blk-core.c 48.6 KB
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/*
 * 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>
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 * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au>
 *	-  July2000
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 * 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>
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#include <linux/blk-mq.h>
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#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>
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#include <linux/task_io_accounting_ops.h>
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#include <linux/fault-inject.h>
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#include <linux/list_sort.h>
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#include <linux/delay.h>
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#include <linux/ratelimit.h>
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#include <linux/pm_runtime.h>
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#include <linux/blk-cgroup.h>
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#include <linux/debugfs.h>
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#include <linux/bpf.h>
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#define CREATE_TRACE_POINTS
#include <trace/events/block.h>
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#include "blk.h"
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#include "blk-mq.h"
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#include "blk-mq-sched.h"
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#include "blk-pm.h"
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#include "blk-rq-qos.h"
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#ifdef CONFIG_DEBUG_FS
struct dentry *blk_debugfs_root;
#endif

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EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
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EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
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EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
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EXPORT_TRACEPOINT_SYMBOL_GPL(block_split);
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EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
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DEFINE_IDA(blk_queue_ida);

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/*
 * For queue allocation
 */
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struct kmem_cache *blk_requestq_cachep;
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/*
 * Controlling structure to kblockd
 */
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static struct workqueue_struct *kblockd_workqueue;
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/**
 * blk_queue_flag_set - atomically set a queue flag
 * @flag: flag to be set
 * @q: request queue
 */
void blk_queue_flag_set(unsigned int flag, struct request_queue *q)
{
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	set_bit(flag, &q->queue_flags);
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}
EXPORT_SYMBOL(blk_queue_flag_set);

/**
 * blk_queue_flag_clear - atomically clear a queue flag
 * @flag: flag to be cleared
 * @q: request queue
 */
void blk_queue_flag_clear(unsigned int flag, struct request_queue *q)
{
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	clear_bit(flag, &q->queue_flags);
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}
EXPORT_SYMBOL(blk_queue_flag_clear);

/**
 * blk_queue_flag_test_and_set - atomically test and set a queue flag
 * @flag: flag to be set
 * @q: request queue
 *
 * Returns the previous value of @flag - 0 if the flag was not set and 1 if
 * the flag was already set.
 */
bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q)
{
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	return test_and_set_bit(flag, &q->queue_flags);
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}
EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set);

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void blk_rq_init(struct request_queue *q, struct request *rq)
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{
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	memset(rq, 0, sizeof(*rq));

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	INIT_LIST_HEAD(&rq->queuelist);
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	rq->q = q;
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	rq->__sector = (sector_t) -1;
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	INIT_HLIST_NODE(&rq->hash);
	RB_CLEAR_NODE(&rq->rb_node);
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	rq->tag = -1;
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	rq->internal_tag = -1;
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	rq->start_time_ns = ktime_get_ns();
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	rq->part = NULL;
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}
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EXPORT_SYMBOL(blk_rq_init);
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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" },
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	[BLK_STS_DEV_RESOURCE]	= { -EBUSY,	"device resource" },
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	[BLK_STS_AGAIN]		= { -EAGAIN,	"nonblocking retry" },
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	/* device mapper special case, should not leak out: */
	[BLK_STS_DM_REQUEUE]	= { -EREMCHG, "dm internal retry" },

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	/* 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;

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	if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
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		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;

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	if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
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		return;

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	printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu flags %x\n",
				__func__, blk_errors[idx].name,
				req->rq_disk ?  req->rq_disk->disk_name : "?",
				(unsigned long long)blk_rq_pos(req),
				req->cmd_flags);
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}

