#ifndef IO_URING_TYPES_H
#define IO_URING_TYPES_H

#include <linux/blkdev.h>
#include <linux/hashtable.h>
#include <linux/task_work.h>
#include <linux/bitmap.h>
#include <linux/llist.h>
#include <uapi/linux/io_uring.h>

enum {
        /*
         * A hint to not wake right away but delay until there are enough of
         * tw's queued to match the number of CQEs the task is waiting for.
         *
         * Must not be used with requests generating more than one CQE.
         * It's also ignored unless IORING_SETUP_DEFER_TASKRUN is set.
         */
        IOU_F_TWQ_LAZY_WAKE                     = 1,
};

enum io_uring_cmd_flags {
        IO_URING_F_COMPLETE_DEFER       = 1,
        IO_URING_F_UNLOCKED             = 2,
        /* the request is executed from poll, it should not be freed */
        IO_URING_F_MULTISHOT            = 4,
        /* executed by io-wq */
        IO_URING_F_IOWQ                 = 8,
        /* executed inline from syscall */
        IO_URING_F_INLINE               = 16,
        /* int's last bit, sign checks are usually faster than a bit test */
        IO_URING_F_NONBLOCK             = INT_MIN,

        /* ctx state flags, for URING_CMD */
        IO_URING_F_SQE128               = (1 << 8),
        IO_URING_F_CQE32                = (1 << 9),
        IO_URING_F_IOPOLL               = (1 << 10),

        /* set when uring wants to cancel a previously issued command */
        IO_URING_F_CANCEL               = (1 << 11),
        IO_URING_F_COMPAT               = (1 << 12),
};

struct io_wq_work_node {
        struct io_wq_work_node *next;
};

struct io_wq_work_list {
        struct io_wq_work_node *first;
        struct io_wq_work_node *last;
};

struct io_wq_work {
        struct io_wq_work_node list;
        atomic_t flags;
        /* place it here instead of io_kiocb as it fills padding and saves 4B */
        int cancel_seq;
};

struct io_rsrc_data {
        unsigned int                    nr;
        struct io_rsrc_node             **nodes;
};

struct io_file_table {
        struct io_rsrc_data data;
        unsigned long *bitmap;
        unsigned int alloc_hint;
};

struct io_hash_bucket {
        struct hlist_head       list;
} ____cacheline_aligned_in_smp;

struct io_hash_table {
        struct io_hash_bucket   *hbs;
        unsigned                hash_bits;
};

struct io_mapped_region {
        struct page             **pages;
        void                    *ptr;
        unsigned                nr_pages;
        unsigned                flags;
};

/*
 * Return value from io_buffer_list selection, to avoid stashing it in
 * struct io_kiocb. For legacy/classic provided buffers, keeping a reference
 * across execution contexts are fine. But for ring provided buffers, the
 * list may go away as soon as ->uring_lock is dropped. As the io_kiocb
 * persists, it's better to just keep the buffer local for those cases.
 */
struct io_br_sel {
        struct io_buffer_list *buf_list;
        /*
         * Some selection parts return the user address, others return an error.
         */
        union {
                void __user *addr;
                ssize_t val;
        };
};


/*
 * Arbitrary limit, can be raised if need be
 */
#define IO_RINGFD_REG_MAX 16

struct io_uring_task {
        /* submission side */
        int                             cached_refs;
        const struct io_ring_ctx        *last;
        struct task_struct              *task;
        struct io_wq                    *io_wq;
        struct file                     *registered_rings[IO_RINGFD_REG_MAX];

        struct xarray                   xa;
        struct wait_queue_head          wait;
        atomic_t                        in_cancel;
        atomic_t                        inflight_tracked;
        struct percpu_counter           inflight;

        struct { /* task_work */
                struct llist_head       task_list;
                struct callback_head    task_work;
        } ____cacheline_aligned_in_smp;
};

struct iou_vec {
        union {
                struct iovec    *iovec;
                struct bio_vec  *bvec;
        };
        unsigned                nr; /* number of struct iovec it can hold */
};

struct io_uring {
        u32 head;
        u32 tail;
};

