Merge tag 'pidfd-v5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner...

[thirdparty/linux.git] / include / linux / blkdev.h

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

#include <linux/sched.h>
#include <linux/sched/clock.h>

#ifdef CONFIG_BLOCK

#include <linux/major.h>
#include <linux/genhd.h>
#include <linux/list.h>
#include <linux/llist.h>
#include <linux/timer.h>
#include <linux/workqueue.h>
#include <linux/pagemap.h>
#include <linux/backing-dev-defs.h>
#include <linux/wait.h>
#include <linux/mempool.h>
#include <linux/pfn.h>
#include <linux/bio.h>
#include <linux/stringify.h>
#include <linux/gfp.h>
#include <linux/bsg.h>
#include <linux/smp.h>
#include <linux/rcupdate.h>
#include <linux/percpu-refcount.h>
#include <linux/scatterlist.h>
#include <linux/blkzoned.h>

struct module;
struct scsi_ioctl_command;

struct request_queue;
struct elevator_queue;
struct blk_trace;
struct request;
struct sg_io_hdr;
struct bsg_job;
struct blkcg_gq;
struct blk_flush_queue;
struct pr_ops;
struct rq_qos;
struct blk_queue_stats;
struct blk_stat_callback;

#define BLKDEV_MIN_RQ   4
#define BLKDEV_MAX_RQ   128     /* Default maximum */

/* Must be consistent with blk_mq_poll_stats_bkt() */
#define BLK_MQ_POLL_STATS_BKTS 16

/*
 * Maximum number of blkcg policies allowed to be registered concurrently.
 * Defined here to simplify include dependency.
 */
#define BLKCG_MAX_POLS          5

typedef void (rq_end_io_fn)(struct request *, blk_status_t);

/*
 * request flags */
typedef __u32 __bitwise req_flags_t;

/* elevator knows about this request */
#define RQF_SORTED              ((__force req_flags_t)(1 << 0))
/* drive already may have started this one */
#define RQF_STARTED             ((__force req_flags_t)(1 << 1))
/* may not be passed by ioscheduler */
#define RQF_SOFTBARRIER         ((__force req_flags_t)(1 << 3))
/* request for flush sequence */
#define RQF_FLUSH_SEQ           ((__force req_flags_t)(1 << 4))
/* merge of different types, fail separately */
#define RQF_MIXED_MERGE         ((__force req_flags_t)(1 << 5))
/* track inflight for MQ */
#define RQF_MQ_INFLIGHT         ((__force req_flags_t)(1 << 6))
/* don't call prep for this one */
#define RQF_DONTPREP            ((__force req_flags_t)(1 << 7))
/* set for "ide_preempt" requests and also for requests for which the SCSI
   "quiesce" state must be ignored. */
#define RQF_PREEMPT             ((__force req_flags_t)(1 << 8))
/* contains copies of user pages */
#define RQF_COPY_USER           ((__force req_flags_t)(1 << 9))
/* vaguely specified driver internal error.  Ignored by the block layer */
#define RQF_FAILED              ((__force req_flags_t)(1 << 10))
/* don't warn about errors */
#define RQF_QUIET               ((__force req_flags_t)(1 << 11))
/* elevator private data attached */
#define RQF_ELVPRIV             ((__force req_flags_t)(1 << 12))
/* account into disk and partition IO statistics */
#define RQF_IO_STAT             ((__force req_flags_t)(1 << 13))
/* request came from our alloc pool */
#define RQF_ALLOCED             ((__force req_flags_t)(1 << 14))
/* runtime pm request */
#define RQF_PM                  ((__force req_flags_t)(1 << 15))
/* on IO scheduler merge hash */
#define RQF_HASHED              ((__force req_flags_t)(1 << 16))
/* track IO completion time */
#define RQF_STATS               ((__force req_flags_t)(1 << 17))
/* Look at ->special_vec for the actual data payload instead of the
   bio chain. */
#define RQF_SPECIAL_PAYLOAD     ((__force req_flags_t)(1 << 18))
/* The per-zone write lock is held for this request */
#define RQF_ZONE_WRITE_LOCKED   ((__force req_flags_t)(1 << 19))
/* already slept for hybrid poll */
#define RQF_MQ_POLL_SLEPT       ((__force req_flags_t)(1 << 20))
/* ->timeout has been called, don't expire again */
#define RQF_TIMED_OUT           ((__force req_flags_t)(1 << 21))

/* flags that prevent us from merging requests: */
#define RQF_NOMERGE_FLAGS \
        (RQF_STARTED | RQF_SOFTBARRIER | RQF_FLUSH_SEQ | RQF_SPECIAL_PAYLOAD)

/*
 * Request state for blk-mq.
 */
enum mq_rq_state {
        MQ_RQ_IDLE              = 0,
        MQ_RQ_IN_FLIGHT         = 1,
        MQ_RQ_COMPLETE          = 2,
};

/*
 * Try to put the fields that are referenced together in the same cacheline.
 *
 * If you modify this structure, make sure to update blk_rq_init() and
 * especially blk_mq_rq_ctx_init() to take care of the added fields.
 */
struct request {
        struct request_queue *q;
        struct blk_mq_ctx *mq_ctx;
        struct blk_mq_hw_ctx *mq_hctx;

        unsigned int cmd_flags;         /* op and common flags */
        req_flags_t rq_flags;

        int internal_tag;

        /* the following two fields are internal, NEVER access directly */
        unsigned int __data_len;        /* total data len */
        int tag;
        sector_t __sector;              /* sector cursor */

        struct bio *bio;
        struct bio *biotail;

        struct list_head queuelist;

        /*
         * The hash is used inside the scheduler, and killed once the
         * request reaches the dispatch list. The ipi_list is only used
         * to queue the request for softirq completion, which is long
         * after the request has been unhashed (and even removed from
         * the dispatch list).
         */
        union {
                struct hlist_node hash; /* merge hash */
                struct list_head ipi_list;
        };

        /*
         * The rb_node is only used inside the io scheduler, requests
         * are pruned when moved to the dispatch queue. So let the
         * completion_data share space with the rb_node.
         */
        union {
                struct rb_node rb_node; /* sort/lookup */
                struct bio_vec special_vec;
                void *completion_data;
                int error_count; /* for legacy drivers, don't use */
        };

        /*
         * Three pointers are available for the IO schedulers, if they need
         * more they have to dynamically allocate it.  Flush requests are
         * never put on the IO scheduler. So let the flush fields share
         * space with the elevator data.
         */
        union {
                struct {
                        struct io_cq            *icq;
                        void                    *priv[2];
                } elv;

                struct {
                        unsigned int            seq;
                        struct list_head        list;
                        rq_end_io_fn            *saved_end_io;
                } flush;
        };

        struct gendisk *rq_disk;
        struct hd_struct *part;
        /* Time that I/O was submitted to the kernel. */
        u64 start_time_ns;
        /* Time that I/O was submitted to the device. */
        u64 io_start_time_ns;

#ifdef CONFIG_BLK_WBT
        unsigned short wbt_flags;
#endif
#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
        unsigned short throtl_size;
#endif

        /*
         * Number of scatter-gather DMA addr+len pairs after
         * physical address coalescing is performed.
         */
        unsigned short nr_phys_segments;

