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blk-core.c 95.21 KiB
/*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright (C) 1994, Karl Keyte: Added support for disk statistics
* Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
* Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de>
* kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au>
* - July2000
* bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
*/
/*
* This handles all read/write requests to block devices
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/backing-dev.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/blk-mq.h>
#include <linux/highmem.h>
#include <linux/mm.h>
#include <linux/kernel_stat.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/completion.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include <linux/writeback.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/fault-inject.h>
#include <linux/list_sort.h>
#include <linux/delay.h>
#include <linux/ratelimit.h>
#include <linux/pm_runtime.h>
#include <linux/blk-cgroup.h>
#include <linux/debugfs.h>
#define CREATE_TRACE_POINTS
#include <trace/events/block.h>
#include "blk.h"
#include "blk-mq.h"
#include "blk-mq-sched.h"
#include "blk-wbt.h"
#ifdef CONFIG_DEBUG_FS
struct dentry *blk_debugfs_root;
#endif
EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
EXPORT_TRACEPOINT_SYMBOL_GPL(block_split);
EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
DEFINE_IDA(blk_queue_ida);
/*
* For the allocated request tables
*/
struct kmem_cache *request_cachep;
/*
* For queue allocation
*/
struct kmem_cache *blk_requestq_cachep;
/*
* Controlling structure to kblockd
*/static struct workqueue_struct *kblockd_workqueue;
static void blk_clear_congested(struct request_list *rl, int sync)
{
#ifdef CONFIG_CGROUP_WRITEBACK
clear_wb_congested(rl->blkg->wb_congested, sync);
#else
/*
* If !CGROUP_WRITEBACK, all blkg's map to bdi->wb and we shouldn't
* flip its congestion state for events on other blkcgs.
*/
if (rl == &rl->q->root_rl)
clear_wb_congested(rl->q->backing_dev_info->wb.congested, sync);
#endif
}
static void blk_set_congested(struct request_list *rl, int sync)
{
#ifdef CONFIG_CGROUP_WRITEBACK
set_wb_congested(rl->blkg->wb_congested, sync);
#else
/* see blk_clear_congested() */
if (rl == &rl->q->root_rl)
set_wb_congested(rl->q->backing_dev_info->wb.congested, sync);
#endif
}
void blk_queue_congestion_threshold(struct request_queue *q)
{
int nr;
nr = q->nr_requests - (q->nr_requests / 8) + 1;
if (nr > q->nr_requests)
nr = q->nr_requests;
q->nr_congestion_on = nr;
nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
if (nr < 1)
nr = 1;
q->nr_congestion_off = nr;
}
void blk_rq_init(struct request_queue *q, struct request *rq)
{
memset(rq, 0, sizeof(*rq));
INIT_LIST_HEAD(&rq->queuelist);
INIT_LIST_HEAD(&rq->timeout_list);
rq->cpu = -1;
rq->q = q;
rq->__sector = (sector_t) -1;
INIT_HLIST_NODE(&rq->hash);
RB_CLEAR_NODE(&rq->rb_node);
rq->tag = -1;
rq->internal_tag = -1;
rq->start_time = jiffies;
set_start_time_ns(rq);
rq->part = NULL;
}
EXPORT_SYMBOL(blk_rq_init);
static const struct {
int errno;
const char *name;
} blk_errors[] = {
[BLK_STS_OK] = { 0, "" },
[BLK_STS_NOTSUPP] = { -EOPNOTSUPP, "operation not supported" },
[BLK_STS_TIMEOUT] = { -ETIMEDOUT, "timeout" },
[BLK_STS_NOSPC] = { -ENOSPC, "critical space allocation" },
[BLK_STS_TRANSPORT] = { -ENOLINK, "recoverable transport" }, [BLK_STS_TARGET] = { -EREMOTEIO, "critical target" },
[BLK_STS_NEXUS] = { -EBADE, "critical nexus" },
[BLK_STS_MEDIUM] = { -ENODATA, "critical medium" },
[BLK_STS_PROTECTION] = { -EILSEQ, "protection" },
[BLK_STS_RESOURCE] = { -ENOMEM, "kernel resource" },
[BLK_STS_AGAIN] = { -EAGAIN, "nonblocking retry" },
/* device mapper special case, should not leak out: */
[BLK_STS_DM_REQUEUE] = { -EREMCHG, "dm internal retry" },
/* everything else not covered above: */
[BLK_STS_IOERR] = { -EIO, "I/O" },
};
blk_status_t errno_to_blk_status(int errno)
{
int i;
for (i = 0; i < ARRAY_SIZE(blk_errors); i++) {
if (blk_errors[i].errno == errno)
return (__force blk_status_t)i;
}
return BLK_STS_IOERR;
}
EXPORT_SYMBOL_GPL(errno_to_blk_status);
int blk_status_to_errno(blk_status_t status)
{
int idx = (__force int)status;
if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
return -EIO;
return blk_errors[idx].errno;
}
EXPORT_SYMBOL_GPL(blk_status_to_errno);
static void print_req_error(struct request *req, blk_status_t status)
{
int idx = (__force int)status;
if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
return;
printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu\n",
__func__, blk_errors[idx].name, req->rq_disk ?
req->rq_disk->disk_name : "?",
(unsigned long long)blk_rq_pos(req));
}
static void req_bio_endio(struct request *rq, struct bio *bio,
unsigned int nbytes, blk_status_t error)
{
if (error)
bio->bi_status = error;
if (unlikely(rq->rq_flags & RQF_QUIET))
bio_set_flag(bio, BIO_QUIET);
bio_advance(bio, nbytes);
/* don't actually finish bio if it's part of flush sequence */
if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ))
bio_endio(bio);
}
void blk_dump_rq_flags(struct request *rq, char *msg)
{
printk(KERN_INFO "%s: dev %s: flags=%llx\n", msg,
rq->rq_disk ? rq->rq_disk->disk_name : "?", (unsigned long long) rq->cmd_flags);
printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n",
(unsigned long long)blk_rq_pos(rq),
blk_rq_sectors(rq), blk_rq_cur_sectors(rq));
printk(KERN_INFO " bio %p, biotail %p, len %u\n",
rq->bio, rq->biotail, blk_rq_bytes(rq));
}
EXPORT_SYMBOL(blk_dump_rq_flags);
static void blk_delay_work(struct work_struct *work)
{
struct request_queue *q;
q = container_of(work, struct request_queue, delay_work.work);
spin_lock_irq(q->queue_lock);
__blk_run_queue(q);
spin_unlock_irq(q->queue_lock);
}
/**
* blk_delay_queue - restart queueing after defined interval
* @q: The &struct request_queue in question
* @msecs: Delay in msecs
*
* Description:
* Sometimes queueing needs to be postponed for a little while, to allow
* resources to come back. This function will make sure that queueing is
* restarted around the specified time.
*/
void blk_delay_queue(struct request_queue *q, unsigned long msecs)
{
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);
if (likely(!blk_queue_dead(q)))
queue_delayed_work(kblockd_workqueue, &q->delay_work,
msecs_to_jiffies(msecs));
}
EXPORT_SYMBOL(blk_delay_queue);
/**
* blk_start_queue_async - asynchronously restart a previously stopped queue
* @q: The &struct request_queue in question
*
* Description:
* blk_start_queue_async() will clear the stop flag on the queue, and
* ensure that the request_fn for the queue is run from an async
* context.
**/
void blk_start_queue_async(struct request_queue *q)
{
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);
queue_flag_clear(QUEUE_FLAG_STOPPED, q);
blk_run_queue_async(q);
}
EXPORT_SYMBOL(blk_start_queue_async);
/**
* blk_start_queue - restart a previously stopped queue
* @q: The &struct request_queue in question
*
* Description:
* blk_start_queue() will clear the stop flag on the queue, and call
* the request_fn for the queue if it was in a stopped state when
* entered. Also see blk_stop_queue().
**/
void blk_start_queue(struct request_queue *q){
lockdep_assert_held(q->queue_lock);
WARN_ON(!irqs_disabled());
WARN_ON_ONCE(q->mq_ops);
queue_flag_clear(QUEUE_FLAG_STOPPED, q);
__blk_run_queue(q);
}
EXPORT_SYMBOL(blk_start_queue);
/**
* blk_stop_queue - stop a queue
* @q: The &struct request_queue in question
*
* Description:
* The Linux block layer assumes that a block driver will consume all
* entries on the request queue when the request_fn strategy is called.
* Often this will not happen, because of hardware limitations (queue
* depth settings). If a device driver gets a 'queue full' response,
* or if it simply chooses not to queue more I/O at one point, it can
* call this function to prevent the request_fn from being called until
* the driver has signalled it's ready to go again. This happens by calling
* blk_start_queue() to restart queue operations.
**/
void blk_stop_queue(struct request_queue *q)
{
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);
cancel_delayed_work(&q->delay_work);
queue_flag_set(QUEUE_FLAG_STOPPED, q);
}
EXPORT_SYMBOL(blk_stop_queue);
/**
* blk_sync_queue - cancel any pending callbacks on a queue
* @q: the queue
*
* Description:
* The block layer may perform asynchronous callback activity
* on a queue, such as calling the unplug function after a timeout.
* A block device may call blk_sync_queue to ensure that any
* such activity is cancelled, thus allowing it to release resources
* that the callbacks might use. The caller must already have made sure
* that its ->make_request_fn will not re-add plugging prior to calling
* this function.
*
* This function does not cancel any asynchronous activity arising
* out of elevator or throttling code. That would require elevator_exit()
* and blkcg_exit_queue() to be called with queue lock initialized.
*
*/
void blk_sync_queue(struct request_queue *q)
{
del_timer_sync(&q->timeout);
if (q->mq_ops) {
struct blk_mq_hw_ctx *hctx;
int i;
queue_for_each_hw_ctx(q, hctx, i)
cancel_delayed_work_sync(&hctx->run_work);
} else {
cancel_delayed_work_sync(&q->delay_work);
}
}
EXPORT_SYMBOL(blk_sync_queue);
/**
* __blk_run_queue_uncond - run a queue whether or not it has been stopped * @q: The queue to run
*
* Description:
* Invoke request handling on a queue if there are any pending requests.
* May be used to restart request handling after a request has completed.
* This variant runs the queue whether or not the queue has been
* stopped. Must be called with the queue lock held and interrupts
* disabled. See also @blk_run_queue.
*/
inline void __blk_run_queue_uncond(struct request_queue *q)
{
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);
if (unlikely(blk_queue_dead(q)))
return;
/*
* Some request_fn implementations, e.g. scsi_request_fn(), unlock
* the queue lock internally. As a result multiple threads may be
* running such a request function concurrently. Keep track of the
* number of active request_fn invocations such that blk_drain_queue()
* can wait until all these request_fn calls have finished.
*/
q->request_fn_active++;
q->request_fn(q);
q->request_fn_active--;
}
EXPORT_SYMBOL_GPL(__blk_run_queue_uncond);
/**
* __blk_run_queue - run a single device queue
* @q: The queue to run
*
* Description:
* See @blk_run_queue.
*/
void __blk_run_queue(struct request_queue *q)
{
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);
if (unlikely(blk_queue_stopped(q)))
return;
__blk_run_queue_uncond(q);
}
EXPORT_SYMBOL(__blk_run_queue);
/**
* blk_run_queue_async - run a single device queue in workqueue context
* @q: The queue to run
*
* Description:
* Tells kblockd to perform the equivalent of @blk_run_queue on behalf
* of us.
*
* Note:
* Since it is not allowed to run q->delay_work after blk_cleanup_queue()
* has canceled q->delay_work, callers must hold the queue lock to avoid
* race conditions between blk_cleanup_queue() and blk_run_queue_async().
*/
void blk_run_queue_async(struct request_queue *q)
{
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);
if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q)))
mod_delayed_work(kblockd_workqueue, &q->delay_work, 0);
}EXPORT_SYMBOL(blk_run_queue_async);
/**
* blk_run_queue - run a single device queue
* @q: The queue to run
*
* Description:
* Invoke request handling on this queue, if it has pending work to do.
* May be used to restart queueing when a request has completed.
*/
void blk_run_queue(struct request_queue *q)
{
unsigned long flags;
WARN_ON_ONCE(q->mq_ops);
spin_lock_irqsave(q->queue_lock, flags);
__blk_run_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
}
EXPORT_SYMBOL(blk_run_queue);
void blk_put_queue(struct request_queue *q)
{
kobject_put(&q->kobj);
}
EXPORT_SYMBOL(blk_put_queue);
/**
* __blk_drain_queue - drain requests from request_queue
* @q: queue to drain
* @drain_all: whether to drain all requests or only the ones w/ ELVPRIV
*
* Drain requests from @q. If @drain_all is set, all requests are drained.
