
err_hctxs:
for (i = 0; i < reg->nr_hw_queues; i++) {
if (!hctxs[i])
break;
reg->ops->free_hctx(hctxs[i], i);
}
kfree(hctxs);
err_percpu:
free_percpu(ctx);
return ERR_PTR(-ENOMEM);
}
EXPORT_SYMBOL(blk_mq_init_queue);
void blk_mq_free_queue(struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
int i;
queue_for_each_hw_ctx(q, hctx, i) {
kfree(hctx->ctx_map);
kfree(hctx->ctxs);
blk_mq_free_rq_map(hctx);
blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
if (q->mq_ops->exit_hctx)
q->mq_ops->exit_hctx(hctx, i);
q->mq_ops->free_hctx(hctx, i);
}
free_percpu(q->queue_ctx);
kfree(q->queue_hw_ctx);
kfree(q->mq_map);
q->queue_ctx = NULL;
q->queue_hw_ctx = NULL;
q->mq_map = NULL;
mutex_lock(&all_q_mutex);
list_del_init(&q->all_q_node);
mutex_unlock(&all_q_mutex);
}
/* Basically redo blk_mq_init_queue with queue frozen */
static void blk_mq_queue_reinit(struct request_queue *q)
{
blk_mq_freeze_queue(q);
blk_mq_update_queue_map(q->mq_map, q->nr_hw_queues);
/*
* 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);
blk_mq_unfreeze_queue(q);
}
static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
unsigned long action, void *hcpu)
{
struct request_queue *q;
/*
* Before new mapping is established, hotadded cpu might already start
* handling requests. This doesn't break anything as we map offline
* CPUs to first hardware queue. We will re-init queue below to get
* optimal settings.
*/
if (action != CPU_DEAD && action != CPU_DEAD_FROZEN &&
action != CPU_ONLINE && action != CPU_ONLINE_FROZEN)
return NOTIFY_OK;
mutex_lock(&all_q_mutex);
list_for_each_entry(q, &all_q_list, all_q_node)
blk_mq_queue_reinit(q);
mutex_unlock(&all_q_mutex);
return NOTIFY_OK;
}
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)
{
blk_mq_cpu_init();
/* Must be called after percpu_counter_hotcpu_callback() */
hotcpu_notifier(blk_mq_queue_reinit_notify, -10);
return 0;
}
subsys_initcall(blk_mq_init);