/*
 * This data is shared with the application through the mmap at offsets
 * IORING_OFF_SQ_RING and IORING_OFF_CQ_RING.
 *
 * The offsets to the member fields are published through struct
 * io_sqring_offsets when calling io_uring_setup.
 */
struct io_rings {
        /*
         * Head and tail offsets into the ring; the offsets need to be
         * masked to get valid indices.
         *
         * The kernel controls head of the sq ring and the tail of the cq ring,
         * and the application controls tail of the sq ring and the head of the
         * cq ring.
         */
        struct io_uring         sq, cq;
        /*
         * Bitmasks to apply to head and tail offsets (constant, equals
         * ring_entries - 1)
         */
        u32                     sq_ring_mask, cq_ring_mask;
        /* Ring sizes (constant, power of 2) */
        u32                     sq_ring_entries, cq_ring_entries;
        /*
         * Number of invalid entries dropped by the kernel due to
         * invalid index stored in array
         *
         * Written by the kernel, shouldn't be modified by the
         * application (i.e. get number of "new events" by comparing to
         * cached value).
         *
         * After a new SQ head value was read by the application this
         * counter includes all submissions that were dropped reaching
         * the new SQ head (and possibly more).
         */
        u32                     sq_dropped;
        /*
         * Runtime SQ flags
         *
         * Written by the kernel, shouldn't be modified by the
         * application.
         *
         * The application needs a full memory barrier before checking
         * for IORING_SQ_NEED_WAKEUP after updating the sq tail.
         */
        atomic_t                sq_flags;
        /*
         * Runtime CQ flags
         *
         * Written by the application, shouldn't be modified by the
         * kernel.
         */
        u32                     cq_flags;
        /*
         * Number of completion events lost because the queue was full;
         * this should be avoided by the application by making sure
         * there are not more requests pending than there is space in
         * the completion queue.
         *
         * Written by the kernel, shouldn't be modified by the
         * application (i.e. get number of "new events" by comparing to
         * cached value).
         *
         * As completion events come in out of order this counter is not
         * ordered with any other data.
         */
        u32                     cq_overflow;
        /*
         * Ring buffer of completion events.
         *
         * The kernel writes completion events fresh every time they are
         * produced, so the application is allowed to modify pending
         * entries.
         */
        struct io_uring_cqe     cqes[] ____cacheline_aligned_in_smp;
};

struct io_bpf_filter;
struct io_bpf_filters {
        refcount_t refs;        /* ref for ->bpf_filters */
        spinlock_t lock;        /* protects ->bpf_filters modifications */
        struct io_bpf_filter __rcu **filters;
        struct rcu_head rcu_head;
};

struct io_restriction {
        DECLARE_BITMAP(register_op, IORING_REGISTER_LAST);
        DECLARE_BITMAP(sqe_op, IORING_OP_LAST);
        struct io_bpf_filters *bpf_filters;
        /* ->bpf_filters needs COW on modification */
        bool bpf_filters_cow;
        u8 sqe_flags_allowed;
        u8 sqe_flags_required;
        /* IORING_OP_* restrictions exist */
        bool op_registered;
        /* IORING_REGISTER_* restrictions exist */
        bool reg_registered;
};

struct io_submit_link {
        struct io_kiocb         *head;
        struct io_kiocb         *last;
};

struct io_submit_state {
        /* inline/task_work completion list, under ->uring_lock */
        struct io_wq_work_node  free_list;
        /* batch completion logic */
        struct io_wq_work_list  compl_reqs;
        struct io_submit_link   link;

        bool                    plug_started;
        bool                    need_plug;
        bool                    cq_flush;
        unsigned short          submit_nr;
        struct blk_plug         plug;
};

struct io_alloc_cache {
        void                    **entries;
        unsigned int            nr_cached;
        unsigned int            max_cached;
        unsigned int            elem_size;
        unsigned int            init_clear;
};