* If not, only ELVPRIV requests are drained. The caller is responsible
* for ensuring that no new requests which need to be drained are queued.
*/
static void __blk_drain_queue(struct request_queue *q, bool drain_all)
__releases(q->queue_lock)
__acquires(q->queue_lock)
{
int i;
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);
while (true) {
bool drain = false;
/*
* The caller might be trying to drain @q before its
* elevator is initialized.
*/
if (q->elevator)
elv_drain_elevator(q);
blkcg_drain_queue(q);
/*
* This function might be called on a queue which failed
* driver init after queue creation or is not yet fully
* active yet. Some drivers (e.g. fd and loop) get unhappy
* in such cases. Kick queue iff dispatch queue has
* something on it and @q has request_fn set.
*/
if (!list_empty(&q->queue_head) && q->request_fn)
__blk_run_queue(q);
drain |= q->nr_rqs_elvpriv;
drain |= q->request_fn_active;
/*
* Unfortunately, requests are queued at and tracked from
* multiple places and there's no single counter which can
* be drained. Check all the queues and counters.
*/
if (drain_all) {
struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
drain |= !list_empty(&q->queue_head);
for (i = 0; i < 2; i++) {
drain |= q->nr_rqs[i];
drain |= q->in_flight[i];
if (fq)
drain |= !list_empty(&fq->flush_queue[i]);
}
}
if (!drain)
break;
spin_unlock_irq(q->queue_lock);
msleep(10);
spin_lock_irq(q->queue_lock);
}
/*
* With queue marked dead, any woken up waiter will fail the
* allocation path, so the wakeup chaining is lost and we're
* left with hung waiters. We need to wake up those waiters.
*/
if (q->request_fn) {
struct request_list *rl;
blk_queue_for_each_rl(rl, q)
for (i = 0; i < ARRAY_SIZE(rl->wait); i++)
wake_up_all(&rl->wait[i]);
}
}
/**
* blk_queue_bypass_start - enter queue bypass mode
* @q: queue of interest
*
* In bypass mode, only the dispatch FIFO queue of @q is used. This
* function makes @q enter bypass mode and drains all requests which were
* throttled or issued before. On return, it's guaranteed that no request
* is being throttled or has ELVPRIV set and blk_queue_bypass() %true
* inside queue or RCU read lock.
*/
void blk_queue_bypass_start(struct request_queue *q)
{
WARN_ON_ONCE(q->mq_ops);
spin_lock_irq(q->queue_lock);
q->bypass_depth++;
queue_flag_set(QUEUE_FLAG_BYPASS, q);
spin_unlock_irq(q->queue_lock);
/*
* Queues start drained. Skip actual draining till init is
* complete. This avoids lenghty delays during queue init which
* can happen many times during boot.
*/
if (blk_queue_init_done(q)) {
spin_lock_irq(q->queue_lock);
__blk_drain_queue(q, false);
spin_unlock_irq(q->queue_lock);
/* ensure blk_queue_bypass() is %true inside RCU read lock */
synchronize_rcu();
}
}
EXPORT_SYMBOL_GPL(blk_queue_bypass_start);
/**
* blk_queue_bypass_end - leave queue bypass mode
* @q: queue of interest
*
* Leave bypass mode and restore the normal queueing behavior.
*
* Note: although blk_queue_bypass_start() is only called for blk-sq queues,
* this function is called for both blk-sq and blk-mq queues.
*/
void blk_queue_bypass_end(struct request_queue *q)
{
spin_lock_irq(q->queue_lock);
if (!--q->bypass_depth)
queue_flag_clear(QUEUE_FLAG_BYPASS, q);
WARN_ON_ONCE(q->bypass_depth < 0);
spin_unlock_irq(q->queue_lock);
}
EXPORT_SYMBOL_GPL(blk_queue_bypass_end);
void blk_set_queue_dying(struct request_queue *q)
{
spin_lock_irq(q->queue_lock);
queue_flag_set(QUEUE_FLAG_DYING, q);
spin_unlock_irq(q->queue_lock);
/*
* When queue DYING flag is set, we need to block new req
* entering queue, so we call blk_freeze_queue_start() to
* prevent I/O from crossing blk_queue_enter().
*/
blk_freeze_queue_start(q);
if (q->mq_ops)
blk_mq_wake_waiters(q);
else {
struct request_list *rl;
spin_lock_irq(q->queue_lock);
blk_queue_for_each_rl(rl, q) {
if (rl->rq_pool) {
wake_up(&rl->wait[BLK_RW_SYNC]);
wake_up(&rl->wait[BLK_RW_ASYNC]);
}
}
spin_unlock_irq(q->queue_lock);
}
}
EXPORT_SYMBOL_GPL(blk_set_queue_dying);
/**
* blk_cleanup_queue - shutdown a request queue
* @q: request queue to shutdown
*
* Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
* put it. All future requests will be failed immediately with -ENODEV.
*/
void blk_cleanup_queue(struct request_queue *q)
{
spinlock_t *lock = q->queue_lock;
/* mark @q DYING, no new request or merges will be allowed afterwards */
mutex_lock(&q->sysfs_lock);
blk_set_queue_dying(q);
spin_lock_irq(lock);
/*
* A dying queue is permanently in bypass mode till released. Note
* that, unlike blk_queue_bypass_start(), we aren't performing
* synchronize_rcu() after entering bypass mode to avoid the delay
* as some drivers create and destroy a lot of queues while
* probing. This is still safe because blk_release_queue() will be
* called only after the queue refcnt drops to zero and nothing,
* RCU or not, would be traversing the queue by then.
*/
q->bypass_depth++;
queue_flag_set(QUEUE_FLAG_BYPASS, q);
queue_flag_set(QUEUE_FLAG_NOMERGES, q);
queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
queue_flag_set(QUEUE_FLAG_DYING, q);
spin_unlock_irq(lock);
mutex_unlock(&q->sysfs_lock);
/*
* Drain all requests queued before DYING marking. Set DEAD flag to
* prevent that q->request_fn() gets invoked after draining finished.
*/
blk_freeze_queue(q);
spin_lock_irq(lock);
if (!q->mq_ops)
__blk_drain_queue(q, true);
queue_flag_set(QUEUE_FLAG_DEAD, q);
spin_unlock_irq(lock);
/* for synchronous bio-based driver finish in-flight integrity i/o */
blk_flush_integrity();
/* @q won't process any more request, flush async actions */
del_timer_sync(&q->backing_dev_info->laptop_mode_wb_timer);
blk_sync_queue(q);
if (q->mq_ops)
blk_mq_free_queue(q);
percpu_ref_exit(&q->q_usage_counter);
spin_lock_irq(lock);
if (q->queue_lock != &q->__queue_lock)
q->queue_lock = &q->__queue_lock;
spin_unlock_irq(lock);
/* @q is and will stay empty, shutdown and put */
blk_put_queue(q);
}
EXPORT_SYMBOL(blk_cleanup_queue);
/* Allocate memory local to the request queue */
static void *alloc_request_simple(gfp_t gfp_mask, void *data)
{
struct request_queue *q = data;
return kmem_cache_alloc_node(request_cachep, gfp_mask, q->node);
}
static void free_request_simple(void *element, void *data)
{
kmem_cache_free(request_cachep, element);
}
static void *alloc_request_size(gfp_t gfp_mask, void *data)
{
struct request_queue *q = data;
struct request *rq;
rq = kmalloc_node(sizeof(struct request) + q->cmd_size, gfp_mask, q->node);
if (rq && q->init_rq_fn && q->init_rq_fn(q, rq, gfp_mask) < 0) {
kfree(rq);
rq = NULL;
}
return rq;
}
static void free_request_size(void *element, void *data)
{
struct request_queue *q = data;
if (q->exit_rq_fn)
q->exit_rq_fn(q, element);
kfree(element);
}
int blk_init_rl(struct request_list *rl, struct request_queue *q,
gfp_t gfp_mask)
{
if (unlikely(rl->rq_pool))
return 0;
rl->q = q;
rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
init_waitqueue_head(&rl->wait[BLK_RW_SYNC]);
init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]);
if (q->cmd_size) {
rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ,
alloc_request_size, free_request_size,
q, gfp_mask, q->node);
} else {
rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ,
alloc_request_simple, free_request_simple,
q, gfp_mask, q->node);
}
if (!rl->rq_pool)
return -ENOMEM;
if (rl != &q->root_rl)
WARN_ON_ONCE(!blk_get_queue(q));
return 0;
}
void blk_exit_rl(struct request_queue *q, struct request_list *rl)
{
if (rl->rq_pool) {
mempool_destroy(rl->rq_pool);
if (rl != &q->root_rl)
blk_put_queue(q);
}
}
struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
{
return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE);
}
EXPORT_SYMBOL(blk_alloc_queue);
int blk_queue_enter(struct request_queue *q, bool nowait)
{
while (true) {
int ret;
if (percpu_ref_tryget_live(&q->q_usage_counter))
return 0;
if (nowait)
return -EBUSY;
/*
* read pair of barrier in blk_freeze_queue_start(),
* we need to order reading __PERCPU_REF_DEAD flag of
* .q_usage_counter and reading .mq_freeze_depth or
* queue dying flag, otherwise the following wait may
* never return if the two reads are reordered.
*/
smp_rmb();
ret = wait_event_interruptible(q->mq_freeze_wq,
!atomic_read(&q->mq_freeze_depth) ||
blk_queue_dying(q));
if (blk_queue_dying(q))
return -ENODEV;
if (ret)
return ret;
}
}
void blk_queue_exit(struct request_queue *q)
{
percpu_ref_put(&q->q_usage_counter);
}
static void blk_queue_usage_counter_release(struct percpu_ref *ref)
{
struct request_queue *q =
container_of(ref, struct request_queue, q_usage_counter);
wake_up_all(&q->mq_freeze_wq);
}
static void blk_rq_timed_out_timer(unsigned long data)
{
struct request_queue *q = (struct request_queue *)data;
kblockd_schedule_work(&q->timeout_work);
}
struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
{
struct request_queue *q;
q = kmem_cache_alloc_node(blk_requestq_cachep,
gfp_mask | __GFP_ZERO, node_id);
if (!q)
return NULL;
q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask);
if (q->id < 0)
goto fail_q;
q->bio_split = bioset_create(BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
if (!q->bio_split)
goto fail_id;
q->backing_dev_info = bdi_alloc_node(gfp_mask, node_id);
if (!q->backing_dev_info)
goto fail_split;
q->stats = blk_alloc_queue_stats();
if (!q->stats)
goto fail_stats;
q->backing_dev_info->ra_pages =
(VM_MAX_READAHEAD * 1024) / PAGE_SIZE;
q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK; q->backing_dev_info->name = "block";
q->node = node_id;
setup_timer(&q->backing_dev_info->laptop_mode_wb_timer,
laptop_mode_timer_fn, (unsigned long) q);
setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
INIT_LIST_HEAD(&q->queue_head);
INIT_LIST_HEAD(&q->timeout_list);
INIT_LIST_HEAD(&q->icq_list);
#ifdef CONFIG_BLK_CGROUP
INIT_LIST_HEAD(&q->blkg_list);
#endif
INIT_DELAYED_WORK(&q->delay_work, blk_delay_work);
kobject_init(&q->kobj, &blk_queue_ktype);
mutex_init(&q->sysfs_lock);
spin_lock_init(&q->__queue_lock);
/*
* By default initialize queue_lock to internal lock and driver can
* override it later if need be.
*/
q->queue_lock = &q->__queue_lock;
/*
* A queue starts its life with bypass turned on to avoid
* unnecessary bypass on/off overhead and nasty surprises during
* init. The initial bypass will be finished when the queue is
* registered by blk_register_queue().
*/
q->bypass_depth = 1;
__set_bit(QUEUE_FLAG_BYPASS, &q->queue_flags);
init_waitqueue_head(&q->mq_freeze_wq);
/*
* Init percpu_ref in atomic mode so that it's faster to shutdown.
* See blk_register_queue() for details.
