[PATCH v3 2/6] io_uring/zcrx: return error from io_zcrx_map_area_*

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

io_zcrx_map_area_*() helpers return the number of processed niovs, which
we use to unroll some of the mappings for user memory areas. It's
unhandy, and dmabuf doesn't care about it. Return an error code instead
and move failure partial unmapping into io_zcrx_map_area_umem().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 io_uring/zcrx.c | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index 99a253c1c6c5..2cde88988260 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -139,13 +139,13 @@ static int io_zcrx_map_area_dmabuf(struct io_zcrx_ifq *ifq, struct io_zcrx_area
 			struct net_iov *niov = &area->nia.niovs[niov_idx];
 
 			if (net_mp_niov_set_dma_addr(niov, dma))
-				return 0;
+				return -EFAULT;
 			sg_len -= PAGE_SIZE;
 			dma += PAGE_SIZE;
 			niov_idx++;
 		}
 	}
-	return niov_idx;
+	return 0;
 }
 
 static int io_import_umem(struct io_zcrx_ifq *ifq,
@@ -254,29 +254,30 @@ static int io_zcrx_map_area_umem(struct io_zcrx_ifq *ifq, struct io_zcrx_area *a
 			break;
 		}
 	}
-	return i;
+
+	if (i != area->nia.num_niovs) {
+		__io_zcrx_unmap_area(ifq, area, i);
+		return -EINVAL;
+	}
+	return 0;
 }
 
 static int io_zcrx_map_area(struct io_zcrx_ifq *ifq, struct io_zcrx_area *area)
 {
-	unsigned nr;
+	int ret;
 
 	guard(mutex)(&ifq->dma_lock);
 	if (area->is_mapped)
 		return 0;
 
 	if (area->mem.is_dmabuf)
-		nr = io_zcrx_map_area_dmabuf(ifq, area);
+		ret = io_zcrx_map_area_dmabuf(ifq, area);
 	else
-		nr = io_zcrx_map_area_umem(ifq, area);
+		ret = io_zcrx_map_area_umem(ifq, area);
 
-	if (nr != area->nia.num_niovs) {
-		__io_zcrx_unmap_area(ifq, area, nr);
-		return -EINVAL;
-	}
-
-	area->is_mapped = true;
-	return 0;
+	if (ret == 0)
+		area->is_mapped = true;
+	return ret;
 }
 
 static void io_zcrx_sync_for_device(const struct page_pool *pool,
-- 
2.49.0