path: root/block/blk-core.c

// SPDX-License-Identifier: GPL-2.0
/*
 * 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/bio.h>
#include <linux/blkdev.h>
#include <linux/blk-pm.h>
#include <linux/blk-integrity.h>
#include <linux/highmem.h>
#include <linux/mm.h>
#include <linux/pagemap.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/t10-pi.h>
#include <linux/debugfs.h>
#include <linux/bpf.h>
#include <linux/part_stat.h>
#include <linux/sched/sysctl.h>
#include <linux/blk-crypto.h>

#define CREATE_TRACE_POINTS
#include <trace/events/block.h>

#include "blk.h"
#include "blk-mq-sched.h"
#include "blk-pm.h"
#include "blk-cgroup.h"
#include "blk-throttle.h"
#include "blk-ioprio.h"

struct dentry *blk_debugfs_root;

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);
EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_insert);

static DEFINE_IDA(blk_queue_ida);

/*
 * For queue allocation
 */
static struct kmem_cache *blk_requestq_cachep;

/*
 * Controlling structure to kblockd
 */
static struct workqueue_struct *kblockd_workqueue;

/**
 * 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)
{
	set_bit(flag, &q->queue_flags);
}
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)
{
	clear_bit(flag, &q->queue_flags);
}
EXPORT_SYMBOL(blk_queue_flag_clear);

#define REQ_OP_NAME(name) [REQ_OP_##name] = #name
static const char *const blk_op_name[] = {
	REQ_OP_NAME(READ),
	REQ_OP_NAME(WRITE),
	REQ_OP_NAME(FLUSH),
	REQ_OP_NAME(DISCARD),
	REQ_OP_NAME(SECURE_ERASE),
	REQ_OP_NAME(ZONE_RESET),
	REQ_OP_NAME(ZONE_RESET_ALL),
	REQ_OP_NAME(ZONE_OPEN),
	REQ_OP_NAME(ZONE_CLOSE),
	REQ_OP_NAME(ZONE_FINISH),
	REQ_OP_NAME(ZONE_APPEND),
	REQ_OP_NAME(WRITE_ZEROES),
	REQ_OP_NAME(DRV_IN),
	REQ_OP_NAME(DRV_OUT),
};
#undef REQ_OP_NAME

/**
 * blk_op_str - Return string XXX in the REQ_OP_XXX.
 * @op: REQ_OP_XXX.
 *
 * Description: Centralize block layer function to convert REQ_OP_XXX into
 * string format. Useful in the debugging and tracing bio or request. For
 * invalid REQ_OP_XXX it returns string "UNKNOWN".
 */
inline const char *blk_op_str(enum req_op op)
{
	const char *op_str = "UNKNOWN";

	if (op < ARRAY_SIZE(blk_op_name) && blk_op_name[op])
		op_str = blk_op_name[op];

	return op_str;
}
EXPORT_SYMBOL_GPL(blk_op_str);

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_RESV_CONFLICT]	= { -EBADE,	"reservation conflict" },
	[BLK_STS_MEDIUM]	= { -ENODATA,	"critical medium" },
	[BLK_STS_PROTECTION]	= { -EILSEQ,	"protection" },
	[BLK_STS_RESOURCE]	= { -ENOMEM,	"kernel resource" },
	[BLK_STS_DEV_RESOURCE]	= { -EBUSY,	"device resource" },
	[BLK_STS_AGAIN]		= { -EAGAIN,	"nonblocking retry" },
	[BLK_STS_OFFLINE]	= { -ENODEV,	"device offline" },

	/* device mapper special case, should not leak out: */
	[BLK_STS_DM_REQUEUE]	= { -EREMCHG, "dm internal retry" },

	/* zone device specific errors */
	[BLK_STS_ZONE_OPEN_RESOURCE]	= { -ETOOMANYREFS, "open zones exceeded" },
	[BLK_STS_ZONE_ACTIVE_RESOURCE]	= { -EOVERFLOW, "active zones exceeded" },

	/* Command duration limit device-side timeout */
	[BLK_STS_DURATION_LIMIT]	= { -ETIME, "duration limit exceeded" },

	[BLK_STS_INVAL]		= { -EINVAL,	"invalid" },

	/* 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);

const char *blk_status_to_str(blk_status_t status)
{
	int idx = (__force int)status;

	if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
		return "<null>";
	return blk_errors[idx].name;
}
EXPORT_SYMBOL_GPL(blk_status_to_str);

/**
 * 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 ->submit_bio 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);
	cancel_work_sync(&q->timeout_work);
}
EXPORT_SYMBOL(blk_sync_queue);

