xref: /linux/block/blk.h (revision 55ab7e14222e5f0b0fd9f7711ca391d2924b35e3)

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef BLK_INTERNAL_H
#define BLK_INTERNAL_H

#include <linux/bio-integrity.h>
#include <linux/blk-crypto.h>
#include <linux/part_stat.h>
#include <linux/lockdep.h>
#include <linux/memblock.h>	/* for max_pfn/max_low_pfn */
#include <linux/sched/sysctl.h>
#include <linux/timekeeping.h>
#include <xen/xen.h>
#include "blk-crypto-internal.h"

struct elv_change_ctx;

/*
 * Default upper limit for the software max_sectors limit used for regular I/Os.
 * This can be increased through sysfs.
 *
 * This should not be confused with the max_hw_sector limit that is entirely
 * controlled by the block device driver, usually based on hardware limits.
 */
#define BLK_DEF_MAX_SECTORS_CAP	(SZ_4M >> SECTOR_SHIFT)

#define	BLK_DEV_MAX_SECTORS	(LLONG_MAX >> 9)
#define	BLK_MIN_SEGMENT_SIZE	4096

/* Max future timer expiry for timeouts */
#define BLK_MAX_TIMEOUT		(5 * HZ)

extern const struct kobj_type blk_queue_ktype;
extern struct dentry *blk_debugfs_root;

struct blk_flush_queue {
	spinlock_t		mq_flush_lock;
	unsigned int		flush_pending_idx:1;
	unsigned int		flush_running_idx:1;
	blk_status_t 		rq_status;
	unsigned long		flush_pending_since;
	struct list_head	flush_queue[2];
	unsigned long		flush_data_in_flight;
	struct request		*flush_rq;
	struct rcu_head		rcu_head;
};

bool is_flush_rq(struct request *req);

struct blk_flush_queue *blk_alloc_flush_queue(int node, int cmd_size,
					      gfp_t flags);
void blk_free_flush_queue(struct blk_flush_queue *q);

const char *blk_status_to_str(blk_status_t status);
const char *blk_status_to_tag(blk_status_t status);
blk_status_t tag_to_blk_status(const char *tag);
enum req_op str_to_blk_op(const char *op);

bool __blk_mq_unfreeze_queue(struct request_queue *q, bool force_atomic);
bool blk_queue_start_drain(struct request_queue *q);
bool __blk_freeze_queue_start(struct request_queue *q,
			      struct task_struct *owner);
int __bio_queue_enter(struct request_queue *q, struct bio *bio);
void submit_bio_noacct_nocheck(struct bio *bio, bool split);
int bio_submit_or_kill(struct bio *bio, unsigned int flags);

static inline bool blk_try_enter_queue(struct request_queue *q, bool pm)
{
	rcu_read_lock();
	if (!percpu_ref_tryget_live_rcu(&q->q_usage_counter))
		goto fail;

	/*
	 * The code that increments the pm_only counter must ensure that the
	 * counter is globally visible before the queue is unfrozen.
	 */
	if (blk_queue_pm_only(q) &&
	    (!pm || queue_rpm_status(q) == RPM_SUSPENDED))
		goto fail_put;

	rcu_read_unlock();
	return true;

fail_put:
	blk_queue_exit(q);
fail:
	rcu_read_unlock();
	return false;
}

static inline int bio_queue_enter(struct bio *bio)
{
	struct request_queue *q = bdev_get_queue(bio->bi_bdev);

	if (blk_try_enter_queue(q, false)) {
		rwsem_acquire_read(&q->io_lockdep_map, 0, 0, _RET_IP_);
		rwsem_release(&q->io_lockdep_map, _RET_IP_);
		return 0;
	}
	return __bio_queue_enter(q, bio);
}

static inline void blk_wait_io(struct completion *done)
{
	/* Prevent hang_check timer from firing at us during very long I/O */
	unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2;

	if (timeout)
		while (!wait_for_completion_io_timeout(done, timeout))
			;
	else
		wait_for_completion_io(done);
}

struct block_device *blkdev_get_no_open(dev_t dev, bool autoload);
void blkdev_put_no_open(struct block_device *bdev);

bool bvec_try_merge_hw_page(struct request_queue *q, struct bio_vec *bv,
		struct page *page, unsigned len, unsigned offset);

static inline bool biovec_phys_mergeable(struct request_queue *q,
		struct bio_vec *vec1, struct bio_vec *vec2)
{
	unsigned long mask = queue_segment_boundary(q);
	phys_addr_t addr1 = bvec_phys(vec1);
	phys_addr_t addr2 = bvec_phys(vec2);

