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 void 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 
io_kbuf_recycle_ring(struct io_kiocb * req)65 static inline void 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 		}
89 	}
90 }
91 
io_do_buffer_select(struct io_kiocb * req)92 static inline bool io_do_buffer_select(struct io_kiocb *req)
93 {
94 	if (!(req->flags & REQ_F_BUFFER_SELECT))
95 		return false;
96 	return !(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING));
97 }
98 
io_kbuf_recycle(struct io_kiocb * req,unsigned issue_flags)99 static inline void io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags)
100 {
101 	if (req->flags & REQ_F_BUFFER_SELECTED)
102 		io_kbuf_recycle_legacy(req, issue_flags);
103 	if (req->flags & REQ_F_BUFFER_RING)
104 		io_kbuf_recycle_ring(req);
105 }
106 
__io_put_kbuf_list(struct io_kiocb * req,struct list_head * list)107 static inline unsigned int __io_put_kbuf_list(struct io_kiocb *req,
108 					      struct list_head *list)
109 {
110 	unsigned int ret = IORING_CQE_F_BUFFER | (req->buf_index << IORING_CQE_BUFFER_SHIFT);
111 
112 	if (req->flags & REQ_F_BUFFER_RING) {
113 		if (req->buf_list) {
114 			req->buf_index = req->buf_list->bgid;
115 			req->buf_list->head++;
116 		}
117 		req->flags &= ~REQ_F_BUFFER_RING;
118 	} else {
119 		req->buf_index = req->kbuf->bgid;
120 		list_add(&req->kbuf->list, list);
121 		req->flags &= ~REQ_F_BUFFER_SELECTED;
122 	}
123 
124 	return ret;
125 }
126 
io_put_kbuf_comp(struct io_kiocb * req)127 static inline unsigned int io_put_kbuf_comp(struct io_kiocb *req)
128 {
129 	lockdep_assert_held(&req->ctx->completion_lock);
130 
131 	if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
132 		return 0;
133 	return __io_put_kbuf_list(req, &req->ctx->io_buffers_comp);
134 }
135 
io_put_kbuf(struct io_kiocb * req,unsigned issue_flags)136 static inline unsigned int io_put_kbuf(struct io_kiocb *req,
137 				       unsigned issue_flags)
138 {
139 
140 	if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
141 		return 0;
142 	return __io_put_kbuf(req, issue_flags);
143 }
144 #endif
145