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 };
  30
  31 struct io_buffer {
  32         struct list_head list;
  33         __u64 addr;
  34         __u32 len;
  35         __u16 bid;
  36         __u16 bgid;
  37 };
  38
  39 void __user *io_buffer_select(struct io_kiocb *req, size_t *len,
  40                               unsigned int issue_flags);
  41 void io_destroy_buffers(struct io_ring_ctx *ctx);
  42
  43 int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
  44 int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags);
  45
  46 int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
  47 int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags);
  48
  49 int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg);
  50 int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg);
  51
  52 unsigned int __io_put_kbuf(struct io_kiocb *req, unsigned issue_flags);
  53
  54 void io_kbuf_recycle_legacy(struct io_kiocb *req, unsigned issue_flags);
  55
  56 static inline void io_kbuf_recycle_ring(struct io_kiocb *req)
  57 {
  58         /*
  59          * We don't need to recycle for REQ_F_BUFFER_RING, we can just clear
  60          * the flag and hence ensure that bl->head doesn't get incremented.
  61          * If the tail has already been incremented, hang on to it.
  62          * The exception is partial io, that case we should increment bl->head
  63          * to monopolize the buffer.
  64          */
  65         if (req->buf_list) {
  66                 if (req->flags & REQ_F_PARTIAL_IO) {
  67                         /*
  68                          * If we end up here, then the io_uring_lock has
  69                          * been kept held since we retrieved the buffer.
  70                          * For the io-wq case, we already cleared
  71                          * req->buf_list when the buffer was retrieved,
  72                          * hence it cannot be set here for that case.
  73                          */
  74                         req->buf_list->head++;
  75                         req->buf_list = NULL;
  76                 } else {
  77                         req->buf_index = req->buf_list->bgid;
  78                         req->flags &= ~REQ_F_BUFFER_RING;
  79                 }
  80         }
  81 }
  82
  83 static inline bool io_do_buffer_select(struct io_kiocb *req)
  84 {
  85         if (!(req->flags & REQ_F_BUFFER_SELECT))
  86                 return false;
  87         return !(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING));
  88 }
  89
  90 static inline void io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags)
  91 {
  92         if (req->flags & REQ_F_BUFFER_SELECTED)
  93                 io_kbuf_recycle_legacy(req, issue_flags);
  94         if (req->flags & REQ_F_BUFFER_RING)
  95                 io_kbuf_recycle_ring(req);
  96 }
  97
  98 static inline unsigned int __io_put_kbuf_list(struct io_kiocb *req,
  99                                               struct list_head *list)
 100 {
 101         unsigned int ret = IORING_CQE_F_BUFFER | (req->buf_index << IORING_CQE_BUFFER_SHIFT);
 102
 103         if (req->flags & REQ_F_BUFFER_RING) {
 104                 if (req->buf_list) {
 105                         req->buf_index = req->buf_list->bgid;
 106                         req->buf_list->head++;
 107                 }
 108                 req->flags &= ~REQ_F_BUFFER_RING;
 109         } else {
 110                 req->buf_index = req->kbuf->bgid;
 111                 list_add(&req->kbuf->list, list);
 112                 req->flags &= ~REQ_F_BUFFER_SELECTED;
 113         }
 114
 115         return ret;
 116 }
 117
 118 static inline unsigned int io_put_kbuf_comp(struct io_kiocb *req)
 119 {
 120         lockdep_assert_held(&req->ctx->completion_lock);
 121
 122         if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
 123                 return 0;
 124         return __io_put_kbuf_list(req, &req->ctx->io_buffers_comp);
 125 }
 126
 127 static inline unsigned int io_put_kbuf(struct io_kiocb *req,
 128                                        unsigned issue_flags)
 129 {
 130
 131         if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
 132                 return 0;
 133         return __io_put_kbuf(req, issue_flags);
 134 }
 135 #endif