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static void req_bio_endio(struct request *rq, struct bio *bio,
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			  unsigned int nbytes, blk_status_t error)
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{
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	if (error)
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		bio->bi_status = error;
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	if (unlikely(rq->rq_flags & RQF_QUIET))
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		bio_set_flag(bio, BIO_QUIET);
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	bio_advance(bio, nbytes);
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	/* don't actually finish bio if it's part of flush sequence */
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	if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ))
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		bio_endio(bio);
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}

void blk_dump_rq_flags(struct request *rq, char *msg)
{
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	printk(KERN_INFO "%s: dev %s: flags=%llx\n", msg,
		rq->rq_disk ? rq->rq_disk->disk_name : "?",
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		(unsigned long long) rq->cmd_flags);
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	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));
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	printk(KERN_INFO "  bio %p, biotail %p, len %u\n",
	       rq->bio, rq->biotail, blk_rq_bytes(rq));
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}
EXPORT_SYMBOL(blk_dump_rq_flags);

/**
 * 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
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 *     that the callbacks might use. The caller must already have made sure
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 *     that its ->make_request_fn will not re-add plugging prior to calling
 *     this function.
 *
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 *     This function does not cancel any asynchronous activity arising
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 *     out of elevator or throttling code. That would require elevator_exit()
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 *     and blkcg_exit_queue() to be called with queue lock initialized.
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 *
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 */
void blk_sync_queue(struct request_queue *q)
{
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	del_timer_sync(&q->timeout);
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	cancel_work_sync(&q->timeout_work);
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	if (queue_is_mq(q)) {
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		struct blk_mq_hw_ctx *hctx;
		int i;

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		cancel_delayed_work_sync(&q->requeue_work);
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		queue_for_each_hw_ctx(q, hctx, i)
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			cancel_delayed_work_sync(&hctx->run_work);
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	}
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}
EXPORT_SYMBOL(blk_sync_queue);

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/**
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 * blk_set_pm_only - increment pm_only counter
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 * @q: request queue pointer
 */
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void blk_set_pm_only(struct request_queue *q)
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{
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	atomic_inc(&q->pm_only);
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}
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EXPORT_SYMBOL_GPL(blk_set_pm_only);
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void blk_clear_pm_only(struct request_queue *q)
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{
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	int pm_only;

	pm_only = atomic_dec_return(&q->pm_only);
	WARN_ON_ONCE(pm_only < 0);
	if (pm_only == 0)
		wake_up_all(&q->mq_freeze_wq);
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}
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EXPORT_SYMBOL_GPL(blk_clear_pm_only);
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void blk_put_queue(struct request_queue *q)
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{
	kobject_put(&q->kobj);
}
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EXPORT_SYMBOL(blk_put_queue);
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void blk_set_queue_dying(struct request_queue *q)
{
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	blk_queue_flag_set(QUEUE_FLAG_DYING, q);
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	/*
	 * 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);

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	if (queue_is_mq(q))
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		blk_mq_wake_waiters(q);
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	/* Make blk_queue_enter() reexamine the DYING flag. */
	wake_up_all(&q->mq_freeze_wq);
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}
EXPORT_SYMBOL_GPL(blk_set_queue_dying);

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/* Unconfigure the I/O scheduler and dissociate from the cgroup controller. */
void blk_exit_queue(struct request_queue *q)
{
	/*
	 * Since the I/O scheduler exit code may access cgroup information,
	 * perform I/O scheduler exit before disassociating from the block
	 * cgroup controller.
	 */
	if (q->elevator) {
		ioc_clear_queue(q);
		elevator_exit(q, q->elevator);
		q->elevator = NULL;
	}

	/*
	 * Remove all references to @q from the block cgroup controller before
	 * restoring @q->queue_lock to avoid that restoring this pointer causes
	 * e.g. blkcg_print_blkgs() to crash.
	 */
	blkcg_exit_queue(q);

	/*
	 * Since the cgroup code may dereference the @q->backing_dev_info
	 * pointer, only decrease its reference count after having removed the
	 * association with the block cgroup controller.
	 */
	bdi_put(q->backing_dev_info);
}

