ksmbd: reorganize ksmbd_iov_pin_rsp()

If ksmbd_iov_pin_rsp fail, io vertor should be rollback.
This patch moves memory allocations to before setting the io vector
to avoid rollbacks.

Fixes: e2b76ab ("ksmbd: add support for read compound")
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/server/ksmbd_work.c

@@ -95,11 +95,28 @@ bool ksmbd_queue_work(struct ksmbd_work *work)
 	return queue_work(ksmbd_wq, &work->work);
 }
 
-static int ksmbd_realloc_iov_pin(struct ksmbd_work *work, void *ib,
-				 unsigned int ib_len)
+static inline void __ksmbd_iov_pin(struct ksmbd_work *work, void *ib,
+				   unsigned int ib_len)
 {
+	work->iov[++work->iov_idx].iov_base = ib;
+	work->iov[work->iov_idx].iov_len = ib_len;
+	work->iov_cnt++;
+}
+
+static int __ksmbd_iov_pin_rsp(struct ksmbd_work *work, void *ib, int len,
+			       void *aux_buf, unsigned int aux_size)
+{
+	struct aux_read *ar;
+	int need_iov_cnt = 1;
 
-	if (work->iov_alloc_cnt <= work->iov_cnt) {
+	if (aux_size) {
+		need_iov_cnt++;
+		ar = kmalloc(sizeof(struct aux_read), GFP_KERNEL);
+		if (!ar)
+			return -ENOMEM;
+	}
+
+	if (work->iov_alloc_cnt < work->iov_cnt + need_iov_cnt) {
 		struct kvec *new;
 
 		work->iov_alloc_cnt += 4;
@@ -111,16 +128,6 @@ static int ksmbd_realloc_iov_pin(struct ksmbd_work *work, void *ib,
 		work->iov = new;
 	}
 
-	work->iov[++work->iov_idx].iov_base = ib;
-	work->iov[work->iov_idx].iov_len = ib_len;
-	work->iov_cnt++;
-
-	return 0;
-}
-
-static int __ksmbd_iov_pin_rsp(struct ksmbd_work *work, void *ib, int len,
-			       void *aux_buf, unsigned int aux_size)
-{
 	/* Plus rfc_length size on first iov */
 	if (!work->iov_idx) {
 		work->iov[work->iov_idx].iov_base = work->response_buf;
@@ -129,19 +136,13 @@ static int __ksmbd_iov_pin_rsp(struct ksmbd_work *work, void *ib, int len,
 		work->iov_cnt++;
 	}
 
-	ksmbd_realloc_iov_pin(work, ib, len);
+	__ksmbd_iov_pin(work, ib, len);
 	inc_rfc1001_len(work->iov[0].iov_base, len);
 
 	if (aux_size) {
-		struct aux_read *ar;
-
-		ksmbd_realloc_iov_pin(work, aux_buf, aux_size);
+		__ksmbd_iov_pin(work, aux_buf, aux_size);
 		inc_rfc1001_len(work->iov[0].iov_base, aux_size);
 
-		ar = kmalloc(sizeof(struct aux_read), GFP_KERNEL);
-		if (!ar)
-			return -ENOMEM;
-
 		ar->buf = aux_buf;
 		list_add(&ar->entry, &work->aux_read_list);
 	}