*/
if (percpu_ref_init(&q->q_usage_counter,
blk_queue_usage_counter_release,
PERCPU_REF_INIT_ATOMIC, GFP_KERNEL))
goto fail_bdi;
if (blkcg_init_queue(q))
goto fail_ref;
return q;
fail_ref:
percpu_ref_exit(&q->q_usage_counter);
fail_bdi:
blk_free_queue_stats(q->stats);
fail_stats:
bdi_put(q->backing_dev_info);
fail_split:
bioset_free(q->bio_split);
fail_id:
ida_simple_remove(&blk_queue_ida, q->id);
fail_q:
kmem_cache_free(blk_requestq_cachep, q);
return NULL;
}
EXPORT_SYMBOL(blk_alloc_queue_node);
/**
* blk_init_queue - prepare a request queue for use with a block device
* @rfn: The function to be called to process requests that have been
* placed on the queue. * @lock: Request queue spin lock
*
* Description:
* If a block device wishes to use the standard request handling procedures,
* which sorts requests and coalesces adjacent requests, then it must
* call blk_init_queue(). The function @rfn will be called when there
* are requests on the queue that need to be processed. If the device
* supports plugging, then @rfn may not be called immediately when requests
* are available on the queue, but may be called at some time later instead.
* Plugged queues are generally unplugged when a buffer belonging to one
* of the requests on the queue is needed, or due to memory pressure.
*
* @rfn is not required, or even expected, to remove all requests off the
* queue, but only as many as it can handle at a time. If it does leave
* requests on the queue, it is responsible for arranging that the requests
* get dealt with eventually.
*
* The queue spin lock must be held while manipulating the requests on the
* request queue; this lock will be taken also from interrupt context, so irq
* disabling is needed for it.
*
* Function returns a pointer to the initialized request queue, or %NULL if
* it didn't succeed.
*
* Note:
* blk_init_queue() must be paired with a blk_cleanup_queue() call
* when the block device is deactivated (such as at module unload).
**/
struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
{
return blk_init_queue_node(rfn, lock, NUMA_NO_NODE);
}
EXPORT_SYMBOL(blk_init_queue);
struct request_queue *
blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
{
struct request_queue *q;
q = blk_alloc_queue_node(GFP_KERNEL, node_id);
if (!q)
return NULL;
q->request_fn = rfn;
if (lock)
q->queue_lock = lock;
if (blk_init_allocated_queue(q) < 0) {
blk_cleanup_queue(q);
return NULL;
}
return q;
}
EXPORT_SYMBOL(blk_init_queue_node);
static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio);
int blk_init_allocated_queue(struct request_queue *q)
{
WARN_ON_ONCE(q->mq_ops);
q->fq = blk_alloc_flush_queue(q, NUMA_NO_NODE, q->cmd_size);
if (!q->fq)
return -ENOMEM;
if (q->init_rq_fn && q->init_rq_fn(q, q->fq->flush_rq, GFP_KERNEL))
goto out_free_flush_queue;
if (blk_init_rl(&q->root_rl, q, GFP_KERNEL))
goto out_exit_flush_rq;
INIT_WORK(&q->timeout_work, blk_timeout_work);
q->queue_flags |= QUEUE_FLAG_DEFAULT;
/*
* This also sets hw/phys segments, boundary and size
*/
blk_queue_make_request(q, blk_queue_bio);
q->sg_reserved_size = INT_MAX;
/* Protect q->elevator from elevator_change */
mutex_lock(&q->sysfs_lock);
/* init elevator */
if (elevator_init(q, NULL)) {
mutex_unlock(&q->sysfs_lock);
goto out_exit_flush_rq;
}
mutex_unlock(&q->sysfs_lock);
return 0;
out_exit_flush_rq:
if (q->exit_rq_fn)
q->exit_rq_fn(q, q->fq->flush_rq);
out_free_flush_queue:
blk_free_flush_queue(q->fq);
return -ENOMEM;
}
EXPORT_SYMBOL(blk_init_allocated_queue);
bool blk_get_queue(struct request_queue *q)
{
if (likely(!blk_queue_dying(q))) {
__blk_get_queue(q);
return true;
}
return false;
}
EXPORT_SYMBOL(blk_get_queue);
static inline void blk_free_request(struct request_list *rl, struct request *rq)
{
if (rq->rq_flags & RQF_ELVPRIV) {
elv_put_request(rl->q, rq);
if (rq->elv.icq)
put_io_context(rq->elv.icq->ioc);
}
mempool_free(rq, rl->rq_pool);
}
/*
* ioc_batching returns true if the ioc is a valid batching request and
* should be given priority access to a request.
*/
static inline int ioc_batching(struct request_queue *q, struct io_context *ioc)
{
if (!ioc)
return 0;
/*
* Make sure the process is able to allocate at least 1 request
* even if the batch times out, otherwise we could theoretically
* lose wakeups.
*/ return ioc->nr_batch_requests == q->nr_batching ||
(ioc->nr_batch_requests > 0
&& time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
}
/*
* ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
* will cause the process to be a "batcher" on all queues in the system. This
* is the behaviour we want though - once it gets a wakeup it should be given
* a nice run.
*/
static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
{
if (!ioc || ioc_batching(q, ioc))
return;
ioc->nr_batch_requests = q->nr_batching;
ioc->last_waited = jiffies;
}
static void __freed_request(struct request_list *rl, int sync)
{
struct request_queue *q = rl->q;
if (rl->count[sync] < queue_congestion_off_threshold(q))
blk_clear_congested(rl, sync);
if (rl->count[sync] + 1 <= q->nr_requests) {
if (waitqueue_active(&rl->wait[sync]))
wake_up(&rl->wait[sync]);
blk_clear_rl_full(rl, sync);
}
}
/*
* A request has just been released. Account for it, update the full and
* congestion status, wake up any waiters. Called under q->queue_lock.
*/
static void freed_request(struct request_list *rl, bool sync,
req_flags_t rq_flags)
{
struct request_queue *q = rl->q;
q->nr_rqs[sync]--;
rl->count[sync]--;
if (rq_flags & RQF_ELVPRIV)
q->nr_rqs_elvpriv--;
__freed_request(rl, sync);
if (unlikely(rl->starved[sync ^ 1]))
__freed_request(rl, sync ^ 1);
}
int blk_update_nr_requests(struct request_queue *q, unsigned int nr)
{
struct request_list *rl;
int on_thresh, off_thresh;
WARN_ON_ONCE(q->mq_ops);
spin_lock_irq(q->queue_lock);
q->nr_requests = nr;
blk_queue_congestion_threshold(q);
on_thresh = queue_congestion_on_threshold(q);
off_thresh = queue_congestion_off_threshold(q);
blk_queue_for_each_rl(rl, q) {
if (rl->count[BLK_RW_SYNC] >= on_thresh) blk_set_congested(rl, BLK_RW_SYNC);
else if (rl->count[BLK_RW_SYNC] < off_thresh)
blk_clear_congested(rl, BLK_RW_SYNC);
if (rl->count[BLK_RW_ASYNC] >= on_thresh)
blk_set_congested(rl, BLK_RW_ASYNC);
else if (rl->count[BLK_RW_ASYNC] < off_thresh)
blk_clear_congested(rl, BLK_RW_ASYNC);
if (rl->count[BLK_RW_SYNC] >= q->nr_requests) {
blk_set_rl_full(rl, BLK_RW_SYNC);
} else {
blk_clear_rl_full(rl, BLK_RW_SYNC);
wake_up(&rl->wait[BLK_RW_SYNC]);
}
if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) {
blk_set_rl_full(rl, BLK_RW_ASYNC);
} else {
blk_clear_rl_full(rl, BLK_RW_ASYNC);
wake_up(&rl->wait[BLK_RW_ASYNC]);
}
}
spin_unlock_irq(q->queue_lock);
return 0;
}
/**
* __get_request - get a free request
* @rl: request list to allocate from
* @op: operation and flags
* @bio: bio to allocate request for (can be %NULL)
* @gfp_mask: allocation mask
*
* Get a free request from @q. This function may fail under memory
* pressure or if @q is dead.
*
* Must be called with @q->queue_lock held and,
* Returns ERR_PTR on failure, with @q->queue_lock held.
* Returns request pointer on success, with @q->queue_lock *not held*.
*/
static struct request *__get_request(struct request_list *rl, unsigned int op,
struct bio *bio, gfp_t gfp_mask)
{
struct request_queue *q = rl->q;
struct request *rq;
struct elevator_type *et = q->elevator->type;
struct io_context *ioc = rq_ioc(bio);
struct io_cq *icq = NULL;
const bool is_sync = op_is_sync(op);
int may_queue;
req_flags_t rq_flags = RQF_ALLOCED;
lockdep_assert_held(q->queue_lock);
if (unlikely(blk_queue_dying(q)))
return ERR_PTR(-ENODEV);
may_queue = elv_may_queue(q, op);
if (may_queue == ELV_MQUEUE_NO)
goto rq_starved;
if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
if (rl->count[is_sync]+1 >= q->nr_requests) {
/*
* The queue will fill after this allocation, so set
* it as full, and mark this process as "batching".
* This process will be allowed to complete a batch of
* requests, others will be blocked. */
if (!blk_rl_full(rl, is_sync)) {
ioc_set_batching(q, ioc);
blk_set_rl_full(rl, is_sync);
} else {
if (may_queue != ELV_MQUEUE_MUST
&& !ioc_batching(q, ioc)) {
/*
* The queue is full and the allocating
* process is not a "batcher", and not
* exempted by the IO scheduler
*/
return ERR_PTR(-ENOMEM);
}
}
}
blk_set_congested(rl, is_sync);
}
/*
* Only allow batching queuers to allocate up to 50% over the defined
* limit of requests, otherwise we could have thousands of requests
* allocated with any setting of ->nr_requests
*/
if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
return ERR_PTR(-ENOMEM);
q->nr_rqs[is_sync]++;
rl->count[is_sync]++;
rl->starved[is_sync] = 0;
/*
* Decide whether the new request will be managed by elevator. If
* so, mark @rq_flags and increment elvpriv. Non-zero elvpriv will
* prevent the current elevator from being destroyed until the new
* request is freed. This guarantees icq's won't be destroyed and
* makes creating new ones safe.
*
* Flush requests do not use the elevator so skip initialization.
* This allows a request to share the flush and elevator data.
*
* Also, lookup icq while holding queue_lock. If it doesn't exist,
* it will be created after releasing queue_lock.
*/
if (!op_is_flush(op) && !blk_queue_bypass(q)) {
rq_flags |= RQF_ELVPRIV;
q->nr_rqs_elvpriv++;
if (et->icq_cache && ioc)
icq = ioc_lookup_icq(ioc, q);
}
if (blk_queue_io_stat(q))
rq_flags |= RQF_IO_STAT;
spin_unlock_irq(q->queue_lock);
/* allocate and init request */
rq = mempool_alloc(rl->rq_pool, gfp_mask);
if (!rq)
goto fail_alloc;
blk_rq_init(q, rq);
blk_rq_set_rl(rq, rl);
rq->cmd_flags = op;
rq->rq_flags = rq_flags;
/* init elvpriv */
if (rq_flags & RQF_ELVPRIV) {
if (unlikely(et->icq_cache && !icq)) {
if (ioc)
icq = ioc_create_icq(ioc, q, gfp_mask); if (!icq)
goto fail_elvpriv;
}
rq->elv.icq = icq;
if (unlikely(elv_set_request(q, rq, bio, gfp_mask)))
goto fail_elvpriv;
/* @rq->elv.icq holds io_context until @rq is freed */
if (icq)
get_io_context(icq->ioc);
}
out:
/*
* ioc may be NULL here, and ioc_batching will be false. That's
* OK, if the queue is under the request limit then requests need
* not count toward the nr_batch_requests limit. There will always
* be some limit enforced by BLK_BATCH_TIME.
*/
if (ioc_batching(q, ioc))
ioc->nr_batch_requests--;
trace_block_getrq(q, bio, op);
return rq;
fail_elvpriv:
/*
* elvpriv init failed. ioc, icq and elvpriv aren't mempool backed
* and may fail indefinitely under memory pressure and thus
* shouldn't stall IO. Treat this request as !elvpriv. This will
* disturb iosched and blkcg but weird is bettern than dead.
*/
printk_ratelimited(KERN_WARNING "%s: dev %s: request aux data allocation failed, iosched may be disturbed\n",
__func__, dev_name(q->backing_dev_info->dev));
rq->rq_flags &= ~RQF_ELVPRIV;
rq->elv.icq = NULL;
spin_lock_irq(q->queue_lock);
q->nr_rqs_elvpriv--;
spin_unlock_irq(q->queue_lock);
goto out;
fail_alloc:
/*
* Allocation failed presumably due to memory. Undo anything we
* might have messed up.
