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-rw-r--r--io_uring/kbuf.h140
1 files changed, 140 insertions, 0 deletions
diff --git a/io_uring/kbuf.h b/io_uring/kbuf.h
new file mode 100644
index 000000000000..d6af208d109f
--- /dev/null
+++ b/io_uring/kbuf.h
@@ -0,0 +1,140 @@
+// 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