	/*
	 * Merging adjacent physical pages may not work correctly under KMSAN
	 * if their metadata pages aren't adjacent. Just disable merging.
	 */
	if (IS_ENABLED(CONFIG_KMSAN))
		return false;

	if (addr1 + vec1->bv_len != addr2)
		return false;
	if (!zone_device_pages_have_same_pgmap(vec1->bv_page, vec2->bv_page))
		return false;
	if (xen_domain() && !xen_biovec_phys_mergeable(vec1, vec2->bv_page))
		return false;
	if ((addr1 | mask) != ((addr2 + vec2->bv_len - 1) | mask))
		return false;
	return true;
}

/*
 * Check if two pages from potentially different zone device pgmaps can
 * coexist as separate bvec entries in the same bio.
 *
 * The block DMA iterator (blk_dma_map_iter_start) caches the P2PDMA mapping
 * state from the first segment and applies it to all subsequent segments, so
 * P2PDMA pages from different pgmaps must not be mixed in the same bio.
 *
 * Other zone device types (FS_DAX, GENERIC) use the same dma_map_phys() path
 * as normal RAM.  PRIVATE and COHERENT pages never appear in bios.
 */
static inline bool zone_device_pages_compatible(const struct page *a,
						const struct page *b)
{
	if (is_pci_p2pdma_page(a) || is_pci_p2pdma_page(b))
		return zone_device_pages_have_same_pgmap(a, b);
	return true;
}

static inline bool __bvec_gap_to_prev(const struct queue_limits *lim,
		struct bio_vec *bprv, unsigned int offset)
{
	return (offset & lim->virt_boundary_mask) ||
		((bprv->bv_offset + bprv->bv_len) & lim->virt_boundary_mask);
}

/*
 * Check if adding a bio_vec after bprv with offset would create a gap in
 * the SG list. Most drivers don't care about this, but some do.
 */
static inline bool bvec_gap_to_prev(const struct queue_limits *lim,
		struct bio_vec *bprv, unsigned int offset)
{
	if (!lim->virt_boundary_mask)
		return false;
	return __bvec_gap_to_prev(lim, bprv, offset);
}

static inline bool rq_mergeable(struct request *rq)
{
	if (blk_rq_is_passthrough(rq))
		return false;

	if (req_op(rq) == REQ_OP_FLUSH)
		return false;

	if (req_op(rq) == REQ_OP_WRITE_ZEROES)
		return false;

	if (req_op(rq) == REQ_OP_ZONE_APPEND)
		return false;

	if (rq->cmd_flags & REQ_NOMERGE_FLAGS)
		return false;
	if (rq->rq_flags & RQF_NOMERGE_FLAGS)
		return false;

	return true;
}

/*
 * There are two different ways to handle DISCARD merges:
 *  1) If max_discard_segments > 1, the driver treats every bio as a range and
 *     send the bios to controller together. The ranges don't need to be
 *     contiguous.
 *  2) Otherwise, the request will be normal read/write requests.  The ranges
 *     need to be contiguous.
 */
static inline bool blk_discard_mergable(struct request *req)
{
	if (req_op(req) == REQ_OP_DISCARD &&
	    queue_max_discard_segments(req->q) > 1)
		return true;
	return false;
}

static inline unsigned int blk_rq_get_max_segments(struct request *rq)
{
	if (req_op(rq) == REQ_OP_DISCARD)
		return queue_max_discard_segments(rq->q);
	return queue_max_segments(rq->q);
}

static inline unsigned int blk_queue_get_max_sectors(struct request *rq)
{
	struct request_queue *q = rq->q;
	enum req_op op = req_op(rq);

	if (unlikely(op == REQ_OP_DISCARD))
		return min(q->limits.max_discard_sectors,
			   UINT_MAX >> SECTOR_SHIFT);

	if (unlikely(op == REQ_OP_SECURE_ERASE))
		return min(q->limits.max_secure_erase_sectors,
			   UINT_MAX >> SECTOR_SHIFT);

	if (unlikely(op == REQ_OP_WRITE_ZEROES))
		return q->limits.max_write_zeroes_sectors;

	if (rq->cmd_flags & REQ_ATOMIC)
		return q->limits.atomic_write_max_sectors;

	return q->limits.max_sectors;
}

#ifdef CONFIG_BLK_DEV_INTEGRITY
void blk_flush_integrity(void);
void bio_integrity_free(struct bio *bio);

