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