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	/* 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
 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
 60unsigned int __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_pbuf_get_address(struct io_ring_ctx *ctx, unsigned long bgid);
 65
 66static inline bool io_kbuf_recycle_ring(struct io_kiocb *req)
 67{
 68	/*
 69	 * We don't need to recycle for REQ_F_BUFFER_RING, we can just clear
 70	 * the flag and hence ensure that bl->head doesn't get incremented.
 71	 * If the tail has already been incremented, hang on to it.
 72	 * The exception is partial io, that case we should increment bl->head
 73	 * to monopolize the buffer.
 74	 */
 75	if (req->buf_list) {
 76		if (req->flags & REQ_F_PARTIAL_IO) {
 77			/*
 78			 * If we end up here, then the io_uring_lock has
 79			 * been kept held since we retrieved the buffer.
 80			 * For the io-wq case, we already cleared
 81			 * req->buf_list when the buffer was retrieved,
 82			 * hence it cannot be set here for that case.
 83			 */
 84			req->buf_list->head++;
 85			req->buf_list = NULL;
 86		} else {
 87			req->buf_index = req->buf_list->bgid;
 88			req->flags &= ~REQ_F_BUFFER_RING;
 89			return true;
 90		}
 91	}
 92	return false;
 93}
 94
 95static inline bool io_do_buffer_select(struct io_kiocb *req)
 96{
 97	if (!(req->flags & REQ_F_BUFFER_SELECT))
 98		return false;
 99	return !(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING));
100}
101
102static inline bool io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags)
103{
104	if (req->flags & REQ_F_BUFFER_SELECTED)
105		return io_kbuf_recycle_legacy(req, issue_flags);
106	if (req->flags & REQ_F_BUFFER_RING)
107		return io_kbuf_recycle_ring(req);
108	return false;
109}
110
111static inline unsigned int __io_put_kbuf_list(struct io_kiocb *req,
112					      struct list_head *list)
113{
114	unsigned int ret = IORING_CQE_F_BUFFER | (req->buf_index << IORING_CQE_BUFFER_SHIFT);
115
116	if (req->flags & REQ_F_BUFFER_RING) {
117		if (req->buf_list) {
118			req->buf_index = req->buf_list->bgid;
119			req->buf_list->head++;
120		}
121		req->flags &= ~REQ_F_BUFFER_RING;
122	} else {
123		req->buf_index = req->kbuf->bgid;
124		list_add(&req->kbuf->list, list);
125		req->flags &= ~REQ_F_BUFFER_SELECTED;
126	}
127
128	return ret;
129}
130
131static inline unsigned int io_put_kbuf_comp(struct io_kiocb *req)
132{
133	lockdep_assert_held(&req->ctx->completion_lock);
134
135	if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
136		return 0;
137	return __io_put_kbuf_list(req, &req->ctx->io_buffers_comp);
138}
139
140static inline unsigned int io_put_kbuf(struct io_kiocb *req,
141				       unsigned issue_flags)
142{
143
144	if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
145		return 0;
146	return __io_put_kbuf(req, issue_flags);
147}
148#endif