io_uring: kbuf: inline io_kbuf_recycle_ring()

Make io_kbuf_recycle_ring() inline since it is the fast path of
provided buffer.

Signed-off-by: Hao Xu <howeyxu@tencent.com>
Link: https://lore.kernel.org/r/20220623130126.179232-1-hao.xu@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 27 insertions, 1 deletions

diff --git a/io_uring/kbuf.h b/io_uring/kbuf.h
index 721465c5d809..b3e8c6c5fee1 100644
--- a/io_uring/kbuf.h
+++ b/io_uring/kbuf.h
@@ -49,7 +49,33 @@ 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);
-void io_kbuf_recycle_ring(struct io_kiocb *req);
+
+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)
 {