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

void blk_clear_pm_only(struct request_queue *q)
{
	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);
}
EXPORT_SYMBOL_GPL(blk_clear_pm_only);

static void blk_free_queue_rcu(struct rcu_head *rcu_head)
{
	struct request_queue *q = container_of(rcu_head,
			struct request_queue, rcu_head);

	percpu_ref_exit(&q->q_usage_counter);
	kmem_cache_free(blk_requestq_cachep, q);
}

static void blk_free_queue(struct request_queue *q)
{
	blk_free_queue_stats(q->stats);
	if (queue_is_mq(q))
		blk_mq_release(q);

	ida_free(&blk_queue_ida, q->id);
	call_rcu(&q->rcu_head, blk_free_queue_rcu);
}

/**
 * blk_put_queue - decrement the request_queue refcount
 * @q: the request_queue structure to decrement the refcount for
 *
 * Decrements the refcount of the request_queue and free it when the refcount
 * reaches 0.
 */
void blk_put_queue(struct request_queue *q)
{
	if (refcount_dec_and_test(&q->refs))
		blk_free_queue(q);
}
EXPORT_SYMBOL(blk_put_queue);

void blk_queue_start_drain(struct request_queue *q)
{
	/*
	 * 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 (queue_is_mq(q))
		blk_mq_wake_waiters(q);
	/* Make blk_queue_enter() reexamine the DYING flag. */
	wake_up_all(&q->mq_freeze_wq);
}

/**
 * blk_queue_enter() - try to increase q->q_usage_counter
 * @q: request queue pointer
 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PM
 */
int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags)
{
	const bool pm = flags & BLK_MQ_REQ_PM;

	while (!blk_try_enter_queue(q, pm)) {
		if (flags & BLK_MQ_REQ_NOWAIT)
			return -EAGAIN;

		/*
		 * 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();
		wait_event(q->mq_freeze_wq,
			   (!q->mq_freeze_depth &&
			    blk_pm_resume_queue(pm, q)) ||
			   blk_queue_dying(q));
		if (blk_queue_dying(q))
			return -ENODEV;
	}

	return 0;
}

int __bio_queue_enter(struct request_queue *q, struct bio *bio)
{
	while (!blk_try_enter_queue(q, false)) {
		struct gendisk *disk = bio->bi_bdev->bd_disk;

		if (bio->bi_opf & REQ_NOWAIT) {
			if (test_bit(GD_DEAD, &disk->state))
				goto dead;
			bio_wouldblock_error(bio);
			return -EAGAIN;
		}

		/*
		 * 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();
		wait_event(q->mq_freeze_wq,
			   (!q->mq_freeze_depth &&
			    blk_pm_resume_queue(false, q)) ||
			   test_bit(GD_DEAD, &disk->state));
		if (test_bit(GD_DEAD, &disk->state))
			goto dead;
	}

	return 0;
dead:
	bio_io_error(bio);
	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);
}

static void blk_rq_timed_out_timer(struct timer_list *t)
{
	struct request_queue *q = from_timer(q, t, timeout);

	kblockd_schedule_work(&q->timeout_work);
}

static void blk_timeout_work(struct work_struct *work)
{
}

struct request_queue *blk_alloc_queue(struct queue_limits *lim, int node_id)
{
	struct request_queue *q;
	int error;

	q = kmem_cache_alloc_node(blk_requestq_cachep, GFP_KERNEL | __GFP_ZERO,
				  node_id);
	if (!q)
		return ERR_PTR(-ENOMEM);

	q->last_merge = NULL;

	q->id = ida_alloc(&blk_queue_ida, GFP_KERNEL);
	if (q->id < 0) {
		error = q->id;
		goto fail_q;
	}

	q->stats = blk_alloc_queue_stats();
	if (!q->stats) {
		error = -ENOMEM;
		goto fail_id;
	}

	error = blk_set_default_limits(lim);
	if (error)
		goto fail_stats;
	q->limits = *lim;

	q->node = node_id;

	atomic_set(&q->nr_active_requests_shared_tags, 0);

	timer_setup(&q->timeout, blk_rq_timed_out_timer, 0);
	INIT_WORK(&q->timeout_work, blk_timeout_work);
	INIT_LIST_HEAD(&q->icq_list);

	refcount_set(&q->refs, 1);
	mutex_init(&q->debugfs_mutex);
	mutex_init(&q->sysfs_lock);
	mutex_init(&q->sysfs_dir_lock);
	mutex_init(&q->limits_lock);
	mutex_init(&q->rq_qos_mutex);
	spin_lock_init(&q->queue_lock);

	init_waitqueue_head(&q->mq_freeze_wq);
	mutex_init(&q->mq_freeze_lock);

	blkg_init_queue(q);

	/*
	 * Init percpu_ref in atomic mode so that it's faster to shutdown.
	 * See blk_register_queue() for details.
	 */
	error = percpu_ref_init(&q->q_usage_counter,
				blk_queue_usage_counter_release,
				PERCPU_REF_INIT_ATOMIC, GFP_KERNEL);
	if (error)
		goto fail_stats;

	q->nr_requests = BLKDEV_DEFAULT_RQ;

	return q;

fail_stats:
	blk_free_queue_stats(q->stats);
fail_id:
	ida_free(&blk_queue_ida, q->id);
fail_q:
	kmem_cache_free(blk_requestq_cachep, q);
	return ERR_PTR(error);
}