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/**
 * blk_cleanup_queue - shutdown a request queue
 * @q: request queue to shutdown
 *
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 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
 * put it.  All future requests will be failed immediately with -ENODEV.
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 */
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void blk_cleanup_queue(struct request_queue *q)
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{
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	/* mark @q DYING, no new request or merges will be allowed afterwards */
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	mutex_lock(&q->sysfs_lock);
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	blk_set_queue_dying(q);
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	blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q);
	blk_queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
	blk_queue_flag_set(QUEUE_FLAG_DYING, q);
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	mutex_unlock(&q->sysfs_lock);

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	/*
	 * Drain all requests queued before DYING marking. Set DEAD flag to
	 * prevent that q->request_fn() gets invoked after draining finished.
	 */
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	blk_freeze_queue(q);
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	rq_qos_exit(q);

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	blk_queue_flag_set(QUEUE_FLAG_DEAD, q);
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	/*
	 * make sure all in-progress dispatch are completed because
	 * blk_freeze_queue() can only complete all requests, and
	 * dispatch may still be in-progress since we dispatch requests
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	 * from more than one contexts.
	 *
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	 * We rely on driver to deal with the race in case that queue
	 * initialization isn't done.
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	 */
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	if (queue_is_mq(q) && blk_queue_init_done(q))
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		blk_mq_quiesce_queue(q);

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	/* for synchronous bio-based driver finish in-flight integrity i/o */
	blk_flush_integrity();

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	/* @q won't process any more request, flush async actions */
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	del_timer_sync(&q->backing_dev_info->laptop_mode_wb_timer);
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	blk_sync_queue(q);

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	/*
	 * I/O scheduler exit is only safe after the sysfs scheduler attribute
	 * has been removed.
	 */
	WARN_ON_ONCE(q->kobj.state_in_sysfs);

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	blk_exit_queue(q);
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	if (queue_is_mq(q))
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		blk_mq_free_queue(q);
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	percpu_ref_exit(&q->q_usage_counter);
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	/* @q is and will stay empty, shutdown and put */
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	blk_put_queue(q);
}
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EXPORT_SYMBOL(blk_cleanup_queue);

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struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
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{
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	return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE);
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}
EXPORT_SYMBOL(blk_alloc_queue);
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/**
 * blk_queue_enter() - try to increase q->q_usage_counter
 * @q: request queue pointer
 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PREEMPT
 */
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int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags)
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{
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	const bool pm = flags & BLK_MQ_REQ_PREEMPT;
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	while (true) {
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		bool success = false;
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		rcu_read_lock();
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		if (percpu_ref_tryget_live(&q->q_usage_counter)) {
			/*
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			 * The code that increments the pm_only counter is
			 * responsible for ensuring that that counter is
			 * globally visible before the queue is unfrozen.
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			 */
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			if (pm || !blk_queue_pm_only(q)) {
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				success = true;
			} else {
				percpu_ref_put(&q->q_usage_counter);
			}
		}
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		rcu_read_unlock();
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		if (success)
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			return 0;

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		if (flags & BLK_MQ_REQ_NOWAIT)
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			return -EBUSY;

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		/*
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		 * read pair of barrier in blk_freeze_queue_start(),
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		 * we need to order reading __PERCPU_REF_DEAD flag of
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		 * .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.
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		 */
		smp_rmb();

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		wait_event(q->mq_freeze_wq,
			   (atomic_read(&q->mq_freeze_depth) == 0 &&
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			    (pm || (blk_pm_request_resume(q),
				    !blk_queue_pm_only(q)))) ||
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			   blk_queue_dying(q));
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		if (blk_queue_dying(q))
			return -ENODEV;
	}
}

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);
}

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static void blk_rq_timed_out_timer(struct timer_list *t)
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{
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	struct request_queue *q = from_timer(q, t, timeout);
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	kblockd_schedule_work(&q->timeout_work);
}

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static void blk_timeout_work(struct work_struct *work)
{
}

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/**
 * blk_alloc_queue_node - allocate a request queue
 * @gfp_mask: memory allocation flags
 * @node_id: NUMA node to allocate memory from
 */
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struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
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{
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	struct request_queue *q;
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	int ret;
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	q = kmem_cache_alloc_node(blk_requestq_cachep,
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				gfp_mask | __GFP_ZERO, node_id);
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	if (!q)
		return NULL;

