io_uring/net: use REQ_F_IMPORT_BUFFER for send_zc

Instead of a bool field in struct io_sr_msg, use REQ_F_IMPORT_BUFFER to
track whether io_send_zc() has already imported the buffer. This flag
already serves a similar purpose for sendmsg_zc and {read,write}v_fixed.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Suggested-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/20250325143943.1226467-1-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

include/linux/io_uring_types.h

@@ -585,7 +585,10 @@ enum {
 	REQ_F_BUF_NODE		= IO_REQ_FLAG(REQ_F_BUF_NODE_BIT),
 	/* request has read/write metadata assigned */
 	REQ_F_HAS_METADATA	= IO_REQ_FLAG(REQ_F_HAS_METADATA_BIT),
-	/* resolve padded iovec to registered buffers */
+	/*
+	 * For vectored fixed buffers, resolve iovec to registered buffers.
+	 * For SEND_ZC, whether to import buffers (i.e. the first issue).
+	 */
 	REQ_F_IMPORT_BUFFER	= IO_REQ_FLAG(REQ_F_IMPORT_BUFFER_BIT),
 };
 

io_uring/net.c

@@ -77,7 +77,6 @@ struct io_sr_msg {
 	/* initialised and used only by !msg send variants */
 	u16				buf_group;
 	bool				retry;
-	bool				imported; /* only for io_send_zc */
 	void __user			*msg_control;
 	/* used only for send zerocopy */
 	struct io_kiocb 		*notif;
@@ -1307,7 +1306,6 @@ int io_send_zc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 
 	zc->done_io = 0;
 	zc->retry = false;
-	zc->imported = false;
 	req->flags |= REQ_F_POLL_NO_LAZY;
 
 	if (unlikely(READ_ONCE(sqe->__pad2[0]) || READ_ONCE(sqe->addr3)))
@@ -1353,8 +1351,10 @@ int io_send_zc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 
 	if (unlikely(!io_msg_alloc_async(req)))
 		return -ENOMEM;
-	if (req->opcode != IORING_OP_SENDMSG_ZC)
+	if (req->opcode == IORING_OP_SEND_ZC) {
+		req->flags |= REQ_F_IMPORT_BUFFER;
 		return io_send_setup(req, sqe);
+	}
 	return io_sendmsg_zc_setup(req, sqe);
 }
 
@@ -1453,8 +1453,8 @@ int io_send_zc(struct io_kiocb *req, unsigned int issue_flags)
 	    (zc->flags & IORING_RECVSEND_POLL_FIRST))
 		return -EAGAIN;
 
-	if (!zc->imported) {
-		zc->imported = true;
+	if (req->flags & REQ_F_IMPORT_BUFFER) {
+		req->flags &= ~REQ_F_IMPORT_BUFFER;
 		ret = io_send_zc_import(req, issue_flags);
 		if (unlikely(ret))
 			return ret;