/*
 * Integrity payloads can either be owned by the submitter, in which case
 * bio_uninit will free them, or owned and generated by the block layer,
 * in which case we'll verify them here (for reads) and free them before
 * the bio is handed back to the submitted.
 */
bool __bio_integrity_endio(struct bio *bio);
static inline bool bio_integrity_endio(struct bio *bio)
{
	struct bio_integrity_payload *bip = bio_integrity(bio);

	if (bip && (bip->bip_flags & BIP_BLOCK_INTEGRITY))
		return __bio_integrity_endio(bio);
	return true;
}

bool blk_integrity_merge_rq(struct request_queue *, struct request *,
		struct request *);
bool blk_integrity_merge_bio(struct request_queue *, struct request *,
		struct bio *);

static inline bool integrity_req_gap_back_merge(struct request *req,
		struct bio *next)
{
	struct bio_integrity_payload *bip = bio_integrity(req->bio);
	struct bio_integrity_payload *bip_next = bio_integrity(next);

	return bvec_gap_to_prev(&req->q->limits,
				&bip->bip_vec[bip->bip_vcnt - 1],
				bip_next->bip_vec[0].bv_offset);
}

static inline bool integrity_req_gap_front_merge(struct request *req,
		struct bio *bio)
{
	struct bio_integrity_payload *bip = bio_integrity(bio);
	struct bio_integrity_payload *bip_next = bio_integrity(req->bio);

	return bvec_gap_to_prev(&req->q->limits,
				&bip->bip_vec[bip->bip_vcnt - 1],
				bip_next->bip_vec[0].bv_offset);
}

extern const struct attribute_group blk_integrity_attr_group;
#else /* CONFIG_BLK_DEV_INTEGRITY */
static inline bool blk_integrity_merge_rq(struct request_queue *rq,
		struct request *r1, struct request *r2)
{
	return true;
}
static inline bool blk_integrity_merge_bio(struct request_queue *rq,
		struct request *r, struct bio *b)
{
	return true;
}
static inline bool integrity_req_gap_back_merge(struct request *req,
		struct bio *next)
{
	return false;
}
static inline bool integrity_req_gap_front_merge(struct request *req,
		struct bio *bio)
{
	return false;
}

static inline void blk_flush_integrity(void)
{
}
static inline bool bio_integrity_endio(struct bio *bio)
{
	return true;
}
static inline void bio_integrity_free(struct bio *bio)
{
}
#endif /* CONFIG_BLK_DEV_INTEGRITY */

unsigned long blk_rq_timeout(unsigned long timeout);
void blk_add_timer(struct request *req);

enum bio_merge_status {
	BIO_MERGE_OK,
	BIO_MERGE_NONE,
	BIO_MERGE_FAILED,
};

enum bio_merge_status bio_attempt_back_merge(struct request *req,
		struct bio *bio, unsigned int nr_segs);
bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
		unsigned int nr_segs);
bool blk_bio_list_merge(struct request_queue *q, struct list_head *list,
			struct bio *bio, unsigned int nr_segs);

/*
 * Plug flush limits
 */
#define BLK_MAX_REQUEST_COUNT	32
#define BLK_PLUG_FLUSH_SIZE	(128 * 1024)