*
* Allocating task should really be put onto the front of the wait
* queue, but this is pretty rare.
*/
spin_lock_irq(q->queue_lock);
freed_request(rl, is_sync, rq_flags);
/*
* in the very unlikely event that allocation failed and no
* requests for this direction was pending, mark us starved so that
* freeing of a request in the other direction will notice
* us. another possible fix would be to split the rq mempool into
* READ and WRITE
*/
rq_starved:
if (unlikely(rl->count[is_sync] == 0))
rl->starved[is_sync] = 1;
return ERR_PTR(-ENOMEM);
}
/**
* get_request - get a free request
* @q: request_queue to allocate request from * @op: operation and flags
* @bio: bio to allocate request for (can be %NULL)
* @gfp_mask: allocation mask
*
* Get a free request from @q. If %__GFP_DIRECT_RECLAIM is set in @gfp_mask,
* this function keeps retrying under memory pressure and fails iff @q is dead.
*
* Must be called with @q->queue_lock held and,
* Returns ERR_PTR on failure, with @q->queue_lock held.
* Returns request pointer on success, with @q->queue_lock *not held*.
*/
static struct request *get_request(struct request_queue *q, unsigned int op,
struct bio *bio, gfp_t gfp_mask)
{
const bool is_sync = op_is_sync(op);
DEFINE_WAIT(wait);
struct request_list *rl;
struct request *rq;
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);
rl = blk_get_rl(q, bio); /* transferred to @rq on success */
retry:
rq = __get_request(rl, op, bio, gfp_mask);
if (!IS_ERR(rq))
return rq;
if (op & REQ_NOWAIT) {
blk_put_rl(rl);
return ERR_PTR(-EAGAIN);
}
if (!gfpflags_allow_blocking(gfp_mask) || unlikely(blk_queue_dying(q))) {
blk_put_rl(rl);
return rq;
}
/* wait on @rl and retry */
prepare_to_wait_exclusive(&rl->wait[is_sync], &wait,
TASK_UNINTERRUPTIBLE);
trace_block_sleeprq(q, bio, op);
spin_unlock_irq(q->queue_lock);
io_schedule();
/*
* After sleeping, we become a "batching" process and will be able
* to allocate at least one request, and up to a big batch of them
* for a small period time. See ioc_batching, ioc_set_batching
*/
ioc_set_batching(q, current->io_context);
spin_lock_irq(q->queue_lock);
finish_wait(&rl->wait[is_sync], &wait);
goto retry;
}
static struct request *blk_old_get_request(struct request_queue *q,
unsigned int op, gfp_t gfp_mask)
{
struct request *rq;
WARN_ON_ONCE(q->mq_ops);
/* create ioc upfront */
create_io_context(gfp_mask, q->node);
spin_lock_irq(q->queue_lock);
rq = get_request(q, op, NULL, gfp_mask);
if (IS_ERR(rq)) {
spin_unlock_irq(q->queue_lock);
return rq;
}
/* q->queue_lock is unlocked at this point */
rq->__data_len = 0;
rq->__sector = (sector_t) -1;
rq->bio = rq->biotail = NULL;
return rq;
}
struct request *blk_get_request(struct request_queue *q, unsigned int op,
gfp_t gfp_mask)
{
struct request *req;
if (q->mq_ops) {
req = blk_mq_alloc_request(q, op,
(gfp_mask & __GFP_DIRECT_RECLAIM) ?
0 : BLK_MQ_REQ_NOWAIT);
if (!IS_ERR(req) && q->mq_ops->initialize_rq_fn)
q->mq_ops->initialize_rq_fn(req);
} else {
req = blk_old_get_request(q, op, gfp_mask);
if (!IS_ERR(req) && q->initialize_rq_fn)
q->initialize_rq_fn(req);
}
return req;
}
EXPORT_SYMBOL(blk_get_request);
/**
* blk_requeue_request - put a request back on queue
* @q: request queue where request should be inserted
* @rq: request to be inserted
*
* Description:
* Drivers often keep queueing requests until the hardware cannot accept
* more, when that condition happens we need to put the request back
* on the queue. Must be called with queue lock held.
*/
void blk_requeue_request(struct request_queue *q, struct request *rq)
{
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);
blk_delete_timer(rq);
blk_clear_rq_complete(rq);
trace_block_rq_requeue(q, rq);
wbt_requeue(q->rq_wb, &rq->issue_stat);
if (rq->rq_flags & RQF_QUEUED)
blk_queue_end_tag(q, rq);
BUG_ON(blk_queued_rq(rq));
elv_requeue_request(q, rq);
}
EXPORT_SYMBOL(blk_requeue_request);
static void add_acct_request(struct request_queue *q, struct request *rq,
int where)
{
blk_account_io_start(rq, true);
__elv_add_request(q, rq, where);
}
static void part_round_stats_single(int cpu, struct hd_struct *part,
unsigned long now)
{
int inflight;
if (now == part->stamp)
return;
inflight = part_in_flight(part);
if (inflight) {
__part_stat_add(cpu, part, time_in_queue,
inflight * (now - part->stamp));
__part_stat_add(cpu, part, io_ticks, (now - part->stamp));
}
part->stamp = now;
}
/**
* part_round_stats() - Round off the performance stats on a struct disk_stats.
* @cpu: cpu number for stats access
* @part: target partition
*
* The average IO queue length and utilisation statistics are maintained
* by observing the current state of the queue length and the amount of
* time it has been in this state for.
*
* Normally, that accounting is done on IO completion, but that can result
* in more than a second's worth of IO being accounted for within any one
* second, leading to >100% utilisation. To deal with that, we call this
* function to do a round-off before returning the results when reading
* /proc/diskstats. This accounts immediately for all queue usage up to
* the current jiffies and restarts the counters again.
*/
void part_round_stats(int cpu, struct hd_struct *part)
{
unsigned long now = jiffies;
if (part->partno)
part_round_stats_single(cpu, &part_to_disk(part)->part0, now);
part_round_stats_single(cpu, part, now);
}
EXPORT_SYMBOL_GPL(part_round_stats);
#ifdef CONFIG_PM
static void blk_pm_put_request(struct request *rq)
{
if (rq->q->dev && !(rq->rq_flags & RQF_PM) && !--rq->q->nr_pending)
pm_runtime_mark_last_busy(rq->q->dev);
}
#else
static inline void blk_pm_put_request(struct request *rq) {}
#endif
void __blk_put_request(struct request_queue *q, struct request *req)
{
req_flags_t rq_flags = req->rq_flags;
if (unlikely(!q))
return;
if (q->mq_ops) {
blk_mq_free_request(req);
return;
}
lockdep_assert_held(q->queue_lock);
blk_pm_put_request(req);
elv_completed_request(q, req);
/* this is a bio leak */
WARN_ON(req->bio != NULL);
wbt_done(q->rq_wb, &req->issue_stat);
/*
* Request may not have originated from ll_rw_blk. if not,
* it didn't come out of our reserved rq pools
*/
if (rq_flags & RQF_ALLOCED) {
struct request_list *rl = blk_rq_rl(req);
bool sync = op_is_sync(req->cmd_flags);
BUG_ON(!list_empty(&req->queuelist));
BUG_ON(ELV_ON_HASH(req));
blk_free_request(rl, req);
freed_request(rl, sync, rq_flags);
blk_put_rl(rl);
}
}
EXPORT_SYMBOL_GPL(__blk_put_request);
void blk_put_request(struct request *req)
{
struct request_queue *q = req->q;
if (q->mq_ops)
blk_mq_free_request(req);
else {
unsigned long flags;
spin_lock_irqsave(q->queue_lock, flags);
__blk_put_request(q, req);
spin_unlock_irqrestore(q->queue_lock, flags);
}
}
EXPORT_SYMBOL(blk_put_request);
bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
struct bio *bio)
{
const int ff = bio->bi_opf & REQ_FAILFAST_MASK;
if (!ll_back_merge_fn(q, req, bio))
return false;
trace_block_bio_backmerge(q, req, bio);
if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
blk_rq_set_mixed_merge(req);
req->biotail->bi_next = bio;
req->biotail = bio;
req->__data_len += bio->bi_iter.bi_size;
req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
blk_account_io_start(req, false);
return true;
}
bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
struct bio *bio)
{
const int ff = bio->bi_opf & REQ_FAILFAST_MASK;
if (!ll_front_merge_fn(q, req, bio))
return false;
trace_block_bio_frontmerge(q, req, bio);
if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
blk_rq_set_mixed_merge(req);
bio->bi_next = req->bio;
req->bio = bio;
req->__sector = bio->bi_iter.bi_sector;
req->__data_len += bio->bi_iter.bi_size;
req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
blk_account_io_start(req, false);
return true;
}
bool bio_attempt_discard_merge(struct request_queue *q, struct request *req,
struct bio *bio)
{
unsigned short segments = blk_rq_nr_discard_segments(req);
if (segments >= queue_max_discard_segments(q))
goto no_merge;
if (blk_rq_sectors(req) + bio_sectors(bio) >
blk_rq_get_max_sectors(req, blk_rq_pos(req)))
goto no_merge;
req->biotail->bi_next = bio;
req->biotail = bio;
req->__data_len += bio->bi_iter.bi_size;
req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
req->nr_phys_segments = segments + 1;
blk_account_io_start(req, false);
return true;
no_merge:
req_set_nomerge(q, req);
return false;
}
/**
* blk_attempt_plug_merge - try to merge with %current's plugged list
* @q: request_queue new bio is being queued at
* @bio: new bio being queued
* @request_count: out parameter for number of traversed plugged requests
* @same_queue_rq: pointer to &struct request that gets filled in when
* another request associated with @q is found on the plug list
* (optional, may be %NULL)
*
* Determine whether @bio being queued on @q can be merged with a request
* on %current's plugged list. Returns %true if merge was successful,
* otherwise %false.
*
* Plugging coalesces IOs from the same issuer for the same purpose without
* going through @q->queue_lock. As such it's more of an issuing mechanism
* than scheduling, and the request, while may have elvpriv data, is not
* added on the elevator at this point. In addition, we don't have
* reliable access to the elevator outside queue lock. Only check basic
* merging parameters without querying the elevator.
*
* Caller must ensure !blk_queue_nomerges(q) beforehand.
*/
bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
unsigned int *request_count,
struct request **same_queue_rq)
{
struct blk_plug *plug;
struct request *rq;
struct list_head *plug_list;
plug = current->plug;
if (!plug)
return false;
*request_count = 0;
if (q->mq_ops)
plug_list = &plug->mq_list;
else
plug_list = &plug->list;
list_for_each_entry_reverse(rq, plug_list, queuelist) {
bool merged = false;
if (rq->q == q) {
(*request_count)++;
/*
* Only blk-mq multiple hardware queues case checks the
* rq in the same queue, there should be only one such
* rq in a queue
**/
if (same_queue_rq)
*same_queue_rq = rq;
}
if (rq->q != q || !blk_rq_merge_ok(rq, bio))
continue;
switch (blk_try_merge(rq, bio)) {
case ELEVATOR_BACK_MERGE:
merged = bio_attempt_back_merge(q, rq, bio);
break;
case ELEVATOR_FRONT_MERGE:
merged = bio_attempt_front_merge(q, rq, bio);
break;
case ELEVATOR_DISCARD_MERGE:
merged = bio_attempt_discard_merge(q, rq, bio);
break;
default:
break;
}
if (merged)
return true;
}
return false;
}
unsigned int blk_plug_queued_count(struct request_queue *q)
{
struct blk_plug *plug;
struct request *rq;
struct list_head *plug_list;
unsigned int ret = 0;
plug = current->plug;
if (!plug)
goto out;
if (q->mq_ops)
plug_list = &plug->mq_list;
else
plug_list = &plug->list;
list_for_each_entry(rq, plug_list, queuelist) {
if (rq->q == q)
ret++;
}
out: return ret;
}
void blk_init_request_from_bio(struct request *req, struct bio *bio)
{
struct io_context *ioc = rq_ioc(bio);
if (bio->bi_opf & REQ_RAHEAD)
req->cmd_flags |= REQ_FAILFAST_MASK;
req->__sector = bio->bi_iter.bi_sector;
if (ioprio_valid(bio_prio(bio)))
req->ioprio = bio_prio(bio);
else if (ioc)
req->ioprio = ioc->ioprio;
else
req->ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
req->write_hint = bio->bi_write_hint;
blk_rq_bio_prep(req->q, req, bio);
}
EXPORT_SYMBOL_GPL(blk_init_request_from_bio);
static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio)
{
struct blk_plug *plug;
int where = ELEVATOR_INSERT_SORT;
struct request *req, *free;
unsigned int request_count = 0;
unsigned int wb_acct;
/*
* low level driver can indicate that it wants pages above a
* certain limit bounced to low memory (ie for highmem, or even
* ISA dma in theory)
*/
blk_queue_bounce(q, &bio);
blk_queue_split(q, &bio);
if (!bio_integrity_prep(bio))
return BLK_QC_T_NONE;
if (op_is_flush(bio->bi_opf)) {
spin_lock_irq(q->queue_lock);
where = ELEVATOR_INSERT_FLUSH;
goto get_rq;
}
/*
* Check if we can merge with the plugged list before grabbing
* any locks.