struct io_ring_ctx {
        /* const or read-mostly hot data */
        struct {
                unsigned int            flags;
                unsigned int            drain_next: 1;
                unsigned int            op_restricted: 1;
                unsigned int            reg_restricted: 1;
                unsigned int            off_timeout_used: 1;
                unsigned int            drain_active: 1;
                unsigned int            has_evfd: 1;
                /* all CQEs should be posted only by the submitter task */
                unsigned int            task_complete: 1;
                unsigned int            lockless_cq: 1;
                unsigned int            syscall_iopoll: 1;
                unsigned int            poll_activated: 1;
                unsigned int            drain_disabled: 1;
                unsigned int            compat: 1;
                unsigned int            iowq_limits_set : 1;

                struct task_struct      *submitter_task;
                struct io_rings         *rings;
                /* cache of ->restrictions.bpf_filters->filters */
                struct io_bpf_filter __rcu      **bpf_filters;
                struct percpu_ref       refs;

                clockid_t               clockid;
                enum tk_offsets         clock_offset;

                enum task_work_notify_mode      notify_method;
                unsigned                        sq_thread_idle;
        } ____cacheline_aligned_in_smp;

        /* submission data */
        struct {
                struct mutex            uring_lock;

                /*
                 * Ring buffer of indices into array of io_uring_sqe, which is
                 * mmapped by the application using the IORING_OFF_SQES offset.
                 *
                 * This indirection could e.g. be used to assign fixed
                 * io_uring_sqe entries to operations and only submit them to
                 * the queue when needed.
                 *
                 * The kernel modifies neither the indices array nor the entries
                 * array.
                 */
                u32                     *sq_array;
                struct io_uring_sqe     *sq_sqes;
                unsigned                cached_sq_head;
                unsigned                sq_entries;

                /*
                 * Fixed resources fast path, should be accessed only under
                 * uring_lock, and updated through io_uring_register(2)
                 */
                atomic_t                cancel_seq;

                /*
                 * ->iopoll_list is protected by the ctx->uring_lock for
                 * io_uring instances that don't use IORING_SETUP_SQPOLL.
                 * For SQPOLL, only the single threaded io_sq_thread() will
                 * manipulate the list, hence no extra locking is needed there.
                 */
                bool                    poll_multi_queue;
                struct list_head        iopoll_list;

                struct io_file_table    file_table;
                struct io_rsrc_data     buf_table;
                struct io_alloc_cache   node_cache;
                struct io_alloc_cache   imu_cache;

                struct io_submit_state  submit_state;

                /*
                 * Modifications are protected by ->uring_lock and ->mmap_lock.
                 * The buffer list's io mapped region should be stable once
                 * published.
                 */
                struct xarray           io_bl_xa;

                struct io_hash_table    cancel_table;
                struct io_alloc_cache   apoll_cache;
                struct io_alloc_cache   netmsg_cache;
                struct io_alloc_cache   rw_cache;
                struct io_alloc_cache   cmd_cache;

                /*
                 * Any cancelable uring_cmd is added to this list in
                 * ->uring_cmd() by io_uring_cmd_insert_cancelable()
                 */
                struct hlist_head       cancelable_uring_cmd;
                /*
                 * For Hybrid IOPOLL, runtime in hybrid polling, without
                 * scheduling time
                 */
                u64                                     hybrid_poll_time;
        } ____cacheline_aligned_in_smp;

        struct {
                /*
                 * We cache a range of free CQEs we can use, once exhausted it
                 * should go through a slower range setup, see __io_get_cqe()
                 */
                struct io_uring_cqe     *cqe_cached;
                struct io_uring_cqe     *cqe_sentinel;

                unsigned                cached_cq_tail;
                unsigned                cq_entries;
                struct io_ev_fd __rcu   *io_ev_fd;

                void                    *cq_wait_arg;
                size_t                  cq_wait_size;
        } ____cacheline_aligned_in_smp;

        /*
         * task_work and async notification delivery cacheline. Expected to
         * regularly bounce b/w CPUs.
         */
        struct {
                struct io_rings __rcu   *rings_rcu;
                struct llist_head       work_llist;
                struct llist_head       retry_llist;
                unsigned long           check_cq;
                atomic_t                cq_wait_nr;
                atomic_t                cq_timeouts;
                struct wait_queue_head  cq_wait;
        } ____cacheline_aligned_in_smp;

