smb: client: reduce stack usage in smb2_query_reparse_point()

Clang warns about exceeded stack frame size

  fs/smb/client/smb2ops.c:2973:12: warning: stack frame size (1336)
  exceeds limit (1024) in 'smb2_query_reparse_point'
  [-Wframe-larger-than]

Fix this by allocating a structure that will hold most of the large
variables.
Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/client/smb2ops.c

@@ -2965,6 +2965,7 @@ static int smb2_query_reparse_point(const unsigned int xid,
 				    u32 *tag, struct kvec *rsp,
 				    int *rsp_buftype)
 {
+	struct smb2_compound_vars *vars;
 	int rc;
 	__le16 *utf16_path = NULL;
 	__u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
@@ -2972,12 +2973,9 @@ static int smb2_query_reparse_point(const unsigned int xid,
 	struct cifs_fid fid;
 	struct TCP_Server_Info *server = cifs_pick_channel(tcon->ses);
 	int flags = CIFS_CP_CREATE_CLOSE_OP;
-	struct smb_rqst rqst[3];
+	struct smb_rqst *rqst;
 	int resp_buftype[3];
-	struct kvec rsp_iov[3];
-	struct kvec open_iov[SMB2_CREATE_IOV_SIZE];
-	struct kvec io_iov[SMB2_IOCTL_IOV_SIZE];
-	struct kvec close_iov[1];
+	struct kvec *rsp_iov;
 	struct smb2_ioctl_rsp *ioctl_rsp;
 	struct reparse_data_buffer *reparse_buf;
 	u32 plen;
@@ -2987,20 +2985,24 @@ static int smb2_query_reparse_point(const unsigned int xid,
 	if (smb3_encryption_required(tcon))
 		flags |= CIFS_TRANSFORM_REQ;
 
-	memset(rqst, 0, sizeof(rqst));
-	resp_buftype[0] = resp_buftype[1] = resp_buftype[2] = CIFS_NO_BUFFER;
-	memset(rsp_iov, 0, sizeof(rsp_iov));
-
 	utf16_path = cifs_convert_path_to_utf16(full_path, cifs_sb);
 	if (!utf16_path)
 		return -ENOMEM;
 
+	resp_buftype[0] = resp_buftype[1] = resp_buftype[2] = CIFS_NO_BUFFER;
+	vars = kzalloc(sizeof(*vars), GFP_KERNEL);
+	if (!vars) {
+		rc = -ENOMEM;
+		goto out_free_path;
+	}
+	rqst = vars->rqst;
+	rsp_iov = vars->rsp_iov;
+
 	/*
 	 * setup smb2open - TODO add optimization to call cifs_get_readable_path
 	 * to see if there is a handle already open that we can use
 	 */
-	memset(&open_iov, 0, sizeof(open_iov));
-	rqst[0].rq_iov = open_iov;
+	rqst[0].rq_iov = vars->open_iov;
 	rqst[0].rq_nvec = SMB2_CREATE_IOV_SIZE;
 
 	oparms = (struct cifs_open_parms) {
@@ -3020,8 +3022,7 @@ static int smb2_query_reparse_point(const unsigned int xid,
 
 
 	/* IOCTL */
-	memset(&io_iov, 0, sizeof(io_iov));
-	rqst[1].rq_iov = io_iov;
+	rqst[1].rq_iov = vars->io_iov;
 	rqst[1].rq_nvec = SMB2_IOCTL_IOV_SIZE;
 
 	rc = SMB2_ioctl_init(tcon, server,
@@ -3036,10 +3037,8 @@ static int smb2_query_reparse_point(const unsigned int xid,
 	smb2_set_next_command(tcon, &rqst[1]);
 	smb2_set_related(&rqst[1]);
 
-
 	/* Close */
-	memset(&close_iov, 0, sizeof(close_iov));
-	rqst[2].rq_iov = close_iov;
+	rqst[2].rq_iov = &vars->close_iov;
 	rqst[2].rq_nvec = 1;
 
 	rc = SMB2_close_init(tcon, server,
@@ -3080,13 +3079,15 @@ static int smb2_query_reparse_point(const unsigned int xid,
 	}
 
  query_rp_exit:
-	kfree(utf16_path);
 	SMB2_open_free(&rqst[0]);
 	SMB2_ioctl_free(&rqst[1]);
 	SMB2_close_free(&rqst[2]);
 	free_rsp_buf(resp_buftype[0], rsp_iov[0].iov_base);
 	free_rsp_buf(resp_buftype[1], rsp_iov[1].iov_base);
 	free_rsp_buf(resp_buftype[2], rsp_iov[2].iov_base);
+	kfree(vars);
+out_free_path:
+	kfree(utf16_path);
 	return rc;
 }