Merge tag 'pipe-nonblock-2023-05-06' of git://git.kernel.dk/linux
[platform/kernel/linux-starfive.git] / 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