From: Dave Watson <davejwatson@fb.com>
Date: Thu, 22 Mar 2018 10:09:53 -0700
Subject: tls: Generalize zerocopy_from_iter
Patch-mainline: v4.17-rc1
Git-commit: 69ca9293e8dd9323c6cde579e1855d6ce9489a46
References: bsc#1103990 FATE#326006

Refactor zerocopy_from_iter to take arguments for pages and size,
such that it can be used for both tx and rx. RX will also support
zerocopy direct to output iter, as long as the full message can
be copied at once (a large enough userspace buffer was provided).

Signed-off-by: Dave Watson <davejwatson@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/tls/tls_sw.c |   31 +++++++++++++++++++------------
 1 file changed, 19 insertions(+), 12 deletions(-)

--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -226,23 +226,24 @@ static int tls_sw_push_pending_record(st
 }
 
 static int zerocopy_from_iter(struct sock *sk, struct iov_iter *from,
-			      int length)
+			      int length, int *pages_used,
+			      unsigned int *size_used,
+			      struct scatterlist *to, int to_max_pages,
+			      bool charge)
 {
-	struct tls_context *tls_ctx = tls_get_ctx(sk);
-	struct tls_sw_context *ctx = tls_sw_ctx(tls_ctx);
 	struct page *pages[MAX_SKB_FRAGS];
 
 	size_t offset;
 	ssize_t copied, use;
 	int i = 0;
-	unsigned int size = ctx->sg_plaintext_size;
-	int num_elem = ctx->sg_plaintext_num_elem;
+	unsigned int size = *size_used;
+	int num_elem = *pages_used;
 	int rc = 0;
 	int maxpages;
 
 	while (length > 0) {
 		i = 0;
-		maxpages = ARRAY_SIZE(ctx->sg_plaintext_data) - num_elem;
+		maxpages = to_max_pages - num_elem;
 		if (maxpages == 0) {
 			rc = -EFAULT;
 			goto out;
@@ -262,10 +263,11 @@ static int zerocopy_from_iter(struct soc
 		while (copied) {
 			use = min_t(int, copied, PAGE_SIZE - offset);
 
-			sg_set_page(&ctx->sg_plaintext_data[num_elem],
+			sg_set_page(&to[num_elem],
 				    pages[i], use, offset);
-			sg_unmark_end(&ctx->sg_plaintext_data[num_elem]);
-			sk_mem_charge(sk, use);
+			sg_unmark_end(&to[num_elem]);
+			if (charge)
+				sk_mem_charge(sk, use);
 
 			offset = 0;
 			copied -= use;
@@ -276,8 +278,9 @@ static int zerocopy_from_iter(struct soc
 	}
 
 out:
-	ctx->sg_plaintext_size = size;
-	ctx->sg_plaintext_num_elem = num_elem;
+	*size_used = size;
+	*pages_used = num_elem;
+
 	return rc;
 }
 
@@ -374,7 +377,11 @@ alloc_encrypted:
 
 		if (full_record || eor) {
 			ret = zerocopy_from_iter(sk, &msg->msg_iter,
-						 try_to_copy);
+				try_to_copy, &ctx->sg_plaintext_num_elem,
+				&ctx->sg_plaintext_size,
+				ctx->sg_plaintext_data,
+				ARRAY_SIZE(ctx->sg_plaintext_data),
+				true);
 			if (ret)
 				goto fallback_to_reg_send;