#if defined(CONFIG_BLK_DEV_INTEGRITY)
        unsigned short nr_integrity_segments;
#endif

        unsigned short write_hint;
        unsigned short ioprio;

        unsigned int extra_len; /* length of alignment and padding */

        enum mq_rq_state state;
        refcount_t ref;

        unsigned int timeout;
        unsigned long deadline;

        union {
                struct __call_single_data csd;
                u64 fifo_time;
        };

        /*
         * completion callback.
         */
        rq_end_io_fn *end_io;
        void *end_io_data;
};

static inline bool blk_op_is_scsi(unsigned int op)
{
        return op == REQ_OP_SCSI_IN || op == REQ_OP_SCSI_OUT;
}

static inline bool blk_op_is_private(unsigned int op)
{
        return op == REQ_OP_DRV_IN || op == REQ_OP_DRV_OUT;
}

static inline bool blk_rq_is_scsi(struct request *rq)
{
        return blk_op_is_scsi(req_op(rq));
}

static inline bool blk_rq_is_private(struct request *rq)
{
        return blk_op_is_private(req_op(rq));
}

static inline bool blk_rq_is_passthrough(struct request *rq)
{
        return blk_rq_is_scsi(rq) || blk_rq_is_private(rq);
}

static inline bool bio_is_passthrough(struct bio *bio)
{
        unsigned op = bio_op(bio);

        return blk_op_is_scsi(op) || blk_op_is_private(op);
}

static inline unsigned short req_get_ioprio(struct request *req)
{
        return req->ioprio;
}

#include <linux/elevator.h>

struct blk_queue_ctx;

typedef blk_qc_t (make_request_fn) (struct request_queue *q, struct bio *bio);

struct bio_vec;
typedef int (dma_drain_needed_fn)(struct request *);

enum blk_eh_timer_return {
        BLK_EH_DONE,            /* drivers has completed the command */
        BLK_EH_RESET_TIMER,     /* reset timer and try again */
};

enum blk_queue_state {
        Queue_down,
        Queue_up,
};

#define BLK_TAG_ALLOC_FIFO 0 /* allocate starting from 0 */
#define BLK_TAG_ALLOC_RR 1 /* allocate starting from last allocated tag */

#define BLK_SCSI_MAX_CMDS       (256)
#define BLK_SCSI_CMD_PER_LONG   (BLK_SCSI_MAX_CMDS / (sizeof(long) * 8))

/*
 * Zoned block device models (zoned limit).
 */
enum blk_zoned_model {
        BLK_ZONED_NONE, /* Regular block device */
        BLK_ZONED_HA,   /* Host-aware zoned block device */
        BLK_ZONED_HM,   /* Host-managed zoned block device */
};

struct queue_limits {
        unsigned long           bounce_pfn;
        unsigned long           seg_boundary_mask;
        unsigned long           virt_boundary_mask;

        unsigned int            max_hw_sectors;
        unsigned int            max_dev_sectors;
        unsigned int            chunk_sectors;
        unsigned int            max_sectors;
        unsigned int            max_segment_size;
        unsigned int            physical_block_size;
        unsigned int            alignment_offset;
        unsigned int            io_min;
        unsigned int            io_opt;
        unsigned int            max_discard_sectors;
        unsigned int            max_hw_discard_sectors;
        unsigned int            max_write_same_sectors;
        unsigned int            max_write_zeroes_sectors;
        unsigned int            discard_granularity;
        unsigned int            discard_alignment;

        unsigned short          logical_block_size;
        unsigned short          max_segments;
        unsigned short          max_integrity_segments;
        unsigned short          max_discard_segments;

        unsigned char           misaligned;
        unsigned char           discard_misaligned;
        unsigned char           raid_partial_stripes_expensive;
        enum blk_zoned_model    zoned;
};

#ifdef CONFIG_BLK_DEV_ZONED

extern unsigned int blkdev_nr_zones(struct block_device *bdev);
extern int blkdev_report_zones(struct block_device *bdev,
                               sector_t sector, struct blk_zone *zones,
                               unsigned int *nr_zones, gfp_t gfp_mask);
extern int blkdev_reset_zones(struct block_device *bdev, sector_t sectors,
                              sector_t nr_sectors, gfp_t gfp_mask);
extern int blk_revalidate_disk_zones(struct gendisk *disk);

extern int blkdev_report_zones_ioctl(struct block_device *bdev, fmode_t mode,
                                     unsigned int cmd, unsigned long arg);
extern int blkdev_reset_zones_ioctl(struct block_device *bdev, fmode_t mode,
                                    unsigned int cmd, unsigned long arg);

#else /* CONFIG_BLK_DEV_ZONED */

static inline unsigned int blkdev_nr_zones(struct block_device *bdev)
{
        return 0;
}

static inline int blk_revalidate_disk_zones(struct gendisk *disk)
{
        return 0;
}

static inline int blkdev_report_zones_ioctl(struct block_device *bdev,
                                            fmode_t mode, unsigned int cmd,
                                            unsigned long arg)
{
        return -ENOTTY;
}

static inline int blkdev_reset_zones_ioctl(struct block_device *bdev,
                                           fmode_t mode, unsigned int cmd,
                                           unsigned long arg)
{
        return -ENOTTY;
}

#endif /* CONFIG_BLK_DEV_ZONED */

struct request_queue {
        /*
         * Together with queue_head for cacheline sharing
         */
        struct list_head        queue_head;
        struct request          *last_merge;
        struct elevator_queue   *elevator;

        struct blk_queue_stats  *stats;
        struct rq_qos           *rq_qos;

        make_request_fn         *make_request_fn;
        dma_drain_needed_fn     *dma_drain_needed;

        const struct blk_mq_ops *mq_ops;

        /* sw queues */
        struct blk_mq_ctx __percpu      *queue_ctx;
        unsigned int            nr_queues;

        unsigned int            queue_depth;

        /* hw dispatch queues */
        struct blk_mq_hw_ctx    **queue_hw_ctx;
        unsigned int            nr_hw_queues;

        struct backing_dev_info *backing_dev_info;

        /*
         * The queue owner gets to use this for whatever they like.
         * ll_rw_blk doesn't touch it.
         */
        void                    *queuedata;

        /*
         * various queue flags, see QUEUE_* below
         */
        unsigned long           queue_flags;
        /*
         * Number of contexts that have called blk_set_pm_only(). If this
         * counter is above zero then only RQF_PM and RQF_PREEMPT requests are
         * processed.
         */
        atomic_t                pm_only;

        /*
         * ida allocated id for this queue.  Used to index queues from
         * ioctx.
         */
        int                     id;

        /*
         * queue needs bounce pages for pages above this limit
         */
        gfp_t                   bounce_gfp;

        spinlock_t              queue_lock;

        /*
         * queue kobject
         */
        struct kobject kobj;

        /*
         * mq queue kobject
         */
        struct kobject *mq_kobj;

#ifdef  CONFIG_BLK_DEV_INTEGRITY
        struct blk_integrity integrity;
#endif  /* CONFIG_BLK_DEV_INTEGRITY */

#ifdef CONFIG_PM
        struct device           *dev;
        int                     rpm_status;
        unsigned int            nr_pending;
#endif