        /* timeouts */
        struct {
                raw_spinlock_t          timeout_lock;
                struct list_head        timeout_list;
                struct list_head        ltimeout_list;
                unsigned                cq_last_tm_flush;
        } ____cacheline_aligned_in_smp;

        spinlock_t              completion_lock;

        struct list_head        cq_overflow_list;

        struct hlist_head       waitid_list;

#ifdef CONFIG_FUTEX
        struct hlist_head       futex_list;
        struct io_alloc_cache   futex_cache;
#endif

        const struct cred       *sq_creds;      /* cred used for __io_sq_thread() */
        struct io_sq_data       *sq_data;       /* if using sq thread polling */

        struct wait_queue_head  sqo_sq_wait;
        struct list_head        sqd_list;

        unsigned int            file_alloc_start;
        unsigned int            file_alloc_end;

        /* Keep this last, we don't need it for the fast path */
        struct wait_queue_head          poll_wq;
        struct io_restriction           restrictions;

        /* Stores zcrx object pointers of type struct io_zcrx_ifq */
        struct xarray                   zcrx_ctxs;

        u32                     pers_next;
        struct xarray           personalities;

        /* hashed buffered write serialization */
        struct io_wq_hash               *hash_map;

        /* Only used for accounting purposes */
        struct user_struct              *user;
        struct mm_struct                *mm_account;

        /*
         * List of tctx nodes for this ctx, protected by tctx_lock. For
         * cancelation purposes, nests under uring_lock.
         */
        struct list_head                tctx_list;
        struct mutex                    tctx_lock;

        /* ctx exit and cancelation */
        struct llist_head               fallback_llist;
        struct delayed_work             fallback_work;
        struct work_struct              exit_work;
        struct completion               ref_comp;

        /* io-wq management, e.g. thread count */
        u32                             iowq_limits[2];

        struct callback_head            poll_wq_task_work;
        struct list_head                defer_list;
        unsigned                        nr_drained;

        /* protected by ->completion_lock */
        unsigned                        nr_req_allocated;

#ifdef CONFIG_NET_RX_BUSY_POLL
        struct list_head        napi_list;      /* track busy poll napi_id */
        spinlock_t              napi_lock;      /* napi_list lock */

        /* napi busy poll default timeout */
        ktime_t                 napi_busy_poll_dt;
        bool                    napi_prefer_busy_poll;
        u8                      napi_track_mode;

        DECLARE_HASHTABLE(napi_ht, 4);
#endif

        /*
         * Protection for resize vs mmap races - both the mmap and resize
         * side will need to grab this lock, to prevent either side from
         * being run concurrently with the other.
         */
        struct mutex                    mmap_lock;

        struct io_mapped_region         sq_region;
        struct io_mapped_region         ring_region;
        /* used for optimised request parameter and wait argument passing  */
        struct io_mapped_region         param_region;
};

/*
 * Token indicating function is called in task work context:
 * ctx->uring_lock is held and any completions generated will be flushed.
 * ONLY core io_uring.c should instantiate this struct.
 */
struct io_tw_state {
        bool cancel;
};
/* Alias to use in code that doesn't instantiate struct io_tw_state */
typedef struct io_tw_state io_tw_token_t;

enum {
        REQ_F_FIXED_FILE_BIT    = IOSQE_FIXED_FILE_BIT,
        REQ_F_IO_DRAIN_BIT      = IOSQE_IO_DRAIN_BIT,
        REQ_F_LINK_BIT          = IOSQE_IO_LINK_BIT,
        REQ_F_HARDLINK_BIT      = IOSQE_IO_HARDLINK_BIT,
        REQ_F_FORCE_ASYNC_BIT   = IOSQE_ASYNC_BIT,
        REQ_F_BUFFER_SELECT_BIT = IOSQE_BUFFER_SELECT_BIT,
        REQ_F_CQE_SKIP_BIT      = IOSQE_CQE_SKIP_SUCCESS_BIT,