/*
 * Internal elevator interface
 */
#define ELV_ON_HASH(rq) ((rq)->rq_flags & RQF_HASHED)

bool blk_insert_flush(struct request *rq);

void elv_update_nr_hw_queues(struct request_queue *q,
		struct elv_change_ctx *ctx);
void elevator_set_default(struct request_queue *q);
void elevator_set_none(struct request_queue *q);

ssize_t part_size_show(struct device *dev, struct device_attribute *attr,
		char *buf);
ssize_t part_stat_show(struct device *dev, struct device_attribute *attr,
		char *buf);
ssize_t part_inflight_show(struct device *dev, struct device_attribute *attr,
		char *buf);
ssize_t part_fail_show(struct device *dev, struct device_attribute *attr,
		char *buf);
ssize_t part_fail_store(struct device *dev, struct device_attribute *attr,
		const char *buf, size_t count);
ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
ssize_t part_timeout_store(struct device *, struct device_attribute *,
				const char *, size_t);

struct bio *bio_split_discard(struct bio *bio, const struct queue_limits *lim,
		unsigned *nsegs);
struct bio *bio_split_write_zeroes(struct bio *bio,
		const struct queue_limits *lim, unsigned *nsegs);
struct bio *bio_split_rw(struct bio *bio, const struct queue_limits *lim,
		unsigned *nr_segs);
struct bio *bio_split_zone_append(struct bio *bio,
		const struct queue_limits *lim, unsigned *nr_segs);

/*
 * All drivers must accept single-segments bios that are smaller than PAGE_SIZE.
 *
 * This is a quick and dirty check that relies on the fact that bi_io_vec[0] is
 * always valid if a bio has data.  The check might lead to occasional false
 * positives when bios are cloned, but compared to the performance impact of
 * cloned bios themselves the loop below doesn't matter anyway.
 */
static inline bool bio_may_need_split(struct bio *bio,
		const struct queue_limits *lim)
{
	const struct bio_vec *bv;

	if (lim->chunk_sectors)
		return true;

	if (!bio->bi_io_vec)
		return true;

	bv = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
	if (bio->bi_iter.bi_size > bv->bv_len - bio->bi_iter.bi_offset)
		return true;
	if ((bv->bv_offset | bv->bv_len) & lim->dma_alignment)
		return true;
	return bv->bv_len + bv->bv_offset > lim->max_fast_segment_size;
}

/**
 * __bio_split_to_limits - split a bio to fit the queue limits
 * @bio:     bio to be split
 * @lim:     queue limits to split based on
 * @nr_segs: returns the number of segments in the returned bio
 *
 * Check if @bio needs splitting based on the queue limits, and if so split off
 * a bio fitting the limits from the beginning of @bio and return it.  @bio is
 * shortened to the remainder and re-submitted.
 *
 * The split bio is allocated from @q->bio_split, which is provided by the
 * block layer.
 */
static inline struct bio *__bio_split_to_limits(struct bio *bio,
		const struct queue_limits *lim, unsigned int *nr_segs)
{
	switch (bio_op(bio)) {
	case REQ_OP_READ:
	case REQ_OP_WRITE:
		if (bio_may_need_split(bio, lim))
			return bio_split_rw(bio, lim, nr_segs);
		*nr_segs = 1;
		return bio;
	case REQ_OP_ZONE_APPEND:
		return bio_split_zone_append(bio, lim, nr_segs);
	case REQ_OP_DISCARD:
	case REQ_OP_SECURE_ERASE:
		return bio_split_discard(bio, lim, nr_segs);
	case REQ_OP_WRITE_ZEROES:
		return bio_split_write_zeroes(bio, lim, nr_segs);
	default:
		/* other operations can't be split */
		*nr_segs = 0;
		return bio;
	}
}

/**
 * get_max_segment_size() - maximum number of bytes to add as a single segment
 * @lim: Request queue limits.
 * @paddr: address of the range to add
 * @len: maximum length available to add at @paddr
 *
 * Returns the maximum number of bytes of the range starting at @paddr that can
 * be added to a single segment.
 */
static inline unsigned get_max_segment_size(const struct queue_limits *lim,
		phys_addr_t paddr, unsigned int len)
{
	/*
	 * Prevent an overflow if mask = ULONG_MAX and offset = 0 by adding 1
	 * after having calculated the minimum.
	 */
	return min_t(unsigned long, len,
		min(lim->seg_boundary_mask - (lim->seg_boundary_mask & paddr),
		    (unsigned long)lim->max_segment_size - 1) + 1);
}