/**
 * blk_get_queue - increment the request_queue refcount
 * @q: the request_queue structure to increment the refcount for
 *
 * Increment the refcount of the request_queue kobject.
 *
 * Context: Any context.
 */
bool blk_get_queue(struct request_queue *q)
{
	if (unlikely(blk_queue_dying(q)))
		return false;
	refcount_inc(&q->refs);
	return true;
}
EXPORT_SYMBOL(blk_get_queue);

#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);

bool should_fail_request(struct block_device *part, unsigned int bytes)
{
	return bdev_test_flag(part, BD_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);
#endif /* CONFIG_FAIL_MAKE_REQUEST */

static inline void bio_check_ro(struct bio *bio)
{
	if (op_is_write(bio_op(bio)) && bdev_read_only(bio->bi_bdev)) {
		if (op_is_flush(bio->bi_opf) && !bio_sectors(bio))
			return;

		if (bdev_test_flag(bio->bi_bdev, BD_RO_WARNED))
			return;

		bdev_set_flag(bio->bi_bdev, BD_RO_WARNED);

		/*
		 * Use ioctl to set underlying disk of raid/dm to read-only
		 * will trigger this.
		 */
		pr_warn("Trying to write to read-only block-device %pg\n",
			bio->bi_bdev);
	}
}

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

/*
 * 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 = bdev_nr_sectors(bio->bi_bdev);
	unsigned int nr_sectors = bio_sectors(bio);

	if (nr_sectors &&
	    (nr_sectors > maxsector ||
	     bio->bi_iter.bi_sector > maxsector - nr_sectors)) {
		pr_info_ratelimited("%s: attempt to access beyond end of device\n"
				    "%pg: rw=%d, sector=%llu, nr_sectors = %u limit=%llu\n",
				    current->comm, bio->bi_bdev, bio->bi_opf,
				    bio->bi_iter.bi_sector, nr_sectors, maxsector);
		return -EIO;
	}
	return 0;
}

/*
 * Remap block n of partition p to block n+start(p) of the disk.
 */
static int blk_partition_remap(struct bio *bio)
{
	struct block_device *p = bio->bi_bdev;

	if (unlikely(should_fail_request(p, bio->bi_iter.bi_size)))
		return -EIO;
	if (bio_sectors(bio)) {
		bio->bi_iter.bi_sector += p->bd_start_sect;
		trace_block_bio_remap(bio, p->bd_dev,
				      bio->bi_iter.bi_sector -
				      p->bd_start_sect);
	}
	bio_set_flag(bio, BIO_REMAPPED);
	return 0;
}

/*
 * Check write append to a zoned block device.
 */
static inline blk_status_t blk_check_zone_append(struct request_queue *q,
						 struct bio *bio)
{
	int nr_sectors = bio_sectors(bio);

	/* Only applicable to zoned block devices */
	if (!bdev_is_zoned(bio->bi_bdev))
		return BLK_STS_NOTSUPP;

	/* The bio sector must point to the start of a sequential zone */
	if (!bdev_is_zone_start(bio->bi_bdev, bio->bi_iter.bi_sector))
		return BLK_STS_IOERR;

	/*
	 * Not allowed to cross zone boundaries. Otherwise, the BIO will be
	 * split and could result in non-contiguous sectors being written in
	 * different zones.
	 */
	if (nr_sectors > q->limits.chunk_sectors)
		return BLK_STS_IOERR;

	/* Make sure the BIO is small enough and will not get split */
	if (nr_sectors > queue_max_zone_append_sectors(q))
		return BLK_STS_IOERR;

	bio->bi_opf |= REQ_NOMERGE;

	return BLK_STS_OK;
}

static void __submit_bio(struct bio *bio)
{
	/* If plug is not used, add new plug here to cache nsecs time. */
	struct blk_plug plug;

	if (unlikely(!blk_crypto_bio_prep(&bio)))
		return;

	blk_start_plug(&plug);

	if (!bdev_test_flag(bio->bi_bdev, BD_HAS_SUBMIT_BIO)) {
		blk_mq_submit_bio(bio);
	} else if (likely(bio_queue_enter(bio) == 0)) {
		struct gendisk *disk = bio->bi_bdev->bd_disk;

		disk->fops->submit_bio(bio);
		blk_queue_exit(disk->queue);
	}

	blk_finish_plug(&plug);
}

/*
 * The loop in this function 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.  ->submit_bio() may indeed add some more
 *    bios through a recursive call to submit_bio_noacct.  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 ->submit_bio()
 *    again.
 *
 * bio_list_on_stack[0] contains bios submitted by