*/
if (!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);
spin_lock_irq(q->queue_lock);
switch (elv_merge(q, &req, bio)) {
case ELEVATOR_BACK_MERGE:
if (!bio_attempt_back_merge(q, req, bio))
break;
elv_bio_merged(q, req, bio);
free = attempt_back_merge(q, req);
if (free)
__blk_put_request(q, free);
else
elv_merged_request(q, req, ELEVATOR_BACK_MERGE); goto out_unlock;
case ELEVATOR_FRONT_MERGE:
if (!bio_attempt_front_merge(q, req, bio))
break;
elv_bio_merged(q, req, bio);
free = attempt_front_merge(q, req);
if (free)
__blk_put_request(q, free);
else
elv_merged_request(q, req, ELEVATOR_FRONT_MERGE);
goto out_unlock;
default:
break;
}
get_rq:
wb_acct = wbt_wait(q->rq_wb, bio, q->queue_lock);
/*
* Grab a free request. This is might sleep but can not fail.
* Returns with the queue unlocked.
*/
req = get_request(q, bio->bi_opf, bio, GFP_NOIO);
if (IS_ERR(req)) {
__wbt_done(q->rq_wb, wb_acct);
if (PTR_ERR(req) == -ENOMEM)
bio->bi_status = BLK_STS_RESOURCE;
else
bio->bi_status = BLK_STS_IOERR;
bio_endio(bio);
goto out_unlock;
}
wbt_track(&req->issue_stat, wb_acct);
/*
* After dropping the lock and possibly sleeping here, our request
* may now be mergeable after it had proven unmergeable (above).
* We don't worry about that case for efficiency. It won't happen
* often, and the elevators are able to handle it.
*/
blk_init_request_from_bio(req, bio);
if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags))
req->cpu = raw_smp_processor_id();
plug = current->plug;
if (plug) {
/*
* If this is the first request added after a plug, fire
* of a plug trace.
*
* @request_count may become stale because of schedule
* out, so check plug list again.
*/
if (!request_count || list_empty(&plug->list))
trace_block_plug(q);
else {
struct request *last = list_entry_rq(plug->list.prev);
if (request_count >= BLK_MAX_REQUEST_COUNT ||
blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE) {
blk_flush_plug_list(plug, false);
trace_block_plug(q);
}
}
list_add_tail(&req->queuelist, &plug->list);
blk_account_io_start(req, true);
} else {
spin_lock_irq(q->queue_lock);
add_acct_request(q, req, where); __blk_run_queue(q);
out_unlock:
spin_unlock_irq(q->queue_lock);
}
return BLK_QC_T_NONE;
}
/*
* If bio->bi_dev is a partition, remap the location
*/
static inline void blk_partition_remap(struct bio *bio)
{
struct block_device *bdev = bio->bi_bdev;
/*
* Zone reset does not include bi_size so bio_sectors() is always 0.
* Include a test for the reset op code and perform the remap if needed.
*/
if (bdev != bdev->bd_contains &&
(bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET)) {
struct hd_struct *p = bdev->bd_part;
bio->bi_iter.bi_sector += p->start_sect;
bio->bi_bdev = bdev->bd_contains;
trace_block_bio_remap(bdev_get_queue(bio->bi_bdev), bio,
bdev->bd_dev,
bio->bi_iter.bi_sector - p->start_sect);
}
}
static void handle_bad_sector(struct bio *bio)
{
char b[BDEVNAME_SIZE];
printk(KERN_INFO "attempt to access beyond end of device\n");
printk(KERN_INFO "%s: rw=%d, want=%Lu, limit=%Lu\n",
bdevname(bio->bi_bdev, b),
bio->bi_opf,
(unsigned long long)bio_end_sector(bio),
(long long)(i_size_read(bio->bi_bdev->bd_inode) >> 9));
}
#ifdef CONFIG_FAIL_MAKE_REQUEST
static DECLARE_FAULT_ATTR(fail_make_request);
static int __init setup_fail_make_request(char *str)
{
return setup_fault_attr(&fail_make_request, str);
}
__setup("fail_make_request=", setup_fail_make_request);
static bool should_fail_request(struct hd_struct *part, unsigned int bytes)
{
return part->make_it_fail && should_fail(&fail_make_request, bytes);
}
static int __init fail_make_request_debugfs(void)
{
struct dentry *dir = fault_create_debugfs_attr("fail_make_request",
NULL, &fail_make_request);
return PTR_ERR_OR_ZERO(dir);
}
late_initcall(fail_make_request_debugfs);
#else /* CONFIG_FAIL_MAKE_REQUEST */
static inline bool should_fail_request(struct hd_struct *part,
unsigned int bytes)
{
return false;
}
#endif /* CONFIG_FAIL_MAKE_REQUEST */
/*
* Check whether this bio extends beyond the end of the device.
*/
static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
{
sector_t maxsector;
if (!nr_sectors)
return 0;
/* Test device or partition size, when known. */
maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9;
if (maxsector) {
sector_t sector = bio->bi_iter.bi_sector;
if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
/*
* This may well happen - the kernel calls bread()
* without checking the size of the device, e.g., when
* mounting a device.
*/
handle_bad_sector(bio);
return 1;
}
}
return 0;
}
static noinline_for_stack bool
generic_make_request_checks(struct bio *bio)
{
struct request_queue *q;
int nr_sectors = bio_sectors(bio);
blk_status_t status = BLK_STS_IOERR;
char b[BDEVNAME_SIZE];
struct hd_struct *part;
might_sleep();
if (bio_check_eod(bio, nr_sectors))
goto end_io;
q = bdev_get_queue(bio->bi_bdev);
if (unlikely(!q)) {
printk(KERN_ERR
"generic_make_request: Trying to access "
"nonexistent block-device %s (%Lu)\n",
bdevname(bio->bi_bdev, b),
(long long) bio->bi_iter.bi_sector);
goto end_io;
}
/*
* For a REQ_NOWAIT based request, return -EOPNOTSUPP
* if queue is not a request based queue.
*/
if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_rq_based(q))
goto not_supported;
part = bio->bi_bdev->bd_part;
if (should_fail_request(part, bio->bi_iter.bi_size) ||
should_fail_request(&part_to_disk(part)->part0,
bio->bi_iter.bi_size))
goto end_io;
/*
* If this device has partitions, remap block n
* of partition p to block n+start(p) of the disk.
*/
blk_partition_remap(bio);
if (bio_check_eod(bio, nr_sectors))
goto end_io;
/*
* Filter flush bio's early so that make_request based
* drivers without flush support don't have to worry
* about them.
*/
if (op_is_flush(bio->bi_opf) &&
!test_bit(QUEUE_FLAG_WC, &q->queue_flags)) {
bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA);
if (!nr_sectors) {
status = BLK_STS_OK;
goto end_io;
}
}
switch (bio_op(bio)) {
case REQ_OP_DISCARD:
if (!blk_queue_discard(q))
goto not_supported;
break;
case REQ_OP_SECURE_ERASE:
if (!blk_queue_secure_erase(q))
goto not_supported;
break;
case REQ_OP_WRITE_SAME:
if (!bdev_write_same(bio->bi_bdev))
goto not_supported;
break;
case REQ_OP_ZONE_REPORT:
case REQ_OP_ZONE_RESET:
if (!bdev_is_zoned(bio->bi_bdev))
goto not_supported;
break;
case REQ_OP_WRITE_ZEROES:
if (!bdev_write_zeroes_sectors(bio->bi_bdev))
goto not_supported;
break;
default:
break;
}
/*
* Various block parts want %current->io_context and lazy ioc
* allocation ends up trading a lot of pain for a small amount of
* memory. Just allocate it upfront. This may fail and block
* layer knows how to live with it.
*/
create_io_context(GFP_ATOMIC, q->node);
if (!blkcg_bio_issue_check(q, bio))
return false;
if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) {
trace_block_bio_queue(q, bio);
/* Now that enqueuing has been traced, we need to trace
* completion as well. */
bio_set_flag(bio, BIO_TRACE_COMPLETION);
}
return true;
not_supported:
status = BLK_STS_NOTSUPP;
end_io:
bio->bi_status = status;
bio_endio(bio);
return false;
}
/**
* generic_make_request - hand a buffer to its device driver for I/O
* @bio: The bio describing the location in memory and on the device.
*
* generic_make_request() is used to make I/O requests of block
* devices. It is passed a &struct bio, which describes the I/O that needs
* to be done.
*
* generic_make_request() does not return any status. The
* success/failure status of the request, along with notification of
* completion, is delivered asynchronously through the bio->bi_end_io
* function described (one day) else where.
*
* The caller of generic_make_request must make sure that bi_io_vec
* are set to describe the memory buffer, and that bi_dev and bi_sector are
* set to describe the device address, and the
* bi_end_io and optionally bi_private are set to describe how
* completion notification should be signaled.
*
* generic_make_request and the drivers it calls may use bi_next if this
* bio happens to be merged with someone else, and may resubmit the bio to
* a lower device by calling into generic_make_request recursively, which
* means the bio should NOT be touched after the call to ->make_request_fn.
*/
blk_qc_t generic_make_request(struct bio *bio)
{
/*
* bio_list_on_stack[0] contains bios submitted by the current
* make_request_fn.
* bio_list_on_stack[1] contains bios that were submitted before
* the current make_request_fn, but that haven't been processed
* yet.
*/
struct bio_list bio_list_on_stack[2];
blk_qc_t ret = BLK_QC_T_NONE;
if (!generic_make_request_checks(bio))
goto out;
/*
* We only want one ->make_request_fn to be active at a time, else
* stack usage with stacked devices could be a problem. So use
* current->bio_list to keep a list of requests submited by a
* make_request_fn function. current->bio_list is also used as a
* flag to say if generic_make_request is currently active in this
* task or not. If it is NULL, then no make_request is active. If
* it is non-NULL, then a make_request is active, and new requests
* should be added at the tail
*/
if (current->bio_list) {
bio_list_add(¤t->bio_list[0], bio);
goto out;
}
/* following loop may be a bit non-obvious, and so deserves some
* explanation.
* Before entering the loop, bio->bi_next is NULL (as all callers * ensure that) so we have a list with a single bio.
* We pretend that we have just taken it off a longer list, so
* we assign bio_list to a pointer to the bio_list_on_stack,
* thus initialising the bio_list of new bios to be
* added. ->make_request() may indeed add some more bios
* through a recursive call to generic_make_request. If it
* did, we find a non-NULL value in bio_list and re-enter the loop
* from the top. In this case we really did just take the bio
* of the top of the list (no pretending) and so remove it from
* bio_list, and call into ->make_request() again.
*/
BUG_ON(bio->bi_next);
bio_list_init(&bio_list_on_stack[0]);
current->bio_list = bio_list_on_stack;
do {
struct request_queue *q = bdev_get_queue(bio->bi_bdev);
if (likely(blk_queue_enter(q, bio->bi_opf & REQ_NOWAIT) == 0)) {
struct bio_list lower, same;
/* Create a fresh bio_list for all subordinate requests */
bio_list_on_stack[1] = bio_list_on_stack[0];
bio_list_init(&bio_list_on_stack[0]);
ret = q->make_request_fn(q, bio);
blk_queue_exit(q);
/* sort new bios into those for a lower level
* and those for the same level
*/
bio_list_init(&lower);
bio_list_init(&same);
while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL)
if (q == bdev_get_queue(bio->bi_bdev))
bio_list_add(&same, bio);
else
bio_list_add(&lower, bio);
/* now assemble so we handle the lowest level first */
bio_list_merge(&bio_list_on_stack[0], &lower);
bio_list_merge(&bio_list_on_stack[0], &same);
bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]);
} else {
if (unlikely(!blk_queue_dying(q) &&
(bio->bi_opf & REQ_NOWAIT)))
bio_wouldblock_error(bio);
else
bio_io_error(bio);
}
bio = bio_list_pop(&bio_list_on_stack[0]);
} while (bio);
current->bio_list = NULL; /* deactivate */
out:
return ret;
}
EXPORT_SYMBOL(generic_make_request);
/**
* submit_bio - submit a bio to the block device layer for I/O
* @bio: The &struct bio which describes the I/O
*
* submit_bio() is very similar in purpose to generic_make_request(), and
* uses that function to do most of the work. Both are fairly rough
* interfaces; @bio must be presetup and ready for I/O.
