From e7b96331703e929e75d93c574573c9736e34b0c0 Mon Sep 17 00:00:00 2001
From: Santiago Gimeno <santiago.gimeno@gmail.com>
Date: Thu, 25 May 2023 12:09:51 +0200
Subject: [PATCH] linux: fs_read to use io_uring if iovcnt > IOV_MAX (#4023)

Just cap it to `IOV_MAX` as it's already done when performing reads
using the threadpool.
---
 src/unix/linux.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/unix/linux.c b/src/unix/linux.c
index 183e781b..77dac84b 100644
--- a/src/unix/linux.c
+++ b/src/unix/linux.c
@@ -914,10 +914,14 @@ int uv__iou_fs_read_or_write(uv_loop_t* loop,
   struct uv__io_uring_sqe* sqe;
   struct uv__iou* iou;
 
-  /* For the moment, if iovcnt is greater than IOV_MAX, fallback to the
-   * threadpool. In the future we might take advantage of IOSQE_IO_LINK. */
-  if (req->nbufs > IOV_MAX)
-    return 0;
+  /* If iovcnt is greater than IOV_MAX, cap it to IOV_MAX on reads and fallback
+   * to the threadpool on writes */
+  if (req->nbufs > IOV_MAX) {
+    if (is_read)
+      req->nbufs = IOV_MAX;
+    else
+      return 0;
+  }
 
   iou = &uv__get_internal_fields(loop)->iou;