[PATCH 1/4] io_uring/zcrx: add helper for importing user memory

[Pavel Begunkov <asml.silence@gmail.com>]

There are two distinct steps for creating an area. First, we import
user memory, and then populate net_iov. In preparation to changes for
the first step, extract a helper function for it.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 io_uring/zcrx.c | 47 +++++++++++++++++++++++++++++++----------------
 1 file changed, 31 insertions(+), 16 deletions(-)

diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index a8a9b79d3c23..0f9375e889c3 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -203,13 +203,38 @@ static void io_zcrx_free_area(struct io_zcrx_area *area)
 	kfree(area);
 }
 
+static int io_import_area_memory(struct io_zcrx_ifq *ifq,
+				 struct io_zcrx_area *area,
+				 struct io_uring_zcrx_area_reg *area_reg)
+{
+	struct iovec iov;
+	int nr_pages;
+	int ret;
+
+	iov.iov_base = u64_to_user_ptr(area_reg->addr);
+	iov.iov_len = area_reg->len;
+	ret = io_buffer_validate(&iov);
+	if (ret)
+		return ret;
+
+	area->pages = io_pin_pages((unsigned long)area_reg->addr, area_reg->len,
+				   &nr_pages);
+	if (IS_ERR(area->pages)) {
+		ret = PTR_ERR(area->pages);
+		area->pages = NULL;
+		return ret;
+	}
+	area->nr_folios = nr_pages;
+	return 0;
+}
+
 static int io_zcrx_create_area(struct io_zcrx_ifq *ifq,
 			       struct io_zcrx_area **res,
 			       struct io_uring_zcrx_area_reg *area_reg)
 {
+	unsigned nr_iovs = area_reg->len >> PAGE_SHIFT;
 	struct io_zcrx_area *area;
-	int i, ret, nr_pages, nr_iovs;
-	struct iovec iov;
+	int i, ret;
 
 	if (area_reg->flags || area_reg->rq_area_token)
 		return -EINVAL;
@@ -218,27 +243,17 @@ static int io_zcrx_create_area(struct io_zcrx_ifq *ifq,
 	if (area_reg->addr & ~PAGE_MASK || area_reg->len & ~PAGE_MASK)
 		return -EINVAL;
 
-	iov.iov_base = u64_to_user_ptr(area_reg->addr);
-	iov.iov_len = area_reg->len;
-	ret = io_buffer_validate(&iov);
-	if (ret)
-		return ret;
-
 	ret = -ENOMEM;
 	area = kzalloc(sizeof(*area), GFP_KERNEL);
 	if (!area)
 		goto err;
+	area->nia.num_niovs = nr_iovs;
 
-	area->pages = io_pin_pages((unsigned long)area_reg->addr, area_reg->len,
-				   &nr_pages);
-	if (IS_ERR(area->pages)) {
-		ret = PTR_ERR(area->pages);
-		area->pages = NULL;
+	ret = io_import_area_memory(ifq, area, area_reg);
+	if (ret)
 		goto err;
-	}
-	area->nr_folios = nr_iovs = nr_pages;
-	area->nia.num_niovs = nr_iovs;
 
+	ret = -ENOMEM;
 	area->nia.niovs = kvmalloc_array(nr_iovs, sizeof(area->nia.niovs[0]),
 					 GFP_KERNEL | __GFP_ZERO);
 	if (!area->nia.niovs)
-- 
2.48.1