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                 struct rcu_head rcu;
  19         };
  20         __u16 bgid;
  21
  22         /* below is for ring provided buffers */
  23         __u16 buf_nr_pages;
  24         __u16 nr_entries;
  25         __u16 head;
  26         __u16 mask;
  27
  28         /* ring mapped provided buffers */
  29         __u8 is_mapped;
  30         /* ring mapped provided buffers, but mmap'ed by application */
  31         __u8 is_mmap;
  32         /* bl is visible from an RCU point of view for lookup */
  33         __u8 is_ready;
  34 };
  35
  36 struct io_buffer {
  37         struct list_head list;
  38         __u64 addr;
  39         __u32 len;
  40         __u16 bid;
  41         __u16 bgid;
  42 };
  43
  44 void __user *io_buffer_select(struct io_kiocb *req, size_t *len,
  45                               unsigned int issue_flags);
  46 void io_destroy_buffers(struct io_ring_ctx *ctx);
  47
  48 int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
  49 int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags);
  50
  51 int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
  52 int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags);
  53
  54 int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg);
  55 int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg);
  56
  57 void io_kbuf_mmap_list_free(struct io_ring_ctx *ctx);
  58
  59 unsigned int __io_put_kbuf(struct io_kiocb *req, unsigned issue_flags);
  60
  61 bool io_kbuf_recycle_legacy(struct io_kiocb *req, unsigned issue_flags);
  62
  63 void *io_pbuf_get_address(struct io_ring_ctx *ctx, unsigned long bgid);
  64
  65 static inline bool io_kbuf_recycle_ring(struct io_kiocb *req)
  66 {
  67         /*
  68          * We don't need to recycle for REQ_F_BUFFER_RING, we can just clear
  69          * the flag and hence ensure that bl->head doesn't get incremented.
  70          * If the tail has already been incremented, hang on to it.
  71          * The exception is partial io, that case we should increment bl->head
  72          * to monopolize the buffer.
  73          */
  74         if (req->buf_list) {
  75                 if (req->flags & REQ_F_PARTIAL_IO) {
  76                         /*
  77                          * If we end up here, then the io_uring_lock has
  78                          * been kept held since we retrieved the buffer.
  79                          * For the io-wq case, we already cleared
  80                          * req->buf_list when the buffer was retrieved,
  81                          * hence it cannot be set here for that case.
  82                          */
  83                         req->buf_list->head++;
  84                         req->buf_list = NULL;
  85                 } else {
  86                         req->buf_index = req->buf_list->bgid;
  87                         req->flags &= ~REQ_F_BUFFER_RING;
  88                         return true;
  89                 }
  90         }
  91         return false;
  92 }
  93
  94 static inline bool io_do_buffer_select(struct io_kiocb *req)
  95 {
  96         if (!(req->flags & REQ_F_BUFFER_SELECT))
  97                 return false;
  98         return !(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING));
  99 }
 100
 101 static inline bool io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags)
 102 {
 103         if (req->flags & REQ_F_BUFFER_SELECTED)
 104                 return io_kbuf_recycle_legacy(req, issue_flags);
 105         if (req->flags & REQ_F_BUFFER_RING)
 106                 return io_kbuf_recycle_ring(req);
 107         return false;
 108 }
 109
 110 static inline unsigned int __io_put_kbuf_list(struct io_kiocb *req,
 111                                               struct list_head *list)
 112 {
 113         unsigned int ret = IORING_CQE_F_BUFFER | (req->buf_index << IORING_CQE_BUFFER_SHIFT);
 114
 115         if (req->flags & REQ_F_BUFFER_RING) {
 116                 if (req->buf_list) {
 117                         req->buf_index = req->buf_list->bgid;
 118                         req->buf_list->head++;
 119                 }
 120                 req->flags &= ~REQ_F_BUFFER_RING;
 121         } else {
 122                 req->buf_index = req->kbuf->bgid;
 123                 list_add(&req->kbuf->list, list);
 124                 req->flags &= ~REQ_F_BUFFER_SELECTED;
 125         }
 126
 127         return ret;
 128 }
 129
 130 static inline unsigned int io_put_kbuf_comp(struct io_kiocb *req)
 131 {
 132         lockdep_assert_held(&req->ctx->completion_lock);
 133
 134         if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
 135                 return 0;
 136         return __io_put_kbuf_list(req, &req->ctx->io_buffers_comp);
 137 }
 138
 139 static inline unsigned int io_put_kbuf(struct io_kiocb *req,
 140                                        unsigned issue_flags)
 141 {
 142
 143         if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
 144                 return 0;
 145         return __io_put_kbuf(req, issue_flags);
 146 }
 147 #endif