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	INIT_LIST_HEAD(&q->queue_head);
	q->last_merge = NULL;

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	q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask);
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	if (q->id < 0)
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		goto fail_q;
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	ret = bioset_init(&q->bio_split, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
	if (ret)
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		goto fail_id;

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	q->backing_dev_info = bdi_alloc_node(gfp_mask, node_id);
	if (!q->backing_dev_info)
		goto fail_split;

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	q->stats = blk_alloc_queue_stats();
	if (!q->stats)
		goto fail_stats;

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	q->backing_dev_info->ra_pages =
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			(VM_MAX_READAHEAD * 1024) / PAGE_SIZE;
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	q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK;
	q->backing_dev_info->name = "block";
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	q->node = node_id;
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	timer_setup(&q->backing_dev_info->laptop_mode_wb_timer,
		    laptop_mode_timer_fn, 0);
	timer_setup(&q->timeout, blk_rq_timed_out_timer, 0);
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	INIT_WORK(&q->timeout_work, blk_timeout_work);
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	INIT_LIST_HEAD(&q->icq_list);
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#ifdef CONFIG_BLK_CGROUP
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	INIT_LIST_HEAD(&q->blkg_list);
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#endif
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	kobject_init(&q->kobj, &blk_queue_ktype);
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#ifdef CONFIG_BLK_DEV_IO_TRACE
	mutex_init(&q->blk_trace_mutex);
#endif
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	mutex_init(&q->sysfs_lock);
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	spin_lock_init(&q->queue_lock);
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	init_waitqueue_head(&q->mq_freeze_wq);

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	/*
	 * 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))
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		goto fail_bdi;
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	if (blkcg_init_queue(q))
		goto fail_ref;

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	return q;
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fail_ref:
	percpu_ref_exit(&q->q_usage_counter);
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fail_bdi:
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	blk_free_queue_stats(q->stats);
fail_stats:
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	bdi_put(q->backing_dev_info);
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fail_split:
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	bioset_exit(&q->bio_split);
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fail_id:
	ida_simple_remove(&blk_queue_ida, q->id);
fail_q:
	kmem_cache_free(blk_requestq_cachep, q);
	return NULL;
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}
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EXPORT_SYMBOL(blk_alloc_queue_node);
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bool blk_get_queue(struct request_queue *q)
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{
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	if (likely(!blk_queue_dying(q))) {
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		__blk_get_queue(q);
		return true;
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	}

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	return false;
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}
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EXPORT_SYMBOL(blk_get_queue);
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/**
 * blk_get_request - allocate a request
 * @q: request queue to allocate a request for
 * @op: operation (REQ_OP_*) and REQ_* flags, e.g. REQ_SYNC.
 * @flags: BLK_MQ_REQ_* flags, e.g. BLK_MQ_REQ_NOWAIT.
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 */
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struct request *blk_get_request(struct request_queue *q, unsigned int op,
				blk_mq_req_flags_t flags)
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{
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	struct request *req;
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	WARN_ON_ONCE(op & REQ_NOWAIT);
	WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PREEMPT));
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	req = blk_mq_alloc_request(q, op, flags);
	if (!IS_ERR(req) && q->mq_ops->initialize_rq_fn)
		q->mq_ops->initialize_rq_fn(req);
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	return req;
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}
589
EXPORT_SYMBOL(blk_get_request);
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void blk_put_request(struct request *req)
{
593
	blk_mq_free_request(req);
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}
EXPORT_SYMBOL(blk_put_request);

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bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
			    struct bio *bio)
599
{
600
	const int ff = bio->bi_opf & REQ_FAILFAST_MASK;
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	if (!ll_back_merge_fn(q, req, bio))
		return false;

