// SPDX-License-Identifier: GPL-2.0
#ifndef IOU_KBUF_H
#define IOU_KBUF_H

#include <uapi/linux/io_uring.h>
#include <linux/io_uring_types.h>

enum {
        /* ring mapped provided buffers */
        IOBL_BUF_RING   = 1,
        /* buffers are consumed incrementally rather than always fully */
        IOBL_INC        = 2,
};

struct io_buffer_list {
        /*
         * If the IOBL_BUF_RING flag is set, then buf_ring is used. If not, then
         * these are classic provided buffers and ->buf_list is used.
         */
        union {
                struct list_head buf_list;
                struct io_uring_buf_ring *buf_ring;
        };
        /* count of classic/legacy buffers in buffer list */
        int nbufs;

        __u16 bgid;

        /* below is for ring provided buffers */
        __u16 nr_entries;
        __u16 head;
        __u16 mask;

        __u16 flags;

        struct io_mapped_region region;
};

struct io_buffer {
        struct list_head list;
        __u64 addr;
        __u32 len;
        __u16 bid;
        __u16 bgid;
};

enum {
        /* can alloc a bigger vec */
        KBUF_MODE_EXPAND        = 1,
        /* if bigger vec allocated, free old one */
        KBUF_MODE_FREE          = 2,
};

struct buf_sel_arg {
        struct iovec *iovs;
        size_t out_len;
        size_t max_len;
        unsigned short nr_iovs;
        unsigned short mode;
        unsigned short buf_group;
        unsigned short partial_map;
};

struct io_br_sel io_buffer_select(struct io_kiocb *req, size_t *len,
                                  unsigned buf_group, unsigned int issue_flags);
int io_buffers_select(struct io_kiocb *req, struct buf_sel_arg *arg,
                      struct io_br_sel *sel, unsigned int issue_flags);
int io_buffers_peek(struct io_kiocb *req, struct buf_sel_arg *arg,
                    struct io_br_sel *sel);
void io_destroy_buffers(struct io_ring_ctx *ctx);

int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
int io_manage_buffers_legacy(struct io_kiocb *req, unsigned int issue_flags);

int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg);
int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg);
int io_register_pbuf_status(struct io_ring_ctx *ctx, void __user *arg);

bool io_kbuf_recycle_legacy(struct io_kiocb *req, unsigned issue_flags);
void io_kbuf_drop_legacy(struct io_kiocb *req);

unsigned int __io_put_kbufs(struct io_kiocb *req, struct io_buffer_list *bl,
                            int len, int nbufs);
bool io_kbuf_commit(struct io_kiocb *req,
                    struct io_buffer_list *bl, int len, int nr);

struct io_mapped_region *io_pbuf_get_region(struct io_ring_ctx *ctx,
                                            unsigned int bgid);

static inline bool io_kbuf_recycle_ring(struct io_kiocb *req,
                                        struct io_buffer_list *bl)
{
        if (bl) {
                req->flags &= ~(REQ_F_BUFFER_RING|REQ_F_BUFFERS_COMMIT);
                return true;
        }
        return false;
}

static inline bool io_do_buffer_select(struct io_kiocb *req)
{
        if (!(req->flags & REQ_F_BUFFER_SELECT))
                return false;
        return !(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING));
}

static inline bool io_kbuf_recycle(struct io_kiocb *req, struct io_buffer_list *bl,
                                   unsigned issue_flags)
{
        if (req->flags & REQ_F_BL_NO_RECYCLE)
                return false;
        if (req->flags & REQ_F_BUFFER_RING)
                return io_kbuf_recycle_ring(req, bl);
        if (req->flags & REQ_F_BUFFER_SELECTED)
                return io_kbuf_recycle_legacy(req, issue_flags);
        return false;
}

static inline unsigned int io_put_kbuf(struct io_kiocb *req, int len,
                                       struct io_buffer_list *bl)
{
        if (!(req->flags & (REQ_F_BUFFER_RING | REQ_F_BUFFER_SELECTED)))
                return 0;
        return __io_put_kbufs(req, bl, len, 1);
}

static inline unsigned int io_put_kbufs(struct io_kiocb *req, int len,
                                        struct io_buffer_list *bl, int nbufs)
{
        if (!(req->flags & (REQ_F_BUFFER_RING | REQ_F_BUFFER_SELECTED)))
                return 0;
        return __io_put_kbufs(req, bl, len, nbufs);
}
#endif