        /*
         * queue settings
         */
        unsigned long           nr_requests;    /* Max # of requests */

        unsigned int            dma_drain_size;
        void                    *dma_drain_buffer;
        unsigned int            dma_pad_mask;
        unsigned int            dma_alignment;

        unsigned int            rq_timeout;
        int                     poll_nsec;

        struct blk_stat_callback        *poll_cb;
        struct blk_rq_stat      poll_stat[BLK_MQ_POLL_STATS_BKTS];

        struct timer_list       timeout;
        struct work_struct      timeout_work;

        struct list_head        icq_list;
#ifdef CONFIG_BLK_CGROUP
        DECLARE_BITMAP          (blkcg_pols, BLKCG_MAX_POLS);
        struct blkcg_gq         *root_blkg;
        struct list_head        blkg_list;
#endif

        struct queue_limits     limits;

#ifdef CONFIG_BLK_DEV_ZONED
        /*
         * Zoned block device information for request dispatch control.
         * nr_zones is the total number of zones of the device. This is always
         * 0 for regular block devices. seq_zones_bitmap is a bitmap of nr_zones
         * bits which indicates if a zone is conventional (bit clear) or
         * sequential (bit set). seq_zones_wlock is a bitmap of nr_zones
         * bits which indicates if a zone is write locked, that is, if a write
         * request targeting the zone was dispatched. All three fields are
         * initialized by the low level device driver (e.g. scsi/sd.c).
         * Stacking drivers (device mappers) may or may not initialize
         * these fields.
         *
         * Reads of this information must be protected with blk_queue_enter() /
         * blk_queue_exit(). Modifying this information is only allowed while
         * no requests are being processed. See also blk_mq_freeze_queue() and
         * blk_mq_unfreeze_queue().
         */
        unsigned int            nr_zones;
        unsigned long           *seq_zones_bitmap;
        unsigned long           *seq_zones_wlock;
#endif /* CONFIG_BLK_DEV_ZONED */

        /*
         * sg stuff
         */
        unsigned int            sg_timeout;
        unsigned int            sg_reserved_size;
        int                     node;
#ifdef CONFIG_BLK_DEV_IO_TRACE
        struct blk_trace        *blk_trace;
        struct mutex            blk_trace_mutex;
#endif
        /*
         * for flush operations
         */
        struct blk_flush_queue  *fq;

        struct list_head        requeue_list;
        spinlock_t              requeue_lock;
        struct delayed_work     requeue_work;

        struct mutex            sysfs_lock;

        atomic_t                mq_freeze_depth;

#if defined(CONFIG_BLK_DEV_BSG)
        struct bsg_class_device bsg_dev;
#endif

#ifdef CONFIG_BLK_DEV_THROTTLING
        /* Throttle data */
        struct throtl_data *td;
#endif
        struct rcu_head         rcu_head;
        wait_queue_head_t       mq_freeze_wq;
        struct percpu_ref       q_usage_counter;
        struct list_head        all_q_node;

        struct blk_mq_tag_set   *tag_set;
        struct list_head        tag_set_list;
        struct bio_set          bio_split;

#ifdef CONFIG_BLK_DEBUG_FS
        struct dentry           *debugfs_dir;
        struct dentry           *sched_debugfs_dir;
        struct dentry           *rqos_debugfs_dir;
#endif

        bool                    mq_sysfs_init_done;

        size_t                  cmd_size;

        struct work_struct      release_work;

#define BLK_MAX_WRITE_HINTS     5
        u64                     write_hints[BLK_MAX_WRITE_HINTS];
};

#define QUEUE_FLAG_STOPPED      0       /* queue is stopped */
#define QUEUE_FLAG_DYING        1       /* queue being torn down */
#define QUEUE_FLAG_NOMERGES     3       /* disable merge attempts */
#define QUEUE_FLAG_SAME_COMP    4       /* complete on same CPU-group */
#define QUEUE_FLAG_FAIL_IO      5       /* fake timeout */
#define QUEUE_FLAG_NONROT       6       /* non-rotational device (SSD) */
#define QUEUE_FLAG_VIRT         QUEUE_FLAG_NONROT /* paravirt device */
#define QUEUE_FLAG_IO_STAT      7       /* do disk/partitions IO accounting */
#define QUEUE_FLAG_DISCARD      8       /* supports DISCARD */
#define QUEUE_FLAG_NOXMERGES    9       /* No extended merges */
#define QUEUE_FLAG_ADD_RANDOM   10      /* Contributes to random pool */
#define QUEUE_FLAG_SECERASE     11      /* supports secure erase */
#define QUEUE_FLAG_SAME_FORCE   12      /* force complete on same CPU */
#define QUEUE_FLAG_DEAD         13      /* queue tear-down finished */
#define QUEUE_FLAG_INIT_DONE    14      /* queue is initialized */
#define QUEUE_FLAG_POLL         16      /* IO polling enabled if set */
#define QUEUE_FLAG_WC           17      /* Write back caching */
#define QUEUE_FLAG_FUA          18      /* device supports FUA writes */
#define QUEUE_FLAG_DAX          19      /* device supports DAX */
#define QUEUE_FLAG_STATS        20      /* track IO start and completion times */
#define QUEUE_FLAG_POLL_STATS   21      /* collecting stats for hybrid polling */
#define QUEUE_FLAG_REGISTERED   22      /* queue has been registered to a disk */
#define QUEUE_FLAG_SCSI_PASSTHROUGH 23  /* queue supports SCSI commands */
#define QUEUE_FLAG_QUIESCED     24      /* queue has been quiesced */
#define QUEUE_FLAG_PCI_P2PDMA   25      /* device supports PCI p2p requests */

#define QUEUE_FLAG_MQ_DEFAULT   ((1 << QUEUE_FLAG_IO_STAT) |            \
                                 (1 << QUEUE_FLAG_SAME_COMP))

void blk_queue_flag_set(unsigned int flag, struct request_queue *q);
void blk_queue_flag_clear(unsigned int flag, struct request_queue *q);
bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q);

#define blk_queue_stopped(q)    test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
#define blk_queue_dying(q)      test_bit(QUEUE_FLAG_DYING, &(q)->queue_flags)
#define blk_queue_dead(q)       test_bit(QUEUE_FLAG_DEAD, &(q)->queue_flags)
#define blk_queue_init_done(q)  test_bit(QUEUE_FLAG_INIT_DONE, &(q)->queue_flags)
#define blk_queue_nomerges(q)   test_bit(QUEUE_FLAG_NOMERGES, &(q)->queue_flags)
#define blk_queue_noxmerges(q)  \
        test_bit(QUEUE_FLAG_NOXMERGES, &(q)->queue_flags)
#define blk_queue_nonrot(q)     test_bit(QUEUE_FLAG_NONROT, &(q)->queue_flags)
#define blk_queue_io_stat(q)    test_bit(QUEUE_FLAG_IO_STAT, &(q)->queue_flags)
#define blk_queue_add_random(q) test_bit(QUEUE_FLAG_ADD_RANDOM, &(q)->queue_flags)
#define blk_queue_discard(q)    test_bit(QUEUE_FLAG_DISCARD, &(q)->queue_flags)
#define blk_queue_secure_erase(q) \
        (test_bit(QUEUE_FLAG_SECERASE, &(q)->queue_flags))
#define blk_queue_dax(q)        test_bit(QUEUE_FLAG_DAX, &(q)->queue_flags)
#define blk_queue_scsi_passthrough(q)   \
        test_bit(QUEUE_FLAG_SCSI_PASSTHROUGH, &(q)->queue_flags)
#define blk_queue_pci_p2pdma(q) \
        test_bit(QUEUE_FLAG_PCI_P2PDMA, &(q)->queue_flags)