605
	trace_block_bio_backmerge(q, req, bio);
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	if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
		blk_rq_set_mixed_merge(req);

	req->biotail->bi_next = bio;
	req->biotail = bio;
612
	req->__data_len += bio->bi_iter.bi_size;
613

614
	blk_account_io_start(req, false);
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	return true;
}

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bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
			     struct bio *bio)
620
{
621
	const int ff = bio->bi_opf & REQ_FAILFAST_MASK;
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	if (!ll_front_merge_fn(q, req, bio))
		return false;

626
	trace_block_bio_frontmerge(q, req, bio);
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	if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
		blk_rq_set_mixed_merge(req);

	bio->bi_next = req->bio;
	req->bio = bio;

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	req->__sector = bio->bi_iter.bi_sector;
	req->__data_len += bio->bi_iter.bi_size;
636

637
	blk_account_io_start(req, false);
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	return true;
}

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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->nr_phys_segments = segments + 1;

	blk_account_io_start(req, false);
	return true;
no_merge:
	req_set_nomerge(q, req);
	return false;
}

664
/**
665
 * blk_attempt_plug_merge - try to merge with %current's plugged list
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 * @q: request_queue new bio is being queued at
 * @bio: new bio being queued
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 * @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)
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 *
 * 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.
 *
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 * 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.
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 *
 * Caller must ensure !blk_queue_nomerges(q) beforehand.
684
 */
685
bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
686
			    struct request **same_queue_rq)
687 688 689
{
	struct blk_plug *plug;
	struct request *rq;
690
	struct list_head *plug_list;
691

692
	plug = current->plug;
693
	if (!plug)
694
		return false;
695

696
	plug_list = &plug->mq_list;
697 698

	list_for_each_entry_reverse(rq, plug_list, queuelist) {
699
		bool merged = false;
700

701
		if (rq->q == q && same_queue_rq) {
702 703 704 705 706
			/*
			 * Only blk-mq multiple hardware queues case checks the
			 * rq in the same queue, there should be only one such
			 * rq in a queue
			 **/
707
			*same_queue_rq = rq;
708
		}
709

710
		if (rq->q != q || !blk_rq_merge_ok(rq, bio))
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			continue;

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		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;
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		case ELEVATOR_DISCARD_MERGE:
			merged = bio_attempt_discard_merge(q, rq, bio);
			break;
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		default:
			break;
725
		}
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		if (merged)
			return true;
729
	}
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	return false;
732 733
}

734
void blk_init_request_from_bio(struct request *req, struct bio *bio)
735
{
736
	if (bio->bi_opf & REQ_RAHEAD)
737
		req->cmd_flags |= REQ_FAILFAST_MASK;
738

739
	req->__sector = bio->bi_iter.bi_sector;
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	req->ioprio = bio_prio(bio);
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	req->write_hint = bio->bi_write_hint;
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	blk_rq_bio_prep(req->q, req, bio);
743
}
744
EXPORT_SYMBOL_GPL(blk_init_request_from_bio);
745

746
static void handle_bad_sector(struct bio *bio, sector_t maxsector)
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{
	char b[BDEVNAME_SIZE];

	printk(KERN_INFO "attempt to access beyond end of device\n");
751
	printk(KERN_INFO "%s: rw=%d, want=%Lu, limit=%Lu\n",
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			bio_devname(bio, b), bio->bi_opf,
753
			(unsigned long long)bio_end_sector(bio),
754
			(long long)maxsector);
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}

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#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);

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static bool should_fail_request(struct hd_struct *part, unsigned int bytes)
768
{
769
	return part->make_it_fail && should_fail(&fail_make_request, bytes);
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}

static int __init fail_make_request_debugfs(void)
{
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	struct dentry *dir = fault_create_debugfs_attr("fail_make_request",
						NULL, &fail_make_request);

777
	return PTR_ERR_OR_ZERO(dir);
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}

late_initcall(fail_make_request_debugfs);

#else /* CONFIG_FAIL_MAKE_REQUEST */

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static inline bool should_fail_request(struct hd_struct *part,
					unsigned int bytes)
786
{
787
	return false;
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}

