[PATCH] knfsd: nfsd: mark rqstp to prevent use of sendfile in privacy case

Add a rq_sendfile_ok flag to svc_rqst which will be cleared in the privacy
case so that the wrapping code will get copies of the read data instead of
real page cache pages.  This makes life simpler when we encrypt the response.
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

fs/nfsd/vfs.c

@@ -837,7 +837,7 @@ nfsd_vfs_read(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
 	if (ra && ra->p_set)
 		file->f_ra = ra->p_ra;
 
-	if (file->f_op->sendfile) {
+	if (file->f_op->sendfile && rqstp->rq_sendfile_ok) {
 		svc_pushback_unused_pages(rqstp);
 		err = file->f_op->sendfile(file, &offset, *count,
 						 nfsd_read_actor, rqstp);

include/linux/sunrpc/svc.h

@@ -159,7 +159,9 @@ struct svc_rqst {
 						 * determine what device number
 						 * to report (real or virtual)
 						 */
-
+	int			rq_sendfile_ok; /* turned off in gss privacy
+						 * to prevent encrypting page
+						 * cache pages */
 	wait_queue_head_t	rq_wait;	/* synchronization */
 };
 

net/sunrpc/svc.c

@@ -281,6 +281,8 @@ svc_process(struct svc_serv *serv, struct svc_rqst *rqstp)
 	rqstp->rq_res.page_len = 0;
 	rqstp->rq_res.buflen = PAGE_SIZE;
 	rqstp->rq_res.tail[0].iov_len = 0;
+	/* Will be turned off only in gss privacy case: */
+	rqstp->rq_sendfile_ok = 1;
 	/* tcp needs a space for the record length... */
 	if (rqstp->rq_prot == IPPROTO_TCP)
 		svc_putu32(resv, 0);