#define blk_noretry_request(rq) \
        ((rq)->cmd_flags & (REQ_FAILFAST_DEV|REQ_FAILFAST_TRANSPORT| \
                             REQ_FAILFAST_DRIVER))
#define blk_queue_quiesced(q)   test_bit(QUEUE_FLAG_QUIESCED, &(q)->queue_flags)
#define blk_queue_pm_only(q)    atomic_read(&(q)->pm_only)
#define blk_queue_fua(q)        test_bit(QUEUE_FLAG_FUA, &(q)->queue_flags)

extern void blk_set_pm_only(struct request_queue *q);
extern void blk_clear_pm_only(struct request_queue *q);

static inline bool blk_account_rq(struct request *rq)
{
        return (rq->rq_flags & RQF_STARTED) && !blk_rq_is_passthrough(rq);
}

#define list_entry_rq(ptr)      list_entry((ptr), struct request, queuelist)

#define rq_data_dir(rq)         (op_is_write(req_op(rq)) ? WRITE : READ)

static inline bool queue_is_mq(struct request_queue *q)
{
        return q->mq_ops;
}

static inline enum blk_zoned_model
blk_queue_zoned_model(struct request_queue *q)
{
        return q->limits.zoned;
}

static inline bool blk_queue_is_zoned(struct request_queue *q)
{
        switch (blk_queue_zoned_model(q)) {
        case BLK_ZONED_HA:
        case BLK_ZONED_HM:
                return true;
        default:
                return false;
        }
}

static inline unsigned int blk_queue_zone_sectors(struct request_queue *q)
{
        return blk_queue_is_zoned(q) ? q->limits.chunk_sectors : 0;
}

#ifdef CONFIG_BLK_DEV_ZONED
static inline unsigned int blk_queue_nr_zones(struct request_queue *q)
{
        return blk_queue_is_zoned(q) ? q->nr_zones : 0;
}

static inline unsigned int blk_queue_zone_no(struct request_queue *q,
                                             sector_t sector)
{
        if (!blk_queue_is_zoned(q))
                return 0;
        return sector >> ilog2(q->limits.chunk_sectors);
}

static inline bool blk_queue_zone_is_seq(struct request_queue *q,
                                         sector_t sector)
{
        if (!blk_queue_is_zoned(q) || !q->seq_zones_bitmap)
                return false;
        return test_bit(blk_queue_zone_no(q, sector), q->seq_zones_bitmap);
}
#else /* CONFIG_BLK_DEV_ZONED */
static inline unsigned int blk_queue_nr_zones(struct request_queue *q)
{
        return 0;
}
#endif /* CONFIG_BLK_DEV_ZONED */

static inline bool rq_is_sync(struct request *rq)
{
        return op_is_sync(rq->cmd_flags);
}

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

        return true;
}

static inline bool blk_write_same_mergeable(struct bio *a, struct bio *b)
{
        if (bio_page(a) == bio_page(b) &&
            bio_offset(a) == bio_offset(b))
                return true;

        return false;
}

static inline unsigned int blk_queue_depth(struct request_queue *q)
{
        if (q->queue_depth)
                return q->queue_depth;

        return q->nr_requests;
}

extern unsigned long blk_max_low_pfn, blk_max_pfn;

/*
 * standard bounce addresses:
 *
 * BLK_BOUNCE_HIGH      : bounce all highmem pages
 * BLK_BOUNCE_ANY       : don't bounce anything
 * BLK_BOUNCE_ISA       : bounce pages above ISA DMA boundary
 */

#if BITS_PER_LONG == 32
#define BLK_BOUNCE_HIGH         ((u64)blk_max_low_pfn << PAGE_SHIFT)
#else
#define BLK_BOUNCE_HIGH         -1ULL
#endif
#define BLK_BOUNCE_ANY          (-1ULL)
#define BLK_BOUNCE_ISA          (DMA_BIT_MASK(24))

/*
 * default timeout for SG_IO if none specified
 */
#define BLK_DEFAULT_SG_TIMEOUT  (60 * HZ)
#define BLK_MIN_SG_TIMEOUT      (7 * HZ)

struct rq_map_data {
        struct page **pages;
        int page_order;
        int nr_entries;
        unsigned long offset;
        int null_mapped;
        int from_user;
};

struct req_iterator {
        struct bvec_iter iter;
        struct bio *bio;
};

/* This should not be used directly - use rq_for_each_segment */
#define for_each_bio(_bio)              \
        for (; _bio; _bio = _bio->bi_next)
#define __rq_for_each_bio(_bio, rq)     \
        if ((rq->bio))                  \
                for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)

#define rq_for_each_segment(bvl, _rq, _iter)                    \
        __rq_for_each_bio(_iter.bio, _rq)                       \
                bio_for_each_segment(bvl, _iter.bio, _iter.iter)

#define rq_for_each_bvec(bvl, _rq, _iter)                       \
        __rq_for_each_bio(_iter.bio, _rq)                       \
                bio_for_each_bvec(bvl, _iter.bio, _iter.iter)

#define rq_iter_last(bvec, _iter)                               \
                (_iter.bio->bi_next == NULL &&                  \
                 bio_iter_last(bvec, _iter.iter))

#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
# error "You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
#endif
#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
extern void rq_flush_dcache_pages(struct request *rq);
#else
static inline void rq_flush_dcache_pages(struct request *rq)
{
}
#endif

extern int blk_register_queue(struct gendisk *disk);
extern void blk_unregister_queue(struct gendisk *disk);
extern blk_qc_t generic_make_request(struct bio *bio);
extern blk_qc_t direct_make_request(struct bio *bio);
extern void blk_rq_init(struct request_queue *q, struct request *rq);
extern void blk_init_request_from_bio(struct request *req, struct bio *bio);
extern void blk_put_request(struct request *);
extern struct request *blk_get_request(struct request_queue *, unsigned int op,
                                       blk_mq_req_flags_t flags);
extern int blk_lld_busy(struct request_queue *q);
extern int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
                             struct bio_set *bs, gfp_t gfp_mask,
                             int (*bio_ctr)(struct bio *, struct bio *, void *),
                             void *data);
extern void blk_rq_unprep_clone(struct request *rq);
extern blk_status_t blk_insert_cloned_request(struct request_queue *q,
                                     struct request *rq);
extern int blk_rq_append_bio(struct request *rq, struct bio **bio);
extern void blk_queue_split(struct request_queue *, struct bio **);
extern void blk_recount_segments(struct request_queue *, struct bio *);
extern int scsi_verify_blk_ioctl(struct block_device *, unsigned int);
extern int scsi_cmd_blk_ioctl(struct block_device *, fmode_t,
                              unsigned int, void __user *);
extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t,
                          unsigned int, void __user *);
extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t,
                         struct scsi_ioctl_command __user *);

extern int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags);
extern void blk_queue_exit(struct request_queue *q);
extern void blk_sync_queue(struct request_queue *q);
extern int blk_rq_map_user(struct request_queue *, struct request *,
                           struct rq_map_data *, void __user *, unsigned long,
                           gfp_t);
extern int blk_rq_unmap_user(struct bio *);
extern int blk_rq_map_kern(struct request_queue *, struct request *, void *, unsigned int, gfp_t);
extern int blk_rq_map_user_iov(struct request_queue *, struct request *,
                               struct rq_map_data *, const struct iov_iter *,
                               gfp_t);
extern void blk_execute_rq(struct request_queue *, struct gendisk *,
                          struct request *, int);
extern void blk_execute_rq_nowait(struct request_queue *, struct gendisk *,
                                  struct request *, int, rq_end_io_fn *);

int blk_status_to_errno(blk_status_t status);
blk_status_t errno_to_blk_status(int errno);

int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin);

static inline struct request_queue *bdev_get_queue(struct block_device *bdev)
{
        return bdev->bd_disk->queue;    /* this is never NULL */
}

