io_uring/kbuf.h

   1 // SPDX-License-Identifier: GPL-2.0
   2 #ifndef IOU_KBUF_H
   3 #define IOU_KBUF_H
   4
   5 #include <uapi/linux/io_uring.h>
   6
   7 struct io_buffer_list {
   8         /*
   9          * If ->buf_nr_pages is set, then buf_pages/buf_ring are used. If not,
  10          * then these are classic provided buffers and ->buf_list is used.
  11          */
  12         union {
  13                 struct list_head buf_list;
  14                 struct {
  15                         struct page **buf_pages;
  16                         struct io_uring_buf_ring *buf_ring;
  17                 };
  18         };
  19         __u16 bgid;
  20
  21         /* below is for ring provided buffers */
  22         __u16 buf_nr_pages;
  23         __u16 nr_entries;
  24         __u16 head;
  25         __u16 mask;
  26
  27         /* ring mapped provided buffers */
  28         __u8 is_mapped;
  29         /* ring mapped provided buffers, but mmap'ed by application */
  30         __u8 is_mmap;
  31 };
  32
  33 struct io_buffer {
  34         struct list_head list;
  35         __u64 addr;
  36         __u32 len;
  37         __u16 bid;
  38         __u16 bgid;
  39 };
  40
  41 void __user *io_buffer_select(struct io_kiocb *req, size_t *len,
  42                               unsigned int issue_flags);
  43 void io_destroy_buffers(struct io_ring_ctx *ctx);
  44
  45 int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
  46 int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags);
  47
  48 int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
  49 int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags);
  50
  51 int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg);
  52 int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg);
  53
  54 unsigned int __io_put_kbuf(struct io_kiocb *req, unsigned issue_flags);
  55
  56 void io_kbuf_recycle_legacy(struct io_kiocb *req, unsigned issue_flags);
  57
  58 void *io_pbuf_get_address(struct io_ring_ctx *ctx, unsigned long bgid);
  59
  60 static inline void io_kbuf_recycle_ring(struct io_kiocb *req)
  61 {
  62         /*
  63          * We don't need to recycle for REQ_F_BUFFER_RING, we can just clear
  64          * the flag and hence ensure that bl->head doesn't get incremented.
  65          * If the tail has already been incremented, hang on to it.
  66          * The exception is partial io, that case we should increment bl->head
  67          * to monopolize the buffer.
  68          */
  69         if (req->buf_list) {
  70                 if (req->flags & REQ_F_PARTIAL_IO) {
  71                         /*
  72                          * If we end up here, then the io_uring_lock has
  73                          * been kept held since we retrieved the buffer.
  74                          * For the io-wq case, we already cleared
  75                          * req->buf_list when the buffer was retrieved,
  76                          * hence it cannot be set here for that case.
  77                          */
  78                         req->buf_list->head++;
  79                         req->buf_list = NULL;
  80                 } else {
  81                         req->buf_index = req->buf_list->bgid;
  82                         req->flags &= ~REQ_F_BUFFER_RING;
  83                 }
  84         }
  85 }
  86
  87 static inline bool io_do_buffer_select(struct io_kiocb *req)
  88 {
  89         if (!(req->flags & REQ_F_BUFFER_SELECT))
  90                 return false;
  91         return !(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING));
  92 }
  93
  94 static inline void io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags)
  95 {
  96         if (req->flags & REQ_F_BUFFER_SELECTED)
  97                 io_kbuf_recycle_legacy(req, issue_flags);
  98         if (req->flags & REQ_F_BUFFER_RING)
  99                 io_kbuf_recycle_ring(req);
 100 }
 101
 102 static inline unsigned int __io_put_kbuf_list(struct io_kiocb *req,
 103                                               struct list_head *list)
 104 {
 105         unsigned int ret = IORING_CQE_F_BUFFER | (req->buf_index << IORING_CQE_BUFFER_SHIFT);
 106
 107         if (req->flags & REQ_F_BUFFER_RING) {
 108                 if (req->buf_list) {
 109                         req->buf_index = req->buf_list->bgid;
 110                         req->buf_list->head++;
 111                 }
 112                 req->flags &= ~REQ_F_BUFFER_RING;
 113         } else {
 114                 req->buf_index = req->kbuf->bgid;
 115                 list_add(&req->kbuf->list, list);
 116                 req->flags &= ~REQ_F_BUFFER_SELECTED;
 117         }
 118
 119         return ret;
 120 }
 121
 122 static inline unsigned int io_put_kbuf_comp(struct io_kiocb *req)
 123 {
 124         lockdep_assert_held(&req->ctx->completion_lock);
 125
 126         if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
 127                 return 0;
 128         return __io_put_kbuf_list(req, &req->ctx->io_buffers_comp);
 129 }
 130
 131 static inline unsigned int io_put_kbuf(struct io_kiocb *req,
 132                                        unsigned issue_flags)
 133 {
 134
 135         if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
 136                 return 0;
 137         return __io_put_kbuf(req, issue_flags);
 138 }
 139 #endif