*
*/
blk_qc_t submit_bio(struct bio *bio)
{
/*
* If it's a regular read/write or a barrier with data attached, * go through the normal accounting stuff before submission.
*/
if (bio_has_data(bio)) {
unsigned int count;
if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME))
count = bdev_logical_block_size(bio->bi_bdev) >> 9;
else
count = bio_sectors(bio);
if (op_is_write(bio_op(bio))) {
count_vm_events(PGPGOUT, count);
} else {
task_io_account_read(bio->bi_iter.bi_size);
count_vm_events(PGPGIN, count);
}
if (unlikely(block_dump)) {
char b[BDEVNAME_SIZE];
printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n",
current->comm, task_pid_nr(current),
op_is_write(bio_op(bio)) ? "WRITE" : "READ",
(unsigned long long)bio->bi_iter.bi_sector,
bdevname(bio->bi_bdev, b),
count);
}
}
return generic_make_request(bio);
}
EXPORT_SYMBOL(submit_bio);
/**
* blk_cloned_rq_check_limits - Helper function to check a cloned request
* for new the queue limits
* @q: the queue
* @rq: the request being checked
*
* Description:
* @rq may have been made based on weaker limitations of upper-level queues
* in request stacking drivers, and it may violate the limitation of @q.
* Since the block layer and the underlying device driver trust @rq
* after it is inserted to @q, it should be checked against @q before
* the insertion using this generic function.
*
* Request stacking drivers like request-based dm may change the queue
* limits when retrying requests on other queues. Those requests need
* to be checked against the new queue limits again during dispatch.
*/
static int blk_cloned_rq_check_limits(struct request_queue *q,
struct request *rq)
{
if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, req_op(rq))) {
printk(KERN_ERR "%s: over max size limit.\n", __func__);
return -EIO;
}
/*
* queue's settings related to segment counting like q->bounce_pfn
* may differ from that of other stacking queues.
* Recalculate it to check the request correctly on this queue's
* limitation.
*/
blk_recalc_rq_segments(rq);
if (rq->nr_phys_segments > queue_max_segments(q)) {
printk(KERN_ERR "%s: over max segments limit.\n", __func__);
return -EIO;
}
return 0;}
/**
* blk_insert_cloned_request - Helper for stacking drivers to submit a request
* @q: the queue to submit the request
* @rq: the request being queued
*/
blk_status_t blk_insert_cloned_request(struct request_queue *q, struct request *rq)
{
unsigned long flags;
int where = ELEVATOR_INSERT_BACK;
if (blk_cloned_rq_check_limits(q, rq))
return BLK_STS_IOERR;
if (rq->rq_disk &&
should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq)))
return BLK_STS_IOERR;
if (q->mq_ops) {
if (blk_queue_io_stat(q))
blk_account_io_start(rq, true);
blk_mq_sched_insert_request(rq, false, true, false, false);
return BLK_STS_OK;
}
spin_lock_irqsave(q->queue_lock, flags);
if (unlikely(blk_queue_dying(q))) {
spin_unlock_irqrestore(q->queue_lock, flags);
return BLK_STS_IOERR;
}
/*
* Submitting request must be dequeued before calling this function
* because it will be linked to another request_queue
*/
BUG_ON(blk_queued_rq(rq));
if (op_is_flush(rq->cmd_flags))
where = ELEVATOR_INSERT_FLUSH;
add_acct_request(q, rq, where);
if (where == ELEVATOR_INSERT_FLUSH)
__blk_run_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
return BLK_STS_OK;
}
EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
/**
* blk_rq_err_bytes - determine number of bytes till the next failure boundary
* @rq: request to examine
*
* Description:
* A request could be merge of IOs which require different failure
* handling. This function determines the number of bytes which
* can be failed from the beginning of the request without
* crossing into area which need to be retried further.
*
* Return:
* The number of bytes to fail.
*/
unsigned int blk_rq_err_bytes(const struct request *rq)
{
unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
unsigned int bytes = 0;
struct bio *bio;
if (!(rq->rq_flags & RQF_MIXED_MERGE)) return blk_rq_bytes(rq);
/*
* Currently the only 'mixing' which can happen is between
* different fastfail types. We can safely fail portions
* which have all the failfast bits that the first one has -
* the ones which are at least as eager to fail as the first
* one.
*/
for (bio = rq->bio; bio; bio = bio->bi_next) {
if ((bio->bi_opf & ff) != ff)
break;
bytes += bio->bi_iter.bi_size;
}
/* this could lead to infinite loop */
BUG_ON(blk_rq_bytes(rq) && !bytes);
return bytes;
}
EXPORT_SYMBOL_GPL(blk_rq_err_bytes);
void blk_account_io_completion(struct request *req, unsigned int bytes)
{
if (blk_do_io_stat(req)) {
const int rw = rq_data_dir(req);
struct hd_struct *part;
int cpu;
cpu = part_stat_lock();
part = req->part;
part_stat_add(cpu, part, sectors[rw], bytes >> 9);
part_stat_unlock();
}
}
void blk_account_io_done(struct request *req)
{
/*
* Account IO completion. flush_rq isn't accounted as a
* normal IO on queueing nor completion. Accounting the
* containing request is enough.
*/
if (blk_do_io_stat(req) && !(req->rq_flags & RQF_FLUSH_SEQ)) {
unsigned long duration = jiffies - req->start_time;
const int rw = rq_data_dir(req);
struct hd_struct *part;
int cpu;
cpu = part_stat_lock();
part = req->part;
part_stat_inc(cpu, part, ios[rw]);
part_stat_add(cpu, part, ticks[rw], duration);
part_round_stats(cpu, part);
part_dec_in_flight(part, rw);
hd_struct_put(part);
part_stat_unlock();
}
}
#ifdef CONFIG_PM
/*
* Don't process normal requests when queue is suspended
* or in the process of suspending/resuming
*/
static struct request *blk_pm_peek_request(struct request_queue *q,
struct request *rq)
{
if (q->dev && (q->rpm_status == RPM_SUSPENDED || (q->rpm_status != RPM_ACTIVE && !(rq->rq_flags & RQF_PM))))
return NULL;
else
return rq;
}
#else
static inline struct request *blk_pm_peek_request(struct request_queue *q,
struct request *rq)
{
return rq;
}
#endif
void blk_account_io_start(struct request *rq, bool new_io)
{
struct hd_struct *part;
int rw = rq_data_dir(rq);
int cpu;
if (!blk_do_io_stat(rq))
return;
cpu = part_stat_lock();
if (!new_io) {
part = rq->part;
part_stat_inc(cpu, part, merges[rw]);
} else {
part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
if (!hd_struct_try_get(part)) {
/*
* The partition is already being removed,
* the request will be accounted on the disk only
*
* We take a reference on disk->part0 although that
* partition will never be deleted, so we can treat
* it as any other partition.
*/
part = &rq->rq_disk->part0;
hd_struct_get(part);
}
part_round_stats(cpu, part);
part_inc_in_flight(part, rw);
rq->part = part;
}
part_stat_unlock();
}
/**
* blk_peek_request - peek at the top of a request queue
* @q: request queue to peek at
*
* Description:
* Return the request at the top of @q. The returned request
* should be started using blk_start_request() before LLD starts
* processing it.
*
* Return:
* Pointer to the request at the top of @q if available. Null
* otherwise.
*/
struct request *blk_peek_request(struct request_queue *q)
{
struct request *rq;
int ret;
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);
while ((rq = __elv_next_request(q)) != NULL) {
rq = blk_pm_peek_request(q, rq);
if (!rq)
break;
if (!(rq->rq_flags & RQF_STARTED)) {
/*
* This is the first time the device driver
* sees this request (possibly after
* requeueing). Notify IO scheduler.
*/
if (rq->rq_flags & RQF_SORTED)
elv_activate_rq(q, rq);
/*
* just mark as started even if we don't start
* it, a request that has been delayed should
* not be passed by new incoming requests
*/
rq->rq_flags |= RQF_STARTED;
trace_block_rq_issue(q, rq);
}
if (!q->boundary_rq || q->boundary_rq == rq) {
q->end_sector = rq_end_sector(rq);
q->boundary_rq = NULL;
}
if (rq->rq_flags & RQF_DONTPREP)
break;
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++;
}
if (!q->prep_rq_fn)
break;
ret = q->prep_rq_fn(q, rq);
if (ret == BLKPREP_OK) {
break;
} else if (ret == BLKPREP_DEFER) {
/*
* the request may have been (partially) prepped.
* we need to keep this request in the front to
* avoid resource deadlock. RQF_STARTED will
* prevent other fs requests from passing this one.
*/
if (q->dma_drain_size && blk_rq_bytes(rq) &&
!(rq->rq_flags & RQF_DONTPREP)) {
/*
* remove the space for the drain we added
* so that we don't add it again
*/
--rq->nr_phys_segments;
}
rq = NULL;
break;
} else if (ret == BLKPREP_KILL || ret == BLKPREP_INVALID) {
rq->rq_flags |= RQF_QUIET;
/*
* Mark this request as started so we don't trigger * any debug logic in the end I/O path.
*/
blk_start_request(rq);
__blk_end_request_all(rq, ret == BLKPREP_INVALID ?
BLK_STS_TARGET : BLK_STS_IOERR);
} else {
printk(KERN_ERR "%s: bad return=%d\n", __func__, ret);
break;
}
}
return rq;
}
EXPORT_SYMBOL(blk_peek_request);
void blk_dequeue_request(struct request *rq)
{
struct request_queue *q = rq->q;
BUG_ON(list_empty(&rq->queuelist));
BUG_ON(ELV_ON_HASH(rq));
list_del_init(&rq->queuelist);
/*
* the time frame between a request being removed from the lists
* and to it is freed is accounted as io that is in progress at
* the driver side.
*/
if (blk_account_rq(rq)) {
q->in_flight[rq_is_sync(rq)]++;
set_io_start_time_ns(rq);
}
}
/**
* blk_start_request - start request processing on the driver
* @req: request to dequeue
*
* Description:
* Dequeue @req and start timeout timer on it. This hands off the
* request to the driver.
*
* Block internal functions which don't want to start timer should
* call blk_dequeue_request().
*/
void blk_start_request(struct request *req)
{
lockdep_assert_held(req->q->queue_lock);
WARN_ON_ONCE(req->q->mq_ops);
blk_dequeue_request(req);
if (test_bit(QUEUE_FLAG_STATS, &req->q->queue_flags)) {
blk_stat_set_issue(&req->issue_stat, blk_rq_sectors(req));
req->rq_flags |= RQF_STATS;
wbt_issue(req->q->rq_wb, &req->issue_stat);
}
BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
blk_add_timer(req);
}
EXPORT_SYMBOL(blk_start_request);
/**
* blk_fetch_request - fetch a request from a request queue
* @q: request queue to fetch a request from
*
* Description:
* Return the request at the top of @q. The request is started on * return and LLD can start processing it immediately.
*
* Return:
* Pointer to the request at the top of @q if available. Null
* otherwise.
*/
struct request *blk_fetch_request(struct request_queue *q)
{
struct request *rq;
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);
rq = blk_peek_request(q);
if (rq)
blk_start_request(rq);
return rq;
}
EXPORT_SYMBOL(blk_fetch_request);
/**
* blk_update_request - Special helper function for request stacking drivers
* @req: the request being processed
* @error: block status code
* @nr_bytes: number of bytes to complete @req
*
* Description:
* Ends I/O on a number of bytes attached to @req, but doesn't complete
* the request structure even if @req doesn't have leftover.
* If @req has leftover, sets it up for the next range of segments.
*
* This special helper function is only for request stacking drivers
* (e.g. request-based dm) so that they can handle partial completion.
* Actual device drivers should use blk_end_request instead.
