io_uring: add flag for disabling provided buffer recycling

If we need to continue doing this IO, then we don't want a potentially
selected buffer recycled. Add a flag for that.

Set this for recv/recvmsg if they do partial IO.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -783,6 +783,7 @@ enum {
 	REQ_F_SKIP_LINK_CQES_BIT,
 	REQ_F_SINGLE_POLL_BIT,
 	REQ_F_DOUBLE_POLL_BIT,
+	REQ_F_PARTIAL_IO_BIT,
 	/* keep async read/write and isreg together and in order */
 	REQ_F_SUPPORT_NOWAIT_BIT,
 	REQ_F_ISREG_BIT,
@@ -845,6 +846,8 @@ enum {
 	REQ_F_SINGLE_POLL	= BIT(REQ_F_SINGLE_POLL_BIT),
 	/* double poll may active */
 	REQ_F_DOUBLE_POLL	= BIT(REQ_F_DOUBLE_POLL_BIT),
+	/* request has already done partial IO */
+	REQ_F_PARTIAL_IO	= BIT(REQ_F_PARTIAL_IO_BIT),
 };
 
 struct async_poll {
@@ -1392,6 +1395,9 @@ static void io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags)
 
 	if (likely(!(req->flags & REQ_F_BUFFER_SELECTED)))
 		return;
+	/* don't recycle if we already did IO to this buffer */
+	if (req->flags & REQ_F_PARTIAL_IO)
+		return;
 
 	if (issue_flags & IO_URING_F_UNLOCKED)
 		mutex_lock(&ctx->uring_lock);
@@ -5477,6 +5483,7 @@ static int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
 			ret = -EINTR;
 		if (ret > 0 && io_net_retry(sock, flags)) {
 			sr->done_io += ret;
+			req->flags |= REQ_F_PARTIAL_IO;
 			return io_setup_async_msg(req, kmsg);
 		}
 		req_set_fail(req);
@@ -5546,6 +5553,7 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags)
 			sr->len -= ret;
 			sr->buf += ret;
 			sr->done_io += ret;
+			req->flags |= REQ_F_PARTIAL_IO;
 			return -EAGAIN;
 		}
 		req_set_fail(req);