/*
 * The basic unit of block I/O is a sector. It is used in a number of contexts
 * in Linux (blk, bio, genhd). The size of one sector is 512 = 2**9
 * bytes. Variables of type sector_t represent an offset or size that is a
 * multiple of 512 bytes. Hence these two constants.
 */
#ifndef SECTOR_SHIFT
#define SECTOR_SHIFT 9
#endif
#ifndef SECTOR_SIZE
#define SECTOR_SIZE (1 << SECTOR_SHIFT)
#endif

/*
 * blk_rq_pos()                 : the current sector
 * blk_rq_bytes()               : bytes left in the entire request
 * blk_rq_cur_bytes()           : bytes left in the current segment
 * blk_rq_err_bytes()           : bytes left till the next error boundary
 * blk_rq_sectors()             : sectors left in the entire request
 * blk_rq_cur_sectors()         : sectors left in the current segment
 */
static inline sector_t blk_rq_pos(const struct request *rq)
{
        return rq->__sector;
}

static inline unsigned int blk_rq_bytes(const struct request *rq)
{
        return rq->__data_len;
}

static inline int blk_rq_cur_bytes(const struct request *rq)
{
        return rq->bio ? bio_cur_bytes(rq->bio) : 0;
}

extern unsigned int blk_rq_err_bytes(const struct request *rq);

static inline unsigned int blk_rq_sectors(const struct request *rq)
{
        return blk_rq_bytes(rq) >> SECTOR_SHIFT;
}

static inline unsigned int blk_rq_cur_sectors(const struct request *rq)
{
        return blk_rq_cur_bytes(rq) >> SECTOR_SHIFT;
}

#ifdef CONFIG_BLK_DEV_ZONED
static inline unsigned int blk_rq_zone_no(struct request *rq)
{
        return blk_queue_zone_no(rq->q, blk_rq_pos(rq));
}

static inline unsigned int blk_rq_zone_is_seq(struct request *rq)
{
        return blk_queue_zone_is_seq(rq->q, blk_rq_pos(rq));
}
#endif /* CONFIG_BLK_DEV_ZONED */

/*
 * Some commands like WRITE SAME have a payload or data transfer size which
 * is different from the size of the request.  Any driver that supports such
 * commands using the RQF_SPECIAL_PAYLOAD flag needs to use this helper to
 * calculate the data transfer size.
 */
static inline unsigned int blk_rq_payload_bytes(struct request *rq)
{
        if (rq->rq_flags & RQF_SPECIAL_PAYLOAD)
                return rq->special_vec.bv_len;
        return blk_rq_bytes(rq);
}

static inline unsigned int blk_queue_get_max_sectors(struct request_queue *q,
                                                     int op)
{
        if (unlikely(op == REQ_OP_DISCARD || op == REQ_OP_SECURE_ERASE))
                return min(q->limits.max_discard_sectors,
                           UINT_MAX >> SECTOR_SHIFT);

        if (unlikely(op == REQ_OP_WRITE_SAME))
                return q->limits.max_write_same_sectors;

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

        return q->limits.max_sectors;
}

/*
 * Return maximum size of a request at given offset. Only valid for
 * file system requests.
 */
static inline unsigned int blk_max_size_offset(struct request_queue *q,
                                               sector_t offset)
{
        if (!q->limits.chunk_sectors)
                return q->limits.max_sectors;

        return min(q->limits.max_sectors, (unsigned int)(q->limits.chunk_sectors -
                        (offset & (q->limits.chunk_sectors - 1))));
}

static inline unsigned int blk_rq_get_max_sectors(struct request *rq,
                                                  sector_t offset)
{
        struct request_queue *q = rq->q;

        if (blk_rq_is_passthrough(rq))
                return q->limits.max_hw_sectors;

        if (!q->limits.chunk_sectors ||
            req_op(rq) == REQ_OP_DISCARD ||
            req_op(rq) == REQ_OP_SECURE_ERASE)
                return blk_queue_get_max_sectors(q, req_op(rq));

        return min(blk_max_size_offset(q, offset),
                        blk_queue_get_max_sectors(q, req_op(rq)));
}

static inline unsigned int blk_rq_count_bios(struct request *rq)
{
        unsigned int nr_bios = 0;
        struct bio *bio;

        __rq_for_each_bio(bio, rq)
                nr_bios++;

        return nr_bios;
}

void blk_steal_bios(struct bio_list *list, struct request *rq);

/*
 * Request completion related functions.
 *
 * blk_update_request() completes given number of bytes and updates
 * the request without completing it.
 *
 * blk_end_request() and friends.  __blk_end_request() must be called
 * with the request queue spinlock acquired.
 *
 * Several drivers define their own end_request and call
 * blk_end_request() for parts of the original function.
 * This prevents code duplication in drivers.
 */
extern bool blk_update_request(struct request *rq, blk_status_t error,
                               unsigned int nr_bytes);
extern void blk_end_request_all(struct request *rq, blk_status_t error);
extern bool __blk_end_request(struct request *rq, blk_status_t error,
                              unsigned int nr_bytes);
extern void __blk_end_request_all(struct request *rq, blk_status_t error);
extern bool __blk_end_request_cur(struct request *rq, blk_status_t error);

extern void __blk_complete_request(struct request *);
extern void blk_abort_request(struct request *);