        /* first byte is taken by user flags, shift it to not overlap */
        REQ_F_FAIL_BIT          = 8,
        REQ_F_INFLIGHT_BIT,
        REQ_F_CUR_POS_BIT,
        REQ_F_NOWAIT_BIT,
        REQ_F_LINK_TIMEOUT_BIT,
        REQ_F_NEED_CLEANUP_BIT,
        REQ_F_POLLED_BIT,
        REQ_F_HYBRID_IOPOLL_STATE_BIT,
        REQ_F_BUFFER_SELECTED_BIT,
        REQ_F_BUFFER_RING_BIT,
        REQ_F_REISSUE_BIT,
        REQ_F_CREDS_BIT,
        REQ_F_REFCOUNT_BIT,
        REQ_F_ARM_LTIMEOUT_BIT,
        REQ_F_ASYNC_DATA_BIT,
        REQ_F_SKIP_LINK_CQES_BIT,
        REQ_F_SINGLE_POLL_BIT,
        REQ_F_DOUBLE_POLL_BIT,
        REQ_F_MULTISHOT_BIT,
        REQ_F_APOLL_MULTISHOT_BIT,
        REQ_F_CLEAR_POLLIN_BIT,
        /* keep async read/write and isreg together and in order */
        REQ_F_SUPPORT_NOWAIT_BIT,
        REQ_F_ISREG_BIT,
        REQ_F_POLL_NO_LAZY_BIT,
        REQ_F_CAN_POLL_BIT,
        REQ_F_BL_EMPTY_BIT,
        REQ_F_BL_NO_RECYCLE_BIT,
        REQ_F_BUFFERS_COMMIT_BIT,
        REQ_F_BUF_NODE_BIT,
        REQ_F_BUF_MORE_BIT,
        REQ_F_HAS_METADATA_BIT,
        REQ_F_IMPORT_BUFFER_BIT,
        REQ_F_SQE_COPIED_BIT,

        /* not a real bit, just to check we're not overflowing the space */
        __REQ_F_LAST_BIT,
};

typedef u64 __bitwise io_req_flags_t;
#define IO_REQ_FLAG(bitno)      ((__force io_req_flags_t) BIT_ULL((bitno)))

enum {
        /* ctx owns file */
        REQ_F_FIXED_FILE        = IO_REQ_FLAG(REQ_F_FIXED_FILE_BIT),
        /* drain existing IO first */
        REQ_F_IO_DRAIN          = IO_REQ_FLAG(REQ_F_IO_DRAIN_BIT),
        /* linked sqes */
        REQ_F_LINK              = IO_REQ_FLAG(REQ_F_LINK_BIT),
        /* doesn't sever on completion < 0 */
        REQ_F_HARDLINK          = IO_REQ_FLAG(REQ_F_HARDLINK_BIT),
        /* IOSQE_ASYNC */
        REQ_F_FORCE_ASYNC       = IO_REQ_FLAG(REQ_F_FORCE_ASYNC_BIT),
        /* IOSQE_BUFFER_SELECT */
        REQ_F_BUFFER_SELECT     = IO_REQ_FLAG(REQ_F_BUFFER_SELECT_BIT),
        /* IOSQE_CQE_SKIP_SUCCESS */
        REQ_F_CQE_SKIP          = IO_REQ_FLAG(REQ_F_CQE_SKIP_BIT),