#endif /* CONFIG_FAIL_MAKE_REQUEST */

792 793
static inline bool bio_check_ro(struct bio *bio, struct hd_struct *part)
{
794 795
	const int op = bio_op(bio);

796
	if (part->policy && op_is_write(op)) {
797 798
		char b[BDEVNAME_SIZE];

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		if (op_is_flush(bio->bi_opf) && !bio_sectors(bio))
			return false;

802
		WARN_ONCE(1,
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		       "generic_make_request: Trying to write "
			"to read-only block-device %s (partno %d)\n",
			bio_devname(bio, b), part->partno);
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		/* Older lvm-tools actually trigger this */
		return false;
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	}

	return false;
}

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static noinline int should_fail_bio(struct bio *bio)
{
	if (should_fail_request(&bio->bi_disk->part0, bio->bi_iter.bi_size))
		return -EIO;
	return 0;
}
ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO);

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/*
 * Check whether this bio extends beyond the end of the device or partition.
 * This may well happen - the kernel calls bread() without checking the size of
 * the device, e.g., when mounting a file system.
 */
static inline int bio_check_eod(struct bio *bio, sector_t maxsector)
{
	unsigned int nr_sectors = bio_sectors(bio);

	if (nr_sectors && maxsector &&
	    (nr_sectors > maxsector ||
	     bio->bi_iter.bi_sector > maxsector - nr_sectors)) {
		handle_bad_sector(bio, maxsector);
		return -EIO;
	}
	return 0;
}

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/*
 * Remap block n of partition p to block n+start(p) of the disk.
 */
static inline int blk_partition_remap(struct bio *bio)
{
	struct hd_struct *p;
845
	int ret = -EIO;
846

847 848
	rcu_read_lock();
	p = __disk_get_part(bio->bi_disk, bio->bi_partno);
849 850 851 852 853
	if (unlikely(!p))
		goto out;
	if (unlikely(should_fail_request(p, bio->bi_iter.bi_size)))
		goto out;
	if (unlikely(bio_check_ro(bio, p)))
854 855
		goto out;

856 857 858 859
	/*
	 * 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.
	 */
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	if (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET) {
		if (bio_check_eod(bio, part_nr_sects_read(p)))
			goto out;
		bio->bi_iter.bi_sector += p->start_sect;
		trace_block_bio_remap(bio->bi_disk->queue, bio, part_devt(p),
				      bio->bi_iter.bi_sector - p->start_sect);
	}
867
	bio->bi_partno = 0;
868
	ret = 0;
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out:
	rcu_read_unlock();
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	return ret;
}

874 875
static noinline_for_stack bool
generic_make_request_checks(struct bio *bio)
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{
877
	struct request_queue *q;
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	int nr_sectors = bio_sectors(bio);
879
	blk_status_t status = BLK_STS_IOERR;
880
	char b[BDEVNAME_SIZE];
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	might_sleep();

884
	q = bio->bi_disk->queue;
885 886 887 888
	if (unlikely(!q)) {
		printk(KERN_ERR
		       "generic_make_request: Trying to access "
			"nonexistent block-device %s (%Lu)\n",
889
			bio_devname(bio, b), (long long)bio->bi_iter.bi_sector);
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		goto end_io;
	}
892

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	/*
	 * For a REQ_NOWAIT based request, return -EOPNOTSUPP
	 * if queue is not a request based queue.
	 */
897
	if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_mq(q))
898 899
		goto not_supported;

900
	if (should_fail_bio(bio))
901
		goto end_io;
902

903 904
	if (bio->bi_partno) {
		if (unlikely(blk_partition_remap(bio)))
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			goto end_io;
	} else {
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		if (unlikely(bio_check_ro(bio, &bio->bi_disk->part0)))
			goto end_io;
		if (unlikely(bio_check_eod(bio, get_capacity(bio->bi_disk))))
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			goto end_io;
	}
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	/*
	 * Filter flush bio's early so that make_request based
	 * drivers without flush support don't have to worry
	 * about them.
	 */
918
	if (op_is_flush(bio->bi_opf) &&
919
	    !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) {
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		bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA);
921
		if (!nr_sectors) {
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			status = BLK_STS_OK;
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			goto end_io;
		}
925
	}
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	if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
		bio->bi_opf &= ~REQ_HIPRI;