int ll_back_merge_fn(struct request *req, struct bio *bio,
		unsigned int nr_segs);
bool blk_attempt_req_merge(struct request_queue *q, struct request *rq,
				struct request *next);
unsigned int blk_recalc_rq_segments(struct request *rq);
bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
enum elv_merge blk_try_merge(struct request *rq, struct bio *bio);

int blk_set_default_limits(struct queue_limits *lim);
void blk_apply_bdi_limits(struct backing_dev_info *bdi,
		struct queue_limits *lim);
int blk_dev_init(void);

void update_io_ticks(struct block_device *part, unsigned long now, bool end);

static inline void req_set_nomerge(struct request_queue *q, struct request *req)
{
	req->cmd_flags |= REQ_NOMERGE;
	if (req == q->last_merge)
		q->last_merge = NULL;
}

static inline void bdev_inc_in_flight(struct block_device *bdev,
				      enum req_op op)
{
	bool rw = op_is_write(op);

	part_stat_local_inc(bdev, in_flight[rw]);
	if (bdev_is_partition(bdev))
		part_stat_local_inc(bdev_whole(bdev), in_flight[rw]);
}

static inline void bdev_dec_in_flight(struct block_device *bdev,
				      enum req_op op)
{
	bool rw = op_is_write(op);

	part_stat_local_dec(bdev, in_flight[rw]);
	if (bdev_is_partition(bdev))
		part_stat_local_dec(bdev_whole(bdev), in_flight[rw]);
}

/*
 * Internal io_context interface
 */
struct io_cq *ioc_find_get_icq(struct request_queue *q);
struct io_cq *ioc_lookup_icq(struct request_queue *q);
#ifdef CONFIG_BLK_ICQ
void ioc_clear_queue(struct request_queue *q);
#else
static inline void ioc_clear_queue(struct request_queue *q)
{
}
#endif /* CONFIG_BLK_ICQ */

#ifdef CONFIG_BLK_DEV_ZONED
void disk_init_zone_resources(struct gendisk *disk);
void disk_release_zone_resources(struct gendisk *disk);
static inline bool bio_zone_write_plugging(struct bio *bio)
{
	return bio_flagged(bio, BIO_ZONE_WRITE_PLUGGING);
}
static inline bool blk_req_bio_is_zone_append(struct request *rq,
					      struct bio *bio)
{
	return req_op(rq) == REQ_OP_ZONE_APPEND ||
	       bio_flagged(bio, BIO_EMULATES_ZONE_APPEND);
}
void blk_zone_write_plug_bio_merged(struct bio *bio);
void blk_zone_write_plug_init_request(struct request *rq);
void blk_zone_append_update_request_bio(struct request *rq, struct bio *bio);
void blk_zone_mgmt_bio_endio(struct bio *bio);
void blk_zone_write_plug_bio_endio(struct bio *bio);
static inline void blk_zone_bio_endio(struct bio *bio)
{
	/*
	 * Zone management BIOs may impact zone write plugs (e.g. a zone reset
	 * changes a zone write plug zone write pointer offset), but these
	 * operation do not go through zone write plugging as they may operate
	 * on zones that do not have a zone write
	 * plug. blk_zone_mgmt_bio_endio() handles the potential changes to zone
	 * write plugs that are present.
	 */
	if (op_is_zone_mgmt(bio_op(bio))) {
		blk_zone_mgmt_bio_endio(bio);
		return;
	}

	/*
	 * For write BIOs to zoned devices, signal the completion of the BIO so
	 * that the next write BIO can be submitted by zone write plugging.
	 */
	if (bio_zone_write_plugging(bio))
		blk_zone_write_plug_bio_endio(bio);
}

