[linux-block.git] / io_uring / kbuf.h

// SPDX-License-Identifier: GPL-2.0
#ifndef IOU_KBUF_H
#define IOU_KBUF_H

#include <uapi/linux/io_uring.h>

struct io_buffer_list {
	/*
	 * If ->buf_nr_pages is set, then buf_pages/buf_ring are used. If not,
	 * then these are classic provided buffers and ->buf_list is used.
	 */
	union {
		struct list_head buf_list;
		struct {
			struct page **buf_pages;
			struct io_uring_buf_ring *buf_ring;
		};
	};
	__u16 bgid;

	/* below is for ring provided buffers */
	__u16 buf_nr_pages;
	__u16 nr_entries;
	__u16 head;
	__u16 mask;
};

struct io_buffer {
	struct list_head list;
	__u64 addr;
	__u32 len;
	__u16 bid;
	__u16 bgid;
};

void __user *io_buffer_select(struct io_kiocb *req, size_t *len,
			      unsigned int issue_flags);
void __io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags);
void io_destroy_buffers(struct io_ring_ctx *ctx);

int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags);

int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags);

int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg);
int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg);

static inline bool io_do_buffer_select(struct io_kiocb *req)
{
	if (!(req->flags & REQ_F_BUFFER_SELECT))
		return false;
	return !(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING));
}

static inline void io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags)
{
	if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
		return;
	/*
	 * For legacy provided buffer mode, don't recycle if we already did
	 * IO to this buffer. For ring-mapped provided buffer mode, we should
	 * increment ring->head to explicitly monopolize the buffer to avoid
	 * multiple use.
	 */
	if ((req->flags & REQ_F_BUFFER_SELECTED) &&
	    (req->flags & REQ_F_PARTIAL_IO))
		return;

	/*
	 * READV uses fields in `struct io_rw` (len/addr) to stash the selected
	 * buffer data. However if that buffer is recycled the original request
	 * data stored in addr is lost. Therefore forbid recycling for now.
	 */
	if (req->opcode == IORING_OP_READV)
		return;

	__io_kbuf_recycle(req, issue_flags);
}

static unsigned int __io_put_kbuf(struct io_kiocb *req, struct list_head *list)
{
	if (req->flags & REQ_F_BUFFER_RING) {
		if (req->buf_list)
			req->buf_list->head++;
		req->flags &= ~REQ_F_BUFFER_RING;
	} else {
		list_add(&req->kbuf->list, list);
		req->flags &= ~REQ_F_BUFFER_SELECTED;
	}

	return IORING_CQE_F_BUFFER | (req->buf_index << IORING_CQE_BUFFER_SHIFT);
}

static inline unsigned int io_put_kbuf_comp(struct io_kiocb *req)
{
	lockdep_assert_held(&req->ctx->completion_lock);

	if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
		return 0;
	return __io_put_kbuf(req, &req->ctx->io_buffers_comp);
}

static inline unsigned int io_put_kbuf(struct io_kiocb *req,
				       unsigned issue_flags)
{
	unsigned int cflags;

	if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
		return 0;

	/*
	 * We can add this buffer back to two lists:
	 *
	 * 1) The io_buffers_cache list. This one is protected by the
	 *    ctx->uring_lock. If we already hold this lock, add back to this
	 *    list as we can grab it from issue as well.
	 * 2) The io_buffers_comp list. This one is protected by the
	 *    ctx->completion_lock.
	 *
	 * We migrate buffers from the comp_list to the issue cache list
	 * when we need one.
	 */
	if (req->flags & REQ_F_BUFFER_RING) {
		/* no buffers to recycle for this case */
		cflags = __io_put_kbuf(req, NULL);
	} else if (issue_flags & IO_URING_F_UNLOCKED) {
		struct io_ring_ctx *ctx = req->ctx;

		spin_lock(&ctx->completion_lock);
		cflags = __io_put_kbuf(req, &ctx->io_buffers_comp);
		spin_unlock(&ctx->completion_lock);
	} else {
		lockdep_assert_held(&req->ctx->uring_lock);

