cifs: change signing routines to deal with smb_rqst structs

We need a way to represent a call to be sent on the wire that does not
require having all of the page data kmapped. Behold the smb_rqst struct.
This new struct represents an array of kvecs immediately followed by an
array of pages.

Convert the signing routines to use these structs under the hood and
turn the existing functions for this into wrappers around that. For now,
we're just changing these functions to take different args. Later, we'll
teach them how to deal with arrays of pages.

Reviewed-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index c4f43cf..6786b5e 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -1541,6 +1541,8 @@
 	struct cifs_readdata *rdata = mid->callback_data;
 	struct cifs_tcon *tcon = tlink_tcon(rdata->cfile->tlink);
 	struct TCP_Server_Info *server = tcon->ses->server;
+	struct smb_rqst rqst = { .rq_iov = rdata->iov,
+				 .rq_nvec = rdata->nr_iov };
 
 	cFYI(1, "%s: mid=%llu state=%d result=%d bytes=%u", __func__,
 		mid->mid, mid->mid_state, rdata->result, rdata->bytes);
@@ -1552,9 +1554,8 @@
 		    (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED)) {
 			int rc = 0;
 
-			rc = cifs_verify_signature(rdata->iov, rdata->nr_iov,
-						   server,
-						   mid->sequence_number + 1);
+			rc = cifs_verify_signature(&rqst, server,
+						  mid->sequence_number + 1);
 			if (rc)
 				cERROR(1, "SMB signature verification returned "
 				       "error = %d", rc);