void blk_zone_write_plug_finish_request(struct request *rq);
static inline void blk_zone_finish_request(struct request *rq)
{
	if (rq->rq_flags & RQF_ZONE_WRITE_PLUGGING)
		blk_zone_write_plug_finish_request(rq);
}
int blkdev_report_zones_ioctl(struct block_device *bdev, unsigned int cmd,
		unsigned long arg);
int blkdev_zone_mgmt_ioctl(struct block_device *bdev, blk_mode_t mode,
		unsigned int cmd, unsigned long arg);
#else /* CONFIG_BLK_DEV_ZONED */
static inline void disk_init_zone_resources(struct gendisk *disk)
{
}
static inline void disk_release_zone_resources(struct gendisk *disk)
{
}
static inline bool bio_zone_write_plugging(struct bio *bio)
{
	return false;
}
static inline bool blk_req_bio_is_zone_append(struct request *req,
					      struct bio *bio)
{
	return false;
}
static inline void blk_zone_write_plug_bio_merged(struct bio *bio)
{
}
static inline void blk_zone_write_plug_init_request(struct request *rq)
{
}
static inline void blk_zone_append_update_request_bio(struct request *rq,
						      struct bio *bio)
{
}
static inline void blk_zone_bio_endio(struct bio *bio)
{
}
static inline void blk_zone_finish_request(struct request *rq)
{
}
static inline int blkdev_report_zones_ioctl(struct block_device *bdev,
		unsigned int cmd, unsigned long arg)
{
	return -ENOTTY;
}
static inline int blkdev_zone_mgmt_ioctl(struct block_device *bdev,
		blk_mode_t mode, unsigned int cmd, unsigned long arg)
{
	return -ENOTTY;
}
#endif /* CONFIG_BLK_DEV_ZONED */

struct block_device *bdev_alloc(struct gendisk *disk, u8 partno);
void bdev_add(struct block_device *bdev, dev_t dev);
void bdev_unhash(struct block_device *bdev);
void bdev_drop(struct block_device *bdev);

int blk_alloc_ext_minor(void);
void blk_free_ext_minor(unsigned int minor);
#define ADDPART_FLAG_NONE	0
#define ADDPART_FLAG_RAID	1
#define ADDPART_FLAG_WHOLEDISK	2
#define ADDPART_FLAG_READONLY	4
int bdev_add_partition(struct gendisk *disk, int partno, sector_t start,
		sector_t length);
int bdev_del_partition(struct gendisk *disk, int partno);
int bdev_resize_partition(struct gendisk *disk, int partno, sector_t start,
		sector_t length);
void drop_partition(struct block_device *part);

void bdev_set_nr_sectors(struct block_device *bdev, sector_t sectors);

struct gendisk *__alloc_disk_node(struct request_queue *q, int node_id,
		struct lock_class_key *lkclass);
struct request_queue *blk_alloc_queue(struct queue_limits *lim, int node_id);

int disk_scan_partitions(struct gendisk *disk, blk_mode_t mode);

int disk_alloc_events(struct gendisk *disk);
void disk_add_events(struct gendisk *disk);
void disk_del_events(struct gendisk *disk);
void disk_release_events(struct gendisk *disk);
void disk_block_events(struct gendisk *disk);
void disk_unblock_events(struct gendisk *disk);
void disk_flush_events(struct gendisk *disk, unsigned int mask);
extern struct device_attribute dev_attr_events;
extern struct device_attribute dev_attr_events_async;
extern struct device_attribute dev_attr_events_poll_msecs;

extern struct attribute_group blk_trace_attr_group;

blk_mode_t file_to_blk_mode(struct file *file);
int truncate_bdev_range(struct block_device *bdev, blk_mode_t mode,
		loff_t lstart, loff_t lend);
long blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg);
int blkdev_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags);
long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg);

extern const struct address_space_operations def_blk_aops;

int disk_register_independent_access_ranges(struct gendisk *disk);
void disk_unregister_independent_access_ranges(struct gendisk *disk);

int should_fail_bio(struct bio *bio);
#ifdef CONFIG_FAIL_MAKE_REQUEST
bool should_fail_request(struct block_device *part, unsigned int bytes);
#else /* CONFIG_FAIL_MAKE_REQUEST */
static inline bool should_fail_request(struct block_device *part,
					unsigned int bytes)
{
	return false;
}
#endif /* CONFIG_FAIL_MAKE_REQUEST */

