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
7struct 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	atomic_t refs;
29
30	/* ring mapped provided buffers */
31	__u8 is_buf_ring;
32	/* ring mapped provided buffers, but mmap'ed by application */
33	__u8 is_mmap;
34};
35
36struct io_buffer {
37	struct list_head list;
38	__u64 addr;
39	__u32 len;
40	__u16 bid;
41	__u16 bgid;
42};
43
44void __user *io_buffer_select(struct io_kiocb *req, size_t *len,
45			      unsigned int issue_flags);
46void io_destroy_buffers(struct io_ring_ctx *ctx);
47
48int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
49int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags);
50
51int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
52int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags);
53
54int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg);
55int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg);
56int io_register_pbuf_status(struct io_ring_ctx *ctx, void __user *arg);
57
58void io_kbuf_mmap_list_free(struct io_ring_ctx *ctx);
59
60void __io_put_kbuf(struct io_kiocb *req, unsigned issue_flags);
61
62bool io_kbuf_recycle_legacy(struct io_kiocb *req, unsigned issue_flags);
63
64void io_put_bl(struct io_ring_ctx *ctx, struct io_buffer_list *bl);
65struct io_buffer_list *io_pbuf_get_bl(struct io_ring_ctx *ctx,
66				      unsigned long bgid);
67
68static inline bool io_kbuf_recycle_ring(struct io_kiocb *req)
69{
70	/*
71	 * We don't need to recycle for REQ_F_BUFFER_RING, we can just clear
72	 * the flag and hence ensure that bl->head doesn't get incremented.
73	 * If the tail has already been incremented, hang on to it.
74	 * The exception is partial io, that case we should increment bl->head
75	 * to monopolize the buffer.
76	 */
77	if (req->buf_list) {
78		req->buf_index = req->buf_list->bgid;
79		req->flags &= ~REQ_F_BUFFER_RING;
80		return true;
81	}
82	return false;
83}
84
85static inline bool io_do_buffer_select(struct io_kiocb *req)
86{
87	if (!(req->flags & REQ_F_BUFFER_SELECT))
88		return false;
89	return !(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING));
90}
91
92static inline bool io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags)
93{
94	if (req->flags & REQ_F_BL_NO_RECYCLE)
95		return false;
96	if (req->flags & REQ_F_BUFFER_SELECTED)
97		return io_kbuf_recycle_legacy(req, issue_flags);
98	if (req->flags & REQ_F_BUFFER_RING)
99		return io_kbuf_recycle_ring(req);
100	return false;
101}
102
103static inline void __io_put_kbuf_ring(struct io_kiocb *req)
104{
105	if (req->buf_list) {
106		req->buf_index = req->buf_list->bgid;
107		req->buf_list->head++;
108	}
109	req->flags &= ~REQ_F_BUFFER_RING;
110}
111
112static inline void __io_put_kbuf_list(struct io_kiocb *req,
113				      struct list_head *list)
114{
115	if (req->flags & REQ_F_BUFFER_RING) {
116		__io_put_kbuf_ring(req);
117	} else {
118		req->buf_index = req->kbuf->bgid;
119		list_add(&req->kbuf->list, list);
120		req->flags &= ~REQ_F_BUFFER_SELECTED;
121	}
122}
123
124static inline unsigned int io_put_kbuf_comp(struct io_kiocb *req)
125{
126	unsigned int ret;
127
128	lockdep_assert_held(&req->ctx->completion_lock);
129
130	if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
131		return 0;
132
133	ret = IORING_CQE_F_BUFFER | (req->buf_index << IORING_CQE_BUFFER_SHIFT);
134	__io_put_kbuf_list(req, &req->ctx->io_buffers_comp);
135	return ret;
136}
137
138static inline unsigned int io_put_kbuf(struct io_kiocb *req,
139				       unsigned issue_flags)
140{
141	unsigned int ret;
142
143	if (!(req->flags & (REQ_F_BUFFER_RING | REQ_F_BUFFER_SELECTED)))
144		return 0;
145
146	ret = IORING_CQE_F_BUFFER | (req->buf_index << IORING_CQE_BUFFER_SHIFT);
147	if (req->flags & REQ_F_BUFFER_RING)
148		__io_put_kbuf_ring(req);
149	else
150		__io_put_kbuf(req, issue_flags);
151	return ret;
152}
153#endif
154