*
* Passing the result of blk_rq_bytes() as @nr_bytes guarantees
* %false return from this function.
*
* Return:
* %false - this request doesn't have any more data
* %true - this request has more data
**/
bool blk_update_request(struct request *req, blk_status_t error,
unsigned int nr_bytes)
{
int total_bytes;
trace_block_rq_complete(req, blk_status_to_errno(error), nr_bytes);
if (!req->bio)
return false;
if (unlikely(error && !blk_rq_is_passthrough(req) &&
!(req->rq_flags & RQF_QUIET)))
print_req_error(req, error);
blk_account_io_completion(req, nr_bytes);
total_bytes = 0;
while (req->bio) {
struct bio *bio = req->bio;
unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes);
if (bio_bytes == bio->bi_iter.bi_size)
req->bio = bio->bi_next;
/* Completion has already been traced */
bio_clear_flag(bio, BIO_TRACE_COMPLETION);
req_bio_endio(req, bio, bio_bytes, error);
total_bytes += bio_bytes;
nr_bytes -= bio_bytes;
if (!nr_bytes)
break;
}
/*
* completely done
*/
if (!req->bio) {
/*
* Reset counters so that the request stacking driver
* can find how many bytes remain in the request
* later.
*/
req->__data_len = 0;
return false;
}
req->__data_len -= total_bytes;
/* update sector only for requests with clear definition of sector */
if (!blk_rq_is_passthrough(req))
req->__sector += total_bytes >> 9;
/* mixed attributes always follow the first bio */
if (req->rq_flags & RQF_MIXED_MERGE) {
req->cmd_flags &= ~REQ_FAILFAST_MASK;
req->cmd_flags |= req->bio->bi_opf & REQ_FAILFAST_MASK;
}
if (!(req->rq_flags & RQF_SPECIAL_PAYLOAD)) {
/*
* If total number of sectors is less than the first segment
* size, something has gone terribly wrong.
*/
if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
blk_dump_rq_flags(req, "request botched");
req->__data_len = blk_rq_cur_bytes(req);
}
/* recalculate the number of segments */
blk_recalc_rq_segments(req);
}
return true;
}
EXPORT_SYMBOL_GPL(blk_update_request);
static bool blk_update_bidi_request(struct request *rq, blk_status_t error,
unsigned int nr_bytes,
unsigned int bidi_bytes)
{
if (blk_update_request(rq, error, nr_bytes))
return true;
/* Bidi request must be completed as a whole */
if (unlikely(blk_bidi_rq(rq)) &&
blk_update_request(rq->next_rq, error, bidi_bytes))
return true;
if (blk_queue_add_random(rq->q))
add_disk_randomness(rq->rq_disk);
return false;
}
/**
* blk_unprep_request - unprepare a request * @req: the request
*
* This function makes a request ready for complete resubmission (or
* completion). It happens only after all error handling is complete,
* so represents the appropriate moment to deallocate any resources
* that were allocated to the request in the prep_rq_fn. The queue
* lock is held when calling this.
*/
void blk_unprep_request(struct request *req)
{
struct request_queue *q = req->q;
req->rq_flags &= ~RQF_DONTPREP;
if (q->unprep_rq_fn)
q->unprep_rq_fn(q, req);
}
EXPORT_SYMBOL_GPL(blk_unprep_request);
void blk_finish_request(struct request *req, blk_status_t error)
{
struct request_queue *q = req->q;
lockdep_assert_held(req->q->queue_lock);
WARN_ON_ONCE(q->mq_ops);
if (req->rq_flags & RQF_STATS)
blk_stat_add(req);
if (req->rq_flags & RQF_QUEUED)
blk_queue_end_tag(q, req);
BUG_ON(blk_queued_rq(req));
if (unlikely(laptop_mode) && !blk_rq_is_passthrough(req))
laptop_io_completion(req->q->backing_dev_info);
blk_delete_timer(req);
if (req->rq_flags & RQF_DONTPREP)
blk_unprep_request(req);
blk_account_io_done(req);
if (req->end_io) {
wbt_done(req->q->rq_wb, &req->issue_stat);
req->end_io(req, error);
} else {
if (blk_bidi_rq(req))
__blk_put_request(req->next_rq->q, req->next_rq);
__blk_put_request(q, req);
}
}
EXPORT_SYMBOL(blk_finish_request);
/**
* blk_end_bidi_request - Complete a bidi request
* @rq: the request to complete
* @error: block status code
* @nr_bytes: number of bytes to complete @rq
* @bidi_bytes: number of bytes to complete @rq->next_rq
*
* Description:
* Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
* Drivers that supports bidi can safely call this member for any
* type of request, bidi or uni. In the later case @bidi_bytes is
* just ignored.
*
* Return:
* %false - we are done with this request * %true - still buffers pending for this request
**/
static bool blk_end_bidi_request(struct request *rq, blk_status_t error,
unsigned int nr_bytes, unsigned int bidi_bytes)
{
struct request_queue *q = rq->q;
unsigned long flags;
WARN_ON_ONCE(q->mq_ops);
if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
return true;
spin_lock_irqsave(q->queue_lock, flags);
blk_finish_request(rq, error);
spin_unlock_irqrestore(q->queue_lock, flags);
return false;
}
/**
* __blk_end_bidi_request - Complete a bidi request with queue lock held
* @rq: the request to complete
* @error: block status code
* @nr_bytes: number of bytes to complete @rq
* @bidi_bytes: number of bytes to complete @rq->next_rq
*
* Description:
* Identical to blk_end_bidi_request() except that queue lock is
* assumed to be locked on entry and remains so on return.
*
* Return:
* %false - we are done with this request
* %true - still buffers pending for this request
**/
static bool __blk_end_bidi_request(struct request *rq, blk_status_t error,
unsigned int nr_bytes, unsigned int bidi_bytes)
{
lockdep_assert_held(rq->q->queue_lock);
WARN_ON_ONCE(rq->q->mq_ops);
if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
return true;
blk_finish_request(rq, error);
return false;
}
/**
* blk_end_request - Helper function for drivers to complete the request.
* @rq: the request being processed
* @error: block status code
* @nr_bytes: number of bytes to complete
*
* Description:
* Ends I/O on a number of bytes attached to @rq.
* If @rq has leftover, sets it up for the next range of segments.
*
* Return:
* %false - we are done with this request
* %true - still buffers pending for this request
**/
bool blk_end_request(struct request *rq, blk_status_t error,
unsigned int nr_bytes)
{
WARN_ON_ONCE(rq->q->mq_ops);
return blk_end_bidi_request(rq, error, nr_bytes, 0);
}
EXPORT_SYMBOL(blk_end_request);
/**
* blk_end_request_all - Helper function for drives to finish the request.
* @rq: the request to finish
* @error: block status code
*
* Description:
* Completely finish @rq.
*/
void blk_end_request_all(struct request *rq, blk_status_t error)
{
bool pending;
unsigned int bidi_bytes = 0;
if (unlikely(blk_bidi_rq(rq)))
bidi_bytes = blk_rq_bytes(rq->next_rq);
pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
BUG_ON(pending);
}
EXPORT_SYMBOL(blk_end_request_all);
/**
* __blk_end_request - Helper function for drivers to complete the request.
* @rq: the request being processed
* @error: block status code
* @nr_bytes: number of bytes to complete
*
* Description:
* Must be called with queue lock held unlike blk_end_request().
*
* Return:
* %false - we are done with this request
* %true - still buffers pending for this request
**/
bool __blk_end_request(struct request *rq, blk_status_t error,
unsigned int nr_bytes)
{
lockdep_assert_held(rq->q->queue_lock);
WARN_ON_ONCE(rq->q->mq_ops);
return __blk_end_bidi_request(rq, error, nr_bytes, 0);
}
EXPORT_SYMBOL(__blk_end_request);
/**
* __blk_end_request_all - Helper function for drives to finish the request.
* @rq: the request to finish
* @error: block status code
*
* Description:
* Completely finish @rq. Must be called with queue lock held.
*/
void __blk_end_request_all(struct request *rq, blk_status_t error)
{
bool pending;
unsigned int bidi_bytes = 0;
lockdep_assert_held(rq->q->queue_lock);
WARN_ON_ONCE(rq->q->mq_ops);
if (unlikely(blk_bidi_rq(rq)))
bidi_bytes = blk_rq_bytes(rq->next_rq);
pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
BUG_ON(pending);
}
EXPORT_SYMBOL(__blk_end_request_all);
/** * __blk_end_request_cur - Helper function to finish the current request chunk.
* @rq: the request to finish the current chunk for
* @error: block status code
*
* Description:
* Complete the current consecutively mapped chunk from @rq. Must
* be called with queue lock held.
*
* Return:
* %false - we are done with this request
* %true - still buffers pending for this request
*/
bool __blk_end_request_cur(struct request *rq, blk_status_t error)
{
return __blk_end_request(rq, error, blk_rq_cur_bytes(rq));
}
EXPORT_SYMBOL(__blk_end_request_cur);
void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
struct bio *bio)
{
if (bio_has_data(bio))
rq->nr_phys_segments = bio_phys_segments(q, bio);
rq->__data_len = bio->bi_iter.bi_size;
rq->bio = rq->biotail = bio;
if (bio->bi_bdev)
rq->rq_disk = bio->bi_bdev->bd_disk;
}
#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
/**
* rq_flush_dcache_pages - Helper function to flush all pages in a request
* @rq: the request to be flushed
*
* Description:
* Flush all pages in @rq.
*/
void rq_flush_dcache_pages(struct request *rq)
{
struct req_iterator iter;
struct bio_vec bvec;
rq_for_each_segment(bvec, rq, iter)
flush_dcache_page(bvec.bv_page);
}
EXPORT_SYMBOL_GPL(rq_flush_dcache_pages);
#endif
/**
* blk_lld_busy - Check if underlying low-level drivers of a device are busy
* @q : the queue of the device being checked
*
* Description:
* Check if underlying low-level drivers of a device are busy.
* If the drivers want to export their busy state, they must set own
* exporting function using blk_queue_lld_busy() first.
*
* Basically, this function is used only by request stacking drivers
* to stop dispatching requests to underlying devices when underlying
* devices are busy. This behavior helps more I/O merging on the queue
* of the request stacking driver and prevents I/O throughput regression
* on burst I/O load.
*
* Return:
* 0 - Not busy (The request stacking driver should dispatch request)
* 1 - Busy (The request stacking driver should stop dispatching request)
*/
int blk_lld_busy(struct request_queue *q){
if (q->lld_busy_fn)
return q->lld_busy_fn(q);
return 0;
}
EXPORT_SYMBOL_GPL(blk_lld_busy);
/**
* blk_rq_unprep_clone - Helper function to free all bios in a cloned request
* @rq: the clone request to be cleaned up
*
* Description:
* Free all bios in @rq for a cloned request.
*/
void blk_rq_unprep_clone(struct request *rq)
{
struct bio *bio;
while ((bio = rq->bio) != NULL) {
rq->bio = bio->bi_next;
bio_put(bio);
}
}
EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
/*
* Copy attributes of the original request to the clone request.
* The actual data parts (e.g. ->cmd, ->sense) are not copied.
*/
static void __blk_rq_prep_clone(struct request *dst, struct request *src)
{
dst->cpu = src->cpu;
dst->__sector = blk_rq_pos(src);
dst->__data_len = blk_rq_bytes(src);
dst->nr_phys_segments = src->nr_phys_segments;
dst->ioprio = src->ioprio;
dst->extra_len = src->extra_len;
}
/**
* blk_rq_prep_clone - Helper function to setup clone request
* @rq: the request to be setup
* @rq_src: original request to be cloned
* @bs: bio_set that bios for clone are allocated from
* @gfp_mask: memory allocation mask for bio
* @bio_ctr: setup function to be called for each clone bio.
* Returns %0 for success, non %0 for failure.
* @data: private data to be passed to @bio_ctr
*
* Description:
* Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
* The actual data parts of @rq_src (e.g. ->cmd, ->sense)
* are not copied, and copying such parts is the caller's responsibility.
* Also, pages which the original bios are pointing to are not copied
* and the cloned bios just point same pages.
* So cloned bios must be completed before original bios, which means
* the caller must complete @rq before @rq_src.