        /* fail rest of links */
        REQ_F_FAIL              = IO_REQ_FLAG(REQ_F_FAIL_BIT),
        /* on inflight list, should be cancelled and waited on exit reliably */
        REQ_F_INFLIGHT          = IO_REQ_FLAG(REQ_F_INFLIGHT_BIT),
        /* read/write uses file position */
        REQ_F_CUR_POS           = IO_REQ_FLAG(REQ_F_CUR_POS_BIT),
        /* must not punt to workers */
        REQ_F_NOWAIT            = IO_REQ_FLAG(REQ_F_NOWAIT_BIT),
        /* has or had linked timeout */
        REQ_F_LINK_TIMEOUT      = IO_REQ_FLAG(REQ_F_LINK_TIMEOUT_BIT),
        /* needs cleanup */
        REQ_F_NEED_CLEANUP      = IO_REQ_FLAG(REQ_F_NEED_CLEANUP_BIT),
        /* already went through poll handler */
        REQ_F_POLLED            = IO_REQ_FLAG(REQ_F_POLLED_BIT),
        /* every req only blocks once in hybrid poll */
        REQ_F_IOPOLL_STATE        = IO_REQ_FLAG(REQ_F_HYBRID_IOPOLL_STATE_BIT),
        /* buffer already selected */
        REQ_F_BUFFER_SELECTED   = IO_REQ_FLAG(REQ_F_BUFFER_SELECTED_BIT),
        /* buffer selected from ring, needs commit */
        REQ_F_BUFFER_RING       = IO_REQ_FLAG(REQ_F_BUFFER_RING_BIT),
        /* caller should reissue async */
        REQ_F_REISSUE           = IO_REQ_FLAG(REQ_F_REISSUE_BIT),
        /* supports async reads/writes */
        REQ_F_SUPPORT_NOWAIT    = IO_REQ_FLAG(REQ_F_SUPPORT_NOWAIT_BIT),
        /* regular file */
        REQ_F_ISREG             = IO_REQ_FLAG(REQ_F_ISREG_BIT),
        /* has creds assigned */
        REQ_F_CREDS             = IO_REQ_FLAG(REQ_F_CREDS_BIT),
        /* skip refcounting if not set */
        REQ_F_REFCOUNT          = IO_REQ_FLAG(REQ_F_REFCOUNT_BIT),
        /* there is a linked timeout that has to be armed */
        REQ_F_ARM_LTIMEOUT      = IO_REQ_FLAG(REQ_F_ARM_LTIMEOUT_BIT),
        /* ->async_data allocated */
        REQ_F_ASYNC_DATA        = IO_REQ_FLAG(REQ_F_ASYNC_DATA_BIT),
        /* don't post CQEs while failing linked requests */
        REQ_F_SKIP_LINK_CQES    = IO_REQ_FLAG(REQ_F_SKIP_LINK_CQES_BIT),
        /* single poll may be active */
        REQ_F_SINGLE_POLL       = IO_REQ_FLAG(REQ_F_SINGLE_POLL_BIT),
        /* double poll may active */
        REQ_F_DOUBLE_POLL       = IO_REQ_FLAG(REQ_F_DOUBLE_POLL_BIT),
        /* request posts multiple completions, should be set at prep time */
        REQ_F_MULTISHOT         = IO_REQ_FLAG(REQ_F_MULTISHOT_BIT),
        /* fast poll multishot mode */
        REQ_F_APOLL_MULTISHOT   = IO_REQ_FLAG(REQ_F_APOLL_MULTISHOT_BIT),
        /* recvmsg special flag, clear EPOLLIN */
        REQ_F_CLEAR_POLLIN      = IO_REQ_FLAG(REQ_F_CLEAR_POLLIN_BIT),
        /* don't use lazy poll wake for this request */
        REQ_F_POLL_NO_LAZY      = IO_REQ_FLAG(REQ_F_POLL_NO_LAZY_BIT),
        /* file is pollable */
        REQ_F_CAN_POLL          = IO_REQ_FLAG(REQ_F_CAN_POLL_BIT),
        /* buffer list was empty after selection of buffer */
        REQ_F_BL_EMPTY          = IO_REQ_FLAG(REQ_F_BL_EMPTY_BIT),
        /* don't recycle provided buffers for this request */
        REQ_F_BL_NO_RECYCLE     = IO_REQ_FLAG(REQ_F_BL_NO_RECYCLE_BIT),
        /* buffer ring head needs incrementing on put */
        REQ_F_BUFFERS_COMMIT    = IO_REQ_FLAG(REQ_F_BUFFERS_COMMIT_BIT),
        /* buf node is valid */
        REQ_F_BUF_NODE          = IO_REQ_FLAG(REQ_F_BUF_NODE_BIT),
        /* incremental buffer consumption, more space available */
        REQ_F_BUF_MORE          = IO_REQ_FLAG(REQ_F_BUF_MORE_BIT),
        /* request has read/write metadata assigned */
        REQ_F_HAS_METADATA      = IO_REQ_FLAG(REQ_F_HAS_METADATA_BIT),
        /*
         * For vectored fixed buffers, resolve iovec to registered buffers.
         * For SEND_ZC, whether to import buffers (i.e. the first issue).
         */
        REQ_F_IMPORT_BUFFER     = IO_REQ_FLAG(REQ_F_IMPORT_BUFFER_BIT),
        /* ->sqe_copy() has been called, if necessary */
        REQ_F_SQE_COPIED        = IO_REQ_FLAG(REQ_F_SQE_COPIED_BIT),
};