/*
 * Access functions for manipulating queue properties
 */
extern void blk_cleanup_queue(struct request_queue *);
extern void blk_queue_make_request(struct request_queue *, make_request_fn *);
extern void blk_queue_bounce_limit(struct request_queue *, u64);
extern void blk_queue_max_hw_sectors(struct request_queue *, unsigned int);
extern void blk_queue_chunk_sectors(struct request_queue *, unsigned int);
extern void blk_queue_max_segments(struct request_queue *, unsigned short);
extern void blk_queue_max_discard_segments(struct request_queue *,
                unsigned short);
extern void blk_queue_max_segment_size(struct request_queue *, unsigned int);
extern void blk_queue_max_discard_sectors(struct request_queue *q,
                unsigned int max_discard_sectors);
extern void blk_queue_max_write_same_sectors(struct request_queue *q,
                unsigned int max_write_same_sectors);
extern void blk_queue_max_write_zeroes_sectors(struct request_queue *q,
                unsigned int max_write_same_sectors);
extern void blk_queue_logical_block_size(struct request_queue *, unsigned short);
extern void blk_queue_physical_block_size(struct request_queue *, unsigned int);
extern void blk_queue_alignment_offset(struct request_queue *q,
                                       unsigned int alignment);
extern void blk_limits_io_min(struct queue_limits *limits, unsigned int min);
extern void blk_queue_io_min(struct request_queue *q, unsigned int min);
extern void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt);
extern void blk_queue_io_opt(struct request_queue *q, unsigned int opt);
extern void blk_set_queue_depth(struct request_queue *q, unsigned int depth);
extern void blk_set_default_limits(struct queue_limits *lim);
extern void blk_set_stacking_limits(struct queue_limits *lim);
extern int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
                            sector_t offset);
extern int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev,
                            sector_t offset);
extern void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
                              sector_t offset);
extern void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b);
extern void blk_queue_dma_pad(struct request_queue *, unsigned int);
extern void blk_queue_update_dma_pad(struct request_queue *, unsigned int);
extern int blk_queue_dma_drain(struct request_queue *q,
                               dma_drain_needed_fn *dma_drain_needed,
                               void *buf, unsigned int size);
extern void blk_queue_segment_boundary(struct request_queue *, unsigned long);
extern void blk_queue_virt_boundary(struct request_queue *, unsigned long);
extern void blk_queue_dma_alignment(struct request_queue *, int);
extern void blk_queue_update_dma_alignment(struct request_queue *, int);
extern void blk_queue_rq_timeout(struct request_queue *, unsigned int);
extern void blk_queue_write_cache(struct request_queue *q, bool enabled, bool fua);

/*
 * Number of physical segments as sent to the device.
 *
 * Normally this is the number of discontiguous data segments sent by the
 * submitter.  But for data-less command like discard we might have no
 * actual data segments submitted, but the driver might have to add it's
 * own special payload.  In that case we still return 1 here so that this
 * special payload will be mapped.
 */
static inline unsigned short blk_rq_nr_phys_segments(struct request *rq)
{
        if (rq->rq_flags & RQF_SPECIAL_PAYLOAD)
                return 1;
        return rq->nr_phys_segments;
}

/*
 * Number of discard segments (or ranges) the driver needs to fill in.
 * Each discard bio merged into a request is counted as one segment.
 */
static inline unsigned short blk_rq_nr_discard_segments(struct request *rq)
{
        return max_t(unsigned short, rq->nr_phys_segments, 1);
}

extern int blk_rq_map_sg(struct request_queue *, struct request *, struct scatterlist *);
extern void blk_dump_rq_flags(struct request *, char *);
extern long nr_blockdev_pages(void);

bool __must_check blk_get_queue(struct request_queue *);
struct request_queue *blk_alloc_queue(gfp_t);
struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id);
extern void blk_put_queue(struct request_queue *);
extern void blk_set_queue_dying(struct request_queue *);

/*
 * blk_plug permits building a queue of related requests by holding the I/O
 * fragments for a short period. This allows merging of sequential requests
 * into single larger request. As the requests are moved from a per-task list to
 * the device's request_queue in a batch, this results in improved scalability
 * as the lock contention for request_queue lock is reduced.
 *
 * It is ok not to disable preemption when adding the request to the plug list
 * or when attempting a merge, because blk_schedule_flush_list() will only flush
 * the plug list when the task sleeps by itself. For details, please see
 * schedule() where blk_schedule_flush_plug() is called.
 */
struct blk_plug {
        struct list_head mq_list; /* blk-mq requests */
        struct list_head cb_list; /* md requires an unplug callback */
        unsigned short rq_count;
        bool multiple_queues;
};
#define BLK_MAX_REQUEST_COUNT 16
#define BLK_PLUG_FLUSH_SIZE (128 * 1024)

struct blk_plug_cb;
typedef void (*blk_plug_cb_fn)(struct blk_plug_cb *, bool);
struct blk_plug_cb {
        struct list_head list;
        blk_plug_cb_fn callback;
        void *data;
};
extern struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug,
                                             void *data, int size);
extern void blk_start_plug(struct blk_plug *);
extern void blk_finish_plug(struct blk_plug *);
extern void blk_flush_plug_list(struct blk_plug *, bool);

static inline void blk_flush_plug(struct task_struct *tsk)
{
        struct blk_plug *plug = tsk->plug;

        if (plug)
                blk_flush_plug_list(plug, false);
}

static inline void blk_schedule_flush_plug(struct task_struct *tsk)
{
        struct blk_plug *plug = tsk->plug;

        if (plug)
                blk_flush_plug_list(plug, true);
}

static inline bool blk_needs_flush_plug(struct task_struct *tsk)
{
        struct blk_plug *plug = tsk->plug;

        return plug &&
                 (!list_empty(&plug->mq_list) ||
                 !list_empty(&plug->cb_list));
}

extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *);
extern int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
                sector_t nr_sects, gfp_t gfp_mask, struct page *page);

#define BLKDEV_DISCARD_SECURE   (1 << 0)        /* issue a secure erase */

extern int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
                sector_t nr_sects, gfp_t gfp_mask, unsigned long flags);
extern int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
                sector_t nr_sects, gfp_t gfp_mask, int flags,
                struct bio **biop);

#define BLKDEV_ZERO_NOUNMAP     (1 << 0)  /* do not free blocks */
#define BLKDEV_ZERO_NOFALLBACK  (1 << 1)  /* don't write explicit zeroes */

extern int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
                sector_t nr_sects, gfp_t gfp_mask, struct bio **biop,
                unsigned flags);
extern int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
                sector_t nr_sects, gfp_t gfp_mask, unsigned flags);

static inline int sb_issue_discard(struct super_block *sb, sector_t block,
                sector_t nr_blocks, gfp_t gfp_mask, unsigned long flags)
{
        return blkdev_issue_discard(sb->s_bdev,
                                    block << (sb->s_blocksize_bits -
                                              SECTOR_SHIFT),
                                    nr_blocks << (sb->s_blocksize_bits -
                                                  SECTOR_SHIFT),
                                    gfp_mask, flags);
}
static inline int sb_issue_zeroout(struct super_block *sb, sector_t block,
                sector_t nr_blocks, gfp_t gfp_mask)
{
        return blkdev_issue_zeroout(sb->s_bdev,
                                    block << (sb->s_blocksize_bits -
                                              SECTOR_SHIFT),
                                    nr_blocks << (sb->s_blocksize_bits -
                                                  SECTOR_SHIFT),
                                    gfp_mask, 0);
}

extern int blk_verify_command(unsigned char *cmd, fmode_t mode);

enum blk_default_limits {
        BLK_MAX_SEGMENTS        = 128,
        BLK_SAFE_MAX_SECTORS    = 255,
        BLK_DEF_MAX_SECTORS     = 2560,
        BLK_MAX_SEGMENT_SIZE    = 65536,
        BLK_SEG_BOUNDARY_MASK   = 0xFFFFFFFFUL,
};

static inline unsigned long queue_segment_boundary(struct request_queue *q)
{
        return q->limits.seg_boundary_mask;
}

static inline unsigned long queue_virt_boundary(struct request_queue *q)
{
        return q->limits.virt_boundary_mask;
}

static inline unsigned int queue_max_sectors(struct request_queue *q)
{
        return q->limits.max_sectors;
}