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	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:
940
		if (!q->limits.max_write_same_sectors)
941
			goto not_supported;
942
		break;
943
	case REQ_OP_ZONE_RESET:
944
		if (!blk_queue_is_zoned(q))
945
			goto not_supported;
946
		break;
947
	case REQ_OP_WRITE_ZEROES:
948
		if (!q->limits.max_write_zeroes_sectors)
949 950
			goto not_supported;
		break;
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	default:
		break;
953
	}
954

955 956 957 958 959 960 961 962
	/*
	 * 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);

963 964
	if (!blkcg_bio_issue_check(q, bio))
		return false;
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	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);
	}
973
	return true;
974

975
not_supported:
976
	status = BLK_STS_NOTSUPP;
977
end_io:
978
	bio->bi_status = status;
979
	bio_endio(bio);
980
	return false;
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}

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/**
 * 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.
1006
 */
1007
blk_qc_t generic_make_request(struct bio *bio)
1008
{
1009 1010 1011 1012 1013 1014 1015 1016
	/*
	 * 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];
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	blk_mq_req_flags_t flags = 0;
	struct request_queue *q = bio->bi_disk->queue;
1019
	blk_qc_t ret = BLK_QC_T_NONE;
1020

1021 1022
	if (bio->bi_opf & REQ_NOWAIT)
		flags = BLK_MQ_REQ_NOWAIT;
1023 1024 1025
	if (bio_flagged(bio, BIO_QUEUE_ENTERED))
		blk_queue_enter_live(q);
	else if (blk_queue_enter(q, flags) < 0) {
1026 1027 1028 1029 1030 1031 1032
		if (!blk_queue_dying(q) && (bio->bi_opf & REQ_NOWAIT))
			bio_wouldblock_error(bio);
		else
			bio_io_error(bio);
		return ret;
	}

1033
	if (!generic_make_request_checks(bio))
1034
		goto out;
1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045

	/*
	 * 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
	 */
1046
	if (current->bio_list) {
1047
		bio_list_add(&current->bio_list[0], bio);
1048
		goto out;
1049
	}
1050

1051 1052 1053 1054 1055
	/* 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
1056 1057
	 * we assign bio_list to a pointer to the bio_list_on_stack,
	 * thus initialising the bio_list of new bios to be
1058
	 * added.  ->make_request() may indeed add some more bios
1059 1060 1061
	 * 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
1062
	 * of the top of the list (no pretending) and so remove it from
1063
	 * bio_list, and call into ->make_request() again.
1064 1065
	 */
	BUG_ON(bio->bi_next);
1066 1067
	bio_list_init(&bio_list_on_stack[0]);
	current->bio_list = bio_list_on_stack;
1068
	do {
1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082
		bool enter_succeeded = true;

		if (unlikely(q != bio->bi_disk->queue)) {
			if (q)
				blk_queue_exit(q);
			q = bio->bi_disk->queue;
			flags = 0;
			if (bio->bi_opf & REQ_NOWAIT)
				flags = BLK_MQ_REQ_NOWAIT;
			if (blk_queue_enter(q, flags) < 0) {
				enter_succeeded = false;
				q = NULL;
			}
		}
1083

1084
		if (enter_succeeded) {
1085 1086 1087
			struct bio_list lower, same;

			/* Create a fresh bio_list for all subordinate requests */
1088 1089
			bio_list_on_stack[1] = bio_list_on_stack[0];
			bio_list_init(&bio_list_on_stack[0]);
1090
			ret = q->make_request_fn(q, bio);
1091