/*
 * Optimized request reference counting. Ideally we'd make timeouts be more
 * clever, as that's the only reason we need references at all... But until
 * this happens, this is faster than using refcount_t. Also see:
 *
 * abc54d634334 ("io_uring: switch to atomic_t for io_kiocb reference count")
 */
#define req_ref_zero_or_close_to_overflow(req)	\
	((unsigned int) atomic_read(&(req->ref)) + 127u <= 127u)

static inline bool req_ref_inc_not_zero(struct request *req)
{
	return atomic_inc_not_zero(&req->ref);
}

static inline bool req_ref_put_and_test(struct request *req)
{
	WARN_ON_ONCE(req_ref_zero_or_close_to_overflow(req));
	return atomic_dec_and_test(&req->ref);
}

static inline void req_ref_set(struct request *req, int value)
{
	atomic_set(&req->ref, value);
}

static inline int req_ref_read(struct request *req)
{
	return atomic_read(&req->ref);
}

static inline u64 blk_time_get_ns(void)
{
	struct blk_plug *plug = current->plug;
	u64 now;

	if (!plug || !in_task())
		return ktime_get_ns();

	/*
	 * 0 could very well be a valid time, but rather than flag "this is
	 * a valid timestamp" separately, just accept that we'll do an extra
	 * ktime_get_ns() if we just happen to get 0 as the current time.
	 *
	 * cur_ktime can be zeroed by pre-emption the moment PF_BLOCK_TS is set.
	 */
	now = READ_ONCE(plug->cur_ktime);
	if (!now) {
		now = ktime_get_ns();
		WRITE_ONCE(plug->cur_ktime, now);
		/* Ensure PF_BLOCK_TS is set after cur_ktime. */
		barrier();
		current->flags |= PF_BLOCK_TS;
	}
	return now;
}

static inline ktime_t blk_time_get(void)
{
	return ns_to_ktime(blk_time_get_ns());
}

void bdev_release(struct file *bdev_file);
int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder,
	      const struct blk_holder_ops *hops, struct file *bdev_file);
int bdev_permission(dev_t dev, blk_mode_t mode, void *holder);

void bio_integrity_generate(struct bio *bio);
blk_status_t bio_integrity_verify(struct bio *bio,
		struct bvec_iter *saved_iter);

void blk_integrity_prepare(struct request *rq);
void blk_integrity_complete(struct request *rq, unsigned int nr_bytes);

#ifdef CONFIG_LOCKDEP
static inline void blk_freeze_acquire_lock(struct request_queue *q)
{
	if (!q->mq_freeze_disk_dead)
		rwsem_acquire(&q->io_lockdep_map, 0, 1, _RET_IP_);
	if (!q->mq_freeze_queue_dying)
		rwsem_acquire(&q->q_lockdep_map, 0, 1, _RET_IP_);
}

static inline void blk_unfreeze_release_lock(struct request_queue *q)
{
	if (!q->mq_freeze_queue_dying)
		rwsem_release(&q->q_lockdep_map, _RET_IP_);
	if (!q->mq_freeze_disk_dead)
		rwsem_release(&q->io_lockdep_map, _RET_IP_);
}
#else
static inline void blk_freeze_acquire_lock(struct request_queue *q)
{
}
static inline void blk_unfreeze_release_lock(struct request_queue *q)
{
}
#endif

/*
 * debugfs directory and file creation can trigger fs reclaim, which can enter
 * back into the block layer request_queue. This can cause deadlock if the
 * queue is frozen. Use NOIO context together with debugfs_mutex to prevent fs
 * reclaim from triggering block I/O.
 */
static inline void blk_debugfs_lock_nomemsave(struct request_queue *q)
	__acquires(&q->debugfs_mutex)
{
	mutex_lock(&q->debugfs_mutex);
}

static inline void blk_debugfs_unlock_nomemrestore(struct request_queue *q)
	__releases(&q->debugfs_mutex)
{
	mutex_unlock(&q->debugfs_mutex);
}

static inline unsigned int __must_check blk_debugfs_lock(struct request_queue *q)
	__acquires(&q->debugfs_mutex)
{
	unsigned int memflags = memalloc_noio_save();

	blk_debugfs_lock_nomemsave(q);
	return memflags;
}

static inline void blk_debugfs_unlock(struct request_queue *q,
				      unsigned int memflags)
	__releases(&q->debugfs_mutex)
{
	blk_debugfs_unlock_nomemrestore(q);
	memalloc_noio_restore(memflags);
}

#endif /* BLK_INTERNAL_H */