static inline unsigned int queue_max_hw_sectors(struct request_queue *q)
{
        return q->limits.max_hw_sectors;
}

static inline unsigned short queue_max_segments(struct request_queue *q)
{
        return q->limits.max_segments;
}

static inline unsigned short queue_max_discard_segments(struct request_queue *q)
{
        return q->limits.max_discard_segments;
}

static inline unsigned int queue_max_segment_size(struct request_queue *q)
{
        return q->limits.max_segment_size;
}

static inline unsigned short queue_logical_block_size(struct request_queue *q)
{
        int retval = 512;

        if (q && q->limits.logical_block_size)
                retval = q->limits.logical_block_size;

        return retval;
}

static inline unsigned short bdev_logical_block_size(struct block_device *bdev)
{
        return queue_logical_block_size(bdev_get_queue(bdev));
}

static inline unsigned int queue_physical_block_size(struct request_queue *q)
{
        return q->limits.physical_block_size;
}

static inline unsigned int bdev_physical_block_size(struct block_device *bdev)
{
        return queue_physical_block_size(bdev_get_queue(bdev));
}

static inline unsigned int queue_io_min(struct request_queue *q)
{
        return q->limits.io_min;
}

static inline int bdev_io_min(struct block_device *bdev)
{
        return queue_io_min(bdev_get_queue(bdev));
}

static inline unsigned int queue_io_opt(struct request_queue *q)
{
        return q->limits.io_opt;
}

static inline int bdev_io_opt(struct block_device *bdev)
{
        return queue_io_opt(bdev_get_queue(bdev));
}

static inline int queue_alignment_offset(struct request_queue *q)
{
        if (q->limits.misaligned)
                return -1;

        return q->limits.alignment_offset;
}

static inline int queue_limit_alignment_offset(struct queue_limits *lim, sector_t sector)
{
        unsigned int granularity = max(lim->physical_block_size, lim->io_min);
        unsigned int alignment = sector_div(sector, granularity >> SECTOR_SHIFT)
                << SECTOR_SHIFT;

        return (granularity + lim->alignment_offset - alignment) % granularity;
}

static inline int bdev_alignment_offset(struct block_device *bdev)
{
        struct request_queue *q = bdev_get_queue(bdev);

        if (q->limits.misaligned)
                return -1;

        if (bdev != bdev->bd_contains)
                return bdev->bd_part->alignment_offset;

        return q->limits.alignment_offset;
}

static inline int queue_discard_alignment(struct request_queue *q)
{
        if (q->limits.discard_misaligned)
                return -1;

        return q->limits.discard_alignment;
}

static inline int queue_limit_discard_alignment(struct queue_limits *lim, sector_t sector)
{
        unsigned int alignment, granularity, offset;

        if (!lim->max_discard_sectors)
                return 0;

        /* Why are these in bytes, not sectors? */
        alignment = lim->discard_alignment >> SECTOR_SHIFT;
        granularity = lim->discard_granularity >> SECTOR_SHIFT;
        if (!granularity)
                return 0;

        /* Offset of the partition start in 'granularity' sectors */
        offset = sector_div(sector, granularity);

        /* And why do we do this modulus *again* in blkdev_issue_discard()? */
        offset = (granularity + alignment - offset) % granularity;

        /* Turn it back into bytes, gaah */
        return offset << SECTOR_SHIFT;
}

static inline int bdev_discard_alignment(struct block_device *bdev)
{
        struct request_queue *q = bdev_get_queue(bdev);

        if (bdev != bdev->bd_contains)
                return bdev->bd_part->discard_alignment;

        return q->limits.discard_alignment;
}

static inline unsigned int bdev_write_same(struct block_device *bdev)
{
        struct request_queue *q = bdev_get_queue(bdev);

        if (q)
                return q->limits.max_write_same_sectors;

        return 0;
}

static inline unsigned int bdev_write_zeroes_sectors(struct block_device *bdev)
{
        struct request_queue *q = bdev_get_queue(bdev);

        if (q)
                return q->limits.max_write_zeroes_sectors;

        return 0;
}

static inline enum blk_zoned_model bdev_zoned_model(struct block_device *bdev)
{
        struct request_queue *q = bdev_get_queue(bdev);

        if (q)
                return blk_queue_zoned_model(q);

        return BLK_ZONED_NONE;
}

static inline bool bdev_is_zoned(struct block_device *bdev)
{
        struct request_queue *q = bdev_get_queue(bdev);

        if (q)
                return blk_queue_is_zoned(q);

        return false;
}

static inline unsigned int bdev_zone_sectors(struct block_device *bdev)
{
        struct request_queue *q = bdev_get_queue(bdev);

        if (q)
                return blk_queue_zone_sectors(q);
        return 0;
}

static inline int queue_dma_alignment(struct request_queue *q)
{
        return q ? q->dma_alignment : 511;
}

static inline int blk_rq_aligned(struct request_queue *q, unsigned long addr,
                                 unsigned int len)
{
        unsigned int alignment = queue_dma_alignment(q) | q->dma_pad_mask;
        return !(addr & alignment) && !(len & alignment);
}

/* assumes size > 256 */
static inline unsigned int blksize_bits(unsigned int size)
{
        unsigned int bits = 8;
        do {
                bits++;
                size >>= 1;
        } while (size > 256);
        return bits;
}

static inline unsigned int block_size(struct block_device *bdev)
{
        return bdev->bd_block_size;
}

typedef struct {struct page *v;} Sector;

unsigned char *read_dev_sector(struct block_device *, sector_t, Sector *);

static inline void put_dev_sector(Sector p)
{
        put_page(p.v);
}

int kblockd_schedule_work(struct work_struct *work);
int kblockd_schedule_work_on(int cpu, struct work_struct *work);
int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, unsigned long delay);

#define MODULE_ALIAS_BLOCKDEV(major,minor) \
        MODULE_ALIAS("block-major-" __stringify(major) "-" __stringify(minor))
#define MODULE_ALIAS_BLOCKDEV_MAJOR(major) \
        MODULE_ALIAS("block-major-" __stringify(major) "-*")

#if defined(CONFIG_BLK_DEV_INTEGRITY)

enum blk_integrity_flags {
        BLK_INTEGRITY_VERIFY            = 1 << 0,
        BLK_INTEGRITY_GENERATE          = 1 << 1,
        BLK_INTEGRITY_DEVICE_CAPABLE    = 1 << 2,
        BLK_INTEGRITY_IP_CHECKSUM       = 1 << 3,
};

struct blk_integrity_iter {
        void                    *prot_buf;
        void                    *data_buf;
        sector_t                seed;
        unsigned int            data_size;
        unsigned short          interval;
        const char              *disk_name;
};

typedef blk_status_t (integrity_processing_fn) (struct blk_integrity_iter *);

struct blk_integrity_profile {
        integrity_processing_fn         *generate_fn;
        integrity_processing_fn         *verify_fn;
        const char                      *name;
};

extern void blk_integrity_register(struct gendisk *, struct blk_integrity *);
extern void blk_integrity_unregister(struct gendisk *);
extern int blk_integrity_compare(struct gendisk *, struct gendisk *);
extern int blk_rq_map_integrity_sg(struct request_queue *, struct bio *,
                                   struct scatterlist *);
extern int blk_rq_count_integrity_sg(struct request_queue *, struct bio *);
extern bool blk_integrity_merge_rq(struct request_queue *, struct request *,
                                   struct request *);
extern bool blk_integrity_merge_bio(struct request_queue *, struct request *,
                                    struct bio *);

static inline struct blk_integrity *blk_get_integrity(struct gendisk *disk)
{
        struct blk_integrity *bi = &disk->queue->integrity;

        if (!bi->profile)
                return NULL;

        return bi;
}

static inline
struct blk_integrity *bdev_get_integrity(struct block_device *bdev)
{
        return blk_get_integrity(bdev->bd_disk);
}

static inline bool blk_integrity_rq(struct request *rq)
{
        return rq->cmd_flags & REQ_INTEGRITY;
}

static inline void blk_queue_max_integrity_segments(struct request_queue *q,
                                                    unsigned int segs)
{
        q->limits.max_integrity_segments = segs;
}

static inline unsigned short
queue_max_integrity_segments(struct request_queue *q)
{
        return q->limits.max_integrity_segments;
}