*/
int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
struct bio_set *bs, gfp_t gfp_mask,
int (*bio_ctr)(struct bio *, struct bio *, void *),
void *data)
{
struct bio *bio, *bio_src;
if (!bs)
bs = fs_bio_set;
__rq_for_each_bio(bio_src, rq_src) {
bio = bio_clone_fast(bio_src, gfp_mask, bs);
if (!bio)
goto free_and_out;
if (bio_ctr && bio_ctr(bio, bio_src, data))
goto free_and_out;
if (rq->bio) {
rq->biotail->bi_next = bio;
rq->biotail = bio;
} else
rq->bio = rq->biotail = bio;
}
__blk_rq_prep_clone(rq, rq_src);
return 0;
free_and_out:
if (bio)
bio_put(bio);
blk_rq_unprep_clone(rq);
return -ENOMEM;
}
EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
int kblockd_schedule_work(struct work_struct *work)
{
return queue_work(kblockd_workqueue, work);
}
EXPORT_SYMBOL(kblockd_schedule_work);
int kblockd_schedule_work_on(int cpu, struct work_struct *work)
{
return queue_work_on(cpu, kblockd_workqueue, work);
}
EXPORT_SYMBOL(kblockd_schedule_work_on);
int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork,
unsigned long delay)
{
return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay);
}
EXPORT_SYMBOL(kblockd_mod_delayed_work_on);
int kblockd_schedule_delayed_work(struct delayed_work *dwork,
unsigned long delay)
{
return queue_delayed_work(kblockd_workqueue, dwork, delay);
}
EXPORT_SYMBOL(kblockd_schedule_delayed_work);
int kblockd_schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
unsigned long delay)
{
return queue_delayed_work_on(cpu, kblockd_workqueue, dwork, delay);
}
EXPORT_SYMBOL(kblockd_schedule_delayed_work_on);
/**
* blk_start_plug - initialize blk_plug and track it inside the task_struct
* @plug: The &struct blk_plug that needs to be initialized
*
* Description:
* Tracking blk_plug inside the task_struct will help with auto-flushing the
* pending I/O should the task end up blocking between blk_start_plug() and
* blk_finish_plug(). This is important from a performance perspective, but
* also ensures that we don't deadlock. For instance, if the task is blocking * for a memory allocation, memory reclaim could end up wanting to free a
* page belonging to that request that is currently residing in our private
* plug. By flushing the pending I/O when the process goes to sleep, we avoid
* this kind of deadlock.
*/
void blk_start_plug(struct blk_plug *plug)
{
struct task_struct *tsk = current;
/*
* If this is a nested plug, don't actually assign it.
*/
if (tsk->plug)
return;
INIT_LIST_HEAD(&plug->list);
INIT_LIST_HEAD(&plug->mq_list);
INIT_LIST_HEAD(&plug->cb_list);
/*
* Store ordering should not be needed here, since a potential
* preempt will imply a full memory barrier
*/
tsk->plug = plug;
}
EXPORT_SYMBOL(blk_start_plug);
static int plug_rq_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->q < rqb->q ||
(rqa->q == rqb->q && blk_rq_pos(rqa) < blk_rq_pos(rqb)));
}
/*
* If 'from_schedule' is true, then postpone the dispatch of requests
* until a safe kblockd context. We due this to avoid accidental big
* additional stack usage in driver dispatch, in places where the originally
* plugger did not intend it.
*/
static void queue_unplugged(struct request_queue *q, unsigned int depth,
bool from_schedule)
__releases(q->queue_lock)
{
lockdep_assert_held(q->queue_lock);
trace_block_unplug(q, depth, !from_schedule);
if (from_schedule)
blk_run_queue_async(q);
else
__blk_run_queue(q);
spin_unlock(q->queue_lock);
}
static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule)
{
LIST_HEAD(callbacks);
while (!list_empty(&plug->cb_list)) {
list_splice_init(&plug->cb_list, &callbacks);
while (!list_empty(&callbacks)) {
struct blk_plug_cb *cb = list_first_entry(&callbacks,
struct blk_plug_cb,
list);
list_del(&cb->list);
cb->callback(cb, from_schedule);
} }
}
struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data,
int size)
{
struct blk_plug *plug = current->plug;
struct blk_plug_cb *cb;
if (!plug)
return NULL;
list_for_each_entry(cb, &plug->cb_list, list)
if (cb->callback == unplug && cb->data == data)
return cb;
/* Not currently on the callback list */
BUG_ON(size < sizeof(*cb));
cb = kzalloc(size, GFP_ATOMIC);
if (cb) {
cb->data = data;
cb->callback = unplug;
list_add(&cb->list, &plug->cb_list);
}
return cb;
}
EXPORT_SYMBOL(blk_check_plugged);
void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
{
struct request_queue *q;
unsigned long flags;
struct request *rq;
LIST_HEAD(list);
unsigned int depth;
flush_plug_callbacks(plug, from_schedule);
if (!list_empty(&plug->mq_list))
blk_mq_flush_plug_list(plug, from_schedule);
if (list_empty(&plug->list))
return;
list_splice_init(&plug->list, &list);
list_sort(NULL, &list, plug_rq_cmp);
q = NULL;
depth = 0;
/*
* Save and disable interrupts here, to avoid doing it for every
* queue lock we have to take.
*/
local_irq_save(flags);
while (!list_empty(&list)) {
rq = list_entry_rq(list.next);
list_del_init(&rq->queuelist);
BUG_ON(!rq->q);
if (rq->q != q) {
/*
* This drops the queue lock
*/
if (q)
queue_unplugged(q, depth, from_schedule);
q = rq->q;
depth = 0;
spin_lock(q->queue_lock);
}
/*
* Short-circuit if @q is dead
*/
if (unlikely(blk_queue_dying(q))) {
__blk_end_request_all(rq, BLK_STS_IOERR);
continue;
}
/*
* rq is already accounted, so use raw insert
*/
if (op_is_flush(rq->cmd_flags))
__elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH);
else
__elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE);
depth++;
}
/*
* This drops the queue lock
*/
if (q)
queue_unplugged(q, depth, from_schedule);
local_irq_restore(flags);
}
void blk_finish_plug(struct blk_plug *plug)
{
if (plug != current->plug)
return;
blk_flush_plug_list(plug, false);
current->plug = NULL;
}
EXPORT_SYMBOL(blk_finish_plug);
#ifdef CONFIG_PM
/**
* blk_pm_runtime_init - Block layer runtime PM initialization routine
* @q: the queue of the device
* @dev: the device the queue belongs to
*
* Description:
* Initialize runtime-PM-related fields for @q and start auto suspend for
* @dev. Drivers that want to take advantage of request-based runtime PM
* should call this function after @dev has been initialized, and its
* request queue @q has been allocated, and runtime PM for it can not happen
* yet(either due to disabled/forbidden or its usage_count > 0). In most
* cases, driver should call this function before any I/O has taken place.
*
* This function takes care of setting up using auto suspend for the device,
* the autosuspend delay is set to -1 to make runtime suspend impossible
* until an updated value is either set by user or by driver. Drivers do
* not need to touch other autosuspend settings.
*
* The block layer runtime PM is request based, so only works for drivers
* that use request as their IO unit instead of those directly use bio's.
*/
void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
{
/* not support for RQF_PM and ->rpm_status in blk-mq yet */
if (q->mq_ops)
return;
q->dev = dev;
q->rpm_status = RPM_ACTIVE;
pm_runtime_set_autosuspend_delay(q->dev, -1); pm_runtime_use_autosuspend(q->dev);
}
EXPORT_SYMBOL(blk_pm_runtime_init);
/**
* blk_pre_runtime_suspend - Pre runtime suspend check
* @q: the queue of the device
*
* Description:
* This function will check if runtime suspend is allowed for the device
* by examining if there are any requests pending in the queue. If there
* are requests pending, the device can not be runtime suspended; otherwise,
* the queue's status will be updated to SUSPENDING and the driver can
* proceed to suspend the device.
*
* For the not allowed case, we mark last busy for the device so that
* runtime PM core will try to autosuspend it some time later.
*
* This function should be called near the start of the device's
* runtime_suspend callback.
*
* Return:
* 0 - OK to runtime suspend the device
* -EBUSY - Device should not be runtime suspended
*/
int blk_pre_runtime_suspend(struct request_queue *q)
{
int ret = 0;
if (!q->dev)
return ret;
spin_lock_irq(q->queue_lock);
if (q->nr_pending) {
ret = -EBUSY;
pm_runtime_mark_last_busy(q->dev);
} else {
q->rpm_status = RPM_SUSPENDING;
}
spin_unlock_irq(q->queue_lock);
return ret;
}
EXPORT_SYMBOL(blk_pre_runtime_suspend);
/**
* blk_post_runtime_suspend - Post runtime suspend processing
* @q: the queue of the device
* @err: return value of the device's runtime_suspend function
*
* Description:
* Update the queue's runtime status according to the return value of the
* device's runtime suspend function and mark last busy for the device so
* that PM core will try to auto suspend the device at a later time.
*
* This function should be called near the end of the device's
* runtime_suspend callback.
*/
void blk_post_runtime_suspend(struct request_queue *q, int err)
{
if (!q->dev)
return;
spin_lock_irq(q->queue_lock);
if (!err) {
q->rpm_status = RPM_SUSPENDED;
} else {
q->rpm_status = RPM_ACTIVE;
pm_runtime_mark_last_busy(q->dev);
}
spin_unlock_irq(q->queue_lock);}
EXPORT_SYMBOL(blk_post_runtime_suspend);
/**
* blk_pre_runtime_resume - Pre runtime resume processing
* @q: the queue of the device
*
* Description:
* Update the queue's runtime status to RESUMING in preparation for the
* runtime resume of the device.
*
* This function should be called near the start of the device's
* runtime_resume callback.
*/
void blk_pre_runtime_resume(struct request_queue *q)
{
if (!q->dev)
return;
spin_lock_irq(q->queue_lock);
q->rpm_status = RPM_RESUMING;
spin_unlock_irq(q->queue_lock);
}
EXPORT_SYMBOL(blk_pre_runtime_resume);
/**
* blk_post_runtime_resume - Post runtime resume processing
* @q: the queue of the device
* @err: return value of the device's runtime_resume function
*
* Description:
* Update the queue's runtime status according to the return value of the
* device's runtime_resume function. If it is successfully resumed, process
* the requests that are queued into the device's queue when it is resuming
* and then mark last busy and initiate autosuspend for it.
*
* This function should be called near the end of the device's
* runtime_resume callback.
*/
void blk_post_runtime_resume(struct request_queue *q, int err)
{
if (!q->dev)
return;
spin_lock_irq(q->queue_lock);
if (!err) {
q->rpm_status = RPM_ACTIVE;
__blk_run_queue(q);
pm_runtime_mark_last_busy(q->dev);
pm_request_autosuspend(q->dev);
} else {
q->rpm_status = RPM_SUSPENDED;
}
spin_unlock_irq(q->queue_lock);
}
EXPORT_SYMBOL(blk_post_runtime_resume);
/**
* blk_set_runtime_active - Force runtime status of the queue to be active
* @q: the queue of the device
*
* If the device is left runtime suspended during system suspend the resume
* hook typically resumes the device and corrects runtime status
* accordingly. However, that does not affect the queue runtime PM status
* which is still "suspended". This prevents processing requests from the
* queue.
*
* This function can be used in driver's resume hook to correct queue
* runtime PM status and re-enable peeking requests from the queue. It
* should be called before first request is added to the queue. */
void blk_set_runtime_active(struct request_queue *q)
{
spin_lock_irq(q->queue_lock);
q->rpm_status = RPM_ACTIVE;
pm_runtime_mark_last_busy(q->dev);
pm_request_autosuspend(q->dev);
spin_unlock_irq(q->queue_lock);
}
EXPORT_SYMBOL(blk_set_runtime_active);
#endif
int __init blk_dev_init(void)
{
BUILD_BUG_ON(REQ_OP_LAST >= (1 << REQ_OP_BITS));
BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 *
FIELD_SIZEOF(struct request, cmd_flags));
BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 *
FIELD_SIZEOF(struct bio, bi_opf));
/* used for unplugging and affects IO latency/throughput - HIGHPRI */
kblockd_workqueue = alloc_workqueue("kblockd",
WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
if (!kblockd_workqueue)
panic("Failed to create kblockd\n");
request_cachep = kmem_cache_create("blkdev_requests",
sizeof(struct request), 0, SLAB_PANIC, NULL);
blk_requestq_cachep = kmem_cache_create("request_queue",
sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
#ifdef CONFIG_DEBUG_FS
blk_debugfs_root = debugfs_create_dir("block", NULL);
#endif
return 0;
}