1092 1093 1094 1095 1096
			/* sort new bios into those for a lower level
			 * and those for the same level
			 */
			bio_list_init(&lower);
			bio_list_init(&same);
1097
			while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL)
1098
				if (q == bio->bi_disk->queue)
1099 1100 1101 1102
					bio_list_add(&same, bio);
				else
					bio_list_add(&lower, bio);
			/* now assemble so we handle the lowest level first */
1103 1104 1105
			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]);
1106
		} else {
1107 1108 1109 1110 1111
			if (unlikely(!blk_queue_dying(q) &&
					(bio->bi_opf & REQ_NOWAIT)))
				bio_wouldblock_error(bio);
			else
				bio_io_error(bio);
1112
		}
1113
		bio = bio_list_pop(&bio_list_on_stack[0]);
1114
	} while (bio);
1115
	current->bio_list = NULL; /* deactivate */
1116 1117

out:
1118 1119
	if (q)
		blk_queue_exit(q);
1120
	return ret;
1121
}
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EXPORT_SYMBOL(generic_make_request);

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/**
 * direct_make_request - hand a buffer directly to its device driver for I/O
 * @bio:  The bio describing the location in memory and on the device.
 *
 * This function behaves like generic_make_request(), but does not protect
 * against recursion.  Must only be used if the called driver is known
 * to not call generic_make_request (or direct_make_request) again from
 * its make_request function.  (Calling direct_make_request again from
 * a workqueue is perfectly fine as that doesn't recurse).
 */
blk_qc_t direct_make_request(struct bio *bio)
{
	struct request_queue *q = bio->bi_disk->queue;
	bool nowait = bio->bi_opf & REQ_NOWAIT;
	blk_qc_t ret;

	if (!generic_make_request_checks(bio))
		return BLK_QC_T_NONE;

1143
	if (unlikely(blk_queue_enter(q, nowait ? BLK_MQ_REQ_NOWAIT : 0))) {
1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157
		if (nowait && !blk_queue_dying(q))
			bio->bi_status = BLK_STS_AGAIN;
		else
			bio->bi_status = BLK_STS_IOERR;
		bio_endio(bio);
		return BLK_QC_T_NONE;
	}

	ret = q->make_request_fn(q, bio);
	blk_queue_exit(q);
	return ret;
}
EXPORT_SYMBOL_GPL(direct_make_request);

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/**
1159
 * submit_bio - submit a bio to the block device layer for I/O
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 * @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
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 * interfaces; @bio must be presetup and ready for I/O.
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 *
 */
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blk_qc_t submit_bio(struct bio *bio)
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{
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	/*
	 * If it's a regular read/write or a barrier with data attached,
	 * go through the normal accounting stuff before submission.
	 */
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	if (bio_has_data(bio)) {
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		unsigned int count;

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		if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME))
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			count = queue_logical_block_size(bio->bi_disk->queue) >> 9;
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		else
			count = bio_sectors(bio);

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		if (op_is_write(bio_op(bio))) {
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			count_vm_events(PGPGOUT, count);
		} else {
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			task_io_account_read(bio->bi_iter.bi_size);
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			count_vm_events(PGPGIN, count);
		}

		if (unlikely(block_dump)) {
			char b[BDEVNAME_SIZE];
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			printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n",
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			current->comm, task_pid_nr(current),
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				op_is_write(bio_op(bio)) ? "WRITE" : "READ",
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				(unsigned long long)bio->bi_iter.bi_sector,
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				bio_devname(bio, b), count);
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		}
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	}

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	return generic_make_request(bio);
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}
EXPORT_SYMBOL(submit_bio);

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/**
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 * blk_cloned_rq_check_limits - Helper function to check a cloned request
 *                              for new the queue limits
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 * @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
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 *    limits when retrying requests on other queues. Those requests need
 *    to be checked against the new queue limits again during dispatch.
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 */
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static int blk_cloned_rq_check_limits(struct request_queue *q,
				      struct request *rq)
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{
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	if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, req_op(rq))) {
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		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);