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// 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_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);
unsigned int __io_put_kbuf(struct io_kiocb *req, unsigned issue_flags);
void io_kbuf_recycle_legacy(struct io_kiocb *req, unsigned issue_flags);
static inline void io_kbuf_recycle_ring(struct io_kiocb *req)
{
/*
* We don't need to recycle for REQ_F_BUFFER_RING, we can just clear
* the flag and hence ensure that bl->head doesn't get incremented.
* If the tail has already been incremented, hang on to it.
* The exception is partial io, that case we should increment bl->head
* to monopolize the buffer.
*/
if (req->buf_list) {
if (req->flags & REQ_F_PARTIAL_IO) {
/*
* If we end up here, then the io_uring_lock has
* been kept held since we retrieved the buffer.
* For the io-wq case, we already cleared
* req->buf_list when the buffer was retrieved,
* hence it cannot be set here for that case.
*/
req->buf_list->head++;
req->buf_list = NULL;
} else {
req->buf_index = req->buf_list->bgid;
req->flags &= ~REQ_F_BUFFER_RING;
}
}
}
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)
{
/*
* 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;
if (req->flags & REQ_F_BUFFER_SELECTED)
io_kbuf_recycle_legacy(req, issue_flags);
if (req->flags & REQ_F_BUFFER_RING)
io_kbuf_recycle_ring(req);
}
static inline unsigned int __io_put_kbuf_list(struct io_kiocb *req,
struct list_head *list)
{
unsigned int ret = IORING_CQE_F_BUFFER | (req->buf_index << IORING_CQE_BUFFER_SHIFT);
if (req->flags & REQ_F_BUFFER_RING) {
if (req->buf_list) {
req->buf_index = req->buf_list->bgid;
req->buf_list->head++;
}
req->flags &= ~REQ_F_BUFFER_RING;
} else {
req->buf_index = req->kbuf->bgid;
list_add(&req->kbuf->list, list);
req->flags &= ~REQ_F_BUFFER_SELECTED;
}
return ret;
}
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_list(req, &req->ctx->io_buffers_comp);
}
static inline unsigned int io_put_kbuf(struct io_kiocb *req,
unsigned issue_flags)
{
if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
return 0;
return __io_put_kbuf(req, issue_flags);
}
#endif
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