struct io_tw_req {
        struct io_kiocb *req;
};

typedef void (*io_req_tw_func_t)(struct io_tw_req tw_req, io_tw_token_t tw);

struct io_task_work {
        struct llist_node               node;
        io_req_tw_func_t                func;
};

struct io_cqe {
        __u64   user_data;
        __s32   res;
        /* fd initially, then cflags for completion */
        union {
                __u32   flags;
                int     fd;
        };
};

/*
 * Each request type overlays its private data structure on top of this one.
 * They must not exceed this one in size.
 */
struct io_cmd_data {
        struct file             *file;
        /* each command gets 56 bytes of data */
        __u8                    data[56];
};

static inline void io_kiocb_cmd_sz_check(size_t cmd_sz)
{
        BUILD_BUG_ON(cmd_sz > sizeof(struct io_cmd_data));
}
#define io_kiocb_to_cmd(req, cmd_type) ( \
        io_kiocb_cmd_sz_check(sizeof(cmd_type)) , \
        ((cmd_type *)&(req)->cmd) \
)

static inline struct io_kiocb *cmd_to_io_kiocb(void *ptr)
{
        return ptr;
}

struct io_kiocb {
        union {
                /*
                 * NOTE! Each of the io_kiocb union members has the file pointer
                 * as the first entry in their struct definition. So you can
                 * access the file pointer through any of the sub-structs,
                 * or directly as just 'file' in this struct.
                 */
                struct file             *file;
                struct io_cmd_data      cmd;
        };

        u8                              opcode;
        /* polled IO has completed */
        u8                              iopoll_completed;
        /*
         * Can be either a fixed buffer index, or used with provided buffers.
         * For the latter, it points to the selected buffer ID.
         */
        u16                             buf_index;

        unsigned                        nr_tw;

        /* REQ_F_* flags */
        io_req_flags_t                  flags;

        struct io_cqe                   cqe;

        struct io_ring_ctx              *ctx;
        struct io_uring_task            *tctx;

        union {
                /* stores selected buf, valid IFF REQ_F_BUFFER_SELECTED is set */
                struct io_buffer        *kbuf;

                struct io_rsrc_node     *buf_node;
        };

        union {
                /* used by request caches, completion batching and iopoll */
                struct io_wq_work_node  comp_list;
                /* cache ->apoll->events */
                __poll_t apoll_events;
        };

        struct io_rsrc_node             *file_node;

        atomic_t                        refs;
        bool                            cancel_seq_set;

        union {
                struct io_task_work     io_task_work;
                /* For IOPOLL setup queues, with hybrid polling */
                u64                     iopoll_start;
        };

        union {
                /*
                 * for polled requests, i.e. IORING_OP_POLL_ADD and async armed
                 * poll
                 */
                struct hlist_node       hash_node;
                /* IOPOLL completion handling */
                struct list_head        iopoll_node;
                /* for private io_kiocb freeing */
                struct rcu_head         rcu_head;
        };
        /* internal polling, see IORING_FEAT_FAST_POLL */
        struct async_poll               *apoll;
        /* opcode allocated if it needs to store data for async defer */
        void                            *async_data;
        /* linked requests, IFF REQ_F_HARDLINK or REQ_F_LINK are set */
        atomic_t                        poll_refs;
        struct io_kiocb                 *link;
        /* custom credentials, valid IFF REQ_F_CREDS is set */
        const struct cred               *creds;
        struct io_wq_work               work;

        struct io_big_cqe {
                u64                     extra1;
                u64                     extra2;
        } big_cqe;
};

struct io_overflow_cqe {
        struct list_head list;
        struct io_uring_cqe cqe;
};
#endif