/**
 * bio_integrity_intervals - Return number of integrity intervals for a bio
 * @bi:         blk_integrity profile for device
 * @sectors:    Size of the bio in 512-byte sectors
 *
 * Description: The block layer calculates everything in 512 byte
 * sectors but integrity metadata is done in terms of the data integrity
 * interval size of the storage device.  Convert the block layer sectors
 * to the appropriate number of integrity intervals.
 */
static inline unsigned int bio_integrity_intervals(struct blk_integrity *bi,
                                                   unsigned int sectors)
{
        return sectors >> (bi->interval_exp - 9);
}

static inline unsigned int bio_integrity_bytes(struct blk_integrity *bi,
                                               unsigned int sectors)
{
        return bio_integrity_intervals(bi, sectors) * bi->tuple_size;
}

#else /* CONFIG_BLK_DEV_INTEGRITY */

struct bio;
struct block_device;
struct gendisk;
struct blk_integrity;

static inline int blk_integrity_rq(struct request *rq)
{
        return 0;
}
static inline int blk_rq_count_integrity_sg(struct request_queue *q,
                                            struct bio *b)
{
        return 0;
}
static inline int blk_rq_map_integrity_sg(struct request_queue *q,
                                          struct bio *b,
                                          struct scatterlist *s)
{
        return 0;
}
static inline struct blk_integrity *bdev_get_integrity(struct block_device *b)
{
        return NULL;
}
static inline struct blk_integrity *blk_get_integrity(struct gendisk *disk)
{
        return NULL;
}
static inline int blk_integrity_compare(struct gendisk *a, struct gendisk *b)
{
        return 0;
}
static inline void blk_integrity_register(struct gendisk *d,
                                         struct blk_integrity *b)
{
}
static inline void blk_integrity_unregister(struct gendisk *d)
{
}
static inline void blk_queue_max_integrity_segments(struct request_queue *q,
                                                    unsigned int segs)
{
}
static inline unsigned short queue_max_integrity_segments(struct request_queue *q)
{
        return 0;
}
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 unsigned int bio_integrity_intervals(struct blk_integrity *bi,
                                                   unsigned int sectors)
{
        return 0;
}

static inline unsigned int bio_integrity_bytes(struct blk_integrity *bi,
                                               unsigned int sectors)
{
        return 0;
}

#endif /* CONFIG_BLK_DEV_INTEGRITY */

struct block_device_operations {
        int (*open) (struct block_device *, fmode_t);
        void (*release) (struct gendisk *, fmode_t);
        int (*rw_page)(struct block_device *, sector_t, struct page *, unsigned int);
        int (*ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
        int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
        unsigned int (*check_events) (struct gendisk *disk,
                                      unsigned int clearing);
        /* ->media_changed() is DEPRECATED, use ->check_events() instead */
        int (*media_changed) (struct gendisk *);
        void (*unlock_native_capacity) (struct gendisk *);
        int (*revalidate_disk) (struct gendisk *);
        int (*getgeo)(struct block_device *, struct hd_geometry *);
        /* this callback is with swap_lock and sometimes page table lock held */
        void (*swap_slot_free_notify) (struct block_device *, unsigned long);
        int (*report_zones)(struct gendisk *, sector_t sector,
                            struct blk_zone *zones, unsigned int *nr_zones,
                            gfp_t gfp_mask);
        struct module *owner;
        const struct pr_ops *pr_ops;
};

extern int __blkdev_driver_ioctl(struct block_device *, fmode_t, unsigned int,
                                 unsigned long);
extern int bdev_read_page(struct block_device *, sector_t, struct page *);
extern int bdev_write_page(struct block_device *, sector_t, struct page *,
                                                struct writeback_control *);

#ifdef CONFIG_BLK_DEV_ZONED
bool blk_req_needs_zone_write_lock(struct request *rq);
void __blk_req_zone_write_lock(struct request *rq);
void __blk_req_zone_write_unlock(struct request *rq);

static inline void blk_req_zone_write_lock(struct request *rq)
{
        if (blk_req_needs_zone_write_lock(rq))
                __blk_req_zone_write_lock(rq);
}

static inline void blk_req_zone_write_unlock(struct request *rq)
{
        if (rq->rq_flags & RQF_ZONE_WRITE_LOCKED)
                __blk_req_zone_write_unlock(rq);
}

static inline bool blk_req_zone_is_write_locked(struct request *rq)
{
        return rq->q->seq_zones_wlock &&
                test_bit(blk_rq_zone_no(rq), rq->q->seq_zones_wlock);
}

static inline bool blk_req_can_dispatch_to_zone(struct request *rq)
{
        if (!blk_req_needs_zone_write_lock(rq))
                return true;
        return !blk_req_zone_is_write_locked(rq);
}
#else
static inline bool blk_req_needs_zone_write_lock(struct request *rq)
{
        return false;
}

static inline void blk_req_zone_write_lock(struct request *rq)
{
}

static inline void blk_req_zone_write_unlock(struct request *rq)
{
}
static inline bool blk_req_zone_is_write_locked(struct request *rq)
{
        return false;
}

static inline bool blk_req_can_dispatch_to_zone(struct request *rq)
{
        return true;
}
#endif /* CONFIG_BLK_DEV_ZONED */

#else /* CONFIG_BLOCK */

struct block_device;

/*
 * stubs for when the block layer is configured out
 */
#define buffer_heads_over_limit 0

static inline long nr_blockdev_pages(void)
{
        return 0;
}

struct blk_plug {
};

static inline void blk_start_plug(struct blk_plug *plug)
{
}

static inline void blk_finish_plug(struct blk_plug *plug)
{
}

static inline void blk_flush_plug(struct task_struct *task)
{
}

static inline void blk_schedule_flush_plug(struct task_struct *task)
{
}


static inline bool blk_needs_flush_plug(struct task_struct *tsk)
{
        return false;
}

static inline int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
                                     sector_t *error_sector)
{
        return 0;
}

#endif /* CONFIG_BLOCK */

static inline void blk_wake_io_task(struct task_struct *waiter)
{
        /*
         * If we're polling, the task itself is doing the completions. For
         * that case, we don't need to signal a wakeup, it's enough to just
         * mark us as RUNNING.
         */
        if (waiter == current)
                __set_current_state(TASK_RUNNING);
        else
                wake_up_process(waiter);
}

#endif