io_uring/zcrx: fully clean area on error in io_import_umem()

When accounting fails, io_import_umem() sets the page array, etc. and
returns an error expecting that the error handling code will take care
of the rest. To make the next patch simpler, only return a fully
initialised areas from the function.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://patch.msgid.link/3a602b7fb347dbd4da6797ac49b52ea5dedb856d.1774261953.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: isilence

io_uring/zcrx.c

@@ -207,22 +207,26 @@ static int io_import_umem(struct io_zcrx_ifq *ifq,
 	ret = sg_alloc_table_from_pages(&mem->page_sg_table, pages, nr_pages,
 					0, (unsigned long)nr_pages << PAGE_SHIFT,
 					GFP_KERNEL_ACCOUNT);
-	if (ret) {
-		unpin_user_pages(pages, nr_pages);
-		kvfree(pages);
-		return ret;
-	}
+	if (ret)
+		goto out_err;
 
 	mem->account_pages = io_count_account_pages(pages, nr_pages);
 	ret = io_account_mem(ifq->user, ifq->mm_account, mem->account_pages);
-	if (ret < 0)
+	if (ret < 0) {
 		mem->account_pages = 0;
+		goto out_err;
+	}
 
 	mem->sgt = &mem->page_sg_table;
 	mem->pages = pages;
 	mem->nr_folios = nr_pages;
 	mem->size = area_reg->len;
 	return ret;
+out_err:
+	sg_free_table(&mem->page_sg_table);
+	unpin_user_pages(pages, nr_pages);
+	kvfree(pages);
+	return ret;
 }
 
 static void io_release_area_mem(struct io_zcrx_mem *mem)