		cflags = __io_put_kbuf(req, &req->ctx->io_buffers_cache);
	}

	return cflags;
}
#endif
Commit	Line	Data
3b77495a JA	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_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags);
	39	void io_destroy_buffers(struct io_ring_ctx *ctx);
	40
	41	int io_remove_buffers_prep(struct io_kiocb req, const struct io_uring_sqe sqe);
	42	int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags);
	43
	44	int io_provide_buffers_prep(struct io_kiocb req, const struct io_uring_sqe sqe);
	45	int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags);
	46
	47	int io_register_pbuf_ring(struct io_ring_ctx ctx, void __user arg);
	48	int io_unregister_pbuf_ring(struct io_ring_ctx ctx, void __user arg);
	49
	50	static inline bool io_do_buffer_select(struct io_kiocb *req)
	51	{
	52	if (!(req->flags & REQ_F_BUFFER_SELECT))
	53	return false;
	54	return !(req->flags & (REQ_F_BUFFER_SELECTED\|REQ_F_BUFFER_RING));
	55	}
	56
	57	static inline void io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags)
	58	{
	59	if (!(req->flags & (REQ_F_BUFFER_SELECTED\|REQ_F_BUFFER_RING)))
	60	return;
	61	/*
	62	* For legacy provided buffer mode, don't recycle if we already did
	63	* IO to this buffer. For ring-mapped provided buffer mode, we should
	64	* increment ring->head to explicitly monopolize the buffer to avoid
65	* multiple use.
66	*/
67	if ((req->flags & REQ_F_BUFFER_SELECTED) &&
68	(req->flags & REQ_F_PARTIAL_IO))
69	return;
70
71	/*
72	* READV uses fields in `struct io_rw` (len/addr) to stash the selected
73	* buffer data. However if that buffer is recycled the original request
74	* data stored in addr is lost. Therefore forbid recycling for now.
75	*/
76	if (req->opcode == IORING_OP_READV)
77	return;
78
79	__io_kbuf_recycle(req, issue_flags);
80	}
81
82	static unsigned int __io_put_kbuf(struct io_kiocb req, struct list_head list)
83	{
84	if (req->flags & REQ_F_BUFFER_RING) {
85	if (req->buf_list)
86	req->buf_list->head++;
87	req->flags &= ~REQ_F_BUFFER_RING;
88	} else {
89	list_add(&req->kbuf->list, list);
90	req->flags &= ~REQ_F_BUFFER_SELECTED;
91	}
92
93	return IORING_CQE_F_BUFFER \| (req->buf_index << IORING_CQE_BUFFER_SHIFT);
94	}
95
96	static inline unsigned int io_put_kbuf_comp(struct io_kiocb *req)
97	{
98	lockdep_assert_held(&req->ctx->completion_lock);
99
100	if (!(req->flags & (REQ_F_BUFFER_SELECTED\|REQ_F_BUFFER_RING)))
101	return 0;
102	return __io_put_kbuf(req, &req->ctx->io_buffers_comp);
103	}
104
105	static inline unsigned int io_put_kbuf(struct io_kiocb *req,
106	unsigned issue_flags)
107	{
108	unsigned int cflags;
109
110	if (!(req->flags & (REQ_F_BUFFER_SELECTED\|REQ_F_BUFFER_RING)))
111	return 0;
112
113	/*
114	* We can add this buffer back to two lists:
115	*
116	* 1) The io_buffers_cache list. This one is protected by the
117	* ctx->uring_lock. If we already hold this lock, add back to this
118	* list as we can grab it from issue as well.
119	* 2) The io_buffers_comp list. This one is protected by the
120	* ctx->completion_lock.
121	*
122	* We migrate buffers from the comp_list to the issue cache list
123	* when we need one.
124	*/
125	if (req->flags & REQ_F_BUFFER_RING) {
126	/* no buffers to recycle for this case */
127	cflags = __io_put_kbuf(req, NULL);
128	} else if (issue_flags & IO_URING_F_UNLOCKED) {
129	struct io_ring_ctx *ctx = req->ctx;
130
131	spin_lock(&ctx->completion_lock);
132	cflags = __io_put_kbuf(req, &ctx->io_buffers_comp);
133	spin_unlock(&ctx->completion_lock);
134	} else {
135	lockdep_assert_held(&req->ctx->uring_lock);
136
137	cflags = __io_put_kbuf(req, &req->ctx->io_buffers_cache);
138	}
139
140	return cflags;
141	}
142	#endif